Fig. 5: Diurnal cycle of relative humidity in ERA5.

Mean diurnal cycle of relative humidity at 850 hPa between 50 °S and 50 °N from ERA5 for the time periods 1941–1970 (light blue) and 1991-2020 (dark blue). The grey boxes indicate the start of new data assimilation windows at 09:00 and 21:00 UTC. Initial states for the subsequent forecasts at 18:00 and 06:00 UTC are indicated with a cross.