A study on the detection and future projection of climate change in the city of Rio de Janeiro is here presented, based on the analysis of indices of temperature and precipitation extremes. The aim of this study is to provide information on observed and projected extremes in support of studies on impacts and vulnerability assessments required for adaptation strategies to climate change. Observational data from INMET's weather stations and projections from INPE's EtaHadCM3 regional model are used. The observational analyses indicate that rainfall amount associated with heavy rain events is increasing in recent years in the forest region of Rio de Janeiro. An increase in both the frequency of occurrence and in the rainfall amount associated with heavy precipitation are projected until the end of the 21st Century, as are longer dry periods and shorter wet seasons. In regards to temperature, a warming trend is noted (both in past observations and future projections), with higher maximum air temperature and extremes. The average change in annual maximum (minimum) air temperatures may range between 2˚C and 5˚C (2˚C and 4˚C) above the current weather values in the late 21st Century. The warm (cold) days and nights are becoming more (less) frequent each year, and for the future climate (2100) it has been projected that about 40% to 70% of the days and 55% to 85% of the nights will be hot. Additionally, it can be foreseen that there will be no longer cold days and nights.

Recebido Abril de 2013 -Aceito Agosto de 2014RESUMO O presente trabalho faz uma análise das tendências de extremos climáticos baseada em indicadores calculados a partir de séries de dados observacionais diários de temperatura e de precipitação durante 35 anos em 20 estações meteorológicas do IAPAR, no Estado do Paraná. O objetivo é contribuir para estudos sobre avaliação de impactos e vulnerabilidade climática, requeridos para elaborar estratégias de adaptação às mudanças climáticas. Inicialmente as climatologias de temperatura do ar e de precipitação no Estado são revisitas. Com relação às tendências de extremos climáticos, os resultados dos indicadores associados à temperatura apontam para um padrão de aquecimento generalizado estatisticamente significativo em grande parte do Paraná. A porcentagem de dias e noites quentes no Estado aumentou consideravelmente a uma taxa de 0,1 a 0,4 %/ano entre 1976 e 2010. As médias anuais das temperaturas mínimas e máximas indicam uma elevação em quase todo o Paraná em torno de +0,02°C/ano no mesmo período. Os indicadores de temperatura mínima apresentam tendências de aumento mais significativas que os de temperatura máxima. Por outro lado, a maior parte dos indicadores de extremos climáticos associados à precipitação não apresenta significância estatística, com exceção de alguns poucos em distintas regiões do Estado. Destes, destacam-se apenas as tendências de elevação nos períodos secos (+0,25 mm/ano) em Pato Branco e Planalto no sudoeste do Paraná e de redução das chuvas fortes (-0,5 mm/ano) em Cambará, Ibiporã e Umuarama no norte do Estado. Palavras-Chave: Climatologia; Mudanças Climáticas; Extremos Climáticos; Paraná. ABSTRACT: OBSERVED TRENDS IN CLIMATE EXTREME INDICATORS OF TEMPERATURE AND PRECIPITATION IN THE STATE OF PARANÁ

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Under conditions of atmospheric blocking, the presence of a quasi-stationary anticyclone of large amplitude disrupts the normal eastward progression of the synoptic systems. These blockings correspond mainly to a positive anomaly of the air pressure. As a result, in the regions affected by the blocking occur several consecutive dry days and temperatures above average. This paper aims to discuss synoptically the atmospheric blocking phenomenon occurred in January and February 2014 in the South Atlantic Ocean, affecting especially the Southeastern Brazil and sectors that depend on the quantity of water for their activities in the region, such as agriculture and electricity generation. The significant population concentration makes this area emphatically vulnerable to long periods of drought, especially during the summer, affecting the water supply for the population. In order to achieve this goal, data of geopotential height at 850/500 hPa, streamlines in 850/500 hPa, pressure, temperature, humidity and wind at surface were evaluated through NCEP/ NCAR reanalysis (CFSRv2-Climate Forecast System Reanalysis Version 2) with 0.2˚ × 0.2˚ resolution. The analysis showed that the stationary anticyclone was configured dynamically favorable to blocking in the lower and middle levels of the atmosphere. Thus, atmospheric pressure at mean sea level presented values above normal combined with high average air temperature. By the climatological analysis, it was noted that there were emphatic negative precipitation anomalies over Southeastern Brazil. This atmospheric blocking was characterized as anomalous due to its long duration in a considered rainy season.