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user manual for rfscat simulator

1. 30 40 50 B0 70 Inclination Angle deg Figure 5 Selecting a and displaying b an antenna pattern User Manual Version 1 0 Page 12 3 Generating Pseudo Level Ib Data RFSCAT Simulator 3 1 3 Select Processing Parameters When selecting the processing parameters see Figure 6 one has to be careful because they are not necessarily independent from each other and from the desired orbit The signal travel time at near swath time between Tx and Rx will depend on the antenna pattern smallest inclination angle and orbit height Also swath width and duration of the receiver window will depend on antenna pattern and orbit height The resolution cannot be smaller than the one defined by the measurement geometry and the antenna beamwidth in azimuth of the instrument parameters see Figure 4 In order to reduce the computational effort two simulation parameters are included see Figure 6 which skip the computations of range bins and pulses respectively As shown in the Task 3b Report for values up to 20 for both parameters no significant impact in the quality of the simulation was observed but a considerable gain in computation time This menu allows to control processing parameters If the window does not close with the UK button at least One parameter was set incorrectly Time between Tx and Rx msec 5 40001 Rec Window msec 1 92630 Resolution km 50 0000 Swath Width km 1500 00 Width of spatial Filter Resolut
2. rfscat simulator directory In order to run the RFSCAT simulator start IDL and enter rfscat at the IDL gt prompt The Main Window of the RFSCAT Simulator as depicted in Figure 2 will appear on your computer screen HFSCAI SIMULATOR Version 1 0 beta Figure 2 Main window of the RFSCAT simulator If you start the simulator for the first time neither data for analysis nor data for wind retrieval are available Thus the first thing to do is to use the pseudo level 1b generator in order to create a satellite data set User Manual Version 1 0 Page 9 3 Generating Pseudo Level Ib Data RFSCAT Simulator 3 Generating Pseudo Level 1b Data When starting the RFSCAT simulator the default instrument is the baseline reference system which has been used in the study Via the menu File Generate Pseudo LIb Product this data can be compute immediately for one orbit The menu point Radar System Generate Pseudo LIb Product has the same functionality The progree of the simulation will be displayed in an extra pop up window However various menus are at disposal for selecting the instrument and orbit characteristics in detail This user manual will not describe the meaning and function of all parameters an extensive description can be found in the Task 2b Report 3 4 Defining the Radar System The radar system can be defined via the menu Radar System and the submenus see Figure 3 Select Instrument Parameters Select Antenna
3. Ok Cancel Ok _ Adjust Wind Direction Range Adjust Node Number Range Ta Maximum TT Maximum Cancel Ok Cancel Ok Figure 20 Adjust windows for parameters User Manual Version 1 0 Page 25 5 Analysis RESCAT Simulator 5 6 Further Plotting Options The menu of the main RFSCAT simulator window offers further options of basic statistical analysis under the button More for the Y Axis This button opens a new window for further selections as depicted in Figure 21 Further Selections Ph ah ar a Pas ah Pas a a Pis Figure 21 Selection window for More plotting options User Manual Version 1 0 Page 26 5 Analysis RESCAT Simulator 5 7 Changing the Reference System The wind retrieval performance of a RFSCAT system might depend on the antenna azimuth angle with respect to the wind direction Since the satellite heading varies considerably along one orbit this effect will not be visible when plotting the results as a function of wind direction Therefore the coordinate system for the wind vector can be switched between a geographical which is the standard meteorological convention and a system related the satellite heading which varies accordingly along the orbit The default setting is the geographical system User Manual Version 1 0 Page 27
4. This document provides the details for installing the RFSCAT simulator package in Section 2 The definition of a RFSCAT system and the simulation of a pseudo level Ib product is described in Section 3 The Section 4 is dedicated to the reference wind field and its generation Various predefined tools for analyzing the performance of a RFSCAT system and its detailed performance in wind retrieval are described in Section 5 IDL is a trademark of Research Systems Inc Boulder CO USA User Manual Version 1 0 Page 3 2 Installation RESCAT Simulator 2 Installation The present version of the RFSCAT simulator has been developed under IDL version 5 4 1 on a Linux Intel computer under SuSE Linux version 7 3 Recently it was transferred to SuSE Linux version 8 1 without any problems 2 1 System Requirements Major parts of the RFSCAT simulator software are written in IDL therefore an IDL license of version 5 4 or higher is required to run this software The package with software and look up tables requires approximately 25 MByte of disk space However data files created by the simulator might need significantly more disk space e g the pseudo level Ib file for a single orbit of the baseline RFSCAT system is about 17 MByte large while the same file for a 25 km resolution wide swath instrument 1800 km is about 110 MByte in size Thus it 1s recommended to reserve sufficient disk space when using the simulator Furthermore a minimum
5. Pattern and Select Processing Parameters The menu point Select Default System overwrites all new selections with the parameters of the baseline RFSCAT system File Radar System Orbit Atmosphere Wind Retrieval Select Default System Select Instrument Parameters SCATTEROMET Select antenna Pattern Reference system Instrument Display Antenna Pattern Sete Geographical Radar Bands Select Processing Parameters Cells Folarisatio Generate Pseudo Lib Product Merit we Satellite Heading Resolution R Axis Y Axis Set Ranges Output A Reference llind Speed we Reference Wind Speed A Mone Scatterplat x Rank 1 x blind Direction Rank 1 x Mind Direction x lind Speed PIF Isolines ae Rank 2 se U Component ae Rank 2 se U Component we blind Direction Quality per Node r Rank 3 x V Lomponent x Rank 3 c Component se U Component Figure of Merit x Rank 4 we Node Number xr Rank 4 we Distance to Cone x V Lomponent Reset xr More x Modes Figure 3 Main RFSCAT simulator window with the Radar System menu User Manual Version 1 0 Page 10 3 Generating Pseudo Level Ib Data RFSCAT Simulator 3 1 1 Select Instrument Parameters Figure 4 depicts the selection window for instrument parameters Presently only GMF for C and Ku band scatterometers are available thus the selection is restricted accordingly Multi channel systems cannot be simulated in a single run A pseudo level Ib file has to be created for each
6. RESCAT Simulator It is not expected that the user will need to modify the software however the entire source code except for the Stars Library of Astrium is included An overview of the software in the rfscat simulator directory is given in Table 3 Program Description rfscat pro Main IDL routine initializes the graphical user interface GUI rfscat ini pro rfscat pll pro rfscat events pro rfscat graphic pro rfscat tools pro libStarsIDL so libStarsIDL dlm starsdoc pro wind retrieval small IDL routine for setting the environment This has to be modified during the installation The pseudo level Ib generator which requires the Stars Library of ASTRIUM see below Library of event handling routines used by the GUI Library of graphical output routines Library of varies small routines and functions Stars Library used by the pseudo level Ib generator IDL dynamic link manager for the Stars Library IDL documentation file for the pseudo level Ib generator Wind retrieval module from KNMI called externally from the GUI The FORTRAN source code can be found in the directory rfscat simulator retrieval_ module Table 3 Software in the rfscat simulator directory User Manual Version 1 0 Page 8 2 Installation RESCAT Simulator 2 6 Starting the RFSCAT Simulator Make sure that you either have included the rfscat simulator directory in the IDL search path or that you start IDL from the
7. a function of node across the instrument swath as depicted in Figure 17 Herein the red line is the average performance and represents the FoM of this system The PRINT option creates a PostScript file of plot while the EXPORT option creates an ASCII data file with the values of quality index and node number The code see Figure 17 is generated on the basis of the actual date and time and used within the file name Simulation CV_a04_10_n55h Radar 5 Code 021102100318 0 50193 0 01284 x e 9 E E s gt Cy 27 36 45 54 63 72 Mode Number Figure 17 Display of the Quality per Node User Manual Version 1 0 Page 22 5 Analysis RESCAT Simulator 5 3 Scatterplots The analysis tool allows to plot the data is various ways For comparing two datasets scatterplots are widely used Here the selection buttons on the main RFSCAT simulator window see Figure 15 offer a wide range of possibilities for the X and Y axis The wind retrieval provides up to four solutions for the retrieved wind which are ordered according to their probability from rank 1 to rank 4 Together with the reference wind field five wind fields are at disposal from which wind speed wind direction or one of the wind vector components u or v can be selected Simulation CV a04 10 n55h Eu URL RP VECES Ey Simulation CV a04 10 n55h Radar E T LT nae PEE 5 i Radar E Wind Field n a M d v UA i Wind Field n a Code 021101162824 NU
8. gain Furthermore strong gradients in the pattern should be avoided in order to make the instrument less sensitive to pointing errors The RFSCAT simulator can use any antenna pattern which is provided in the rfscat lut directory As depicted in Figure 5 a the pattern can be selected interactively and displayed for control Figure 5 b The PRINT option creates a PostScript plot of the pattern while the EXPORT option creates an ASCII data file with the values of antenna gain and incidence angle The code see Figure 5 b is generated on the basis of the actual date and time and used within the file name The antenna pattern files are DL save files generated with the IDL command save filename fname i gain2 i incgain whereby fname is the name of the antenna pattern file name i gain2 is a 1 dimensional array with the two way antenna gain linear values and i incgain is a 1 dimensional array with the corresponding inclination angle in radians a Sam Please Select a File for Reading Simulation Radar Codet 021102092531 Directories di rfscat lut antenna 2beams 01 dat E di rfscat lut antenna ascat 00 dat di rfscat lut unused antenna ascat aft Q0 dat antenna ers aft 01 dat antenna ers mid 01 dat antenna gain 01 dat antenna gain 02 dat 7 antenna gain O3 dat asd e a Fi de e Ol PRINT EXPORT DONE o EN F3 2 Way Antenna Gain dB Selection di rfscat lut
9. listed in Table 2 They are based on experimental data as well as on theoretical work as described in the Task 1 Report File Name Description antenna_2beams_0O1 dat Split beam instrument in the study Derived from the ASCAT mid beam antenna Used for the baseline instrument in the study antenna ascat O0 dat antenna seawinds hpol 07 dat SeaWinds inner beam with H polarization antenna seawinds vpol 08 dat SeaWinds outer beam with V polarization antenna shift 04 dat Shifted ASCAT mid beam for a high orbit antenna shift O6 dat Shifted ASCAT mid beam for low orbit wide swath instrument Table 1 Two way antenna pattern of systems which have been simulated within the study File Name v Description c vv2 dat GMF for C band and vertical polarization derived from CMOD 4 GMF for C band and horizontal polarization CMOD 4 was scaled on the basis of c hh2 dat pn i experimental polarization ratio data GMF for the polarimetric correlation coefficient at C band Based on theoretical work at c pol2 dat Ku band and scaled to C band ku vv2 dat GMF for Ku band and vertical polarization derived from the NSCAT model ku hh2 dat GMF for Ku band and horizontal polarization derived from the NSCAT model ku pol2 dat GMF for the polarimetric correlation coefficient at Ku band Based on theoretical work Table 2 Look up tables for different geophysical model functions GMF 2 3 2 Wind Fields wind This direc
10. memory RAM of 512 MByte with at least the same size of swap space is recommended 2 2 Unpacking the Archive File The entire RFSCAT simulator package 1s delivered in a single compressed UNIX TAR file rfscat tar gz For installation please copy this file into a directory for which you have full read write and execute permission and extract all files with the command tar xvzf rfscat tar gz This will create the directory rfscat with the following sub directories simulator with the RFSCAT simulator software lut with look up tables for GMF and antenna pattern wind for reference wind fields and retrieval results lib for pseudo level 1b data plots for output files PostScript graphics or ASCII data Furthermore the directory rfscat simulator retrieval module contains the FORTRAN source code of the wind retrieval module and a respective make file for recompilation In order to run the RFSCAT simulator either include the rfscat simulator path in the IDL search path or start IDL from this directory Prior to running the software few adjustments must be made for the system environment This is being described in the following section Directories User Manual Version 1 0 Page 4 2 Installation RESCAT Simulator 2 3 Directories The default setting of directories and or the location of the software might not be suitable for the desired system All this might be changed but these changes must be d
11. 030 Rea Coeff 0 000 Corr Coeff 0 002 Std Dev 0 000 Ref System geographical Ref System geographical m i E c m rc o a E o i gt uo Q c o o a Reference Wind Speed m s Add Curve Regression Add Curve Regression 23 0 23 Q 13 8 42 5 2 14 6 24 9 FEDI 30 180 270 hill Reference U Component m s EXPORT Reference Wind Direction deg EXPORT a b Figure 19 Examples of PDF plots User Manual Version 1 0 Page 24 5 Analysis RESCAT Simulator 5 5 Set Ranges For a even more detailed analysis it might necessary to restrict the evaluation to certain ranges of wind speed wind direction wind components or node numbers The Set Ranges tool on the main RFSCAT simulator window offers this possibility The ranges can be selected individually in the respective Adjust windows see Figure 20 either by editing the number directly or by using the scroll bar with the mouse The selection None will reset all parameters to their default values which are 25 m s for the u and v component 0 0 25 0 m s for wind speed 0 360 degrees for wind direction and 0 72 for node number corresponding to a 1800 km wide swath and 25 km resolution E Adjust U Component Range E Adjust V Component Range E Adjust Wind Speed Range 25 000 o0 25 00 25 000 o0 25 00 Do0 0 00 25 00 m Maximum um Max imum Maximum Cancel Ok Cancel
12. T K ee on Code 021101164800 Number of Cells 58150 Reg Const 0 068 Reg Coeff 1 005 Corr Coeff 0 983 Std Dev 0 001 Number of Cells 58150 Reg Const 72 268 Reg Coeff 0 600 Corr Coeff 0 599 Std Dev 0 003 Ref Sustem geographical Ref System geographical Rank 1 Wind Speed m s Rank 1 Wind Direction deg Reference Wind Speed m s 15 20 Reference Wind Speed m s 30 180 270 Reference Wind Direction deg c Add Curve Regression PRINT EXPORT DONE Simulation CV a04 10 n55h Radar t Mind Field n a Code 021101164125 Number of Cells 58150 Reg Const 7 030 Reg Coeff 0 000 Corr Coeff 0 002 Std Dev 0 000 Ref System geographical Add Curve Regression PRINT EXPORT DONE Figure 18 Examples for scatterplots RMS Direction Difference deg Add Curve Regression PRINT EXPORT DONE Simulation CV a04 10 n55h Radar n Wind Field n a Code 021101165313 Number of Cells 72 Reg Const 88 963 Reg Coeff 0 028 Corr Coeff 3 0 027 Std Dev 0 125 Ref System geographical Add Curve Regression PRINT EXPORT DONE Different examples of scatterplots are depicted in Figure 18 By default a linear regression is computed through the data points and the respective parameters are given in the display window The regression line can be switched on and off by the Regression button Furthermore the data points can b
13. User Manual for European Space Agency USER MANUAL FOR THE RFSCAT SIMULATOR SOFTWARE PACKAGE ESA CONTRACT NO 14383 00 NL DC fars RESCAT Simulator TABLE OF CONTENTS 1 INTRODUCTION 3 1 1 STRUCTURE OF THIS DOCUMENT 3 2 INSTALLATION 4 2 1 SYSTEM REQUIREMENTS 4 2 2 UNPACKING THE ARCHIVE FILE 4 2 3 DIRECTORIES 5 2 3 1 Look up Tables lut 6 2 3 2 Wind Fields wind 6 2 3 3 Pseudo Level 1b data I1b 7 2 3 4 Output Files plots 7 2 4 FILENAMES 7 2 5 SOFTWARE 8 2 6 STARTING THE RFSCAT SIMULATOR 9 3 GENERATING PSEUDO LEVEL 1B DATA 10 3 1 DEFINING THE RADAR SYSTEM 10 3 1 1 Select Instrument Parameters 11 3 1 2 Select Antenna Pattern 12 3 1 3 Select Processing Parameters 13 3 2 DEFINING THE ORBIT 14 3 3 DEFINING ATMOSPHERIC CONDITIONS 15 4 WIND RETRIEVAL 16 4 1 GENERATING A REFERENCE WIND FIELD 17 4 2 SELECTING A REFERENCE WIND FIELD 18 4 3 SELECTING Pskupo LEVEL 15 DATA 19 4 4 STARTING THE WIND RETRIEVAL 20 5 ANALYSIS 21 5 1 FIGURE or MERIT 22 5 2 OBTAIN THE QUALITY INDEX 22 5 3 SCATTERPLOTS 23 5 4 PDF Prors 24 5 5 Ser RANGES 25 5 6 FURTHER PLOTTING OPTIONS 26 5 7 CHANGING THE REFERENCE SYSTEM 27 User Manual Version 1 0 Page 2 1 Introduction RESCAT Simulator 1 Introduction The software package RFSCAT Simulator was developed within the project Optimisation of rotating range gated fanbeam scatterometer for wind retrieval ESA Contract No 14383 00 NL DC and w
14. al at least one pseudo level Ib dataset must be selected The menu point Select First Pseudo Level Ib Input in Figure 11 opens a file selection window as depicted in Figure 14 Up to three radar channels pseudo level Ib datasets can be combined in the current version of the RFSCAT simulator via the menu points Select Second Pseudo Level 1b Input and Select Third Pseudo Level Ib Input select a File for Reading Directories fdi rfscatewind CM a 4d 10 nbbh rwi A dij rfscatz wind AIL S e j Selection di rfscatzwind Filter Cancel Figure 14 File selection menu for pseudo level Ib data User Manual Version 1 0 Page 19 4 Wind Retrieval RESCAT Simulator 4 4 Starting the Wind Retrieval Before starting the wind retrieval via the menu point Start Wind Retrieval Module see Figure 11 make sure that a reference wind field and at least one pseudo level 1b data file was selected otherwise an error message will remind you The wind retrieval module is written in FORTRAN and called externally by the GUI Consequently all messages issued by this module will show up in the terminal window from which IDL and the RFSCAT simulator were started and will not be displayed in pop up windows like messages from the GUI The wind retrieval is a considerable computational effort thus allow several minutes time for retrieving an entire orbit The progress of th
15. as used for simulating and analyzing various RFSCAT systems The package consists of three major components 1 The generator for simulating pseudo level 1b satellite data is written in IDL and the source code is provided It requires the Stars Library which is an in house development of ASTRIUM and not part of this project A compiled and licensed version is included for Intel Linux systems It might be necessary to recompile the Stars Library for an installation on a different system 2 The wind retrieval module is written in Fortran 90 The source code is provided as well as a compiled version for Intel Linux systems Recompilation could be done for any other system with a Fortran 90 compiler This module requires look up tables LUT which are provided with the software 3 The graphical user interface GUI and analysis tool is written in IDL and the source code is provided The GUI also controls the other two components thus the user will not notice the heterogeneous software structure of the RFSCAT simulator In the course of the project several technical reports have be produced which describe the details and backgrounds of the geophysical wind scatterometer model functions GMF in Task 1 Report the pseudo level 1b generator in Task 2b Report the wind retrieval in Task 2a Report e the system performance evaluation in Task 3a Report and e the overall RFSCAT simulations in Task 3b Report 1 1 Structure of this Document
16. channel 1 e radar band and or polarization and these data files are combined in the wind retrieval Note that for e g a dual polarization instrument two pseudo level Ib files are required for H and V respectively Herein either the PRF has to be divided by 2 for alternating pulses for the two polarizations or the peak power has to be divided by 2 for two antennae fed through a power divider La muss Select Instrument Parameters Please be aware that not all parameters can be chosen freely If the window does not close with the OK button at least one parameter was set incorrectly Radar Band C K Polarisation V H P Peak Power KM 5 00000 PRE 239 000 Duration TH Pulse msec 19998 Pulse Bandwidth MHz 3 52980 Antenna Scan Rate rpm 3 34227 Antenna Azimuth Offset deg b o0000 Antenna Beamwidth in Azimuth dea b enasa Instrument Lossest 2 04968 Frequency of Noise Measurements E Noize Figure Hz 3 41253 Reference Temperature K 230 000 CANCEL Ok Figure 4 The Select Instrument Parameters Window User Manual Version 1 0 Page 11 3 Generating Pseudo Level Ib Data RFSCAT Simulator 3 1 2 Select Antenna Pattern The most crucial design parameter for a RFSCAT system is the shape of the fan beam antenna pattern in the elevation plane The NRCS of the ocean surface is a strong function of the incidence angle which should be compensated as much as possible by the shape of the antenna
17. e connected by a line using the Add Curve button This is recommended only when few data points are plotted like in Figure 18 d The PRINT option creates a PostScript plot of the scatterplot while the EXPORT option creates an ASCH data file with the values pairs of the respective parameters The code is generated on the basis of the actual date and time and used within the file name User Manual Version 1 0 Page 23 5 Analysis RESCAT Simulator 5 4 PDF Plots Scatterplots might be difficult to survey when too many data points are plotted on top of each other Here their density distribution provides important information Thus all scatterplots can be displayed also as probability density functions PDF simply by toggling between the buttons Scatterplot and PDF Isolines on the main window of the RFSCAT simulator Figure 19 depicts examples of PDF displays The PRINT option creates a PostScript plot of the scatterplot while the EXPORT option creates an ASCII data file with the values pairs of the respective parameters The code is generated on the basis of the actual date and time and used within the file name Simulation CV a04 10 nb5h Simulation CV a04 10 nb5h Radar t Radar E Mind Field n a Mind Field n a Code 021101164904 Code 021101154827 Number of Cells 58150 Reg Const 0 016 Reg Coeff 0 002 Corr Coeff 0 002 Std Dev 0 004 Number of Cells 58150 Reg Const 7
18. e retrieval can be followed by the messages issued from the module in the main IDL terminal window The resulting data will be stored in the respective rwi file for further analysis see Section 2 4 File Names for details User Manual Version 1 0 Page 20 5 Analysis RESCAT Simulator 5 Analysis The third component of the RFSCAT simulator is the analysis tool A retrieved wind field can be loaded via the Open Retrieved Wind Field menu point in the File menu see Figure 15 This opens a file selection menu as depicted in Figure 16 RFSCAT SIMULATOR Version 1 0 beta Figure 15 Main RFSCAT simulator window with the File menu Please Select a File for Reading Figure 16 File selection menu for the retrieved wind field User Manual Version 1 0 Page 21 5 Analysis RESCAT Simulator 5 1 Figure of Merit Details on the Figure of Merit FoM concept are given in the Task 3a and Task 3b Reports The FoM is a measure of the quality of the wind retrieval The output selection Figure of Merit starts a comprehensive computation of the retrieval performance as a function of node and finally of the FoM The result displayed in the WIND FIELD box of the main RFSCAT simulator window see Figure 15 5 2 Obtain the Quality Index More detailed information is provided under the output button Quality per Node which also provides the FoM but additionally displays the performance of the the RFSCAT system as
19. fied These tables are not needed anywhere else The antenna pattern files have the extension dat and a two digit number before the dot This number is being used in the filename of the pseudo level Ib data file Make sure that this number allows unequivocal identification of the used antenna pattern The reference wind field files have the extensions ref The entire name before the dot is used in the name of the retrieved wind field Thus it is recommended to keep this name as short as possible e g n55a ref which is provided within the setup has normally distributed components with a mean of 0 0 m s and a width of 5 5 m s The name of pseudo level Ib data file 1s generated by the RFSCAT simulator It consists of information on the radar band e g C the polarization e g V and the antenna pattern number e g 01 and a simulation counter The extension is b thus the filename is like CV a01 25 lIb Together with this file an information file with the same name but the extension inf is being stored with the parameters of the simulation The filename for retrieved wind field is also generated by the RFSCAT simulator It has the extension rwi and consists of all pseudo level Ib files used for the system and the reference wind field name as well Thus for a fully polarimetric system it can be complicated as CV a0 23 CH a01 24 CP a01 25 n55a rwi User Manual Version 1 0 Page 7 2 Installation 2 5 Software
20. ion 1 00000 Max time diff per view s 1 15988 Bandwidth Moise MHz 5 1000 Ho Noise Windows E Simulation Parameters No of Max Visus go Range Skip Factor 10 it Pulse Skip Factor 3 CANCEL Ok User Manual Version 1 0 Page 13 3 Generating Pseudo Level 1b Data RFESCAT Simulator 3 2 Defining the Orbit The measurement geometry is very important for the performance of a RFSCAT system as described in the Task 3 b Report From Figure 8 it can be seen that the RFSCAT simulator allows to define any orbit Setting the duration of one revolution to 1 sec will force the simulator to compute pseudo level Ib data for exactly 1 orbit RFSCAT SIMULATOR Version 1 0 beta Figure 7 Main RFSCAT simulator window with the Orbit menu Select Orbit Parameters Figure 6 Selecting orbit parameters User Manual Version 1 0 Page 14 3 Generating Pseudo Level 1b Data RFESCAT Simulator 3 3 Defining Atmospheric Conditions For an in depth comparison of systems operating at different radar bands the atmospheric influence on the microwave radiation can be considered as well Figure 10 depicts the respective parameters for atmospheric and rain loss Figure 9 Main RFSCAT simulator window with the Atmosphere menu Change Atmospheric Conditions Figure 10 Menu for the atmospheric conditions User Manual Version 1 0 Page 15 4 Wind Retrieval RESCAT Simulator 4 Wind Retrieval Th
21. ocumented in the IDL file rfscat simulator rfscat ini which is shown in Figure below Even if the default setting is being used the name of mydisk in dbpath and printpath must be adjusted to the actual setting rrScak INI pro PURPOSE Environment settings for the main module rfscat pro of the Rotating Fanbeam Scatterometer RFSCAT Simulator INPUT None OUTPUT None USES None Current Setting for Ifars 11 04 2002 Please set the followings paths according to your computer system Make sure that you have write permission for all directories Ne Ne nN Ne Ne Che Ne 05898 Ne Ne Ne Ne Ne Ne N dbpath myddsk vtecsbp printpath mvassk mrscat potobs The following directories are also needed keep this setting lutpat e dbpathi lut JEEP dbpath t llb windpath dbpath wind Swap_bytes e g for files from KNMI nws Number of Wind Cell Simulations random_data Figure 1 Example of a rfscat ini file User Manual Version 1 0 Page 5 2 Installation RESCAT Simulator 2 3 1 Look up Tables lut Two different types of look up tables are provided with the RFSCAT simulator The files with two way antenna pattern of systems which have been simulated within the study are summarized in Table 1 These antenna pattern can be accessed through the GUI and used for further system simulations The wind retrieval module requires look up tables of the geophysical model functions GMF These tables are
22. ree tasks are performed within the wind retrieval module of the RFSCAT simulator 1 Level Ib NRCS data are computed from the pseudo level 1b data using the measurement geometry a reference wind field and a GMF 2 Geophysical and measurement noise is added to the NRCS data 3 Wind vectors are retrieved from the simulated NRCS data based on the measurement geometry and GMF Furthermore if required several radar channels are combined in the retrieval Therefore the Wind Retrieval menu has options for generating a reference wind field for combining several pseudo level 1b data files with one reference wind field and to start the retrieval These options can be seen in Figure 11 HFSCAT SIMULATOR Version 1 0 beta Figure 11 Starting the wind retrieval sub menu The menu point Open Retrieved Wind Field has the same function as under the File menu and opens an retrieved wind field for further analysis Further details are given in Section 5 Analysis User Manual Version 1 0 Page 16 4 Wind Retrieval RESCAT Simulator 4 1 Generating a Reference Wind Field The menu point Generate Input Wind Field allows to create a reference wind field with a defined statistics The u and v components of the wind field as well as the wind speed can be normally or uniformly distributed with a given mean only for normal distribution and a given width If a wind speed distribution is being selected the wind direction is unifo
23. rmly distributed In the case of standard simulations of one orbit with 1500 km or 1800 km swath width and resolutions of 50 km and 25 km the number of cells is set automatically However the number of wind vectors to be used in the retrieval can be set manually as well The reference wind field will be stored under the given filename in the directory rfscat wind see Figure 12 bda Generate a Reference Wind Field Define and generate a reference wind field Please check your selection if this window does nat close with the OK button listributionsz Swath Midth Resolution Normal of Components 1500 km 4 50 km we Normal of Wind Speed ae 1800 km wr 25 km we Uniform of Components se Uniform of Wind Speed Mean m s ho Width m s t 55 0 0 Humber of Cells 2504 File Mame t Reference llind CANCEL Ok Figure 12 Defining the statistics of the reference wind field User Manual Version 1 0 Page 17 4 Wind Retrieval RFESCAT Simulator 4 2 Selecting a Reference Wind Field Before starting the wind retrieval a reference wind field must be selected The menu point Select Input Wind Field in Figure 11 opens a file selection window as depicted in Figure 13 Please select a File for Reading Figure 13 File selection menu for the reference wind field User Manual Version 1 0 Page 18 4 Wind Retrieval RESCAT Simulator 4 3 Selecting Pseudo Level 1b Data Before starting the wind retriev
24. tory is used for storing reference wind fields as well as retrieved wind fields After the installation it will contain a single file n55a ref which contains a reference wind field for one orbit of the baseline RFSCAT system as described in the Task 3b Report It has normally distributed wind components with a mean of 0 0 m s and a width of 5 5 m s The GUI allows to create reference wind fields of any size and statistical properties which will be stored in this directory User Manual Version 1 0 Page 6 2 Installation RESCAT Simulator 2 3 3 Pseudo Level 1b data l1b This directory is empty after the installation The first step in the simulation process is to compute the pseudo level Ib data which includes for each resolution cell the measurement geometry the effective number of sample and the SNR see Task 2b Report for details Together with reference wind fields real level Ib data are created within the retrieval module but only the retrieval results are stored again 2 3 4 Output Files plots The analysis module of the GUI offers various possibilities for displaying plotting and storing of analysis results This is the default location for these outputs 2 4 Filenames The filenames used by the RFSCAT simulator have a defined structure and or specific extensions used in the filters of various file selection menus The look up tables for the GMF are known to the wind retrieval module and their names must not be modi

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