Abstract. Sixteen years of analysis of clear-sky direct aerosol radiative forcing is presented for the Amazon region, with calcu-1 lations of AERONET network, MODIS sensor and MERRA-2 reanalysis data. The results showed that MERRA-2 reanalysis 2 is an excellent tool for calculating and providing the spatial distribution of aerosol direct radiative forcing. In addition, the 3 difference between considering the reference state of the atmosphere without aerosol loading and with natural aerosol to obtain 4 the aerosol direct radiative forcing is discussed. During the dry season, the monthly average direct forcing at the top of atmo- ; this difference was associated with the absorption of aerosols.

ABSTRACT. IWV (Integrated Water Vapor) values from the Brazilian Network for Continuous Monitoring (RBMC) of GPS (Global Positioning System) signals are additional sources of humidity information available for being used in Numerical Weather Prediction (NWP) models operating in the Brazilian meteorological centers.In order to obtain IWV-GPS values in an efficient approach, an optimization of the GPS data processing for estimating the ZTD values (Zenithal Tropospheric Delay) is involved, which should search for the best result with lowest computational cost. In this optimization process it is necessary to determine the ideal size of the so called sliding-window data involved in the real time data processing, which must be the as small as possible but providing results with the required quality. In this paper is investigated the ideal size of such sliding-window. An experiment was carried out in which GPS sliding-windows of different sizes were evaluated using simulations of a real time data processing. Comparing the obtained results with those from post-processed GPS data, it is observed that a sliding-window containing 7 hours of GPS data generated the best results from the operational point of view (rms of 1.61 and 1.82 kg m −2 for latency of 60 and 120 minutes, respectively).Keywords: IWV-GPS, ZTD, NWP, data assimilation. RESUMO. Valores do IWV (Integrated Water Vapor -Vapor D'água Integrado na coluna atmosférica) provenientes da Rede Brasileira de Monitoramento Contínuo(RBMC) dos Satélites GPS (Global Positioning System -Sistema de Posicionamento Global) compõem uma fonte adicional de informações da umidade para a assimilação em modelos operacionais de Previsão Numérica de Tempo (PNT) existentes no Brasil. Para que os valores do IWV-GPS sejam obtidos com maior eficiênciá e necessário uma otimização do processamento de dados GPS para a estimativa do ZTD (Zenithal Tropospheric Delay -Atraso Zenital Troposférico), de forma que resultados com qualidade adequada possam ser obtidos com custo computacional baixo. Nessa otimização deve-se definir o tamanho ideal da chamada janela deslizante (sliding window ) de dados GPS envolvidos no processamento em tempo real, a qual deve ser a menor possível, mas fornecendo resultados satisfatórios. O objetivo desse trabalhoé investigar sobre o tamanho ideal dessa janela de dados. Um experimento foi realizado envolvendo janelas de dados GPS de diferentes tamanhos, as quais foram testadas através de simulações de processamento em tempo real. Comparando os resultados simulados com aqueles obtidos no modo pós-processado, observou-se que do ponto de vista operacional o emprego de uma janela com 7 horas de dados proporciona os melhores resultados (Erro médio Quadrático de 1,61 e 1,82 kg m −2 para 60 e 120 minutos de latência, respectivamente).

No abstract

Eventos extremos associados a fenômenos meteorológicos são ocorrências que causam estragos materiais e impactos socioeconômicos diversos. Esses eventos têm ciclo de vida curto, em geral, até duas horas, mas que podem se estender por até seis e 12 horas. Existem diversas abordagens para previsibilidade e uma delas faz uso de modelos numéricos de previsão de tempo. Neste trabalho se quer investigar o conjunto de parametrizações de camada limite e de microfísica que melhor respondem à previsão de eventos atmosféricos intensos. Será usado o modelo de código livre Weather and Research Forecasting (WRF) para fazer os experimentos e a metodologia será por meio de estudo de caso de evento extremo ocorrido no oeste catarinense em 14 de agosto de 2020. Ao final, espera-se encontrar uma configuração do WRF que possa ser usada operacionalmente para predizer e monitorar eventos atmosféricos intensos.

<p>Biomass burning episodes are quite common in the central region of South America and represent the dominant aerosol sources during the dry/burning, between August and October. Large amounts of trace gases and aerosols injected into the atmosphere from these fire events can then be efficiently transported to urban areas in southeastern South America, thus affecting air quality over those areas. Observational data have been of fundamental importance to understand the evolution and interaction of biomass burning products with meteorology and chemistry. However, supplementing this information with the use of a comprehensive air quality modeling system in order to anticipate very acute air pollution episodes, and thus avoiding severe impacts on human health, is also required. Considering this, a new regional air pollution modeling framework for South America is being implemented by the Center for Weather Forecasting and Climate Studies (CPTEC), the National Weather Service of Brazil. This new system, based on the Weather Research and Forecasting with Chemistry model (WRF-Chem; Grell et al., 2005), is being run experimentally and its operational implementation is underway. The forecasts were driven by global forecast data from the GFS-FV3 model for meteorology and from the WACCM model for chemistry, both data sets provided every 6 hours. WACCM forecasts are employed to map gas and aerosol background concentrations to the WRF-Chem initial and boundary conditions, according to the MOZCART chemical mechanism. Two experiments of 48-hour real-time forecast simulations were performed, on a daily basis, during August and September of 2018 and 2019. The experiment for 2019 includes the very strong 3-week forest fire event when the Metropolitan Area of São Paulo, the largest metropolitan area in South America, plunged into darkness on August 19, with day turning into night. Model results are in good domain-wide agreement with satellite data and also with in situ measurements. Besides forecasts of meteorological parameters, this new system provides forecasts of regional distributions of primary chemical species (CO, SO2, NOx, particulate matter including black carbon), of secondary species (ozone, secondary organic aerosols) and air pollution related health indices, all parameters with a resolution of 20 km and for the next 72 hours.</p>