I have a monthly dataset of GLDAS evapotranspiration (version 3.6 a with 3-hourly temporal resolution). The conversions I have come across suggests multiplying the dataset values with 86400*(Number of days in the month) which sounds reasonable however the dataset values are all greater than 1 thus, this conversion will result in unrealistic ET values (>86400 mm at least).
So, I was wondering if the monthly dataset are actually daily ET values averaged over the month, making the actual units of the dataset kg/m2/day (mm/day) which require multiplication only with the number of days in the month.
Please provide your opinion over this.
Given the density of water, 1000 kg/m^3, the evapotranspiration (ETA) in the units of kg/m2/sec with 3 hours intervals, can be expressed in mm/month as
ETA [mm/month] = ETA [kg/m2/sec] x 10800 [sec/3hr] x 8 [3hr/day] x 30 [days]
Vagner Ferreira I have been through multiple threads regarding this and found this one intriguing:
https://www.researchgate.net/post/How-do-I-convert-ERA-Interim-precipitation-estimates-from-kg-m2-s-to-mm-day
The answer provided by @Roberto Bencini is similar to yours however, he addressed the unrealistic values it yields.
For example, my dataset has an ETA of 1.91 kg/m2/sec for the month of January, 2000 which translates to 1.91 x 10800 x 8 x 31 = 5,115,744 mm/month.
1.91 kg/m2/sec is huge to be daily rate, but it make sense if the number is for cumulative amount in a month
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