Hello everyone,
I’ve tried looking everywhere for an explanation for this question and have only found clear instructions on how to calculate daily precipitation for ERA5 products but not for ISF.
What I’ve understood so far from the documentation I’ve read is that the total precipitation parameter in ISF is the accumulation over hourly steps. Each day the forecast initialises at 00h and 12h, when the accumulation is set to 0. Now, to get the daily total precipitation, I thought it’d make sense to only take step 12 for each of these times, i.e. 00h + 12 = 11h and 12h + 12 = 24h, and to sum the precipitation values at 11h and 24h. However, I’m still unsure if total precipitation in the archive data of ISF follows the same idea as in:
- ERA5-Land, i.e. the daily total precipitation is given by 00h time of the following day
- ERA5, in which each hour is the amount of precipitation calculated for just that hour, without summing past values, i.e. the daily precipitation is given by the sum of all 24h hours in a day.
More here: Conversion table for accumulated variables (total precipitation/fluxes) - Copernicus Knowledge Base - ECMWF Confluence Wiki
If the latter, then I’d have to sum the 12 steps from both 00h and 12h, to get the accumulated rain over 24 hours, instead of only summing 2 steps, as mentioned above.
A MARS request example of the parameter I’m retrieving:
retrieve,
class=od,
date=2024-09-24,
expver=1,
levtype=sfc,
param=228.128,
step=12,
stream=oper,
time=00:00:00/12:00:00,
type=fc,
target="output"
Thanks!