HR: 1340h
AN: A53A-0865    [Abstracts]
TI: Regional Simulations of the Water Cycle and its Relation to Soil Moisture Anomalies
AU: Collini, E
EM: collini@atmos.umd.edu
AF: University of Maryland, Department of Meteorology 3427 CSS Bldg, College Park, MD 20742
AU: * Berbery, E H
EM: berbery@atmos.umd.edu
AF: University of Maryland, Department of Meteorology 3427 CSS Bldg, College Park, MD 20742
AB: The impact of soil moisture on the precipitation associated with the onset of the monsoon of South America is investigated with ensemble simulations of the National Centers for Environmental Prediction (NCEP) regional Mesoscale Eta model. The model has been evaluated in short and long term integration modes. Long term simulations show no evidence of a climate drift, while short term integrations reveal that it is a valuable tool for water cycle studies. The area average precipitation over La Plata basin over a recent two year period is similar to observations. Moreover, the ultimate verification of the reliability of the model estimates is by comparison of moisture flux convergence with river discharge. The long term river discharge of La Plata is equivalent to 0.61 mm day-1, which is very close to the MFC estimated from the Eta model (0.60 mm day-1). On the other hand, the model appears to overestimates evaporation by about 0.2-0.3 mm day-1 in the annual average. Multiple month long simulations are employed in ensemble mode to discuss the sensitivity of these features to changes in soil moisture. In particular, it is a well known fact that El Ni¤o has a strong influence in south eastern South America, and particularly over La Plata basin. However, a less understood feature is that precipitation (and floods) can have additional peaks beyond the El Ni¤o phase of the ENSO cycle. This less understood feature is the subject of the current presentation. We will discuss the hypothesis that abundant El Ni¤o-induced rain during the southern winter favors anomalously moist soils during spring, hence providing an additional source of moisture and instability for precipitation even after El Ni¤o has finished.
DE: 1833 Hydroclimatology
DE: 1836 Hydrologic budget (1655)
DE: 1878 Water/energy interactions
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting