Variabilidade interanual da precipitação simulada de RegCM4: análise de sensibilidade à variação de esquemas de superfície

O objetivo desse trabalho foi analisar a variabilidade interanual da precipitação sobre a AMZ e LPB simulada pelo RegCM4 utilizando duas diferentes parametrizações de superfície.Trabalho publicado em: Ciência e Natura, Santa Maria, v. esp., p. 311-313, dez. 2013

Avaliação da Climatologia na Região Amazônica nos Modelos da Família Higem

This study analyzed the high resolution coupled and atmospheric global models of HiGEM/UJCC project (version 1.2) with different horizontal resolutions over Amazon region (South America). The purpose of this study was to understand the impact of the horizontal resolution of coupled models in simulating atmospheric patterns and processes of interaction between spatial scales over Amazon region. Therefore, we used simulations from HadGEM, HiGEM (coupled), HadGAM, HiGEM (uncoupled), and also observed data from different reanalyzes, with different spatial horizontal resolution (CMAP, CRU, GPCP, NCEP, CPC, ERA-Interim). The precipitation and temperature seasonal patterns and annual cycles were compared with observed data, and some measures of dispersion for the annual cycles were analyzed. To study the annual cycle we considered two subdomains in this region: AMN (North Amazon) and AMN (Amazon). The results indicated that the grid refinement and ocean-atmosphere coupling contributes to a better representation of seasonal patterns, both precipitation and temperature, on the Amazon region. Besides, the climatic models analyzed represent better than other models (regional and global) the climatic characteristics of this region. This indicates a breakthrough in the development of high resolution climate models.Neste trabalho foram analisados os modelos globais acoplados e atmosféricos de alta resolução do projeto HiGEM/UJCC (versão 1.2) com diferentes resoluções horizontais sobre a região da Amazônia (América do Sul). O objetivo é compreender o impacto da resolução horizontal dos modelos acoplados de alta resolução nos padrões atmosféricos e em seus processos de interação entre escalas espaciais sobre a região da Amazônia. Para tanto, foram utilizados além das simulações HadGEM, HiGEM (acopladas), HadGAM e HIGAM (atmosféricas), dados observados de diferentes reanalises, com diferentes resoluções espaciais (CMAP, CRU, GPCP, NCEP, CPC, ERA-Interim). Os padrões sazonais e o ciclo anual da precipitação e da temperatura foram comparados aos dados observados, bem como foram analisadas algumas medidas de dispersão para o ciclo anual. Na análise do ciclo anual foram considerados dois subdomínios nesta região: AMN (Amazônia Norte) e AMZ (Amazônia). Os resultados indicam que, o refinamento da grade e acoplamento oceano-atmosfera contribui para a melhor representação dos padrões, tanto de precipitação como de temperatura, sobre a região da Amazônia. Além disso, os modelos climáticos analisados representaram melhor do que outros modelos (regionais e globais) as características climáticas desta região, indicando um avanço no desenvolvimento de modelos climáticos de alta resolução

Climate projections for South America: RegCM3 driven by HadCM3 and ECHAM5

This study shows climate projections of air temperature and precipitation over South America (SA) from the Regional Climate\ud Model version 3 (RegCM3) nested in ECHAM5 and HadCM3 global models. The projections consider the A1B scenario from\ud Intergovernmental Panel on Climate Change (IPCC) and three time-slices: present (1960–1990), near- (2010–2040), and far-future\ud (2070–2100) climates. In the future, RegCM3 projections indicate general warming throughout all SA and seasons, which is more\ud pronounced in the far-future period. In this late period the RegCM3 projections indicate that the negative trend of precipitation\ud over northern SA is also higher. In addition, a precipitation increase over southeastern SA is projected, mainly during summer\ud and spring. The lifecycle of the South American monsoon (SAM) was also investigated in the present and future climates. In the\ud near-future, the projections show a slight delay (one pentad) of the beginning of the rainy season, resulting in a small reduction of\ud the SAM length. In the far-future, there is no agreement between projections related to the SAM featuresCNPq - 307202/2011-9FAPESP - 2011/51016-9FAPEMIG - APQ-00251-11CAPESEuropean Community’s Seventh Framework Programme - FP7/2007–2013 - agreement n. 212492 (CLARIS LPB

Preliminary analysis on the global features of the NCEP CFSv2 seasonal hindcasts

The representation of the CFSv2 ocean-atmosphere ensemble hindcasts is investigated during Dec-Jan-Feb (DJF) and Jun-Jul-Aug\ud (JJA) from 1983 to 2010.The skill anomaly correlations showed that in some continents the forecasts do not have dependency with\ud changes in the initial conditions. Also, in both seasons the model has a higher skill at the 0-month lead time with the largest spatial\ud biases occurring over the North America, South America, and Oceania. Over the continents the largest biases in the nonlinearity\ud of El Ni˜no minus La Ni˜na events are found over the eastern South Africa, part of Oceania, and central-southeastern parts of South\ud America. During DJF the main biases are related to double-ITCZ, strengthening of SPCZ, and deepening of the Aleutian and\ud Icelandic low pressures.The simulation of a warmer SST on the eastern of most austral oceans, the strengthening (weakening) of\ud the Subtropical (Polar) Jet over the Southern Hemisphere, and the weakening of the zonal circulation near the Antarctic continent\ud are also found in both seasons. Over the central-eastern Equatorial Pacific a cooler bias in SST is found during JJA.These biases\ud are interpreted by analyses of the simulated global mean-state and their impact on the main patterns of variabilityFAPESP - 08/58101-9CNP

Climatologia da função frontogenética sobre a América do Sul em um cenário de clima presente e futuro

Os campos climatológicos da Função Frontogenética de Petterssen (FF) foram calculados com a partir do modelo global HadGEM2-ES para uma série 1975-2005. Os primeiros resultados mostram-se concordantes com aqueles obtidos anteriormente\ud por outros autores, indicando uma maior atividade de sistemas frontais durante o inverno e início da primavera. A partir destas constatações, a mesma metodologia pode ser utilizada com séries de clima futuro geradas pelo modelo.Trabalho publicado em: Ciência e Natura, Santa Maria, v. esp., p. 169-171, dez. 2013

A comparison of statistical downscaling techniques for daily precipitation: results from the CORDEX flagship pilot study in South America

Southeast South America (SESA) is one of the regions of the planet where extreme precipitation events occur and have high impact on human activities. These extreme events result from the complex interactions of a broad range of scales, therefore their study, modelling and projections in a changing climate continue to be a challenging task. The CORDEX Flagship Pilot Study in South America (FPSSESA) addresses this topic in order to advance in the understanding and modelling of extreme precipitation events based on coordinated experiments using different downscaling approaches. In this work we present the results from the collaborative action to intercompare different statistical downscaling techniques in simulating daily precipitation in SESA with special focus on extremes. To this end, seven statistical downscaling models based on the regression and analog families were evaluated over SESA. The sensitivity to the different predictor and predictand datasets were tested using two reanalyses (ECMWF ERA-Interim and Japanese 55-year Reanalysis JRA-55) and two daily precipitation (station data and MSWEP) datasets. The models were calibrated and cross-validated during the 1979-2009 period and also evaluated in the independent warm season of 2009-2010. This season, with record of extreme precipitation events, is the target season chosen in the FPS-SESA to perform the dynamical downscaling simulations as well, and therefore it allows for comparisons between both approaches. The results show that the methods are more skillful when combined predictors including circulation variables at middle levels and local humidity at low levels of the atmosphere are considered. The performance of the models is also sensitive to reanalysis choice. The methods show overall good performance in simulating daily precipitation characteristics over the region, but no single model performs best over all validation metrics and aspects evaluated.Fil: Bettolli, Maria Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; ArgentinaFil: Gutiérrez Llorente, José Manuel. Universidad de Cantabria; EspañaFil: Iturbide, Maialen. Universidad de Cantabria; EspañaFil: Baño Medina, Jorge. Universidad de Cantabria; EspañaFil: Huth, Radan. Karlova Univerzita (cuni); República ChecaFil: Solman, Silvina Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; ArgentinaFil: Fernández, Jesús. Universidad de Cantabria; EspañaFil: da Rocha, Rosmeri Porfirio. Universidade de Sao Paulo; BrasilFil: Llopart, Marta. Universidad Estadual de Sao Paulo; BrasilFil: Lavín Gullón, Álvaro. Universidad de Cantabria; EspañaFil: Coppola, Erika. The Abdus Salam; ItaliaFil: Chou, Sin Chan. Centro de Previsao de Tempo e Estudos Climaticos; BrasilFil: Doyle, Moira Evelina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; ArgentinaFil: Olmo, Matías Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; ArgentinaFil: Feijoó, Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; ArgentinaInternational Conference on Regional ClimateBeijingChinaWorld Climate Research ProgrammeInstituto Sueco de Meteorología e Hidrologí

Evaluation of RegCM4 over the CORDEX South America Domain:\ud sensitivity analysis to the Land Surface Scheme for the Amazon Basin

We compare the performance of the RegCM4 (ICTP Regional Climate Model) coupled to the land surface schemes\ud CLM 3.5 (Community Land Model) and BATS (Biosphere Atmosphere Transfer Scheme) in a 30-year simulation\ud (1979-2009) over CORDEX South America Domain. In general, the coupling of RegCM4 with the CLM substantially\ud improves the simulated climatology over tropical South America relative to the default version of RegCM4\ud (coupled with BATS). One of the main features is that the RegCLM improves the precipitation climatology and\ud annual cycle, reducing the summer wet bias, over the AMZ basin. With respect to the surface energy balance,\ud RegBATS scheme prescribes lower monthly albedos over the AMZ, resulting in higher solar radiation absorption\ud by the surface. Moreover, RegBATS tends to simulate a higher sensible heat flux and lower latent heat fluxes over\ud the AMZ during the dry season, diverging from observations. The surface water balance also changes considerably\ud between the two simulations. Compared with RegBATS, RegCLM simulates lower precipitation and runoff, as\ud well as less water into the total soil column. RegCLM improves the water balance along the year, reducing the\ud ET (Evapotranspiration) overestimation during the wet season, even though still overestimating it, and simulating\ud closer ET values during the dry season. RegBATS simulates higher sensible heat fluxes and lower ET during the\ud dry season. The Bowen Ratio based on fluxes tower observations, in the AMZ basin, suggests a practically constant\ud value along the year, pattern better simulated by CLM (albeit still poorly represented such a pattern), suggesting\ud a better representation of the net surface energy partitioning. This better representation improves, consequently,\ud the simulated precipitation and air surface temperature, when compared with the observations. Even though the\ud RegCLM improves the precipitation and air temperature.Resumo publicado no periódico: Geophysical Research Abstracts, Strasbourg, v. 16, p. EGU 2014-4404-1, 201

An event of stratospheric air intrusion and its associated secondary surface cyclogenesis over the South Atlantic Ocean

This work presents an analysis of a lowermost stratospheric air intrusion event over the coast of Brazil, which may have been responsible for a secondary surface cyclogenesis over the southwestern Atlantic Ocean. The surface cyclone initiated at 0600 UTC 17 April 1999 in a cold air mass in the rear of a cold front after a primary cyclone developed over the same region. The analysis of the secondary cyclone revealed the presence of lowermost stratospheric air intrusion characterized by anomalous potential vorticity (PV), dry air, and high concentration of ozone in atmospheric column. The system developed on the eastern side of an upper level core of PV anomaly, which induced a cyclonic wind circulation at lower levels and favored the onset of the secondary cyclone. In midlevels (500 hPa), the cutoff low development contributed to reduce the propagation speed of the wave pattern. This feature seemed to (1) allow the low-level cold/dry air to heat/moisten associated with sensible and latent fluxes transferred from the ocean to the atmosphere, which intensified a baroclinic zone parallel to the coast, and (2) contribute to the long duration of the system. The present analysis indicates that this secondary cyclone development could be the result of the coupling between the PV anomaly in the upper levels and low-level air-sea interaction.CNPq[135283/2006-0]CNPq[476361/2006-0]CAPES_DGU[151/07

Observed and simulated (RegCM4) climatology of the cold fronts over\ud the cities of São Paulo (1981-2002) and Rio Grande (1991-2008)

The objective of this work was to investigate as RegCM4 model forced in\ud the boundary with as Era-Interim dataset simulates the climatology of frontal systems\ud over the states of Rio Grande do Sul and São Paulo. The cold fronts obtained from\ud RegCM4 were compared with Água Funda (IAG-USP, period of 1981-2002) and\ud FURG-RS weather stations for the period 1991-2008. The cold fronts were identified\ud using an algorithm that checks the tuming of the wind at same time the there is\ud temperature decreases. This algorithm was applied to the four seasons: summer,\ud auturnn, winter and spring. The results show that RegCM4 identifies smaller number of\ud fronts over the city of Rio Grande, underestimating about 15% of total fronts and this\ud underestimation persists in other seasons. In the São Paulo city, RegCM4 overestimates\ud (positive bias) the number of fronts in only 1%, but this overestimates does not persist\ud in all seasons summer and autumn presenting underestimation of about -20% and -2%,\ud respectively. As in São Paulo, in Rio Grande the largest underestimation of fronts by\ud RegCM4 occurs in the summer (~-19%). The climatology of the some meteorological\ud variables was obtained from two day before until two days after the passage of the\ud fronts. In this climatology it was noted large agreement between RegCM4 and\ud observations. Over the city of São Paulo (Rio Grande), from one day before the front\ud (prefrontal) until the day of the front the variab,les . me.ridional wind, relative humidity\ud (except in the autumn and air temperature (zonal wind and air temperature) simulated\ud by RegCM4 have similar values of the observation. Already to zorial wind and\ud precipitation the errors are large for São Paulo city. Therefore, these results show that\ud RegCM4 simulates according with observations the main meteorological features\ud associated with cold fronts in the two cities. The simulation of zonal wind has the\ud greatest errors in São Paulo city, indicating that the location of the extratropical\ud cyclones associated with the cold fronts would not be well represented by RegCM4.\ud Maps of compositions of the simulated and observed fields will be used to verify this\ud hypothesis.Título: V SIC: Interação oceano-atmosfera: impactos climáticos no presente e cenários futuros. Eventos simultâneos ao V SIC: Encontro Sul Brasileiro de Meteorologia, 5. Florianópolis, Brasil, 2013; Congresso Latino-Americano e Ibérico de Meteorologia da FLISMET, 15. Florianópolis, Brasil, 2013

Non-stationary frequency analysis of extreme daily rainfall in São Paulo, Brazil

This work is an assessment of frequency of extreme values (EVs) of daily rainfall in the city of São Paulo. Brazil, over the period 1933-2005, based on the peaks-over-threshold (POT) and Generalized Pareto Distribution (GPD) approach. Usually. a GPD model is fitted to a sample of POT Values Selected With a constant threshold. However. in this work we use time-dependent thresholds, composed of relatively large p quantities (for example p of 0.97) of daily rainfall amounts computed from all available data. Samples of POT values were extracted with several Values of p. Four different GPD models (GPD-1, GPD-2, GPD-3. and GDP-4) were fitted to each one of these samples by the maximum likelihood (ML) method. The shape parameter was assumed constant for the four models, but time-varying covariates were incorporated into scale parameter of GPD-2. GPD-3, and GPD-4, describing annual cycle in GPD-2. linear trend in GPD-3, and both annual cycle and linear trend in GPD-4. The GPD-1 with constant scale and shape parameters is the simplest model. For identification of the best model among the four models WC used rescaled Akaike Information Criterion (AIC) with second-order bias correction. This criterion isolates GPD-3 as the best model, i.e. the one with positive linear trend in the scale parameter. The slope of this trend is significant compared to the null hypothesis of no trend, for about 98% confidence level. The non-parametric Mann-Kendall test also showed presence of positive trend in the annual frequency of excess over high thresholds. with p-value being virtually zero. Therefore. there is strong evidence that high quantiles of daily rainfall in the city of São Paulo have been increasing in magnitude and frequency over time. For example. 0.99 quantiles of daily rainfall amount have increased by about 40 mm between 1933 and 2005. Copyright (C) 2008 Royal Meteorological Societ