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new wrf albedo data details?

I

Izidine

New member
Dear all,

In the new WRFV4.0 the default input SNOALB is changed from old 0.15 deg NCEP data to new 0.05 deg MODIS snow albedo data. If one uses usemonalb = .true. (default value is false), the default dataset from geogrid is changed from 0.15 deg NCEP data to new 0.05 deg MODIS data.
Does anyone have details of the climatology of the new MODIS data?
Or I'm correct to assume that the albedo is from MCD43D61 - MODIS/Terra+Aqua BRDF/Albedo White Sky Albedo Shortwave Daily L3 Global 30ArcSec CMG (https://ladsweb.modaps.eosdis.nasa.gov/missions-and-measurements/products/brdf-and-albedo/MCD43D61/) ?

Thanks
 
Hi,
We are trying to contact the group that provided these data files to us, to get a good response for you. We will let you know when we hear something.
 
Hi,
Thank you, I'm looking forward for the response. I'm currently testing the effect of using the AVHRR albedo vs the MODIS albedo on rainfall/temperature using the WRF.V3.8.1
 
Hi,

This paper should describe in detail how the dataset was produced:
Barlage, M., X. Zeng, H. Wei, and K. Mitchell, 2005: A Global 0.05 Maximum Albedo Dataset of Snow-covered Land Based on MODIS Observations, Geophys. Res. Lett., 32,L17405, doi:10.1029/2005GL022881.

Take a look at that and see if it answers the questions you have. Thanks!
 
Hi,

I had a question that is related to the original post. Is there further information or documentation about how 'albedo_modis' was calculated? Is the actual resulting dataset produced from Barlage et al (2005) equivalent to 'albedo_modis' from the geo download page? Is does the Barlage paper just outline the methodology to derive the global albedo dataset, and the actual 'albedo_modis' is different? I am confused because I can't find any clear documentation anywhere that describes exactly where 'albedo_modis' comes from or how it was derived.

I can't seem to find answers to basic questions such as:
- Who created 'albedo_modis'
- Is it based on black sky albedo, white sky albedo, NBAR, actual albedo?
- What years does it average over?
- etc.

It would be great if anyone pointed me in the right direction to find more information about 'albedo_modis' - Thanks!
 
Hi,
I apologize for the delay. I'm not sure, so I'm reaching out to others who may know. I'll keep you posted if/when I hear anything helpful.
 
Hi,
Okay, I heard back from a member of the group that created the albedo modis dataset. The person who did most of the work is, unfortunately, no longer at NCAR, but this is the information I was given by another member, based on what they were able to dig up.

albedo: MCD43C3 (MODIS product)
LAI/GVF: MCD15A2 (MODIS product)
15s land cover: based on that by Broxton and Xubin
The snow albedo is based on Barlage et al. 2005 GRL paper. The products and names were slightly different back then, but it was based on the 0.05 degree MODIS BRDF product.

Unfortunately that is the extent of what we know about it.
 
kwerner said:
Hi,
Okay, I heard back from a member of the group that created the albedo modis dataset. The person who did most of the work is, unfortunately, no longer at NCAR, but this is the information I was given by another member, based on what they were able to dig up.

albedo: MCD43C3 (MODIS product)
LAI/GVF: MCD15A2 (MODIS product)
15s land cover: based on that by Broxton and Xubin
The snow albedo is based on Barlage et al. 2005 GRL paper. The products and names were slightly different back then, but it was based on the 0.05 degree MODIS BRDF product.

Unfortunately that is the extent of what we know about it.
Click to expand...
Hi

Kwerner, Thanks for providing these information regarding the MODIS albedo products used for geogrid. I have a follow-up question, this albedo product should be snow-free albedo, right? Looking at the Noah LSM code in /phys/module_sf_noahlsm.F, the actual albedo considering the snow effect will be calculated based on this snow-free albedo, is my understanding correct? I have also potted the albedo in these binary files and I can see that in the wintertime in high latitudes, there are not high values of albedo. My understanding is that the snow-related albedo has been removed from this dataset?

Thank you very much,
Jessie
 
Hi Jessie,
Noah has an albedo calculation that uses the snow fraction (SNOW in the output). Where that is non-zero, there should be an effect (the effect may be smaller in forest areas).
 
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