How to use the WRF/Noah/BEP coupled modeling system
Contents
1. ROAD WIDTH 10 0 9 4 8 3 it AH Anthropogenic heat W m 2 UCM AH 90 0 50 0 20 0 FRC_URB Fraction of the urban landscape which does not have natural vegetation Fraction UCM BEP FRC_URB 0 95 0 9 0 5 12 CAPR Heat capacity of roof J m 3 K 1 UCM BEP CAPR 1 0E6 1 0E6 1 0E6 CAPB Heat capacity of building wall J m 3 K 1 UCM BEP CAPB 1 0E6 1 0E6 1 0E6 CAPG Heat capacity of ground road J m 3 K 1 UCM BEP CAPG 1 4E6 1 4E6 1 4E6 AKSR Thermal conductivity of roof J m 1 s 1 K 1 UCM BEP AKSR 0 67 0 67 0 67 13 AKSB Thermal conductivity of building wall J m 1 s 1 K 1 UCM BEP AKSB 0 67 0 67 0 67 AKSG Thermal conductivity of ground road J m 1 s 1 K 1 UCM BEP AKSG 0 4004 0 4004 0 4004 ALBR Surface albedo of roof fraction UCM BEP ALBR 0 20 0 20 0 20 ALBB Surface albedo of building wall fraction UCM BEP ALBB 0 20 0 20 0 20 ALBG Surface albedo of ground road fraction UCM BEP 14 ALBG 0 20 0 20 0 20 EPSR Surface emissivity of roof UCM BEP EPSR 0 90 0 90 0 90 EPSB Surface emissivity of building wall UCM BEP EPSB 0 90 0 90 0 90 EPSG Surface emissivity of ground road UCM BEP2. If we use the 33 categories mentioned below num land cat must be put equal to 33 in namelist input URBPARM TBL In the file URBPARM TBL the urban classes are defined By default we defined three classes Please note that BEP assumes different building heights than UCM in the standard table and people should check for their specific urban area if this is suitable 31 Low Intensity residential Includes areas with a mixture of constructed materials and vegetation Constructed materials account for 30 80 percent of the cover Vegetation may account for 20 to 70 percent of the cover These areas most commonly include single family housing units Population densities will be lower than in high intensity residential areas 32 High Intensity residential Includes highly developed areas where people reside in high numbers Examples include apartment complexes and row houses Vegetation accounts for less than 20 percent of the cover Constructed materials account for 80 to100 percent of the cover 33 Commercial Industrial Transportation Includes infrastructure e g roads railroads etc and all highly developed areas not classified as High Intensity Residential If you are simulating an US city you can use the NLCD 2001 which has following 4 urban categories instead of 3 as is the case with 1992 data 21 Developed Open Space Includes areas with a mixture of some constructed materials but mostly vegetation in the form of lawn
3. meas MYT EXCH H EXCH AM It solves a wo 12 ae era RTHBLTEN RUBLTEN RVBLTEN In the pbl driver everything is managed by an hardcoded flag called idiff If idiff 1 the code uses the new structure If idiff 0 the code uses the old structure Explanation of the routine DIFF3D The routine DIFF3D is called at the end of pbl driver and it solves for each column of the domain the diffusion equation for the two horizontal components of momentum potential temperature water vapor mixing ratio could water mixing ratio In particular the equation solved for a generic variable C that could be U V TH Q etc is a t p z Oz Where K is the exchange coefficient EXCH_H for momentum K and EXCH_M and S represents the sources or sinks terms of the variable C This source term can be written as a linear function of C or S AC B Where A is the implicit component and B is the explicit component The fluxes of heat and momentum coming from the surface and the buildings goes in S I defined then for each diffused variable U V TH QV QC new arrays called a_u a_v a t a_q a_qc andb u b v b t b q b qc that are filled at the beginning of the pbl driver routine and passed to the diff3d routine at the end of pbl driver If some of the pbl schemes has a non local term it can goes in the b variables If BEP is not used the surface fluxes enter in the a and b arrays in the following way
4. For the potential temperature if we choose an explicit resolution as it is now in the code we have a_t 90 HFX rF EF Piaj Cp Xz Lj b If the resolution is implicit like in the standard MYJPBL routine this is now commented in the code 1 a_t akhs LEJ thz0 b taj akhs 4 i l j Which is equivalent to write for the lowest model level n indicates the time EE EK 0 0 For water vapor explicitely a_ ding 0 OFX b_ ga e Pin j Zin And implicitely a akhs 3 linj iij Az qz0 b din akhs AG lj For momentum the resolution is done implicitly starting from the consideration that the momentum flux at the surface for U and V is U g U V gt iy i U 4V Sy V Then taking the U and V at numerator at time n 1 while those at denominator are kept at time n we have 5 ur 1 Sy Us 2 2 U V Az n l 1 Sy u Y 7 U V Az and 2 1 a U U i j A q 2 2 Ja Ging t Ving Anj b_u 9 2 1 a V Uy i j ee a 2 2 Ya Ging Vin AS bv 0 ij If BEP is used those values are weighted average using the fraction of urban area in the cell with the values of a and b terms coming from the BEP routine At the moment this new structure works with MYJPBL and BOULAC schemes It is planned to make it working with any of the PBL schemes Numerical details of the routine If we discreti
5. EPSG 0 95 0 95 0 95 ZOR Roughness length for momentum over roof m UCM BEP ZOR 0 01 0 01 0 01 15 H ZOB Roughness length for momentum over building wall m Only active for CH SCHEME 1 UCM H ZOB 0 01 0 01 0 01 ZOG Roughness length for momentum over ground road m Only active for CH_SCHEME 1 UCM BEP ZOG 0 01 0 01 0 01 ifdef FOR ALBERTO STREET PARAMETERS BEP urban street street building category direction width width index deg from N m m 1 0 0 15 0 15 0 1 90 0 15 0 15 0 2 0 0 15 0 15 0 2 90 0 15 0 15 0 16 3 0 0 15 0 15 0 3 90 0 15 0 15 0 END STREET PARAMETERS BUILDING HEIGHTS 1 height Percentage m 5 0 30 0 10 0 40 0 15 0 30 0 END BUILDING HEIGHTS BUILDING HEIGHTS 2 height Percentage m 10 0 3 0 15 0 7 0 20 0 12 0 25 0 18 0 30 0 20 0 35 0 18 0 17 40 0 12 0 45 0 7 0 50 0 3 0 END BUILDING HEIGHTS BUILDING HEIGHTS 3 height Percentage m 5 0 50 0 10 0 50 0 END BUILDING HEIGHTS endif DDZR Thickness of each roof layer m This is currently NOT a function urban type but a function H of the number of layers Number of layers must be 4 for now UCM DDZR 0 05 0 05 0 05 0 05 DDZB Thickness of each building wall layer m This is currently NOT a function urban type but a function H of the number of layers Number of layers mu
6. Description of the modifications made in WRF 3 1 and short user s manual of BEP Alberto Martilli CIEMAT S pain Susanne Grossmann Clarke Arizona State University Mukul Tewari NCAR Kevin W Manning NCAR 4 Sept 2009 Introduction This document is about three changes introduced in the 3 1 release 1 Change in the structure of the pbl driver routine available with idiff 1 flag hardcoded in module pbl driver F 2 Implementation of the multilayer urban scheme BEP There is now a new entry in the namelist input called sf urban physics When the flag is equal to 2 the BEP routine is used The module is called module sf bep F 3 Implementation of the Bougeault and Lacarrere 1989 PBL scheme This is equivalent to option 8 for flag bl pbl physics The module is called module bl boulac F Below a detailed description of the changes in the pbl driver structure is provided point 1 above and a short user s manual for the use of BEP point 2 above is given 1 Change in the structure of pbl_driver In the new structure each PBL routine does not compute the tendencies but provides only the exchange coefficients called EXCH H for exchange coefficient for heat and EXCH_M the exchange coefficient for momentum Then the tendencies for the different variables are estimated in a routine called DIFF3D at the end of pbl driver This new structure can be represented as pbl driver Included Syse sttface fluxes ro rural
7. LCD 1992 data and the NLCD 2001 data If you are simulating a city not in the US and you have data to identify the three extra urban classes you need to add the extra classes to the landuse file For the moment we limited to only three urban categories It is possible to have more categories but this will need to introduce some changes in the code If the user has detailed 10 information on urban morpohology is encouraged to create as many urban classes as he needs to better represent the city is studying The values of thermal properties and urban morphology for each urban class are defined in URBPARM TBL Several variables are common to UCM and BEP while others are specific only to BEP Below is an example of the file where the variables that are for BEP or UCM are indicated Urban Parameters depending on Urban type USGS Number of urban categories 3 Where there are multiple columns of values the values refer in order to 1 Commercial 2 High intensity residential and 3 Low intensity residential I e UCM BEP Index 1 2 3 Type Commercial Hi dens Res Low dens Res FS FSF FS FH KF HK FH ZR Roof level building height m UCM ZR 10 0 7 5 5 0 11 H ROOF WIDTH Roof i e building width m UCM KWM Just made up some numbers for the time being H ROOF WIDTH 10 0 9 4 8 3 ROAD WIDTH road width m UCM KWM Just made up some numbers for the time being
8. e several numerical layers within the urban canopy The drawback of this approach is that the CPU time may increase For this reason it is suggested to use BEP to reproduce past case studies where the CPU constraint is less important than for weather forecast It is also expected that the impact of BEP will be more relevant for air quality or urban climate studies where the behaviour of the atmosphere in the urban canopy is particularly important because it is where the people live rather than for weather forecast studies The files to modify to run WRF BEP are namelist input and URBPARM TBL see detailed explanation below If new urban classes are added also the landuse file needs to be modified accordingly Respect to the single layer UCM the only extra input needed is the vertical distribution of building heights for each urban class which should be included in URBPARM TBL see below By default there are no new outputs specific for BEP The impact of the scheme will be visible in the 3D temperature and wind fields The 2m temperature and 10m winds have been forced equal to the lowest model level This is mainly for two reasons a Monin Obukhov Similarity Theory is not valid in the urban canopy so that it is impossible to derive the 2m and 10m values using the log law b to run WRE BEP it is necessary to have a very high vertical resolution 5 10m so that the differences between the lowest model level value and the 2m and 10m values are
9. expected to be small I How to run WRF with BEP namelist input To run WRF with BEP it is necessary to set the option sf urban physics 2 in the namelist input file Variable sf urban physics is a multidomain variable so a value should be set for each domain Again it is suggested to use BEP only for the inner domains with horizontal resolution of the order of few kilometres or less to save CPU time We suggest also using the 6 order filter in order to avoid oscillations that may arise at the border of the city where a strong change in roughness is present At the moment BEP has been coupled only with the NOAH land surface scheme so it works only with sf surface physics 2 Moreover BEP works with two PBL schemes MYJ and BOULAC Bougeault and Lacarrere 1989 This latter has been recently implemented option bl pbl phyiscs 8 Future plans are to couple BEP with YSU If the standard USGS classes are used there is only one urban class landuse type 1 The parameters of this class have been set equal to class 2 Hi density residential in the URBPARM TBL see below Alternatively you can add three extra urban classes each one characterized by values of the thermal properties of the materials and of the urban morphology see file URBPARM TBL In namelist input the parameter num_urban_layer should be added in the physics section This should be equal to at least the product of nz_um ndm nwr_u set in module sf bep F
10. grasses Impervious surfaces account for less than 20 percent of total cover These areas most commonly include large lot single family housing units parks golf courses and vegetation planted in developed settings for recreation erosion control or aesthetic purposes 22 Developed Low Intensity Includes areas with a mixture of constructed materials and vegetation Impervious surfaces account for 20 49 percent of total cover These areas most commonly include single family housing units 23 Developed Medium Intensity Includes areas with a mixture of constructed materials and vegetation Impervious surfaces account for 50 79 percent of the total cover These areas most commonly include single family housing units 24 Developed High Intensity Includes highly developed areas where people reside or work in high numbers Examples include apartment complexes row houses and commercial industrial Impervious surfaces account for 80 to100 percent of the total cover The following remapping procedure should be adopted The land use categories 21 and 22 should be mapped to land use category 31 The land use category 23 should be mapped to 32 and The land use category 24 should be mapped to 33 The procedure to download the data and the source code to change the data to the compatible WPS format is described at http www mmm ucar edu people duda files how_to_hires html There are 2 sample programs available at this site to process the N
11. hrough the introduction of the two parameters vl and sf which are the fraction of the volume cell not occupied by buildings v and the fraction of surface at the faces of the grid cell not occupied by buildings sf see eqn 21 in Martilli et al 2002 The equations are then modified as follows 1 cddz sf p K Az i ol At al cddz P vl AZ 1 A a2 1 4 cddz eddz A At Pr VI Az 1 A es P vi Az The routine computes also diagnostically the vertical turbulent fluxes of momentum WU TUR WV_TUR WT TUR WQ TUR These are 3D variables that are in the outputs can be used for analysis of the PBL schemes for example 2 How to use WRF with BEP multilayer Urban Canopy Model This document explains how to use the multilayer urban canopy model BEP implemented in the meteorological model WRF In a city the sources sinks of heat momentum and turbulent kinetic energy are not localized only at the surface but they are vertically distributed in the whole urban canopy layer This is one of the reasons of the differences in the vertical structure of the Surface Layer between cities and flat rural areas The inclusion of BEP attempts to simulate this effect details about the formulation can be found in Martilli et al 2002 In order to get full advantage of the scheme it is necessary to run the model with a very high vertical resolution 5 10m in the lowest levels in order to hav
12. li A Clappier A and Rotach M W 2002 An urban surface exchange parameterization for mesoscale models Boundary Layer Meteorol 104 261 304 24
13. s A b_u_bep this is a 3D variable that brings the explicit part of the momentum sink x component induced by the buildings B a_v_bep this is a 3D variable that brings the implicit part of the momentum sink y component induced by the buildings b_v_bep this is a 3D variable that brings the explicit part of the momentum sink y component induced by the buildings a t bep this is a 3D variable that brings the implicit part of the potential temperature source sink induced by the buildings b_t_bep this is a 3D variable that brings the explicit part of the potential temperature source sink induced by the buildings a_q_bep this is a 3D variable that brings the implicit part of the moisture source sink induced by the buildings b_q_bep this is a 3D variable that brings the explicit part of the moisture source sink induced by the buildings a e bep this is a 3D variable that brings the implicit part of the tke source sink induced by the buildings b_e_bep this is a 3D variable that brings the explicit part of the tke source sink induced by the buildings dig bep dl u bep are length scales needed to estimate the impact of buildings on tke sf bep vl bep are the air surface and volume fraction left by the buildings in the urban canopy References Bougeault P and Lacarr re P 1989 Parameterization of orography induced turbulence in a mesobeta scale model Mon Wea Rev 117 1872 1890 23 Martil
14. st be 4 for now UCM 18 DDZB 0 05 0 05 0 05 0 05 DDZG Thickness of each ground road layer m This is currently NOT a function urban type but a function H of the number of layers Number of layers must be 4 for now UCM DDZG 0 05 0 25 0 50 0 75 BOUNDR Lower boundary condition for roof layer temperature 1 Zero Flux 2 T Constant UCM BOUNDR 1 BOUNDB Lower boundary condition for wall layer temperature 1 Zero Flux 2 T Constant UCM BOUNDB 1 19 BOUNDG Lower boundary condition for ground road layer temperature 1 Zero Flux 2 T Constant UCM BOUNDG 1 TRLEND Lower boundary condition for roof temperature K UCM TRLEND 293 00 293 00 293 00 TBLEND Lower boundary temperature for building wall temperature K UCM TBLEND 293 00 293 00 293 00 TGLEND Lower boundary temperature for ground road temperature K UCM TGLEND 293 00 293 00 293 00 Ch of Wall and Road 1 M O Similarity Theory 2 Empirical Form of Narita et al 1997 recommended UCM 20 CH SCHEME 2 Surface and Layer Temperatures 1 4 layer model 2 Force Restore method UCM TS SCHEME 1 AHOPTION 0 No anthropogenic heating 1 Anthropogenic heating will be added to sensible heat flux term UCM AHOPTION 0 Anthropogenic Heating diurnal profile UCM Multiplica
15. tion factor applied to AH as defined in the table above Hourly values 24 of them starting at 01 hours Local Time For sub hourly model time steps value changes on the hour and is held constant until the next hour 21 AHDIUPRE 0 16 0 13 0 08 0 07 0 08 0 26 0 67 0 99 0 89 0 79 0 74 0 73 0 75 0 76 0 82 0 90 1 00 0 95 0 68 0 61 0 53 0 35 0 21 0 18 Users are invited to adapt these values to their case Initialization The initial temperatures for wall roof and street are initialized in the subroutine urban_var_init of the module_sf_urban F The names of the variables are TRB_URB4D roof temperature TW1 URBAD and TW2_URB4D wall temperatures TGB_URB4D street temperature Note that the values of the initial temperature at the deepest level are kept constant for the whole simulation By default they are initialized with TSLB 2 Routines modified The new urban scheme is in routine module sf bep F Other routines modified are in phys module _ pbl driver F module surface driver F module sf noahdrv F in dyn em module first rk step partl F start em F 3 New variables added in Registry The source sinks induced by the buildings are written as S Ayu B 22 Where can be an horizontal wind component the potential temperature or the moisture The new variables added are a u bep this is a 3D variable that brings the implicit part of the momentum sink x component induced by the building
16. ze the equation lt lip C t pa pP 2 4Ac B Oz coe l Using the convention that n indexes indicate the time lowercase i indicates the face of the level while UPPERCASE I indicates the center of the level or i 3 We have er Cy _ l l p en C Ci Ci At P Az i 1 p K ae A Cr B i i Since the density p is known at the center it is interpolated at the faces as follows NE PAZ PAZ i Az AZ Moreover z Az Az i 2 Then defining a local variable to simplify the notation as cddz p K i The full equation can be rewritten as GEC A i cddz Cui C cddz c Ci A Cre B At Pr Az And re arranged as 1A 1 1 At ae eddz C 01 cde cddz A ANC LE ceddz C C B At Pi Az Pi OZ Pi Az This can be solved by inversion of a tridiagonal matrix a2 a3 ce 2 al a2 a3 cC 2 al a2 a3 c7 2 al a2 a3 Crp al 2 Ley eel Where the lower diagonal is Bin ie Pi Az The main diagonal 1A a2 1 cddz eddz A At i Pi XZ The upper diagonal ee ile Pr Az And the right hand side term B C B At The problem is solved by matrix inversion using the subroutine invert If BEP is used moreover the air volume of the cell without buildings as well as the air surface at the faces of the grid cell are taken into account t
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