Warm‐season precipitation drivers in northeastern Argentina: Diurnal cycle of the atmospheric moisture balance and land?atmosphere coupling

RUSCICA, ROMINA; RUSCICA, ROMINA; GILES, JULIÁN; GILES, JULIÁN; MENÉNDEZ, CLAUDIO G.; MENÉNDEZ, CLAUDIO G.

INTERNATIONAL JOURNAL OF CLIMATOLOGY

JOHN WILEY & SONS LTD

Lugar: Londres; Año: 2020

0899-8418

Southeastern South America is influenced by moisture transport from lowerlatitudes, sustains intense convective storms and is a land?atmosphere couplinghotspot, but the interconnection between these processes is still not wellunderstood. We present the warm-season diurnal cycle climatology of theatmospheric water balance components in the South American Low-Level Jet(SALLJ) exit region in northeastern Argentina during 1998?2012. Different precipitation-based types of events (clear-sky and rainy days) were exploredtogether with processes tied to the land?atmosphere coupling at the daily scale.Our research was based on simulations with and without soil moisture?atmospherecoupling with the RCA4 regional climate model. A control simulationwas compared with a sensitivity simulation where the soil moisture was prescribedwith the daily climatological values from the control run. The ERA5reanalysis and the satellite precipitation products TRMM-3B42 v7 andCMORPH v1.0 bias-corrected were used for comparative purposes. From thediurnal water balance analysis, we found that moisture flux convergence in theregion is the main driver for nocturnal precipitation while local evapotranspirationfeeds afternoon rain events. Rainy afternoons do not show differencesbetween simulations, but rainy nights seem to be affected. Moreover, daily correlationsbetween surface and boundary-layer variables showed that the localcoupling is weaker during rainy days than during clear-sky days. Therefore, wesuggest that changes in non-local drivers, such as the moisture flux throughthe SALLJ, are more relevant for rainy nights than the local coupling.