[Wrf-users] VEGPARM

[Jim Dudhia]

ALBEDO includes snow-cover effects but is equal to ALBBCK when there  
is no snow.
ALBBCK is the constant background snow-free value, which depends only  
on land-use type.
The one to modify is ALBBCK which is used to compute ALBEDO.
Jimy

On May 27, 2009, at 2:28 PM, Matei Georgescu wrote:

> Greetings WRF Users,
>
> I'm trying to overwrite certain vegetation characteristics (for
> example, albedo) read in from VEGPARM.TBL over a portion of my domain
> with my own values, for use in the latest version of WRF.
>
> I'm using the NOAH LSM.
>
> In module_sf_noahdrv.F, i inserted the following snippet:
>        DO 99 I=ids,ide
>          IF((XLAND(I,J)-1.5) < 0.) THEN
>
>            IF (J>=36 .AND. J<=76 .AND. I>=58 .AND. I<=112 .AND. &
>                (IVGTYP(I,J)==2 .OR. IVGTYP(I,J)==3 .OR.  
> IVGTYP(I,J)==4))THEN
> !               ALBEDO(I,J) = 0.16
>                ALBBCK(I,J) = 0.16
>            ENDIF
>
>          ENDIF
>        99 CONTINUE
>
> Two questions from here. First, what's the difference between
> "ALBEDO" and "ALBBCK"? I've seen others ask a similar question, but I
> haven't seen an answer.
>
> Second, when i run the model and then plot both ALBEDO and ALBBCK,  
> neither
> is changed, suggesting these values are perhaps over-written elsewhere
> down the line with the *TBL values?
>
> My task is simple enough but the placement of the code snippet is  
> crucial
> - can someone with more experience suggest where the code snippet  
> can be
> inserted to have the desired (ie maintain albedo through course of
> simulation) effect?
>
> thanks much,
> matt
>
>
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