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MOD16A2 Unit Conversion

Posted: Sun Jul 09, 2023 1:43 pm America/New_York
by denizegeo16
Hello, I'm writing a code in Google Earth Engine to calculate the annual evapotranspiration from 2001 to 2022, and I'm trying hard to convert kg/m^2/8day to mm/year. How to make? I am using product MOD16A2.006.

Re: MOD16A2 Unit Conversion

Posted: Tue Jul 11, 2023 10:00 am America/New_York
by LP DAAC - dgolon
Hi @denizegeo16 please see this post where we had a similar conversation: viewtopic.php?t=2806 According to our science team, the kg/m²/ 8 day is the same as mm/8 day. You might be interested in the Yearly MODIS/Terra Net Evapotranspiration Gap-Filled L4 Global 500 m SIN Grid product that already exists: https://doi.org/10.5067/MODIS/MOD16A3GF.061 Thanks - Danielle

Re: MOD16A2 Unit Conversion

Posted: Fri Aug 18, 2023 12:00 pm America/New_York
by olayowale
I just need to confirm something. I am working on MOD16A3GF yearly data and I discovered the scale is 0.1. What does this mean?, Do I need to divide my extracted ET_500m values by 10 or what?

If yes, when I divided by 10, I obtained strange two digits values of ET in areas where ET is greater than 600m/year

Re: MOD16A2 Unit Conversion

Posted: Mon Aug 21, 2023 9:59 am America/New_York
by LP DAAC - lien
Hi,
Yes the scaling factor is 0.1 (divide by 10). If there seems to be some erroneous numbers you may want to check with the QA bits to see if those pixels are of questionable quality.
Thanks,
Brett

Re: MOD16A2 Unit Conversion

Posted: Mon Aug 21, 2023 10:31 am America/New_York
by olayowale
Thank you for your response, I discovered the software (MATLAB) I am using already considered the scaling factor when I read the netcdf file, so I dont need to divide my result by 10