PXLSM MODIS Vegfrac

WRF-CMAQ
1

Hello,

I am trying to use PXLSM and came across this in the CMAQ User Guide in Appendix E: Configuring the Weather Research and Forecasting Model (WRF) for Use with Air Quality Models.

“Several important updates were made to the Pleim-Xiu LSM in WRF4.1. Soil hydraulics are calculated using analytical equations (Noilhan and Mahfouf, 1996) rather than lookup tables. And, users can opt to use time-varying vegetation fraction from a wrflowinp input file in WRF that can be based off MODIS satellite data instead of the old weighting method that is based on lookup tables and landuse fraction. This satellite data option is activated using the physics namelist option “pxlsm_modis_veg = 1”.”

I havent been able to find a guide on how to fully set this up but piece together the process from a few documents. If there is a guide I would love the link. Ive added this option to the physics namelist options after setting up WRF to create a wrfflowinp_d file by adding “wrflowinp_d” the namelist.input.

I set up WRF to process the VEGFRA and LAI by adding “geog_data_res = ‘nlcd2011_9s+9s+greenfrac_fpar_modis+lai_modis_10m’” to the namelist.wps.

I can run everything fine without “pxlsm_modis_veg = 1” but as soon as I add it I get

------ ERROR while reading namelist physics ------
Maybe here?: sf_urban_physics = 1, 1, 0,
Maybe here?: pxlsm_modis_veg = 1, 1, 1,
-------------- FATAL CALLED ---------------
FATAL CALLED FROM FILE: LINE: 10851
ERRORS while reading one or more namelists from namelist.input.

-------------- FATAL CALLED ---------------
FATAL CALLED FROM FILE: LINE: 10851
ERRORS while reading one or more namelists from namelist.input.

Been banging my head against this problem for a couple of days. Any help is appreciated!

2

I may need to test this on our system with a nest run. It does appear you are using it correct in terms of a value for each domain. This spec with max_domains means a value for each.

rconfig integer pxlsm_modis_veg namelist,physics max_domains 0

I cannot see how this occurs unless you are running a pre-WRFv4.1 executable. Feel a bit odd to ask, but just want to make sure you are using a new version of WRF.

Otherwise I’ll test on one of our domains and get back with you.

3

I just started up a WRFv4.1.1 executable with the modis veg setting. No issue at all. I’ll just need you to verify that you are using a WRFv4.1+ version of WRF and then we can look into it further. May at least you domain 1 inputs and namelist. But let me know.

sf_surface_physics = 3, 3,
bl_pbl_physics = 2, 2,
bldt = 0, 0,
cu_physics = 0, 0,
cudt = 0, 0,
mp_zero_out = 2,
isfflx = 1,
ifsnow = 1,
icloud = 1,
surface_input_source = 1,
num_soil_layers = 6,
num_land_cat = 24
pxlsm_smois_init = 0,0,
pxlsm_modis_veg = 0,0,
slope_rad = 1,1,
topo_shading = 1,1,
shadlen = 25000.,
sst_update = 1

4

The problem was I was running a pre WRF4.1 version. Just updated and everything is working now. Thanks for pointing that out! Sorry for such a stupid question haha.