Testing recipitation results

The Utrack protocol was setup for i) the ERA5 mean monthly evaporation between 2008-2017, and ii) for the ERA5 monthly evaporation plus the changes in ET for each scenario.

The tests below are meant to evaluate the relationship between the footprints estimated by Utrack and the real precipitation from ERA5.



Precipitation results





Comparison with ERA5 precipitation



Seasonal precipitation

Annual average precipitation (mm/day)



For context and comparison, here are similar results obtained by Tuinenburg et al. (2020) (figure 4).

Tuinenburg et al. (2020) - figure 4. Seasonal variability of precipitation recycling ratio over land. Precipitation recycling ratio is the fraction of precipitation that has evaporated from land. (a) January through March. (b) April through June. (c) July through September. (d) October through December.



Tuinenburg et al. (2020) (figure 8).

Tuinenburg et al. (2020) - figure 8. (a) Global precipitation (mm d−1) during 2008–2017 derived from the moisture tracking model UTrack. (b) Global precipitation (mm d−1) during 2008–2017 from the ERA5 dataset. (c) The absolute deviation of the precipitation from UTrack to that from ERA5 (mm d−1). (d) The relative deviation of the precipitation from UTrack to that from ERA5 (deviation as fraction of ERA5 precipitation).



Investigating cases with recycling ratio above 1

When analyzing results in monthly time scale, we find cases in which the recycling ratio is above 1, as shown below.





The amount of gridcells.months in which the recycling ratio is higher than 1 is around 3.1 %, i.e. 998 of 31882 records.