ERA5-Land Liquid rainfall amount calculation by (Total precipitation - snowfall)?

Datasets and Usage C3S - Datasets and Usage
, ,
1

I would like to calculate the liquid rainfall amount using ERA5-land hourly data, as the descriptions of "total precipitation" says it includes both liquid and frozen water (i.e. rain and snow), I wonder if I only want to get liquid rainfall should I calculate it by (total precipitation - snowfall)?

2

You are right, to obtain the liquid rainfall amount simply do Liquid_precipitation = Total_precipitation (liquid+frozen) - Snowfall (frozen). This will provide you the amount of liquid precipitation used to force the land surface model.

The reason for doing this in such a way is quite technical, we don't have a single grib parameter code for rainfall, and there is a step when the liquid and frozen precipitation have to be merged and output by the model.


Best,

Joaquín


3

Thanks and quite useful Joaquin. And if I download these data from ERA5 (not ERA5-Land) and do the calculation as you say, I will get the rain intensity with 1-hour integration time. Am I right?

I have read in this forum that working with ERA5-Land is a bit tricky because the accumulation period.

4

Dear Gustavo,

That's right, if you follow the same principle above you should obtain the liquid part of the precipitation, always taking into account that the period of accumulation is indeed different between ERA5 and ERA5-Land.

Working with ERA5-Land data is not that tricky as it follows the same principle that it was used for ERA-Interim. However, in ERA5 we adopted only an hourly cumulation period as this was a user requirement.

Regards