Use of Satellite Soil Moisture to Diagnose Climate Model Representations of European Soil Moisture-Air Temperature Coupling Strength

Soil moisture-air temperature coupling (SMTC) strength affects European summer air temperature variability. However, due to a lack of spatially extensive ground-based soil moisture observations, General Circulation Model predictions of European-mean SMTC strength have not been adequately verified and contain substantial uncertainties. Here we utilize remotely sensed soil moisture to evaluate estimates of SMTC strength provided by seven Coupled Model Intercomparison Project Phase 5 (CMIP5) General Circulation Models (GCMs). Soil moisture retrievals provided by the Soil Moisture Active/Passive (SMAP) mission are shown to be uniquely suited for this purpose. Comparisons to SMAP-based estimates suggest that CMIP5 GCMs generally underestimate SMTC strengths-particularly in central Europe. This result is consistent with previous modeling work and highlights the value of L-band soil moisture remote sensing for land surface-atmosphere coupling analyses. Plain Language Summary Using newly available soil moisture data sets from Soil Moisture Passive/Active mission, we derive new observation-based estimates of soil moisture-air temperature coupling strengths over Europe, which demonstrate that General Circulation Model predictions of soil moisture and surface air temperature are generally undercoupled in areas of Europe. Since the variability of European summertime air temperatures has been linked to the strength of soil moisture-air temperature coupling, this result has significant implications for efforts to accurately project heat wave risks in Europe during coming the decades.