Using a static (not monthly) dataset for LAI, GREENFRAC.

[MLandreau]

Hi,

I am trying to make realistic simulations lasting few days only and I can have access to a LAI raster data corresponding directly to the days I want to simulate. I would better use this one than the monthly modis_lai data. Thus, I have few questions :

1- Is it possible to use a static and not monthly LAI (and GREENFRAC, ...) dataset as WPS input ?

2- If yes, what kind of format can WPS read ?

3- If no, I think I would be able to interpolate to WRF grid by myself. Would that be sufficient to modify "manually" the value of LAI12M in geo-em ?

4- In this thread (LAI12 and GREENFRAC in geo_em file v.s LAI and VEGFRA in wrfout file) Kwerner mentioned that :
"GREENFRAC is a field interpolated from MODIS FPAR and is a 12-monthly field from geogrid. During the real.exe process, it will be interpolated to the model start time, and stored in the array "vegfra." However, if you're using the Noah LSM scheme, then LAI and VEGRA are computed during WRF, meaning the value for GREENGRAC in geogrid will be overwritten by the new computed value for VEGFRA by the Noah scheme. The Noah scheme uses the VEGPARM.TBL for its values."
Is there some documentation about the physical quantities that VEGFRA represents and about Noah LSM scheme ?

Mathieu

 

[Ming Chen]

Mathieu,
Please see my answers below:

1- Is it possible to use a static and not monthly LAI (and GREENFRAC, ...) dataset as WPS input ?

if you have more realistic static data of LAI, GREENFRAC, etc, you can use them.

2- If yes, what kind of format can WPS read ?

Please see the static datafile format described here: Chapter 3: WRF Standard Initialization

3- If no, I think I would be able to interpolate to WRF grid by myself. Would that be sufficient to modify "manually" the value of LAI12M in geo-em ?

Yes it is sufficient to change lai12m in geo_em files.

Note that LAI in WRF is either from VEGPARM.TBl or from static data, depending on the option of rdlai2d
rdlai2d = .false. ! use LAI from input; false means using values from table

If you modify LAI12M, your changes are only used by WRF with rdlai2d = true.

4- In this thread (LAI12 and GREENFRAC in geo_em file v.s LAI and VEGFRA in wrfout file) Kwerner mentioned that :
"GREENFRAC is a field interpolated from MODIS FPAR and is a 12-monthly field from geogrid. During the real.exe process, it will be interpolated to the model start time, and stored in the array "vegfra." However, if you're using the Noah LSM scheme, then LAI and VEGRA are computed during WRF, meaning the value for GREENGRAC in geogrid will be overwritten by the new computed value for VEGFRA by the Noah scheme. The Noah scheme uses the VEGPARM.TBL for its values."
Is there some documentation about the physical quantities that VEGFRA represents and about Noah LSM scheme ?

Please take a look at the documents here:

Noah-Multiparameterization Land Surface Model (Noah-MP LSM) | Research Applications Laboratory

ral.ucar.edu