Product User Manual for “Cloud Products” (CMa-PGE01
Contents
1. Non processed containing no data or corrupted data or no cloud water cloud ice cloud OS NO undefined due to known separability problems 3 2 IMPLEMENTATION OF CLOUD TYPE CT CT is extracted by PGEO2 of the SAFNWC MSG software package Detailed information on how to run this software package is available in the software user manual AD 3 The software architecture of PGEO2 has been strongly modified in version v2010 to make the life easier for the user It is now very similar to the other PGEs When a new region is defined the user has now to manually prepare the CT model configuration files for this new region using a default CT model configuration file provided in the SAFNWC MSG software package There is an option for the user to monitor the so called CT preparation step before SEVIRI images are available to speed up the process By default this preparation step is performed during the CT execution step The CT execution step which includes the CT preparation step in case it has not been launched before is automatically launched by the Task Manager if real time environment is selected 3 2 1 Manual preparation of Cloud Type CT model configuration file for each region When a new region is defined and added in system and run configuration files the user must manually prepares the CT model configuration files by adapting the default CT model configuration file available in the SAFNWC software package Thre2. palette included in CT HDF files oi Figure 3 Ex mp g f SEVIRI CT cloud type using the colour 20 01 2009 SH 12h00 UTC undefined ice woter noproc Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MEL SCI PUM 01 m o j METEO FRANCE Toujours un temps d avance PGE02 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 NWC SAF File SAF NWC CDOP2 MEFL SCI PUM 01_ v3 2 3 v2 2 Page 26 34 Figure 4 Example of SEVIRI CT cloud phase using the colour palette included in CT HDF files Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MEL SCI PUM 01 m o j METEO FRANCE Toujours un temps d avance NWC SAF PGE02 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 File SAF NWC CDOP2 MFL SCI PUM 01_v3 2 3 V2 2 Page 27 34 4 CLOUD TOP TEMPERATURE AND HEIGHT CTTH PRODUCT 4 1 DESCRIPTION OF CLOUD TOP TEMPERATURE AND HEIGHT CTTH PRODUCT 4 1 1 Goal of Cloud Top Temperature and Height CTTH product The cloud top temperature and height CTTH developed within the SAF NWC context aims to support nowcasting applications This product contributes to the analysis and early warning of thunderstorm development Other applications include the cloud top height assignment for aviation forecast activities The product may also serve as input to mesoscale models or to other SAF NWC product generation element
3. PRODUCT 3 1 DESCRIPTION OF CLOUD TYPE CT PRODUCT 3 1 1 Goal of Cloud Type CT product The cloud type CT developed within the SAF NWC context mainly aims to support nowcasting applications The main objective of this product is to provide a detailed cloud analysis It may be used as input to an objective meso scale analysis which in turn may feed a simple nowcasting scheme as an intermediate product input to other products or as a final image product for display at a forecaster s desk The CT product is essential for the generation of the cloud top temperature and height product and for the identification of precipitation clouds Finally it is also essential for the computation of radiative fluxes over sea or land which are SAF Ocean amp Sea Ice products The CT product therefore contains information on the major cloud classes fractional clouds semitransparent clouds high medium and low clouds including fog for all the pixels identified as cloudy in a scene A second priority is the distinction between convective and stratiform clouds amplementation not planned before 2012 and the identification of clouds for which the top mainly consists of water droplets 3 1 2 Outline of Cloud Type CT algorithm The CT algorithm is a threshold algorithm applied at the pixel scale based on the use of CMa and spectral amp textural features computed from the multispectral satellite images and compared with a set of thresholds
4. 4 1 Summary of Cloud Type CT validation results Table 6 summarises the validation results of the current version More details can be obtained from the validation report for cloud products AD 5 PGE02 Validated accuracy PGE02 cloud type validated over European areas and adjacent seas using interactive targets User accuracy for low opaque high opaque semi transparent high clouds between 78 and 96 depending on illumination the user accuracy is defined as the probability of a pixel being classified into a category to really belong to this category PGEO02 cloud phase flag validated over European areas using ground based radar lidar Hit Rate HR 0 83 Kuiper Skill Score KSS 0 62 Table 6 Summary of validation results of the current PGEO2 version AD 5 3 4 2 Typical known problems and recommendation for use The following problems may be encountered for wrong cloud detection please refer to paragraph 2 4 e Very thin cirrus are often classified as fractional clouds e Very low clouds may be classified as medium clouds in case strong thermal inversion e Low clouds surmounted by thin cirrus may be classified as medium clouds 3 5 EXAMPLE OF CLOUD TYPE CT VISUALISATION It is important to note that the CT product is not just an image but numerical data At first hand the CT is rather thought to be used digitally together with the appended flags quality cloud Product User Manual for Cloud Pr
5. Date 4 December 2014 NWC SAF File SAF NWC CDOP2 MFL SCI PUM 01_ v3 2 3 v2 2 Page 10 34 A second process allowing the identification of dust clouds and volcanic ash clouds is applied to all pixels even already classified as cloud free or contaminated by clouds The result is stored in the dust cloud and volcanic ash cloud flags Details on the tests are given in the algorithm theoretical basis document for cloud products AD 4 Table 3 Test sequence over land Sunglint Twilight Nighttime T10 8um T12 0um T10 8um T12 0um T12 0um T3 9um Re Table 4 Test sequence over sea T3 9um T8 7um T10 8um and T12 0um stand for brightness temperatures at 3 9 8 7 10 8 and 12 0 micrometer RO 6uUm RO 8um and R1 6um stand for VIS NIR bi directional top of atmosphere reflectances at 0 6 0 8 and 1 6 micrometer normalised for solar illumination SST is the split window used for SST calculation computed from T10 8um and T12 0um measurements Low Clouds in Sunglint is a specific module for low clouds identification in sunglint areas Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MEL SCI PUM 01 m A j METEO FRANCE Toujours un temps d avance NWC SAF PGE02 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 File SAF NWC CDOP2 MFL SCI PUM 01_v3 2 3 v2 2 Page 11 34 2 1 3 Description of Cloud Mask CMa output The description of CMa output in HDF format is detaile
6. coast and occasionally over the South Atlantic at latitude larger than 50 degrees The CMa product may be used to identify cloud free surfaces for oceanic or continental surface parameters retrieval Nevertheless as some clouds remains undetected and to account for artefacts such as shadows or aerosols the user should apply a post processing which could include the spreading of the cloud mask that should allow to detect cloud edges and mask shadows or moist areas near cloud edges the use of the cloud mask quality flag not to compute surface parameters in bad quality cloud free areas the implementation of an additional filtering based on the temporal variation around the current slot Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MFL SCI PUM 01 METEO FRANCE 2 Toujours un temps d avance PGEO2 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 File SAF NWC CDOP2 MEL SCI PUM 01_v3 2 3 NWC SAF W2 2 Page 17 34 2 5 EXAMPLE OF CLOUD MASK CMA VISUALISATION It is important to note that the CMa product is not just images but numerical data At first hand the CMa is rather thought to be used digitally together with the appended flags quality dust detection volcanic ash detection as input to mesoscale analysis models objective Nowcasting schemes but also during the extraction of other SAFNWC products CT for example Colour palettes are included in CMa HDF files allowing an e
7. is missing If T8 7um or R1 6um are missing the cloud phase flag is not computed Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MEL SCI PUM 01 m _ i METEO FRANCE 2 bt Toujours un temps d avance PGEO2 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 NWC SAF File SAF NWC CDOP2 MFL SCI PUM 01_v3 2 3 ee Page 23 34 The SEVIRI channels are input by the user in HRIT format and extracted on the processed region by SAFNWC software package e CMa cloud categories The CMa cloud categories are mandatory They are computed by the CMa software e Sun and satellite angles associated to SEVIRI imagery This information is mandatory It is computed by the CT software itself using the definition of the region and the satellite characteristics e NWP parameters The forecast fields of the following parameters remapped onto satellite images are used as input o surface temperatures o air temperature at 950hPa alternatively 925hPa to check low level inversion 850hPa 700hPa 500hPa and at tropopause level o total water vapour content of the atmosphere o altitude of the NWP model grid alternatively surface geopotential of the NWP model grid Required if NWP fields are used as input These remapped fields are elaborated by the SAFNWC software package from the NWP fields input by the user in GRIB format The NWP fields are not mandatory The CT software replaces missing NWP su
8. process consists in the launch of the command PGE03 by the Task manager The CTHT is then performed using the simulated radiances prepared during the preparation step 4 3 INPUTS AND CONFIGURABLE PARAMETERS FOR CLOUD TOP TEMPERATURE AND HEIGHT CT TH 4 3 1 List of inputs for Cloud Top Temperature and Height CTTH The input data to the CTTH algorithm are described in this section Mandatory inputs are flagged whereas the impact of missing non mandatory data on the processing are indicated e Satellite imagery The following SEVIRI brightness temperatures and radiances are needed at full IR spatial resolution Rad7 3um Rad13 4um Rad10 8um T12 0um At least one of these channels is mandatory Mandatory Mandatory Optional the two others are then optional The CTTH software checks the availability of SEVIRI brightness temperatures and radiances for each pixel Full CTTH product is computed only if all mandatory SEVIRI radiances and brightness temperatures are available If T10 8um brightness temperature is missing no result is Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MEL SCI PUM 01 m J METEO FRANCE 2 bt Toujours un temps d avance PGEO2 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 NWC SAF File SAF NWC CDOP2 MFL SCI PUM 01_v3 2 3 1 Page 32 34 available If T10 8um brightness temperature is available but mandatory channels are missing only the clou
9. the temporal analysis should be done TEMPORAL_USE flag is checked at the execution step PGEO1 applies the temporal analysis if its value is TRUE This flag has been made configurable to allow users being blocked by hardware resources to still run the PGEOI by assigning it to FALSE in the configuration file e HRV_NEED default value TRUE a flag indicating whether the HRV analysis should be done HRV_NEED flag is checked at the execution step PGEO1 applies the HRV analysis if its value is TRUE This flag has been made configurable to allow users being blocked by hardware resources to still run the PGEOI by assigning it to FALSE in the configuration file When required and when the 2 HRV images required by the algorihm are not available the PGEO1 is processed without this enhancement For regions being partially covered by HRV measurements only the SEVIRI pixels having HRV benefit from enhancement Moreover as the content of NWP_CONF_FILE is dependent on the local installation the user must make the NWP PARAMXX consistent with the local NWP CONF FILE when the standard one is not used for details see section dedicated to NWP data files in SAF NWC CDOP INM SW SUM 2 AD 3 2 2 2 The Cloud Mask CMa preparation step optional By default this CMa preparation step is performed during the CMa execution step see 2 2 3 But to speed up the CMa processing this preparation step can performed by the command mfcms_next_pgeO1 which can b
10. D 4 4 1 3 Description of Cloud Top Temperature and Height CTTH output The description of CTTH output in HDF format is detailed in the output products format definition document AD 2 This section summarizes the CTTH output fields a colour palette is also included in the HDF output CTTH file for each field see 4 5 e 6 bits for the cloud top pressure Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MEL SCI PUM 01 j METEO FRANCE 2 bt Toujours un temps d avance PGEO2 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 NWC SAF File SAF NWC CDOP2 MFL SCI PUM 01_v3 2 3 a v2 2 Page 29 34 Linear conversion from count to pressure Cloud_Pressure gain Countgpits intercept corresponds to pressures ranging between Cloud_Pressure and Cloud_Pressure 25hPa Gain 25 hPa count 250hPa e 7 bits for the cloud top height Linear conversion from count to height Cloud_Height gain Count intercept corresponds to heights ranging between Cloud_Height and Cloud_Height 200m Gain 200 m count 2000 m e 8 bits for the cloud top temperature Linear conversion from count to temperature Cloud_Temperature gain Countspits intercept corresponds to temperatures ranging between Cloud_Temperature and Cloud_Temperature 1K Gain Intercept Special count K count 150 K e 5 bits for effective cloudiness Linear conversion from count to effective cloudiness Cloudi
11. E01 dust flag POD validated over sea and Africa for solar elevation larger than 20 degrees using interactive targets 55 5 over sea 58 5 over land Table 5 Summary of validation results of the current PGEOI version POD stands for Percentage Of Detection 2 4 2 Typical known problems and recommendation for use The following problems may be encountered Low clouds may be not detected in case low solar elevation over both sea and land It may happen that large areas of low clouds are not detected in night time conditions over land This can be the case in warm sectors but also in areas viewed with high satellite zenith angles or if the low clouds are surmounted by very thin cirrus Snowy grounds are not detected at night time and therefore may confused either with low clouds or cloud free surface This drawback has been reduced with v3 1 in release2011 False detection of volcanic ash clouds happens especially in daytime conditions over low clouds and desertic surfaces but also in night time over cold clouds The volcanic ash clouds detection is not performed in case low solar elevation Over land dust cloud detection is performed only at daytime Over land dust clouds are not well detected when the sun is low or if they are too thin Over sea some dust areas may not be detected especially the thinnest parts Moreover some wrong detection may be observed in oceanic regions especially at nighttime near Namibia
12. FINITIONS ACRONYMS AND ABBREVIATIONS CMa Cloud Mask also PGEO1 CMS Centre de Meteorologie Spatiales M t o France satellite reception centre in Lannion CTTH Cloud Top Temperature and Height CT Cloud Type ECMWE European Centre for Medium range Weather Forecast y Product User Manual for Cloud pa Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MEL SCI PUM 01 o al eb te bebe PGE v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 NWC SAF File SAF NWC CDOP2 MFL SCI PUM 01_v3 2 3 V2 2 Page 8 34 EUMETSAT European Organisation for the Exploitation of Meteorological Satellites FOV Field Of View HDF Hierarchical data Format HRIT High Rate Information Transmission HRV High Resolution Visible ICD Interface Control Document MSG Meteosat Second Generation NWP Numerical Weather Prediction PGE Product Generation Element PUM Product User Manual RO 6um 0 6 visible reflectance RTMOM Radiative Transfer based on Matrix Operator Method RTTOV Rapid Transmissions for TOVs SAF Satellite Application Facility SAF NWC SAF on support to NoWCasting and VSRF SAF OSI Ocean and Sea Ice SAF SEVIRI Spinning Enhanced Visible amp Infrared Imager SW Software T11ym 11 micrometer infrared brightness temperature 1 6 REFERENCES 1 6 1 Applicable Documents Reference Tiie Code Date AD 1 Interface Control Document for the External SAF NWCAOP INM SW ICD 1 2 0 and Internal Interfaces of the SAFNWC MSG AD 2 SAFNWC MSG Output Produ
13. L METEO FR FRANCE NWC SAF ee ne EME TA Ale Ha E LOTS Ape pe Fa Iles sappari to Win SP oik he sib Product User Manual for Cloud Products CMa PGE01 v3 2 CT PGEO02 v2 2 amp CT TH PGE03 v2 2 SAF NWC CDOP2 MFL SCI PUM 01 Issue 3 Rev 2 3 4 December 2014 Applicable to SAFNWC MSG version 2013 Prepared by M t o France Centre de M t orologie Spatiale METEO FRANCE Toujours un temps d avance NWC SAF Function Prepared by Reviewed by Authorised by Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MEL SCI PUM 01 PGE02 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 File SAF NWC CDOP2 MEL SCI PUM 01_v3 2 3 v2 2 Page 2 34 REPORT SIGNATURE TABLE Marcel Derrien 4 December 2014 MF DP CMS Herv Le Gl au 4December 2014 MF DP CMS Manager Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MEL SCI PUM 01 Zo METEO FRANCE p ee eta PGE02 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 NWC SAF File SAF NWC CDOP2 MFL SCI PUM 01_v3 2 3 v2 2 Page 3 34 DOCUMENT CHANGE RECORD Version CHANGE S 1 4 7 November 2007 Initial version content derived from User manual for PGE01 02 03 v1 3 Cloud Products of the SAFNWC MSG scientific part 2 0 Content adapted to version v2 0 3 0 Content adapted to version v3 0 3 1 Content adapted to version v3 1 3 2 Content adapte
14. OR CLOUD TOP TEMPERATURE AND HEIGHT RE A A E E A A 31 4 3 1 List of inputs for Cloud Top Temperature and Height CTTH c ccccccsseecccecceeeeeees 31 4 3 2 Configurable parameters for Cloud Top Temperature and Height CTTH 335 4 4 CLOUD TOP TEMPERATURE AND HEIGHT CTTH VALIDATION cccccccceeeceessseeesseeeeees 33 4 4 1 Summary of Cloud Top Temperature and Height CTTH validation results 33 4 4 2 Typical known problems and recommendation for use 33 4 5 EXAMPLE OF CLOUD TOP TEMPERATURE AND HEIGHT CTTH VISUALISATION 000068 34 gt Product User Manual for Cloud J Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MFL SCI PUM 01 METEO FRANCE Toujours un temps d avance NWC SAF PGE02 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 File SAF NWC CDOP2 MFL SCI PUM 01_v3 2 3 v2 2 Page 6 34 List of Tables and Figures Tbe ECO OAI DORE EEE GEE EIE ieie 8 Tibe Z LR ORe i ned DOUME E e a ERRER NR NRN NRN NRR NENEN REREN 8 Table 3 Test seguence oyver land a ree 10 Table RESTO a ne 10 Table 5 Summary of validation results of the current PGEOI version POD stands for Percentage CD cc nla ny eeemener omer EAA ree eee een reenter ne eer ee 16 Table 6 Summary of validation results of the current PGEO2 version AD 5 24 Table 7 Summary of validation results of the current PGEO03 version std stands for standard CIE TAC 1 S 1 a M A ER 33 Figure 1 Example of SEVIRI
15. T in an interactive visualisation system where individual pixel values top temperature height and pressure cloudiness may be displayed while moving the mouse over the image ae J p az to a ri z S 5 x z dj w ut D ml 1 2 5 i Am w mp s F 2 N Figure 5 Example of SEVIRI CTTH cloud top pressure
16. The set of thresholds to be applied depends mainly on the illumination conditions whereas the values of the thresholds themselves may depend on the illumination the viewing geometry the geographical location and NWP data describing the water vapour content and a coarse vertical structure of the atmosphere Opaque clouds are first separated from semi transparent and from fractional sub pixel clouds using brightness temperature differences T10 8um T12 0um T8 7um T10 8um or T3 9um T10 8um and RO 6uUm at daytime Opaque clouds are then separated in very low low mid level high or very high clouds using their T10 8mm brightness temperatures which are compared to NWP forecast air temperatures at various pressure levels Details are available in the algorithm theoretical basis document for cloud products AD 4 A separate processing is applied to compute the cloud phase flag based on the use of CT cloud type T8 7um T10 8um all illumination RO 6um and R1 6um at daytime 3 1 3 Description of Cloud Type CT output The description of CT output in HDF format is detailed in the output products format definition document AD 2 This section summarizes the CT output fields a colour palette is also included in the HDF CT output file for each field see 3 5 e The main product output consists in the following twenty one categories coded on 5 bits 0 non processed containing no data or corrupted data 1 cloud free land no contaminati
17. asy visualisation of CMa main categories dust and volcanic ash clouds flags No example of CMa main categories s visualisation are given as it is thought that the user will be more interested to visualize the CT product which can be seen as a refinement Example of visualisation of the dust cloud and the volcanic ash cloud flags superimposed on infrared images are given in Figure and Figure 2 using SEVIRI and MODIS imagery dust cloud 50C 40C 30C 20C 10C oc 10C 20C 30C Figure 1 Example of SEVIRI dust cloud flag superimposed on a 10 8um infrared image dust cloud over North Africa on 14 July 2003 at 13h00 UTC Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MFL SCI PUM 01 METEO FRANCE Toujours un temps d avance PGE02 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 File SAF NWC CDOP2 MFL SCI PUM 01_v3 2 3 NWC SAF V2 2 Page 18 34 volcanic ash 40C 33C 30C ZG 20C 15C 10C SC OC Figure 2 Example of MODIS volcanic ash cloud superimposed on a 10 8um infrared image Etna eruption on 22th July 2001 at 9h55 UTC Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MEL SCI PUM 01 m A j METEO FRANCE Toujours un temps d avance NWC SAF PGE02 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 File SAF NWC CDOP2 MFL SCI PUM 01_v3 2 3 v2 2 Page 19 34 3 CLOUD TYPE CT
18. cts Format SAF NWC IOP INM SW ICD 3 Definition application AD 4 Algorithm Theoretical Basis Document for SAF NWC CDOP MFL SCI ATB 3 2 1 20 09 12 Cloud Products CMa PGEOI v3 2 CT D 01 PGE02 v2 2 amp CTTH PGE03 v2 2 AD 5 Validation Report for Cloud Products CMa SAF NWC CDOP MEL SCT V R 06 1 0 15 02 12 PGEO1 v3 2 CT PGE02 v2 2 amp CTTH PGE03 v2 2 AD 6 Validation report for the PGEO1 02 03 v1 2 SAF NWC IOP MFL SCI V AL 01 1 2 17 01 07 Cloud Products of the SAFNWC MSG Table 1 List of Applicable Documents 1 6 2 Reference Documents Reference Code Date RDI Jo ooo a RD 2 a Table 2 List of Referenced Documents Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MEL SCI PUM 01 m __ i METEO FRANCE 2 bt Toujours un temps d avance PGEO2 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 NWC SAF File SAF NWC CDOP2 MFL SCI PUM 01_v3 2 3 ee Page 9 34 2 CLOUD MASK CMA PRODUCT 2 1 DESCRIPTION OF CLOUD MASK CMA PRODUCT 2 1 1 Goal of Cloud Mask CMa product The cloud mask CMa developed within the SAF NWC context aims to support nowcasting applications and additionally the remote sensing of continental and oceanic surfaces The CMa allows identifying cloud free areas where other products total or layer precipitable water land or sea surface temperatures snow ice cover delineation may be computed It also allows identifying clo
19. d in the output products format definition document AD 2 This section summarizes the CMa output fields a colour palette is also included in the HDF CMa output file for each field see 2 5 e The main product output consists in the following six categories coded on 3 bits 0 Non processed containing no data or corrupted data cloud free no contamination by snow ice covered surface no contamination by clouds but contamination by thin dust volcanic clouds not checked n 2 Cloud contaminated partly cloudy or semitransparent May also include dust clouds or volcanic plumes 3 Cloud filled opaque clouds completely filling the FOV May also include thick dust clouds or volcanic plumes Snow Ice contaminated 5 Undefined has been processed but not classified due to known separability problems e 16 bits to describe which test was successful For each cloudy pixel the bits corresponding to the successful tests are activated More than one bit may be activated if tests were not really successful measurement too close to thresholds T10 8um or SST RO 6um land or RO 8um sea Sunglint test using 3 9um Local Spatial Texture T10 8um T12 0um T10 8um T3 9um or T12 0um T3 9um T3 9um T10 8um Spatial smoothing reclassify isolated cloud free pixels T8 7um T3 9um R1 6um sea T8 7um T10 8um or T10 8um T8 7um Snow using R1 6um or T3 9um HRV based test Stationary cloud in twilight Spatial expansion of statio
20. d to version v3 2 3 2 1 15 July 2013 Content adapted to NWP management change 32 2 15 November 2013 See RID ORY OBJ1_Ops201301_Nicola_011 3 2 3 4 December 2014 See RID OR2014 OBJ1_MBL_Kotro_006 Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MFL SCI PUM 01 an METEO FRANCE i i sald at ANCE Go v2 2 amp CTTH PGE03 __ Issue 3 2 3 Date 4 December 2014 NWC SAF File SAF NWC CDOP2 MFL SCI PUM 01_ v3 2 3 v2 2 Page 4 34 Table of contents L JIN RODUC LION sers re aa auuaaumu nu moaaouaman 4 1 1 SCOOP OR TEDO Oi Veer rT N AR E E S 7 12 SCOPROF OTER DOCS siei esisin rosis nee ieis Eei Isisen or nee 7 1 3 OR SO DEN A TT O te ren tense eter ener tee tn rt etr Ts 7 1 4 IMPROVEMENT PROM PREVIOUS VERSION sccecectescssstecetensticctncssneerecececesecccccxccacinscsesssecereceteredeted 7 1 5 DEFINITIONS ACRONYMS AND ABBREVIATIONS ea 7 B me 52 2 252 2 5h ee a ee 8 1 6 1 E D CR ION IO IO O I I O E E re S 1 6 2 Reerence DOCS sorrinte rainn aaa R AAAA S 2 CLOUD MASK CMA PRODUCT 2n ii sesrsnersiessiessiessiessiessiessiessieisienes 9 2 1 DESCRIPTION OF CLOUD MASK CMA PRODUCT ccccceecccescccscccescsceecseeecseeecseecsuesseeeeeueess 9 11 COQ Cloud Mask CMa DUO en 9 nn Outline of Cloud Mask CMa algorithm ss 9 2 1 3 Descripiion of Cloud Mask CMa ON sssrinin 11 22 IMPLEMENTATION OF CLOUD MASK CMA cccccccccceccceeccceecccenccceuceeeucseeueceeueseeneseneseeneee
21. d top temperature is computed using the method based on climatological atmospheric absorption correction The SEVIRI channels are input by the user in HRIT format and extracted on the processed region by SAFNWC software package e CMa and CT cloud categories The CMa and CT cloud categories are mandatory They are computed by the CMa and CT software e Satellite angles associated to SEVIRI imagery This information is mandatory It is computed by the CTTH software itself using the definition of the region and the satellite characteristics e NWP parameters The forecast fields of the following parameters remapped onto satellite images are used as input o surface temperature surface pressure air temperature and relative humidity alternatively dew point temperature at 2m air temperature and relative humidity on vertical pressure levels altitude of the NWP model grid alternatively surface geopotential on the NWP model grid Required if NWP fields are used as input O O O O Vertical pressure levels on which air temperature and humidity are defined by the user All the surface and near surface NWP informations and at least NWP informations every 210hPa on the vertical are mandatory to get full CTTH product Otherwise only the cloud top temperature is retrieved using the method based on climatological atmospheric absorption correction Furthermore it is recommended to provide NWP information on levels at least up to 100hPa to
22. data or corrupted data 1 dust 2 non dust 3 undefined due to known separability problems e 2 bits for volcanic plume detection 0 Non processed containing no data or corrupted data l volcanic plume 2 non volcanic plume 3 undefined due to known separability problems 2 2 IMPLEMENTATION OF CLOUD MASK CMA CMa is extracted by PGEOI of the SAFNWC MSG software package Detailed information on how to run this software package is available in the software user manual AD 3 The software architecture of PGEOI has been strongly modified in version v2010 to make the life easier for the user It is now very similar to the other PGEs When a new region is defined the user has now to manually prepare the CMa model configuration files for this new region using a default CMa model configuration file provided in the SAFNWC MSG software package There is an option for the user to monitor the so called CMa preparation step before SEVIRI images are available to speed up the process By default this preparation step is performed during the CMa execution step The CMa execution step which includes the CMa preparation step in case it has not been launched before is automatically launched by the Task Manager if real time environment is selected gt Product User Manual for Cloud A Products CMa PGE01 v3 2 CT Code SAF NWC CDOP2 MFL SCI PUM 01 METEO FRANCE Toujours un temps d avance NWC SAF PGE02 v2 2 amp CTTH PGE03 Is
23. dust cloud flag superimposed on a 10 8um infrared image dust cloud over North Africa on 14 July 2003 at 13h00 UTC me 17 Figure 2 Example of MODIS volcanic ash cloud superimposed on a 10 8um infrared image Etna eruption on 22th July 2001 at 9h55 UTC due 18 Figure 3 Example of SEVIRI CT cloud type using the colour palette included in CT HDF files 25 Figure 4 Example of SEVIRI CT cloud phase using the colour palette included in CT HDF files Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MEL SCI PUM 01 a o j METEO FRANCE Toujours un temps d avance NWC SAF PGE02 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 File SAF NWC CDOP2 MEL SCI PUM 01_v3 2 3 v2 2 Page 7134 1 INTRODUCTION The Eumetsat Satellite Application Facilities SAF are dedicated centres of excellence for processing satellite data and form an integral part of the distributed EUMETSAT Application Ground Segment http www eumetsat int This documentation is provided by the SAF on Support to Nowcasting and Very Short Range Forecasting SAFNWC The main objective of SAFNWC is to provide further develop and maintain software packages to be used for Nowcasting applications of operational meteorological satellite data by National Meteorological Services More information can be found at the SAFNWC webpage http nwcsaf org This document is applicable to the SAFNWC processing package for Meteosat Second G
24. e launched in advance of satellite data reception according to a pre defined time scheduling to be manually set by the user This preparation step includes the computation on the region at the segment spatial resolution of e the solar amp satellite angles e the monthly climatological amp atlas maps e the thresholds for the CMa algorithm 2 2 3 The Cloud Mask CMa execution step The CMa execution step which by default includes the CMa preparation step see 2 2 2 is the real time processing of the SEVIRI images itself over the region This process consists in the launch of the command PGEOI by the Task manager The cloud masking is then performed using the thresholds prepared during the preparation step Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MEL SCI PUM 01 nf o j METEO FRANCE Toujours un temps d avance NWC SAF PGE02 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 File SAF NWC CDOP2 MEL SCI PUM 01_v3 2 3 W2 2 Page 14 34 2 3 INPUTS AND CONFIGURABLE PARAMETERS FOR CLOUD MASK CMA 2 3 1 List of inputs for Cloud Mask CMa The input data to the CMa algorithm are described in this section Mandatory inputs are flagged whereas the impact of missing non mandatory data on the processing are indicated e Satellite imagery The following SEVIRI bi directional reflectances or brightness temperatures of the scene to be analysed are needed at full IR spatial resolu
25. e parameters are configurable in the default CT model configuration file e CT_SZSEG default value 4 the size of the segment This default value may be manually changed but must be the same as for CMa CMA_SZSEG The new segment size must also updated in the lines NWP_PARAMxx Segments are square boxes in the satellite projection whose size is expressed as the number of IR pixels of one edge of the square box The size of the processed regions must be a multiple of the segment size All the solar and satellite angles the NWP model forecast values the atlas values and the thresholds will be derived over all the processed regions at the horizontal resolution of the segment Note also that the land sea atlas will be available at the full IR resolution allowing the identification of the surface type land or sea of all IR pixels whatever the segment size The quality is not very much dependent on the segment size if lower than 4 A segment size of 4 allows the preparation step to be 9 times faster than if a segment size of 1 was used e PHASE COMPUTATION default value TRUE a flag defining if the cloud phase flag should be computed PHASE_COMPUTATION flag is checked at the execution step It should be assigned to TRUE or FALSE PGE02 computes the cloud phase flag if its value is TRUE This flag has been made configurable to allow users being blocked by hardware resources to still run the PGE02 by assigning it to FALSE in the configurati
26. egion by SAFNWC software package e Sun and satellite angles associated to SEVIRI imager This information is mandatory It is computed by the CMa software itself using the definition of the region and the satellite characteristics e NWP parameters The forecast fields of the following parameters remapped onto satellite images are used as input o surface temperatures required to get good quality results over land but not mandatory o air temperature at 950hPa alternatively 925hPa Used to check low level inversion total water vapour content of the atmosphere o altitude of the NWP model grid alternatively surface geopotential on the NWP model grid Required if NWP fields are used as input O Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MEL SCI PUM 01 m _ METEO FRANCE 2 bt Toujours un temps d avance PGEO2 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 NWC SAF File SAF NWC CDOP2 MFL SCI PUM 01_v3 2 3 wa Page 15 34 These remapped fields are elaborated by the SAFNWC software package from the NWP fields input by the user in GRIB format The NWP fields are not mandatory the CMa software replaces missing NWP surface temperatures or total water vapour content of the atmosphere by climatological values extracted from ancillary dataset but the quality of CMa is then lower CMa has been designed so that the dependency of NWP is limited to the amount that i
27. eneration satellites SAFNWC MSG 1 1 SCOPE OF THE DOCUMENT This document is the Product User Manual for MSG cloud products PGEOI CMa PGEO2 CT and PGEO3 CTTH This document contains practical information on the characteristics of the above mentioned products on their applicability and limitations 1 2 SCOPE OF OTHER DOCUMENTS The algorithms used to extract the MSG Cloud Products PGEOI CMa PGEO2 CT and PGEO3 CTTH are detailed in the algorithm theoretical basis document for cloud products AD 4 The validation of the algorithms used to extract the MSG Cloud Products PGEOI CMa PGEO2 CT and PGE03 CTTH is reported in the validation report for cloud products AD 51 Instructions to install configure and execute the SAFNWC MSG software in order to extract the MSG Cloud Products PGEOI CMa PGEO2 CT and PGEO3 CTTH are detailed in the software user manual AD 3 The interface control documents AD 1 for the External and Internal Interfaces of the SAFNWC MSG and AD 2 MSG Output Product Format Definition detail the input and output data format for the SAFNWC MSG software 1 3 SOFTWARE VERSION IDENTIFICATION This document describes the products obtained from the CMa PGEO1 V3 2 CT PGEO02 v2 2 and CTTH PGE03 v2 2 implemented in the release2013 of the SAFNWC MSG software package 1 4 IMPROVEMENT FROM PREVIOUS VERSION CMa CT and CTTH algorithms remain unchanged since previous version v2012 1 5 DE
28. ensure a good height retrieval quality for very high clouds Additionally the quality of the CTTH for low level clouds is dependent on the description by NWP fields of the low level thermal inversion which can be improved by increasing spatial temporal and especially near surface vertical resolution These remapped fields are elaborated by the SAFNWC software package from the NWP fields input by the user in GRIB format e Ancillary data sets The following ancillary data remapped onto satellite images are mandatory o Land sea atlas o Elevation atlas o Monthly minimum SST climatology o Monthly mean 0 6um atmospheric corrected reflectance climatology land These ancillary data are available in the SAFNWC software package on MSG full disk in the default satellite projection at full IR resolution They are extracted on the processed region by the CTTH software itself RTTOV 9 coefficients file mandatory for RTTOV radiative transfer calculation is available in the SAFNWC software package If RTTOV model cannot be launched only the cloud top temperature is computed using the method based on climatological atmospheric absorption correction Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MEL SCI PUM 01 m __ i METEO FRANCE bt Toujours un temps d avance PGEO2 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 NWC SAF File SAF NWC CDOP2 MFL SCI PUM 01_v3 2 3 w Page 33134 O
29. ess is implemented e The H O IRW intercept method based on a window 10 8um and sounding 13 4um 7 3um or 6 2um radiance bi dimensional histogram analysis is first applied The histograms are built in boxes of 32 32 SEVIRI IR pixels centred on each segment of the image whose size is defined by the user the default value being 16 16 SEVIRI IR pixels It therefore allows the retrieval of cloud top pressure at the segment horizontal resolution 1 e by default 16 16 SEVIRI IR pixels This method is successively applied using the 7 3um 6 2um and 13 4um radiances the final retrieved cloud pressure being the minimum cloud top pressures obtained using single sounding channels e If no result can be obtained with the H O IRW intercept method the radiance ratioing method is then applied to the 10 8um and 7 3um radiances to retrieve the cloud top pressure at a pixel basis If no result can be obtained the method is applied to 6 2um and finally to 13 4um radiances e If the radiance ratioing technique leads to cloud top temperatures warmer than the corresponding 10 8um brightness temperatures the method for thick clouds is used instead e For fractional clouds No technique is proposed in the current version for low broken clouds The sounding channels are nearly unaffected by broken low clouds and are therefore useless the infrared channels at 10 8um and 12 0um are contaminated by the surface and cannot therefore be used as for opaque cloud
30. formed by the command mfcms_next_pge02 which can be launched in advance of satellite data reception according to a pre defined time scheduling to be manually set by the user This preparation step includes the computation on the region at the segment spatial resolution of the solar amp satellite angles the monthly climatological amp atlas maps the thresholds for the CT algorithm the simulated RO 6um and R1 6um cloudy reflectances 3 2 3 The Cloud Type CT execution step The CT execution step which by default includes the CT preparation step see 3 2 2 is the real time processing of the SEVIRI images itself over the region This process consists in the launch of the command PGEQ2 by the Task manager The CT is then performed using the thresholds and simulations prepared during the preparation step 3 3 INPUTS AND CONFIGURABLE PARAMETERS FOR CLOUD TYPE CT 3 3 1 List of inputs for Cloud Type CT The input data to the CT algorithm are described in this section Mandatory inputs are flagged whereas the impact of missing non mandatory data on the processing are indicated e Satellite imagery The following SEVIRI bi directional reflectances or brightness temperatures are needed at full IR spatial resolution __Roum Risum r amp 7um TO8um T120pm Optional Optional Mandatory The CT software checks the availability of SEVIRI channels for each pixel no results are available for pixels where at least one mandatory channel
31. ge the size of the segment can be found in the software user manual AD 3 and in section 2 2 1 e TEMPORAL_USE The flag defining if temporal information is to be used to allow a better detection of fast moving clouds and low clouds in twilight conditions is configurable see its definition in 2 2 1 Its default value is TRUE Information on how to change this value can be found in the software user manual AD 3 and in section 2 2 1 e HRVNEED The flag indicating if HRV data have to be used to allow enhanced sub pixel cumulus detection is configurable see its definition in 2 2 1 Its default value is TRUE Information on how to change this value can be found in the software user manual AD 3 and in section 2 2 1 A NWC SAF m Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MEL SCI PUM 01 METEO FRANCE i 2 mia PGEO2v22 amp CTTH PGEO3 1ssue 3 2 3 Date 4 December 2014 File S AF NWC CDOP2 MFL SCI PUM 01_ v3 2 3 v2 2 Page 16 34 2 4 CLOUD MASK CMA VALIDATION 2 4 1 Summary of Cloud Mask CMa validation results Table 5 summarises the validation results of the current version More details can be obtained from the validation report for cloud products AD 5 The impact of missing NWP data has been analyzed in details and reported in AD 6 PGEO01 flags Validated accuracy PGE01 cloud detection validated over European areas using SYNOP POD 96 5 observations PG
32. he segment resolution In case of the presence of a low level thermal inversion in the forecast NWP fields the very low low or medium clouds are assumed to be above the thermal inversion only if their brightness temperatures are colder than the air temperature below the thermal inversion minus an offset whose value depends on the nature of thermal inversion dry air above the inversion level or not e For high thick clouds a method called the radiance ratioing method see the next bullet for further explanation of this method is first applied to remove any remaining semi transparency that could have been undetected by the cloud type scheme In case of failure the method defined for medium opaque clouds is then applied e For high semi transparent clouds The 10 8um infrared brightness temperatures are contaminated by the underlying surfaces and cannot be used as for opaque clouds A correction of semi transparency is applied which requires the use of two infrared channels a window 10 8um and a sounder 13 4um 7 3um or 6 2um channels The Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MEL SCI PUM 01 m _ METEO FRANCE 2 bet Toujours un temps d avance PGEO2 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 NWC SAF File SAF NWC CDOP2 MFL SCI PUM 01_v3 2 3 w Page 28 34 basis is that clouds have a stronger impact in a window channel than in a sounding channel The following proc
33. line simulations of 0 6um and 1 6um reflectances performed for a set of four water clouds and four ice clouds using RTMOM radiative transfer model is available in the SAFNWC software package and is needed by the CT software Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MEL SCI PUM 01 m TR METEO FRANCE Toujours in temps d avance PGEO02 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 NWC SAF File SAF NWC CDOP2 MFL SCI PUM 01_ v3 2 3 v2 2 Page 24 34 3 3 2 Configurable parameters for Cloud Type CT Three configurables parameters are available in the default CT model configuration file e CT_SZSEG The size of the segment is configurable see its definition in 3 2 1 Its default value is 4 Information on how to change the size of the segment can be found in the software user manual AD 3 and in section 3 2 1 e PHASE COMPUTATION The flag defining if the cloud phase flag should be computed is configurable see its definition in 3 2 1 Its default value is TRUE Information on how to change this value can be found in the software user manual AD 3 and in section 3 2 1 e CT_PHASE SZSEG The size of the segment for cloud phase flag computation is configurable see its definition in 3 2 1 Its default value is 8 Information on how to change the size of the segment can be found in the software user manual AD 3 and in section 3 2 1 3 4 CLOUD TYPE CT VALIDATION 3
34. nary cloud in twilight Temporal differencing CONN MB WN p p pb oe mn nm On R D e 11 bits for quality 3 bits to define illumination and viewing conditions 0 Undefined space l Night 2 Twilight 3 Day 4 Sunglint 2 bits to describe NWP input data 0 Undefined space l All NWP parameters available no low level inversion 2 All NWP parameters available low level inversion 3 At least one NWP parameter missing Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MEL SCI PUM 01 m T METEO FRANCE E Toujours in temps d avance PGEO02 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 NWC SAF File SAF NWC CDOP2 MFL SCI PUM 01_ v3 2 3 v2 2 Page 12 34 2 bits to describe SEVIRI input data 0 Undefined space l All useful SEVIRI channels available 2 At least one useful SEVIRI channel missing 3 A least one mandatory SEVIRI channel missing 2 bits to describe the quality of the processing itself 0 Non processed containing no data or corrupted data Good quality high confidence Poor quality low confidence Reclassified after spatial smoothing very low confidence Ww N m 1 bit for temporal processing indicator significant for cloud free pixels 0 Not performed 1 Performed 1 bit for HRV processing indicator significant for cloud free pixels 0 Not performed 1 Performed e 2 bits for dust detection 0 Non processed containing no
35. nd recommendation for use The following main problems may be encountered e CTTH will be wrong if the cloud is wrongly classified o Underestimation of cloud top height pressure for semi transparent clouds classified as low medium o Over estimation of cloud top height pressure for low medium clouds classified as semi transparent e No CTTH is available for clouds classified as fractional e CTTH may be not computed for thin cirrus clouds e Retrieved low cloud top height may be overestimated Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MFL SCI PUM 01 METEO FRANCE 2 Toujours un temps d avance PGEO2 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 NWC SAF File SAF NWC CDOP2 MFL SCI PUM 01_v3 2 3 w Page 34 34 4 5 EXAMPLE OF CLOUD TOP TEMPERATURE AND HEIGHT CTTH VISUALISATION It is important to note that the CTTH product is not just images but numerical data At first hand the CTTH is rather thought to be used digitally together with the appended quality flags as input to mesoscale analysis models objective Nowcasting schemes but also in the extraction of other SAFNWC products Colour palettes are included in CTTH HDF files thus allowing an easy visualisation of cloud top pressure as illustrated with the SEVIRI example on Figure 5 height temperature and effective cloudiness The product if used as an image on the forecaster desk may be visualized together with C
36. ne coefficients file containing satellite dependent values and one look up table for climatological atmospheric absorption correction is available in the SAFNWC software package and is needed by the CTTH software 4 3 2 Configurable parameters for Cloud Top Temperature and Height CTTH Besides the NWP parameters to be used the levels may be changed by the user only one parameter is configurable in the default CTTH model configuration file e CTTH_SZSEG The size of the segment is configurable see its definition in 4 2 1 Its default value is 16 Information on how to change the size of the segment can be found in the software user manual AD 3 and in section 4 2 1 4 4 CLOUD TOP TEMPERATURE AND HEIGHT CTTH VALIDATION 4 4 1 Summary of Cloud Top Temperature and Height CTTH validation results Table 7 summarises the validation results of the current version More details can be obtained from the validation report for cloud products AD 5 PGE03 products Validated accuracy bias std Top height of opaque low mid level and high cloud validated over European areas using ground based radar lidar 120m 1050m Top height of semi transparent cloud validated over European areas using ground based radar lidar 1020m 940m intercept method 100m 1050m radiance ratioing technique Table 7 Summary of validation results of the current PGEOS version std stands for standard deviation 4 4 2 Typical known problems a
37. ness gain Countspits intercept corresponds to cloudiness ranging between Cloudiness and Cloudiness 5 Gain Intercept Special count 5 count e 14 bits for quality 2 bits to define processing status 0 non processed encompasses CMa and or CT Non processed or undefined Image areas that may not be processed when the images size is not a multiple of the PGEO3 segment size 1 non processed because FOV is cloud free 2 processed because cloudy but without result 3 processed because cloudy with result 1 bit setto 1 when RTTOV IR simulations are available 3 bits to describe NWP input data 0 undefined space 1 All NWP parameters available no thermal inversion 2 All NWP parameters available thermal inversion present 3 Some NWP pressure levels missing no thermal inversion Some NWP pressure levels missing thermal inversion present 5 At least one mandatory NWP information is missing 2 0 l bits to describe SEVIRI input data undefined space all SEVIRI useful channels available Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MEL SCI PUM 01 a o j METEO FRANCE Toujours un temps d avance NWC SAF PGE02 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 File SAF NWC CDOP2 MFL SCI PUM 01_v3 2 3 v2 2 Page 30 34 at least one SEVIRI useful channel missing at least one SEVIRI mandatory channel is missing bits to describe which method has been used Non p
38. oducts CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MFL SCI PUM 01 rs METEO FRANCE F r lle tee PGE02 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 NWC SAF File SAF NWC CDOP2 MFL SCI PUM 01_ v3 2 3 phase as input to mesoscale analysis models objective Nowcasting schemes but also in the extraction of other SAFNWC products CTTH for example Colour palettes are included in CT HDF files thus allowing an easy visualisation of CT cloud type categories as illustrated on Figure 3 The user may be interested in visualising all the available classes please keep in mind that the separation between stratiform and cumuliform clouds is not performed in the current CT version as displayed on a SEVIRI example in Figure 3 or highlight one or a few categories suitable for the application of interest Product s animation will be a help for the user to interpret the visualized CT and to identify artefacts for example the replacement of a snowy area by a low cloud between two successive pictures may be due only to the transition from day to night as the snow detection is not possible at nighttime Sass oS 4562 Cloud Type 20 01 2008 op 12h00 UTC os 4 i A undefined e braken sem above DR aem thick Bem med sem thin very high very high cum high high cum med _ med cum low low cum vary low very law cum seg ice land snow 860 land T gt P r 5 Ce neproc y b F ai
39. on by snow ice covered surface Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MFL SCI PUM 01 Zo j METEO FRANCE Toujours un temps d avance NWC SAF PGE02 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 File SAF NWC CDOP2 MFL SCI PUM 01_v3 2 3 v2 2 Page 20 34 no contamination by clouds but contamination by thin dust volcanic clouds not checked 2 cloud free sea no contamination by snow ice covered surface no contamination by clouds but contamination by thin dust volcanic clouds not checked 3 land contaminated by snow sea contaminated by snow ice 5 very low and cumuliform clouds 6 very low and stratiform clouds 7 low and cumuliform clouds 8 low and stratiform clouds 9 medium and cumuliform clouds 10 medium and stratiform clouds 11 high opaque and cumuliform clouds 12 high opaque and stratiform clouds 13 very high opaque and cumuliform clouds 14 very high opaque and stratiform clouds 15 high semitransparent thin clouds 16 high semitransparent meanly thick clouds 17 high semitransparent thick clouds 18 high semitransparent above low or medium clouds 19 fractional clouds sub pixel water clouds 20 undefined undefined by CMa In the current version of CT the separation between cumuliform and stratiform is not performed low medium or high clouds will be classified as stratiform and a specific bit indicating whether the separation between stratiform and c
40. on file Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MEL SCI PUM 01 m T METEO FRANCE Toujours ae temps d avance PGEO02 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 NWC SAF File SAF NWC CDOP2 MFL SCI PUM 01_ v3 2 3 v2 2 Page 22 34 e CT_PHASE SZSEG default value 8 the size of the segment for the cloud phase flag computation This default value may be manually changed independently from CMA _SZSEG or CT SZSEG or the size available in the lines NWP PARAMxx Segments are square boxes in the satellite projection whose size is expressed as the number of IR pixels of one edge of the square box The size of the processed regions must be a multiple of the segment size The simulated R0 6um and R1 6um cloud reflectances for various clouds used during the processing are computed at the segment resolution The cloud phase flag quality is not very much dependent on the segment size Moreover as the content of NWP_CONF_FILE is dependent on the local installation the user must make the NWP PARAMXX consistent with the local NWP CONF FILE when the standard one is not used for details see section dedicated to NWP data files in SAF NWC CDOP INM SW SUM 2 AD 3 3 2 2 The Cloud Type CT preparation step optional By default this CT preparation step is performed during the CT execution step see 3 2 3 But to speed up the CT processing this preparation step can per
41. pendent look up tables available in coefficients files using as input the viewing geometry sun and satellite viewing angles NWP forecast fields surface temperature and total atmospheric water vapour content and ancillary data elevation and climatological data The thresholds are computed at a spatial resolution called segment size defined by the user as a number of SEVIRI infra red pixels Some thresholds are empirical constant or satellite dependent values available in coefficients files e The quality of the cloud detection process is assessed e A Spatial filtering is applied allowing to reclassify pixels having a class type different from their neighbours and to reduce known defaults as cloud false alarms in coastal area and in edges of snowy areas e A test is applied to cloud contaminated pixels to check whether the cloud cover is opaque and completely fills the FOV This first series of tests allows to determine the cloud cover category of each pixel cloud free cloud contaminated cloud filled snow ice contaminated or undefined non processed and compute a quality flag on the processing itself Moreover the tests that have allowed the cloud detection more that one test are possible if some tests were not really successful are stored Product User Manual for Cloud A Products CMa PGE01 v3 2 CT Code SAF NWC CDOP2 MFL SCI PUM 01 Zo METEO FRANCE 2 eue PGEO2v2 2 amp CTTH PGEO3 Issue 3 2 3
42. performed during the CTTH execution step The CTTH execution step which includes the CTTH preparation step in case it has not been launched before is automatically launched by the Task Manager if real time environment is selected 4 2 1 Manual preparation of Cloud Top Temperature and Height CTTH model configuration file for each region When a new region is defined and added in system and run configuration files the user must manually prepares the CTTH model configuration files by adapting the default CTTH model configuration file available in the SAFNWC software package Only one parameter is configurable in the default CTTH model configuration file Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MEL SCI PUM 01 m J METEO FRANCE 2 RS PGEO2v2 2 amp CTTH PGEO3 su 3 2 3 Date 4 December 2014 NWC SAF File SAF NWC CDOP2 MFL SCI PUM 01_ v3 2 3 v2 2 Page 31 34 e CTTH_SZSEG default value 16 the size of the segment This default value may be manually changed independently of CMA_SZSEG and CT_SZSEG The new segment size must also updated in the lines NWP_PARAMx x Segments are square boxes in the satellite projection whose size is expressed as the number of IR pixels of one edge of the square box The size of the processed regions must be a multiple of the segment size The NWP model forecast values and RTTOV simulations will be derived over all the processed regions at
43. re LD VALIDATION cinsin S EEE 24 3 4 1 Summary of Cloud Type CT validation results xsseassnsensvaesnanmusnasenanadss 24 3 4 2 Typical known problems and recommendation for use 24 3 5 EXAMPLE OF CLOUD TYPE CT VISUALISATION ccccccscccesccceccceeceeesceeesseeesceeueseeeeseeneens 24 4 CLOUD TOP TEMPERATURE AND HEIGHT CTTH PRODUCT 27 4 1 DESCRIPTION OF CLOUD TOP TEMPERATURE AND HEIGHT CTTH PRODUCT occcccncccccccnc Zt 4 1 1 Goal of Cloud Top Temperature and Height CTTH product 27 4 1 2 Outline of Cloud Top Temperature and Height CTTH algorithm 27 4 1 3 Description of Cloud Top Temperature and Height CTTH output 28 4 2 IMPLEMENTATION OF CLOUD TOP TEMPERATURE AND HEIGHT CTTH eccere 30 gt Product User Manual for Cloud A Products CMa PGE01 v3 2 CT Code SAF NWC CDOP2 MFL SCI PUM 01 A METEO FRANCE PGE0 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 b Toujours un temps d avance NWC SAF 22 File SAF NWC CDOP2 MFL SCI PUM 01_v3 2 3 Va Page 5 34 4 2 1 Manual preparation of Cloud Top Temperature and Height CTTH model configuration file for each VEO ION sasicsaicannstesie lt aatecsdactasieisdanecadnihaeeuseiauaetatchanseaiesadiesanaeaeaesraavecadeeeentees 30 4 2 2 The Cloud Top Temperature and Height CTTH preparation step optional 51 4 2 3 The Cloud Top Temperature and Height CTTH execution Step 31 4 3 INPUTS AND CONFIGURABLE PARAMETERS F
44. rface temperatures air temperature at 850hPa 700hPa 500hPa or total water vapour content of the atmosphere by climatological values extracted from ancillary dataset An alternative method is used in case of missing NWP air temperature at tropopause level The quality of CT is lower if some NWP fields are missing CT has been designed so that the dependency of NWP is limited to the amount that is absolutely necessary Provided requested NWP fields are input by the user the impact of changing horizontal and temporal resolution will be limited e Ancillary data sets The following ancillary data remapped onto satellite images are mandatory o Land sea atlas Elevation atlas Monthly minimum SST climatology Monthly mean 0 6m atmospheric corrected reflectance climatology land Monthly 0 6um and 1 6um white sky surface albedo climatology land Monthly integrated atmospheric water vapour content climatology Monthly climatology of mean air temperature at 1000hPa 850hPa 700hPa SOOhPa O O 0O 0O These ancillary data are available in the SAFNWC software package on MSG full disk in the default satellite projection at full IR resolution They are extracted on the processed region by the CT software itself One coefficients file also called threshold table containing satellite dependent values and look up tables for thresholds is available in the SAFNWC software package and is needed by the CT software One file containing off
45. rocessed Opaque cloud using rttov Opaque clouds not using rttov Intercept method 10 8um 13 4um Intercept method 10 8um 6 2uUm Intercept method 10 8um 7 3uUm Radiance Ratioing method 10 8um 13 4um Radiance Ratioing method 10 8um 6 2uUm Radiance Ratioing method 10 8um 7 3um Spare 10 Spare 1 Spare 12 Spare 13 Opaque cloud using RTTOV in case thermal inversion 14 Spatial smoothing gap filling in semi transparent cloud field 15 Spare for not yet defined methods D IN 1 R D OH UDN 2 bits to describe quality of the processing itself 0 No result Non processed cloud free no reliable method 1 Good quality high confidence 2 Poor quality low confidence 4 2 IMPLEMENTATION OF CLOUD TOP TEMPERATURE AND HEIGHT CTTH CTTH is extracted by PGE03 of the SAFNWC MSG software package Detailed information on how to run this software package 1s available in the software user manual AD 3 The software architecture of PGEO3 has been strongly modified in version v2010 to make the life easier for the user It is now very similar to the other PGEs When a new region is defined the user has now to manually prepare the CTTH model configuration files for this new region using a default CTTH model configuration file provided in the SAFNWC MSG software package There is an option for the user to monitor the so called CTTH preparation step before SEVIRI images are available to speed up the process By default this preparation step is
46. s The CTTH product contains information on the cloud top temperature and height for all pixels identified as cloudy in the satellite scene 4 1 2 Outline of Cloud Top Temperature and Height CTTH algorithm The different steps of the processing applied to cloud classified image are listed below The exact process applied to each pixel depend on the availability of NWP and SEVIRI data If all mandatory NWP and SEVIRI data are available see list of input for CTTH The following process is then applied e RTTOV 9 radiative transfer model developed by NWP SAF is applied using NWP temperature and humidity vertical profile to simulate 6 2um 7 3um 13 4um 10 8um and 12 0um cloud free and overcast clouds successively on each vertical pressure levels radiances and brightness temperatures This process is performed in each segment of the image the size of the segment is defined by the user the default value being 16 16 SEVIRI IR pixels The vertical profiles used are temporally interpolated to the exact slot time using the two nearest in time NWP fields input by the user e The techniques used to retrieve the cloud top pressure depend on the cloud s type as available in CT product e For very low low or medium thick clouds The cloud top pressure is retrieved on a pixel basis and corresponds to the best fit between the simulated and the measured 10 8um brightness temperatures The simulated brightness temperature are available at t
47. s e A gap filling procedure is applied in semi transparent cloud top pressure field in boxes of fixed size 32x32 SEVIRI IR pixels a cloud top pressure is computed as the average pressure of all pixels containing semi transparent clouds inside the current and the eight surrounding boxes This average cloud top pressure is then assigned to all pixels of the current box containing semi transparent clouds and having no retrieved cloud top pressure e Cloud top temperature and height above sea level are then computed from their pressure using general modules During these processes the atmospheric vertical profiles are temporally interpolated to the exact slot time using the two nearest in time NWP outputs fields e Effective cloudiness defined as the fraction of the field of view covered by cloud the cloud amount multiplied by the cloud emissivity in the 10 8um window channel is also computed during the processing It is equal to 1 0 for thick clouds and takes a value between 0 and 1 for semi transparent clouds In case some mandatory NWP or SEVIRI data are missing see list of inputs for CTTH Cloud top temperature of very low low medium and high clouds are then computed by applying a climatological atmospheric absorption correction to the 10 8um brightness temperature using look up tables The cloud top pressure and height are not retrieved More details can be found in the algorithm theoretical basis document for cloud products A
48. s 12 Liked Manual preparation of Cloud Mask CMa model configuration file for each region 3 2 The Cloud Mask CMa preparation step 0ptional 13 22 3 The Cloud Mask CMa execution step ccccccccccccssssssscccccceeecneseseececeeeeaaaeseseceeeeeeaaaanses 13 22 INPUTS AND CONFIGURABLE PARAMETERS FOR CLOUD MASK CMA 14 ER List of inputs for Cloud Mask OMG 14 21 2 Configurable parameters for Cloud Mask CM 15 2 4 CLOUD MASK CMAJ OR a a 0 16 2 4 1 Summary of Cloud Mask CMG validation results vices cocscsesesstssxtescteaetsrsivsxteactensanacissss 16 2 4 2 Typical known problems and recommendation for use 16 Zo EXAMPLE OF CLOUD MASK CMA VISUALISATION cganeteires rceteensersteeteestrerirnrtresiensteorbenaicscds 17 Pam CLOUD PP CR PRODUCTS aa ea rrr rrrrrrrr 19 3 1 DESCRIPTION OF CLOUD TYPE CT PRODUCT Se rer ae 19 Sula Goal of Cloud Type CDR he teebdiadddabhaaiddaddicddenddiudiocn 19 3 1 2 Outline of Cloud Type CT algorithm Rs 19 da Description of Cloud Type CTO DRE n 19 32 IMPLEMENTATION OF CLOUD TYPE CT eines sens sense censesenseeenssse 21 Id Manual preparation of Cloud Type CT model configuration file for each region 21 I2 The Cloud Type CT preparation step optional 22 3 2 3 The Cloud Type CCC OR De 22 3 3 INPUTS AND CONFIGURABLE PARAMETERS FOR CLOUD TYPE CT 22 3 3 1 List of inputs for Cloud Type CT ssicciadavniaaGaiadadadavatatasavasans 2a 3 3 2 Configurable parameters for Cloud Type CT 24 3 4 DOU T
49. s absolutely necessary The impact of missing NWP data has been analyzed in details and reported in AD 6 Provided requested NWP fields are input by the user the impact of changing horizontal and temporal resolution will be limited e Ancillary data sets The following ancillary data remapped onto satellite images are mandatory o Land sea atlas Land sea coast atlas Elevation atlas Monthly minimum SST climatology Monthly mean 0 6m atmospheric corrected reflectance climatology land Monthly mean large band visible surface reflectance climatology land for HRV processing Monthly integrated atmospheric water vapour content climatology o Monthly climatology of mean air temperature at 1000 hPa O O 0 O These ancillary data are available in the SAFNWC software package on MSG full disk in the default satellite projection at full IR resolution They are extracted on the processed region by the CMa software itself Coefficients s file also called threshold tables containing satellite dependent values and look up tables for IR thresholds and for solar channels thresholds are available in the SAFNWC software package and are needed by the CMa software 2 3 2 Configurable parameters for Cloud Mask CMa Three configurables parameters are available in the default CMa model configuration file e CMA_SZSEG The size of the segment is configurable see its definition in 2 2 1 Its default value is 4 Information on how to chan
50. sue 3 2 3 Date 4 December 2014 File SAF NWC CDOP2 MEL SCI PUM 01_v3 2 3 v2 2 Page 13 34 2 2 1 Manual preparation of Cloud Mask CMa model configuration file for each region When a new region is defined and added in system and run configuration files the user must manually prepares the CMa model configuration files by adapting the CMa default model configuration file available in the SAFNWC software package Three parameters are configurable in the default CMa model configuration file e CMA_SZSEG default value 4 the size of the segment for CMa The new segment size must also be updated in the lines NWP_PARAMxx Segments are square boxes in the satellite projection whose size is expressed as the number of IR pixels of one edge of the square box The size of the processed regions must be a multiple of the segment size All the solar and satellite angles the NWP model forecast values the atlas values and the thresholds will be derived over all the processed regions at the horizontal resolution of the segment Note also that the land sea atlas will be available at the full IR resolution allowing the identification of the surface type land or sea of all IR pixels whatever the segment size The quality is not very much dependent of the segment size if lower than 4 A segment size of 4 allows the preparation step to be 9 times faster than if a segment size of 1 was used e TEMPORAL_USE default value TRUE a flag defining if
51. the horizontal resolution of the segment A small ctth_szseg will decrease the box aspect in the retrieved cloud top pressure and will be especially useful if the NWP fields have a high horizontal resolution But it may become very time consuming as RTTOV is launched for every segment Moreover as the content of NWP_CONF_FILE is dependent on the local installation the user must make the NWP PARAMXX consistent with the local NWP CONF FILE when the standard one is not used for details see section dedicated to NWP data files in SAF NWC CDOP INM SW SUM 2 AD 3 4 2 2 The Cloud Top Temperature and Height CTTH preparation step optional By default this CTTH preparation step is performed during the CTTH execution step see 4 2 3 But to speed up the CTTH processing this preparation step can performed by the command mfcms_next_pge03 which can be launched in advance of satellite data reception according to a pre defined time scheduling to be manually set by the user This preparation step includes the computation on the region at the segment spatial resolution of e the solar amp satellite angles e the monthly climatological amp atlas maps e the simulated cloud free amp opaque cloud radiances with RTTOV 4 2 3 The Cloud Top Temperature and Height CTTH execution step The CTTH execution step which by default includes the CTTH preparation step see 4 2 2 is the real time processing of the SEVIRI images itself over the region This
52. tion at HRV spatial resolution for HRV R0 6um T8 7um T10 8um T12 0um T13 4 Mandatory Optional _ Mandatory Mandatory The CMa software checks the availability of SEVIRI channels for each pixel If non mandatory channels are missing for one pixel the tests using these channels are not applied or applied differently for example snow detection uses either R1 6um or T3 9um visible channel test over the ocean uses either RO 8um or R0 6um and a result is available for this pixel No results are provided for pixels where at least one mandatory channel is missing The following SEVIRI bi directional reflectances or brightness temperatures or Cma or CT of the scene analysed one hour sooner are optionally needed to improve the cloud detection in day night transition If one of them misses this improvement is not performed T10 8pm T12 0umy CT Optional Optional The following SEVIRI brightness temperatures or Cma or CT of the scene analysed 15 minutes sooner are optionally needed to improve the cloud detection of fast moving clouds If one of them misses this improvement is not performed T10 8pmismn T12 0uMI5mn CTismn Optional Optional Optional The HRV bi directional reflectance of the scene analysed 15 minutes sooner are optionally needed to improve the sub pixel cumulus cloud detection If not available this improvement is not performed The SEVIRI channels are input by the user in HRIT format and extracted on the processed r
53. udy areas where other products cloud types and cloud top temperature height may be derived The central aim of the CMa is therefore to delineate all cloud free pixels in a satellite scene with a high confidence In addition the product provides information on the presence of snow sea ice dust clouds and volcanic plumes 2 1 2 Outline of Cloud Mask CMa algorithm The algorithm is based on multispectral threshold technique applied to each pixel of the image A first process allows the identification of cloudy pixels It consists in a first set of multispectral threshold tests summed up below which is complemented by an analysis of the temporal variation on a short period of time 15 minutes of some spectral combinations of channels to detect rapidly moving clouds a specific treatment combining temporal coherency analysis and region growing technique to improve the detection of low clouds and a temporal analysis of the HRV channel to detect sub pixel cumulus clouds The first series of tests allows the identification of pixels contaminated by clouds or snow ice this process is stopped if one test is really successful 1 e if the threshold is not too close to the measured value The characteristics of this set of tests are summed up below e The tests applied to land or sea pixels depend on the solar illumination and on the viewing angles and are presented in Table 3 and Table 4 e Most thresholds are determined from satellite de
54. umuliform clouds has been attempted will be set to zero see below quality flag e 10 bits for quality 3 bits to define illumination and viewing conditions Undefined space Night Twilight Day Sunglint bits to describe NWP input data Undefined space All NWP parameters available no low level inversion All NWP parameters available low level inversion At least one NWP parameter missing bits to describe SEVIRI input data Undefined space All useful SEVIRI channels available At least one useful SEVIRI channel missing At least one mandatory SEVIRI channel missing bits to describe the quality of the processing itself Non processed containing no data or corrupted data Good quality high confidence Poor quality low confidence Reclassified after spatial smoothing very low confidence re OS DO WNrR ON OS DO D OS D bit setto 1 to indicate that the separation between cumuliform and stratiform clouds has Product User Manual for Cloud Products CMa PGEO1 v3 2 CT Code SAF NWC CDOP2 MEL SCI PUM 01 o j METEO FRANCE chet ae i laine PGE0 2 v2 2 amp CTTH PGE03 Issue 3 2 3 Date 4 December 2014 NWC SAF File SAF NWC CDOP2 MEFL SCI PUM 01_ v3 2 3 v2 2 Page 21 34 been performed In the current version of CT the separation between cumuliform and stratiform is not performed this bit will be set to zero and the low medium or high clouds will be classified as stratiform e 2 bits for cloud phase
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