Precipitation Estimates over South-America during SALLJEX

CELESTE SAULO; JUAN RUIZ; LORENA FERREIRA; SOLEDAD CARDAZZO; JULIA NOGUÉS PAEGLE

Maryland, USA

Workshop; CPPA- Pi's meeting; 2008

NOAA

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:612.0pt 792.0pt; margin:72.0pt 90.0pt 72.0pt 90.0pt; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Subtropical South-America is changing its land-use practices at the same time that rainfall shifts are observed.   Whether such practices modulate rainfall, or are an adjustment to rainfall changes is an unanswered question. Potential explanations require: 1) a  more complete precipitation network over a longer period of time than currently available and 2) to estimate the impact that changes in land-use  have in rainfall distributions. These two topics are addressed in our presentation as follows:        1) Calibration of CMORPH data over South America during SALLJEX period   Several methods for the calibration of precipitation estimates generated from passive microwave sensors are evaluated over Southeastern South America. The SALLJEX period has been selected to test  several  calibration strategies, since a dense network  of precipitation data was available over the area of interest.  Results show that the proposed calibration algorithm effectively removes systematic errors  improving  the skill of precipitation estimates.        2)Land-surface interaction.   The impact of changes in land use in subtropical Argentina in rainfall distribution  is addressed through control experiments with a WRF model in a downscaling mode, with different scenarios of soil moisture for a 10 day period during the 2003 austral summer. The WRF model was previously tested using various physical parameterizations to select the design that gave best estimates of precipitation and 2m Temperature during SALLJEX. It is found that  circulation and precipitation patterns are sensitive to changes in soil moisture content and/or structure, even in the relatively short time period chosen for these experiments.