Claudine Pereira Dereczynski

Climatologia da precipitação no município do Rio de Janeiro

A preliminary 10-year precipitation climatology of Rio de Janeiro is elaborated by means of the Geo-Rio Foundation rain gauge network. The spatial distribution of annual precipitation shows that the maxima coincide with the three hills in the city: Carioca (2200 mm), Mendanha (1400 mm) and Geral de Guaratiba (1200 mm). The precipitation values decrease toward the plain, with minimum values in the Northern Zone. The precipitation is greater at the Sumare gauge than in all the other places throughout the year, especially in September when the monthly mean precipitation (297.5 mm) is seven times greater than the precipitation in other Northern Zone stations. For example, rain occurs 119 days per year at Sumare; at Penha it occurs only 86 days per year. The anaylsis of the intense events shows that 77% of the 160 selected events were caused by frontal systems, which occur throughout the year, though less frequently in winter. South Atlantic Convergence Zone events (13%) and Mesoscale Convective Systems (8%) occurred predominantly in summer. Rainfall caused by a sea breeze circulation occurred only in 2% of cases.

Tendências observadas em indicadores de extremos climáticos de temperatura e precipitação no estado do Paraná

This paper analyzes the trends of climate extremes based on indicators calculated from daily observational temperature and precipitation data series during 35 years at 20 IAPAR meteorological stations,, in the State of Parana. The objective is to contribute to assessing studies on climate impacts and vulnerability, required to develop adapting strategies to climate change. Initially, climatologic values of air temperature and precipitation in the State are revisited. With respect to trends in climate extremes, the results of the indicators associated with temperature indicate a widespread pattern of statistically significant warming in almost all Parana State. The percentage of hot days and nights in the State increased significantly at a rate of 0.1 to 0.4 %/year between 1976 and 2010. The annual minimum and maximum average temperatures indicate an increase in almost all Parana of +0.02°C/year over the same period. The minimum temperature indicators show more significant increasing trends than the maximum temperature does. Furthermore, most indicators of climate extremes associated with precipitation have no statistical significance, except for a few stations in different regions of the State. From these, only Pato Branco and Planalto, at southwestern Parana show an elevation trend of the dry period (+0.25 mm/year), and Cambara, Ibipora and Umuarama, in northern State show a reduction (-0.5 mm/year) of heavy rainfall.

Caracterização Climatológica e Tendências Observadas em Extremos Climáticos no Estado do Rio de Janeiro

In this paper it is elaborated a climatology of air temperature and precipitation and an analysis of trends in climate extremes of such variables for the State of Rio de Janeiro, using observational data between 1961 and 2012. The climatology shows average minimum temperatures ranging between 9.5 and 11oC (15.5 to 17oC) in winter (summer) in the mountainous region. Higher values occur mainly on the coast, where the average minimum temperature ranges between 17 and 18.5oC (21.5 to 23oC) in winter (summer). The lowest average maximum temperatures range between 21.5 and 23oC (26 and 27.5oC) in winter (summer) in the mountainous region. The highest values are in the Metropolitan Region and in the North/Northwest area, ranging between 26 and 27.5oC (32 and 33.5oC) in winter (summer). The annual rainfall shows maxima in higher areas (about 2500 - 2800 mm per year) and minima in the regions of marshland and coastline (between 700 and 1300 mm per year). For the observed trends in climate extremes of temperature, the Metropolitan Region and the North and Northwest Region of the State indicate statistically significant increases in mean maximum temperature (between +0.01 and +0.08oC/year). It is also noted significant rise trends in the percentage of warm nights and days in almost the entire State (between +0.1 and +0.6 %days/year). As for rain, it is observed that there is a statistically significant upward trend in the annual rainfall totals in the Baixadas Litorâneas (between +4.0 and +32.0 mm/year). Also, it is verified a significant increase in rainfall totals of more heavy rains in the year in the Baixadas Litorâneas and in part of the Metropolitan Region, with magnitudes between +2.0 and +20 mm/year.

Erratum to: Climate change projections over three metropolitan regions in Southeast Brazil using the non-hydrostatic Eta regional climate model at 5-km resolution

The objective of this work is to assess changes in three metropolitan regions of Southeast Brazil (Rio de Janeiro, Sao Paulo, and Santos) based on the projections produced by the Eta Regional Climate Model (RCM) at very high spatial resolution, 5 km. The region, which is densely populated and extremely active economically, is frequently affected by intense rainfall events that trigger floods and landslides during the austral summer. The analyses are carried out for the period between 1961 and 2100. The 5-km simulations are results from a second downscaling nesting in the HadGEM2-ES RCP4.5 and RCP8.5 simulations. Prior to the assessment of the projections, the higher resolution simulations were evaluated for the historical period (1961–1990). The comparison between the 5-km and the coarser driver model simulations shows that the spatial patterns of precipitation and temperature of the 5-km Eta simulations are in good agreement with the observations. The simulated frequency distribution of the precipitation and temperature extremes from the 5-km Eta RCM is consistent with the observed structure and extreme values. Projections of future climate change using the 5-km Eta runs show stronger warming in the region, primarily during the summer season, while precipitation is strongly reduced. Projected temperature extremes show widespread heating with maximum temperatures increasing by approximately 9 °C in the three metropolitan regions by the end of the century in the RCP8.5 scenario. A trend of drier climate is also projected using indices based on daily precipitation, which reaches annual rainfall reductions of more than 50 % in the state of Rio de Janeiro and between 40 and 45 % in Sao Paulo and Santos. The magnitude of these changes has negative implications to the population health conditions, energy security, and economy.

Chuvas Extremas no Município do Rio de Janeiro: Histórico a partir do Século XIX

Neste trabalho e feito um levantamento de eventos de chuvas extremas e seus efeitos sobre a populacao da cidade do Rio de Janeiro num periodo de 63 anos, compreendido entre 1881 e 1996. O objetivo do trabalho e, atraves do acompanhamento das noticias publicadas em jornais da epoca, resgatar os principais eventos de chuva extrema a partir do seculo XIX e avaliar a utilidade da informacao meteorologica no sentido de alertar a populacao a respeito dos possiveis desastres deflagrados pelas chuvas intensas. Inicialmente foram pre-selecionados os casos com total pluviometrico diario igual ou superior a 100 mm. Do total de 100 eventos pre-selecionados, 82 casos foram considerados eventos extremos devido aos grandes danos provocados a populacao, incluindo mortos, feridos, danos materiais, desabamentos, inundacoes, alagamentos, deslizamentos entre outros. Isso significa a ocorrencia de 1,3 evento extremo por ano em media (82 casos em 63 anos). Como esperado, a maioria dos casos ocorreu no verao e outono, 40% em cada estacao, e os 20% restantes ficaram igualmente distribuidos durante a primavera (10%) e o inverno (10%). Em todo o periodo analisado verificou-se que as previsoes do tempo divulgadas nos jornais nao eram suficientes para alertar a populacao nos casos de chuvas intensas. Alem disso, explicacoes razoaveis sobre as causas meteorologicas dos fenomenos so passaram a ser divulgadas para a populacao a partir da decada de 1990.

Climatologia no Entorno da Central Nuclear de Angra dos Reis, RJ

The objective of this work is to characterize the mean diurnal and seasonal cycles around the Nuclear Power Plant in Angra dos Reis, RJ. The averages were taken for an hourly dataset in the period January 2005 and December 2012, based on four towers. Tower A measures air temperature and wind at three levels: 10, 60, and 100 m. Towers B, C, and D measure only wind at 15 m. The diurnal cycle of static stability show stable conditions prevailing during most of the day. The static stability starts to reduce at about 6 and 7 LT, whereas the most unstable conditions occur between 8 and 16 LT. Winds are predominantly weak, with the most frequent intensity between 1.5 and 2 m/s. The minimum of 10-m winds occur when the sea breeze starts, at about 9 LT. The catabatic winds are a strong feature of the Tower A-10 m winds, and reveals strong vertical shear. The other towers do not show a clear minimum in the diurnal cycle of the wind, but the maximum occurs between 13 and 15 LT. Stronger wind and heavier precipitations were registered in autumn, MAM, which suggests the period of stronger storms.

Avaliação das Previsões de Precipitação do Modelo Eta para Bacia do Rio São Francisco em Minas Gerais, Brasil

In this work, the CPTEC/INPE’s Eta model (8 km and 40 km) forecasts, with 72 hours in advance, are evaluate for 25 intense rainfall cases, occurred in the period 2005-2012, at Sao Francisco River Basin, upstream Tres Marias Hydroelectric Power Plant, in Minas Gerais. The objective is to contribute to the improvement of intense rainfall forecasts in the studied area. Evaluation of rainfall forecasts is made objectively and subjectively, comparing them with observational data. Moreover, synoptic fields forecasts for several variables are compared with the same fields of ERA-Interim Reanalysis (ECMWF). The Eta model forecasts for 25 intense rainfall cases were generated initially nesting Eta-40km model to the CPTEC/INPEs Global model (T126L28). Finally, the Eta-8km model is integrated using as initial conditions the NCEP analysis and as lateral boundary conditions the Eta-40km model forecasts, updated every 6 hours. Considering the 25 intense rainfall cases, evaluating objetively the rain, Eta-8km has better (worst) performance compared to Eta-40km, to predict daily moderate to strong (weak) precipitation. Based on the subjective evaluation, it is noted that when CPTEC/INPE’s Global model fails in positioning the active meteorological system, both versions of Eta model are affected. In cases where meteorological systems are more pronounced, as in the 25 case, it increases the accuracy of both Eta model versions, with Eta-8km showing better results than Eta-40km.

Indicadores de turbulência a partir de previsões do modelo regional ETA

The Clear Air Turbulence (CAT) which is frequently observed near jet stream regions, usually in the layer between 10,000 and 12,000 m, may cause serious damages to aviation, reaching airplanes without warning. Therefore, predictions of this phenomenon can help to prevent physical damages and discomfort for the crew and passengers. Numerical weather prediction models have been used as powerful tools for operational forecasts of this phenomenon, by application of some indices in the determination of the turbulence areas. In this work, the Brown, Ellrod and Richardson number indices, calculated from ETA model outputs, are used to detect turbulence. The verification was accomplished for 2 events on 24 June 2003 and 17 August 2006 and was based on SIGWX charts. The results show that the three indices correlated well with SIGWX charts. This study showed that the use of ETA model forecasts could help to understand the mechanism of turbulence and to increase the forecast lead time to about 48h or 72h, as compared to 24-h forecast SIGWX maps.