Precipitation comparison for the CFSR, MERRA, TRMM3B42 and Combined Scheme datasets in Bolivia

AbstractAn overwhelming number of applications depend on reliable precipitation estimations. However, over complex terrain in regions such as the Andes or the southwestern Amazon, the spatial coverage of rain gauges is scarce. Two reanalysis datasets, a satellite algorithm and a scheme that combines surface observations with satellite estimations were selected for studying rainfall in the following areas of Bolivia: the central Andes, Altiplano, southwestern Amazonia, and Chaco. These Bolivian regions can be divided into three main basins: the Altiplano, La Plata, and Amazon. The selected reanalyses were the Modern-Era Retrospective Analysis for Research and Applications, which has a horizontal resolution (~50km) conducive for studying rainfall in relatively small precipitation systems, and the Climate Forecast System Reanalysis and Reforecast, which features an improved horizontal resolution (~38km). The third dataset was the seventh version of the Tropical Rainfall Measurement Mission 3B42 algorithm, which is conducive for studying rainfall at an ~25km horizontal resolution. The fourth dataset utilizes a new technique known as the Combined Scheme, which successfully removes satellite bias. All four of these datasets were aggregated to a coarser resolution. Additionally, the daily totals were calculated to match the cumulative daily values of the ground observations. This research aimed to describe and compare precipitations in the two reanalysis datasets, the satellite-algorithm dataset, and the Combined Scheme with ground observations. Two seasons were selected for studying the precipitation estimates: the rainy season (December–February) and the dry season (June–August). The average, bias, standard deviation, correlation coefficient, and root mean square error were calculated. Moreover, a contingency table was generated to calculate the accuracy, bias frequency, probability of detection, false alarm ratio, and equitable threat score.All four datasets correctly depicted the spatial rainfall pattern. However, CFSR and MERRA overestimated precipitation along the Andes' eastern-facing slopes and exhibited a dry bias over the eastern Amazon; TRMM3B42 and the Combined Scheme depicted a more realistic rainfall distribution over both the Amazon and the Andes. When separating the precipitation into classes, MERRA and CFSR overestimated light to moderate precipitation (1–20mm/day) and underestimated very heavy precipitation (>50mm/day). TRMM3B42 and CoSch depicted behaviors similar to the surface observations; however, CoSch underestimated the precipitation in very intense systems (>50mm/day).The statistical variables indicated that CoSch's correlation coefficient was highest for every season and basin. Additionally, the bias and RMSE values suggested that CoSch closely represented the surface observations

The International Summer School on Land Cover Change and Hydroclimate of the La Plata Basin

The La Plata Basin (LPB) in southern South America has been subject to land cover and land use changes (LCLUCs) since colonial times and with an accelerated rate in the last decades and over extensive areas. The work of Ameghino even suggested that there were relations between those land use changes and the frequency of droughts and floods in the region. Despite this early knowledge, not much is known of the potential impacts of LCLUC on the hydroclimate of the La Plata basin. Besides, over the last century much of the La Plata Basin has had a reported increase in precipitation and heavy rains, and these changes along with an increase in population growth - have resulted in more adverse effects from flooding. To draw attention to these issues, during two weeks in November 2009 the International Summer School on Land Cover Change and Hydroclimate of the La Plata Basin was organized at the grounds of the Itaip Hydropower Plant in Brazil. The school was the result of the combination of interests between the La Plata Basin Regional Hydroclimate Project, the Inter-American Institute for Global Change Research (IAI), and the International Hydroinformatics Center (IHC) in Itaip . LPB is an umbrella project endorsed by the Global Energy and Water Cycle Experiment (GEWEX) and the Climate Prediction and Variability (CLIVAR), both of the World Climate Research Programme (WCRP). LPB has made a priority to train young scientists and promote interdisciplinary collaborations in areas related to Climate, Hydrology, Ecology and Agriculture. The IAI, with a similar agenda, was a natural partner to develop this Summer School, which in turn benefited from Itaipu s interest in relating with the scientific community of neighboring countries. The choice of location (Itaip Technological Park) was made so that participants could relate research usually done at academic institutions to applications and operations at one of the largest hydropower plants in the world. The school was attended by 45 advanced graduate students and young scientists with different backgrounds from seven countries, including less technically advanced ones in the region.

Climatological analysis of the precipitation and umidity transport on the SACZ region using the new generation of reanalysis

O conhecimento do desempenho das reanálises e dos erros associados a elas apresenta um papel fundamental na compreensão dos processos físicos que ocorrem na atmosfera. Este trabalho tem por objetivo documentar as principais características da precipitação associada à Zona de Convergência do Atlântico Sul (ZCAS), baseado em seis conjuntos de reanálises atmosféricas (MERRA, ERA-Interim, ERA-40, NCEP 1, NCEP 2 e NCEP CFSR) e cinco conjuntos de produtos observados de precipitação (SALDAS, CPC, CMAP, GPCP e GLDAS). Através destes dados também foi analisado o transporte de umidade sobre a região da ZCAS, para os anos de 1979 a 2007. Em resumo, este trabalho evidencia o avanço das novas reanálises na tentativa de representar de forma mais adequada a variável precipitação acumulada. Os diagramas de Taylor mostram que os produtos de precipitação estão bem correlacionados com o ponto de referência (CPC), com coeficientes entre 0,6 e 0,9. Somente a reanálise do NCEP CFSR possui correlações próximas as dos produtos de precipitação. Os conjuntos mais antigos de reanálises apresentam correlações menores, abaixo de 0,6. O Oceano Atlântico é a fonte principal do fluxo de umidade para a direção da ZCAS, que diminui na direção do continente. Na Região SE do Brasil, a topografia tem um papel importante para a convergência de umidade. Já na parte noroeste da ZCAS, este fator deve estar associado a processos termodinâmicos

Concentrations of Volatile Organic Compounds in the Megacity of São Paulo in 2006 and 2011/2012 - A Comparative Study

The focus of this study was to measure the Volatile Organic Compounds (VOCs) concentrations in the megacity – São Paulo Metropolitan Area (SPMA). The measurements analyzed in this study included 78 hydrocarbon (HC) samples collected during 2006, and 66 samples of HC, 62 of aldehydes and 42 of ethanol collected during 2011-2012. The observational results showed that the consumption of ethanol, gasoline and diesel from 2006 to 2012 increased by 64 %, 23 % and 25 %, respectively, with substantial changes in the atmospheric composition. The 10 most abundant VOCs in the atmosphere found during 2011/2012 at CETESB IPEN/USP air quality monitoring station were ethanol, acetaldehyde, formaldehyde, acetone, propane, ethene, ethane, butane, 1-ethyl-4-methyl benzene, and 1,2,4-trimethyl benzene. During the 2006 campaign, alkanes represented 54.8 % of the total HC concentration, alkenes 29.2 %, aromatics 13.6 %, and alkadienes 2.4 %. On the other hand, during the 2011-2012 campaign, aldehydes represented 35.3 % of the VOCs, ethanol 22.6 %, aromatics 15.5 %, alkanes 13.5 %, acetone 6.8 %, alkenes 6.0 %, and alkadienes with less than 0.1 %.  An increase in VOCs concentrations in the SPMA atmosphere from 2006 to 2012, such as aldehydes and aromatics (which are important ozone precursors) was measured

The South American Land Data Assimilation System (SALDAS) 5-Year Retrospective Atmospheric Forcing Datasets

The definition and derivation of a 5-year, 0.125deg, 3-hourly atmospheric forcing dataset for the South America continent is described which is appropriate for use in a Land Data Assimilation System and which, because of the limited surface observational networks available in this region, uses remotely sensed data merged with surface observations as the basis for the precipitation and downward shortwave radiation fields. The quality of this data set is evaluated against available surface observations. There are regional difference in the biases for all variables in the dataset, with biases in precipitation of the order 0-1 mm/day and RMSE of 5-15 mm/day, biases in surface solar radiation of the order 10 W/sq m and RMSE of 20 W/sq m, positive biases in temperature typically between 0 and 4 K, depending on region, and positive biases in specific humidity around 2-3 g/Kg in tropical regions and negative biases around 1-2 g/Kg further south

A influência das caracteristicas fisicas e geográficas no leste do Nordeste do Brasil utilizando o modelo RAMS

A numerical study of the impacts of terrain and sea breeze circulation over east of northeast Brazil is presented. Simulation with wind and no wind have been compared and showed that the inclusion of wind produce a maximum in convection for most interior areas to be associated with the sea breeze merging with convection over higher terrain.Pages:

Modelos acoplados oceano-atmosfera e a previsão de secas no Nordeste do Brasil: avaliação das previsões para 1993 e 1994

Seasonal to interannual climate predictions for the tropics are becoming a reality with dynamical methods through Coupled Ocean-Atmosphere General Circulation Models (CGCM). Advances in understanding ENSO dynamics and the fundamental role of the tropical oceans on climate variability in these times scales are key elements in this respect. The oceans have the memory of the climate system on seasonal to interannual scales, since they exhibit a mass 260 times larger than the atmosphere with heat capacity about 1000 tiJnes bigger. This paper describes the experimental CGCM predictions for 1993 and 1994 rainy season over Northeast Brazil with the SIO and COLA models, intercompared and verified against the precipitation observed for the same period. Results are quite encouraging, indicating the future roles of the CGCM's for the regional forecasts

Data assimilation impact on the moisture transport from the Amazon to the Plata basin

The assimilation system at CPTEC is performed using the Physical-space Statistical Analysis System (PSAS), both in the Atmospheric Global Circulation Model and the Regional Model. This scheme solves analysis equations globally, thus eliminating the local approximation and data selection of the optimal interpolation (OI) schemes. PSAS is comparable to the global variational spectral analysis system, but unlike spectral analysis schemes, it works directly in physical space. It minimizes an objective function with the control variable defined in observation space. During the SALLJEX (South American Low-level Jet Experiment) experiment, six radiosonde data were added to the normal dataset which comprises the GTS, ATOVS, TPW and QuikScat data. These radiosondes were operating in an area which was not covered by the operational measurements, the area of the Low Level Jet occurrence. Thus, a better description of the moisture flux from the Amazon to the south is expected to be accomplished. The objective is to show the impact of assimilating these additional data in the analysis system during the SALLJEX, and to show the impact on the magnitude of the moisture flow, using the CPTEC Global model. The results show that there is an intensification of the LLJ and a small shifting of its center towards west and an increase of the humidity in the area of the LLJ

Estudo de Caso de um Evento Extremo de Incursão de Ar Frio em Julho de 2013 sobre a Bacia Amazônica Brasileira

Resumo A bacia Amazônica está localizada na região tropical cujas características principais são os elevados valores de temperatura e umidade do ar. Entretanto, incursões de massa de ar frio e seco também adentram a região, como ocorreu em julho de 2013. Essa quarta onda de frio que atuou sobre o continente sul-americano ocasionou neve em cidades da região Sul, caracterizando uma intensa massa polar com deslocamento até a região Norte. O presente trabalho analisou o comportamento de variáveis meteorológicas com intuito de investigar a intensidade do efeito dessa friagem. Os dados empregados foram de observações e das reanálises disponíveis. A anomalia negativa da temperatura máxima em Rio Branco foi de 15,9 °C, em Manicoré de 6,7 °C e Manaus de 2,0 °C. Nesse evento, os valores mais expressivos ocorreram na temperatura máxima. Também destaca-se uma contribuição mensal nas taxas de precipitação, cujos valores foram maiores que 13,0 mm.dia-1. Desse modo, conclui-se que, o evento de julho de 2013 foi um caso de intensa friagem devido deslocar-se até a região central da Amazônia e ocasionar quedas abruptas, principalmente, na temperatura máxima, favorecimento da precipitação nas regiões tropicais, bem como alterações na pressão em superfície, umidade e vento