5 Feb (CLIM) Seo, Diurnal Precipitation & Land-Air Interactions

Eunkyo Seo, Pukyong National University 

Misrepresentation of land-atmosphere interactions due to model fidelity in capturing diurnal precipitation  

Wed, 5 Feb, 1:30pm 

Innovation 134 and via Zoom (for link, email bklinger@gmu.edu) 

Host: Paul Dirmeyer 

The accurate representation of diurnal precipitation is critical for understanding land-atmosphere interactions and their impact on hydrological and energy cycles, but most current research relies on daily averages. This study investigates the systemic phase shift in diurnal precipitation in reanalysis datasets (e.g., ERA5, MERRA2, JRA-55, etc.), which typically occur earlier than peaks from observations. We explore the effects of this early peak on soil moisture climatology and land-atmosphere coupling processes. Results indicate that the early precipitation peak leads to surface cooling, suppressed upward longwave radiation, and increased latent heat flux, ultimately resulting in drier soil moisture climatology over the mid-latitude. Additionally, the early peak strengthens land-atmosphere coupling. This highlights the necessity of resolving diurnal cycles in model physics to mitigate biases in land surface reanalysis datasets and improve the reliability of modeled land-atmosphere interactions.