Hello,
I am trying to calculate ET over the Phoenix, AZ metropolitan area over 2 decades. I have a few questions about the units, first for MOD16A2. I add all of the ET pixels for every month, then multiplied by the scaling factor 0.1, and then took the mean within a defined zone. From my understanding, this returns ET values in mm. Is it correct that the value is only in mm, so the amount of water that evaporated/transpired in that area in a month? A colleague of mine calculated ET for the area using a different method, and has ET in units of mm/m^2/day (for the zone). How can I convert the data in mm/m^2/day to my ET data in mm to compare the values? Also, it seems that many of the MOD16A2 pixels over the Phoenix area are missing. I'd estimate about half of the pixels over my study area are NA. Can my methodology here still work if that many pixels are missing? (I am using Google Earth Engine for this work)
Unit conversions of ET data from MOD16A2 and missing MOD16A2 pixels
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LP DAAC-EDL - lien
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Re: Unit conversions of ET data from MOD16A2 and missing MOD16A2 pixels
Hello,
The MODIS Science team recommends the use of the MOD16A2GF whenever it is available: https://doi.org/10.5067/MODIS/MOD16A2GF.061
Because the 16A2GF can only be processed annually the 16A2 is still being processed as a place holder for the current year. Currently, the MOD16A2 is archive from January 1, 2021, to present. The MOD16A2GF is available from January of 2000 through December 27, 2023.
We certainly encourage users to take our data and manipulate and modify it to fit their needs. However, we do not have specific advice on how to complete what you are looking to do. So, we will leave this open to the science community in case any other users working on similar research and would like to chime in with their own advice.
Thanks,
LPDAAC
The MODIS Science team recommends the use of the MOD16A2GF whenever it is available: https://doi.org/10.5067/MODIS/MOD16A2GF.061
Because the 16A2GF can only be processed annually the 16A2 is still being processed as a place holder for the current year. Currently, the MOD16A2 is archive from January 1, 2021, to present. The MOD16A2GF is available from January of 2000 through December 27, 2023.
We certainly encourage users to take our data and manipulate and modify it to fit their needs. However, we do not have specific advice on how to complete what you are looking to do. So, we will leave this open to the science community in case any other users working on similar research and would like to chime in with their own advice.
Thanks,
LPDAAC