Pereira Filho, Augusto J., Richard E. Carbone, John E. Janowiak, Phillip Arkin, Robert Joyce, Ricardo Hallak, and Camila G.M. Ramos, 2010. Satellite Rainfall Estimates Over South America – Possible Applicability to the Water Management of Large Watersheds. Journal of the American Water Resources Association (JAWRA) 46(2):344‐360. DOI: 10.1111/j.1752‐1688.2009.00406.x Abstract:  This work analyzes high‐resolution precipitation data from satellite‐derived rainfall estimates over South America, especially over the Amazon Basin. The goal is to examine whether satellite‐derived precipitation estimates can be used in hydrology and in the management of larger watersheds of South America. High spatial‐temporal resolution precipitation estimates obtained with the CMORPH method serve this purpose while providing an additional hydrometeorological perspective on the convective regime over South America and its predictability. CMORPH rainfall estimates at 8‐km spatial resolution for 2003 and 2004 were compared with available rain gauge measurements at daily, monthly, and yearly accumulation time scales. The results show the correlation between satellite‐derived and gauge‐measured precipitation increases with accumulation period from daily to monthly, especially during the rainy season. Time‐longitude diagrams of CMORPH hourly rainfall show the genesis, strength, longevity, and phase speed of convective systems. Hourly rainfall analyses indicate that convection over the Amazon region is often more organized than previously thought, thus inferring that basin scale predictions of rainfall for hydrological and water management purposes have the potential to become more skillful. Flow estimates based on CMORPH and the rain gauge network are compared to long‐term observed average flow. The results suggest this satellite‐based rainfall estimation technique has considerable utility. Other statistics for monthly accumulations also suggest CMORPH can be an important source of rainfall information at smaller spatial scales where in situ observations are lacking.

The Metropolitan Area of São Paulo (MASP) is one of the most populated regions of the planet with one of the largest impervious regions as well. This research work aims to characterize MASP heat island (HI) effect and its interaction with the local sea breeze (SB) inflow in rainfall amounts and deep convection. The combined SB-HI produces direct circulation over the MASP and produces severe weather and socioeconomic impacts. All SB-HI episodes between 2005 and 2008 are identified and analyzed with surface and upper air measurements, weather radar, and satellite data. The current work indicates that intense SB-HI episodes are related to air and dew point temperatures above 30 ∘ C and 20 ∘ C, respectively, right after the passage of the SB front over MASP. Results indicate that the precipitation related to SB-HI episodes is up to 600 mm or about four times higher than that in rural or less urbanized areas in its surroundings. Measurements indicate that 74% of SB-HI episodes are related to NW winds in earlier afternoon hours. Moving cold fronts in southern Brazil tend to intensify the SB-HI circulation in MASP. A conceptual model of these patterns is presented in this paper.

Simultaneous observations of an optical and an impact type disdrometer and their application in radar rainfall estimation are evaluated. The disdrometers and two collocated rain gauges were operated in the southwest Amazon region of Brazil in 1999 as part of a NASA Tropical Rainfall Measuring Mission (TRMM) field campaign and the hydro‐meteorological component of the Large Scale Biosphere–Atmosphere Experiment (LBA). During the experiment, we observed large drops with diameters greater than 5 mm. These large drops were not adequately detected by the impact disdrometer and resulted in differences in drop size distribution and integral rain parameters derived from the two sensors. Considering coincident observations, we calculated that the impact disdrometer recorded about 11% lower rainfall accumulations than the optical disdrometer. In addition, radar rainfall algorithms, which we derived from the impact and optical disdrometer measurements, showed instrument dependency. Out of four radar rainfall algorithms that we considered, rain rate derived from specific differential phase has the least dependency, while the rain rate derived from reflectivity at horizontal polarization and differential reflectivity combined exhibited the largest. We also observed the characteristics of rainfall and drop size distribution in two distinct wind regimes present during the TRMM–LBA field campaign. Rain was heavier in the easterly regime, with more large drops being present.

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Foram analisadas características da precipitação estimada a partir de 145.194 campos de refletividade, de um total de 827 dias entre 1998 e 2003, obtidos do Radar Meteorológico de São Paulo (RSP). Os eventos foram classificados de acordo com intensidades de precipitação; em Convectivos (EC) e Estratiformes (EE). Quanto à morfologia, cinco tipos de sistemas foram identificados; Convecção Isolada (CI), Brisa Marítima (BM), Linhas de Instabilidade (LI), Bandas Dispersas (BD) e Frentes Frias (FF). Eventos convectivos dominam na primavera e verão e estratiformes no outono e inverno. A CI e a BM tiveram maiores picos de atuação entre outubro e março enquanto as FF de abril a setembro. BD atuam durante todo o ano e as LI só não foram observadas nos meses de junho e julho. Uma comparação pontual entre a precipitação medida pela telemetria e estimada com o radar foi realizada e, mostrou haver, na maioria dos casos, um viés positivo do RSP, para acumulações de 10, 30 e 60 minutos. Com o objetivo de integrar as estimativas de precipitação do radar com as medidas da rede telemétrica, por meio de uma análise objetiva estatística, foram obtidas dos campos de precipitação do radar as estruturas das correlações espaciais em função da distância para acumulações de chuva de 15, 30, 60 e 120 minutos para os cinco tipos de sistemas precipitantes que foram caracterizados. As curvas das correlações espaciais médias de todos os eventos de precipitação de cada sistema foram ajustadas por funções polinomiais de sexta ordem. Os resultados indicam diferenças significativas na estrutura espacial das correlações entre os sistemas precipitantes.

Quantitative precipitation forecasts (QPFs) were obtained from ensembles of the weather and research forecasting (WRF) model for the Iguaçu river watershed (IRW) in southern Brazil. Thirty-two rainfall events between 2005 and 2010 were simulated with ten configurations of WRF. These rainfall events range from local to synoptic scale convection and caused a significant increase in the level of the Iguaçu river. In the average, the ensembles yielded up to 20% better skill than single WRF forecasts for the events analyzed. WRF ensembles also allow estimating the predictability through the dispersion of the forecasts providing relevant information for decision-making. Phase errors of ensemble forecasts are larger than amplitude errors. More complex microphysics parameterizations yielded better QPFs with smaller phase errors. QPFs were fed to IRW hydrological model with similar phase and amplitude errors. It is suggested that lagged QPFs might reduce phase errors.

RESUMOTempestades seguidas de enchentes e alagamentos em pontos da Região Metropolitana de São Paulo são eventos recorrentes nas estações chuvosas. O desempenho do modelo ARPS nas simulações numéricas de alta resolução espacial, para o evento de 04 de fevereiro de 2004, é avaliado por meio de erros estatísticos e índices de acurácia, com base no confronto entre a distribuição espacial da precipitação acumulada simulada e a estimada com o radar meteorológico de São Paulo. Os resultados quantificam a influência dos termos de advecção das equações primitivas nos erros de fase dos sistemas convectivos simulados, para o tipo de configuração atmosférica dominante no caso estudado. A assimilação incremental de medidas obtidas em estações de superfície durante a execução do modelo, corrige significativamente a fase das células convectivas profundas na região de influência das medidas, a qual é definida durante o processo de análise objetiva. Um novo índice de destreza para modelos de mesoescala é proposto (D PIELKE ). As análises preliminares para o desempenho deste índice indicam adequação de sua formulação para o tipo de simulação efetuada. Palavras-chave: tempestades, simulações numéricas de mesoescala, erros de fase e amplitude, índices de acurácia. ABSTRACT: METODOLOGY FOR PERFORMANCE ANALYSIS OF SIMULATIONS OF CONVECTIVE SYSTEMS IN THE METROPOLITAN AREA OF SÃO PAULO WITH THE ARPS MODEL: SENSITIVITY TO VARIATIONS WITH THE ADVECTION AND THE DATA ASSIMILATION SCHEMESThunderstorms followed by flash flood events are recurrent in the Metropolitan Area of São Paulo during the wet seasons. The performance of several numerical simulations of the February 04, 2004 event carried out with the ARPS system in high horizontal resolution is evaluated through statistical errors and indices of accuracy. The evaluation is based on direct confrontation of the accumulated precipitation fields simulated by the model and measured by the São Paulo weather radar. The results quantify the influence of the advective terms of the primitive equations on phase errors of the simulated convective systems. The incremental assimilation of surface station data done during the model execution improved its performance in the area limited by the influence radius, which is defined during the objective analysis process. A new skill index formulation is presented (D PIELKE ). The preliminary results indicate that the D PIELKE index is adequate for assessing the simulation skill of small-scale convective systems.

The origin of modern disjunct plant distributions in the Brazilian Highlands with strong floristic affinities to distant montane rainforests of isolated mountaintops in the northeast and northern Amazonia and the Guyana Shield remains unknown. We tested the hypothesis that these unexplained biogeographical patterns reflect former ecosystem rearrangements sustained by widespread plant migrations possibly due to climatic patterns that are very dissimilar from present-day conditions. To address this issue, we mapped the presence of the montane arboreal taxa Araucaria, Podocarpus, Drimys, Hedyosmum, Ilex, Myrsine, Symplocos, and Weinmannia, and cool-adapted plants in the families Myrtaceae, Ericaceae, and Arecaceae (palms) in 29 palynological records during Heinrich Stadial 1 Event, encompassing a latitudinal range of 30°S to 0°S. In addition, Principal Component Analysis and Species Distribution Modelling were used to represent past and modern habitat suitability for Podocarpus and Araucaria. The data reveals two long-distance patterns of plant migration connecting south/southeast to northeastern Brazil and Amazonia with a third short route extending from one of them. Their paleofloristic compositions suggest a climatic scenario of abundant rainfall and relative lower continental surface temperatures, possibly intensified by the effects of polar air incursions forming cold fronts into the Brazilian Highlands. Although these taxa are sensitive to changes in temperature, the combined pollen and speleothems proxy data indicate that this montane rainforest expansion during Heinrich Stadial 1 Event was triggered mainly by a less seasonal rainfall regime from the subtropics to the equatorial region.