Flash Drought in CMIP5 Models ‘‘Flash drought’’ (FD) describes the rapid onset of drought on subseasonal times scales. It is of particularinterest for agriculture because it can deplete soil moisture for crop growth in just a few weeks. To better understand theprocesses causing FD, we evaluate the importance of evaporative demand and precipitation by comparing three differentdrought indices that estimate this hazard using meteorological and hydrological parameters from the CMIP5 suite ofmodels. We apply the standardized precipitation index (SPI); the evaporative demand drought index (EDDI), derived fromevaporative demandE0; and the evaporative stress index (ESI), which connects atmospheric and soil moisture conditions bymeasuring the ratio of actual and potential evaporation. The results show moderate-to-strong relationships (r2.0.5)between drought indices and upper-level soil moisture on daily time scales, especially in drought-prone regions. We find thatall indices are able t

‘‘Flash drought’’ (FD) describes the rapid onset of drought on subseasonal times scales. It is of particularinterest for agriculture because it can deplete soil moisture for crop growth in just a few weeks. To better understand theprocesses causing FD, we evaluate the importance of evaporative demand and precipitation by comparing three differentdrought indices that estimate this hazard using meteorological and hydrological parameters from the CMIP5 suite ofmodels. We apply the standardized precipitation index (SPI); the evaporative demand drought index (EDDI), derived fromevaporative demandE0; and the evaporative stress index (ESI), which connects atmospheric and soil moisture conditions bymeasuring the ratio of actual and potential evaporation. The results show moderate-to-strong relationships (r2.0.5)between drought indices and upper-level soil moisture on daily time scales, especially in drought-prone regions. We find thatall indices are able to identify FD in the top 10-cm layer of soil moisture in a similar proportion to that in the models’climatologies. However, there is significant intermodel spread in the characteristics of the FDs identified. This spread ismainly caused by an overestimation ofE0, indicating stark differences in the land surface models and coupling in individualCMIP5 models. Of all indices, the SPI provides the highest skill in predicting FD prior to or at the time of onset in soilmoisture, while both EDDI and ESI show significantly lower skill. The results highlight that the lack of precipitation is themain contributor to FDs in climate models, withE0playing a secondary role. 2021 2022-01-01T00:00:00Z Land surface Drought Atmosphere-land interaction Evaporation Hydrometeorology Climate models Coupled models OAR (Oceanic and Atmospheric Research) PSL (Physical Sciences Laboratory) CIRES (Cooperative Institute for Research in Environmental Sciences) Submitted https://doi.org/10.1175/JHM-D-20-0262.1 Other 1953