Hello
I am trying to estimate freshwater flux (E - P) from the ERA5 data of total precipitation and evaporation but I am totally confused by looking at the documentation. The units of E and P are in m equivalent of water and these data that I am using are at the interval of 3 hours starting from 00:00 and ending at 21:00 (i.e. eight 3-hourly values for a day). So I want to know how to convert m of water equivalent into mm per day using 3-hourly data in the ensemble mean of ERA5 for evaporation and total precipitation?
Also, the evaporation variable has both positive and negative values i.e. condensation and evaporation respectively based on the flux direction. So how to use evaporation in order to compute freshwater flux?
Cheers, Saurabh
Hello
Try with this link:
https://confluence.ecmwf.int/display/CKB/ERA5-Land%3A+data+documentation
The hydrological parameters are in units of "m of water equivalent per day" and so they should be multiplied by 1000 to convert to kgm-2day-1 or mmday-1.
You can convert m to mm. Note that the time increment for that layer of water is 3 hours. Hence, you will get mm/(10800 seconds). You can add the 8 values per day to get mm/day (daily) or retain the 3 hour increments and simple divide each mm/10800 seconds by 8 getting mm/day (3 hourly).
No clue why you would have negative precip values.
Dear Sir, To convert an equivalent cubic meters of ( m3 into mm), of precipitation in a specific area as follows:
Each 1 mm in an area of 1 square meter = 1 liter volume= (1000mm) in meter Square
For example. Each 1 mm in an area of one hectare = 1 mm x 10 = 10 cubic meters. If the average rainfall in 22 hours = 20 mm. The amount of rainfall is estimated as follows: the volume of the amount in millimeters x area = 10 mm x 10 (hectares) = 100 cubic meters in 22 hours per hectare. Best regards.
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