I downloaded the latent heat flux from fluxnet, the latent heat flux is per hour in W m-2. I summed each value per hour of the day to get the daily sum.

Now I have the daily sum of latent heat flux in W m-2 and want to daily evapotranspiration in mm.

You can calculate this with the formula ET= λ LE/λ. First you calculate the heat of vaporization; λ = 2.501 – (2.361 x 10^-3) x Ta. Where Ta is temperature air in celcius, I also have this daily data.

My calculations in my code (df stands just for dataframe and double ** is ^):

df['heat_of_vaporization'] = 2.501-(2.361*10**-3)*df['TA_daily_average']

df['ET'] = df['LE_daily_sum']/(df['heat_of_evaporation']*1000 *1000)*3600

Is the calculation right? It think I get the good data. I did * 3600 because of the seconds in an hour, added all the hours so not 3600*24 I think. Are the *1000 *1000 also right?

Thanks a lot!