Is the canopy to ground reflectance ratio updated post-launch?

[tomosarliuxiao]

Hi all,

I am using the GEDI Level2B canopy cover product (version 2) to detect the change in canopy cover before and after forest disturbance in temperate forests. The canopy to ground reflectance ratio ρ_v⁄ρ_g is an important parameter for estimating canopy cover. This ratio depends on the canopy structure and can change over time. According to the ATBD of the GEDI L2B product, this ratio is planned to be updated after the launch. However, it is a constant value (1.5) in the current GEDI L2B product.

Can someone please explain if the current canopy cover product is estimated using a constant or updated ρ_v⁄ρ_g? If this ratio is updated, where can I find the updated value?

Thank you very much.

Kind regards,
Xiao

[LP DAAC - lien]

Hi Xiao,
We are checking with the developer of the product to find out for sure if it is using the updated or constant version. As soon as we hear for sure we will let you know.
Thanks,
Brett

[LP DAAC - lien]

Hi Xiao,
We heard back from the GEDI developers, and following is their comment:

"Version 2 used a constant (1.5) that was based on average estimates from LVIS. Version 3 will include spatially varying estimates of rhov/rhog, which will be available when that product is released (in the near future as you know).

The version 3 estimates will be gridded (aggregate values), and do not account for temporal change. More accurate estimates can be derived by estimating for individual channels/beams in a local area, assuming there is sufficient quality data to fit the model. The canopy/ground integrals (Rv,Rg) are available in L2B and can be used for this purpose."

Thanks,
LPDAAC

[tomosarliuxiao]

Many thanks for the information.