HR: 14:45h
AN: A33A-05    [Abstracts]
TI: Investigating hydrologic and atmospheric pathways to summertime convective rainfall in the Southeastern United States
AU: * Juang, J
EM: jj19@duke.edu
AF: Nicholas School of the Environment and Earth Sciences, Duke University, Box 90328, Durham, NC 27708 United States
AU: Porporato, A
EM: amilcare@duke.edu
AF: Department of Civil and Environmental Engineering, Duke University, Box 90237, Durham, NC 27708 United States
AU: Stoy, P
EM: pcs3@duke.edu
AF: Nicholas School of the Environment and Earth Sciences, Duke University, Box 90328, Durham, NC 27708 United States
AU: Siqueira, M
EM: mbs4@duke.edu
AF: Nicholas School of the Environment and Earth Sciences, Duke University, Box 90328, Durham, NC 27708 United States
AU: Katul, G
EM: gaby@duke.edu
AF: Nicholas School of the Environment and Earth Sciences, Duke University, Box 90328, Durham, NC 27708 United States
AU: Katul, G
EM: gaby@duke.edu
AF: Department of Civil and Environmental Engineering, Duke University, Box 90237, Durham, NC 27708 United States
AB: The pathways to summertime convective rainfall remains a critical research topic due to the feedbacks between soil moisture content and the atmosphere. Understanding these feedbacks is particularly crucial in the Southeastern U.S. given the high productivity of these ecosystems and the role of convective precipitation in maintaining this productivity. At least 50% of the precipitation events during the summer season can be attributed to convective rainfall (even during a severe drought year). Using a combination of (i) 7 years sensible heat flux and micrometeorological time series data collected at the Duke Forest Ameriflux pine site, (ii) a simplified mixed layer slab model, and (iii) conditional analysis of half hour precipitation, we demonstrate that pathways to convective rainfall can be classified as quadrants on a soil moisture content (SM) and relative humidity (RH) plane. This 7-year record includes among the wettest and driest years within the 50-year record. For days with convective rainfall and for SM in excess of certain thresholds (~0.2), triggers to convective precipitation become primarily controlled by relative humidity (RH) and appear not sensitive to SM variations. However, during excess droughts (e.g. summer of 2002), RH and SM become highly correlated suggesting an entirely different pathway to convective precipitation. The fact that SM can control these feedbacks in the Southeastern U.S. even during drought years may have been underestimated in previous studies of convective rainfall.
DE: 1833 Hydroclimatology
DE: 1851 Plant ecology
DE: 1878 Water/energy interactions
DE: 3307 Boundary layer processes
DE: 3322 Land/atmosphere interactions
SC: Atmospheric Sciences [A]
MN: 2005 Joint Assembly