Impact of the inundation occurrence on the deep convection at continental scale from satellite observations and modeling experiments

Christophe Prigent (1) , N. Rochetin (2) , F. Aires (3) , E. Defer (1) , J. Y. Grandpeix (2) , Chloé Jimenez (1) , F. Papa (4)

1 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique
2 LMD - Laboratoire de Météorologie Dynamique (UMR 8539)
3 Estellus
4 GOHS

This study is an attempt to evidence the impact of the inundation occurrence on the deep convection at continental scale. Three sources of satellite observations are carefully analyzed over the tropics for 3 years: A multisatellite wetland extent and dynamics data set, a deep convective activity index derived from passive microwave satellite measurements at 85 GHz, and precipitation estimates. Although many other effects contribute to the variability in the convection (e. g., large-scale circulation and weather regimes), careful examination of the seasonal and diurnal variations of the satellite-derived information makes it possible to observe two distinct regimes. The first regime corresponds to regions where the inundation is not generated by local precipitation. There it is shown that stronger convection happens during the minimum of the inundation, with a marked diurnal cycle of the deep convective activity. Simulations with a single-column model are in good agreement with these satellite observations. First, calculations show that during the season of minimum inundation, hydrometeors are present higher in altitude, increasing the likelihood of larger ice quantities aloft. Second, the diurnal cycle of the convective activity related to the presence of large ice quantities has a larger amplitude. The second regime corresponds to regions where the inundation is directly generated by local precipitation. There our observational analysis could not isolate any effect of the inundation on the convection.

Mots clés: EXPLICIT HYDROLOGIC-CYCLE; SEA-SURFACE TEMPERATURE; TROPICAL CONVECTION; PART I; PRECIPITATION FEATURES; CUMULUS CONVECTION; WETLAND DYNAMICS; CLOUD SYSTEMS; WATER-VAPOR; SENSITIVITY

Domaines: Océan, Atmosphère

Christophe Prigent, N. Rochetin, F. Aires, E. Defer, J. Y. Grandpeix, et al.. Impact of the inundation occurrence on the deep convection at continental scale from satellite observations and modeling experiments. Journal of Geophysical Research: Atmospheres, 2011, 116, pp.12. ⟨10.1029/2011jd016311⟩. ⟨hal-00991315⟩