Processing steps of the SAI(/LAI)?

[EliseHuysman]

Dear,
I was wondering how the SAI (and LAI) was processed for the lis input? I found the data in the portal (https://portal.nccs.nasa.gov/lisdata_pub/data/PARAMETERS/UMD/), but can't find a readme file for SAI and LAI like I can for the other parameters. How was this data processed? Thank you for your help!
Kind regards,
Elise

[dmocko]

Hi @EliseHuysman

This is a great question, and we're really not 100% sure. I believe that the SAI/LAI data we pre-processed onto these grids also derives from the same AVHRR dataset that produced the GVF dataset. There is a README for the GVF data. However, since both GVF and LAI/SAI are derived from this same product, they should NOT be used at the same time. Please see this document (pages 11-12):

https://ral.ucar.edu/document-or-file/noah-lsm-users-guide

How are you using the SAI/LAI datasets? There are likely more modern products available.

[EliseHuysman]

Hi @dmocko
I am mostly looking for a good, recent SAI dataset for the Congo basin (Cuvette Centrale) region to use with NoahMP vegetation option 7 (use input LAI/SAI; use input GVF) to have most accurate spatially-variable prescribed vegetation input, similar to what they do in the SMAP L4 SM product using the Catchment Land Surface model. For LAI and GVF, I am using copernicus data, but wanted to check where this one came from as I am having some trouble finding a good dataset for SAI.
Thank you for sharing the documentation, I'll look into it.

[karsenau]

Hi @EliseHuysman,

We wanted to provide a bit more background on the source of the LAI/SAI datasets that you found at our LIS public data portal.

That original dataset goes back to the Community Land Model (CLM) days when it was one of the first models implemented into LIS. One of the original published articles on how the LAI and SAI datasets was derived and used in CLM:

https://opensky.ucar.edu/islandora/object/articles%3A17599

For the more recent related data sources, NCAR still has published the data as part of CLM and their "surface" data source:
https://ihesp.github.io/rcesm1/clm_grid.html

And the latest CLM version 5 technical document on how SAI is still utilized in the model:
https://www2.cesm.ucar.edu/models/cesm2/land/CLM50_Tech_Note.pdf
Check out: Section 29.5.2 Definition of Leaf and Stem Area Profile
For more history and background on the SAI calculations.