Pesquisa Antártica Brasileira (2004) 4: 155-169 (Brazilian Antarctic Research) ISSN 0103-4049 www.cnpq.br/areas/terra ¯ meioambiente/proantar/ Air temperature time series for King George Island, Antarctica FRANCISCO A. FERRON 1 , JEFFERSON C. SIMÕES 2 , FRANCISCO E. AQUINO 2 and ALBERTO W. SETZER 3 1 Laboratoire des Sciences du Climat et de l’Environnement (LSCE) Commissariat à l’Energie Atomique (CEA-Saclay), Orme des Merisiers, Bât 709 91191 Gif-Sur-Yvette Cedex, France 2 Núcleo de Pesquisas Antárticas e Climáticas (NUPAC), Instituto de Geociências Universidade Federal do Rio Grande do Sul, Cx. Postal 15001 – 91570-970 Porto Alegre, RS, Brasil 3 Centro de Previsão e Estudos Climáticos (CPTEC), Instituto Nacional de Pesquisas Espaciais (INPE) 12227-010 São José dos Campos, SP, Brasil ABSTRACT In this paper, we present a continuous time series of the mean annual and seasonal air temperatures for King George Island (KGI), for the period of 1947–1995, combining data from several meteorological stations in the South Shetland Islands. These series are analyzed for trends. The series are also compared with the mean monthly sea ice extent, recorded at 60 ◦ W. The mean annual temperature during this period was -2.8 ◦ C, with a minimum of -5.2 ◦ C, in 1959, and a maximum of -0.8 ◦ C, in 1989. This record shows a warming trend of 0.022 ◦ Ca -1 , in the studied time interval, a rise of 1.1 ◦ C in 49 years. Winter shows the most pronounced seasonal warming trend, 0.038 ◦ Ca -1 , or 1.9 ◦ C in the period. These trends are better defined than at the Faraday station. Abrupt variations in the mean annual temperature, up to 3.9 ◦ C over three years, have been recorded. Spectral analysis of these time series shows cycles of 5.3 and 9.6 years. A one-month lag is observed between the winter months mean temperatures in KGI and sea ice extent in the 60 ◦ W sector. Key words: climatology, atmospheric temperature, time series. INTRODUCTION The Antarctic and Subantarctic regions have a greater degree of climatic interannual variability than observed at lower latitudes. This enhanced variability is due to a number of feedbacks that result from complex interactions between atmospheric cir- culation, oceans and cryosphere (King and Turner 1997). Difficulties in the understanding of these Antarctic processes arise partially from the small number of meteorological stations that existed in the region before the International GeophysicalYear (1957/1958). The most comprehensive meteorological re- Correspondence to: Francisco Adolfo Ferron E-mail: francisco.ferron@libero.it cords in the region are those of stations located along the west coast of the Antarctic Peninsula, generally in the form of a continuous record, dating back to the 1940s. Orcadas station (60 ◦ 44’S, 44 ◦ 44’W) located on the South Orkney Islands, has the longest contin- uous meteorological records for the entire Antarctic region, it dates back to 1903. The warming trend over the west coast of the Antarctic Peninsula is greater than over the rest of the continent (Marshall et al. 2002), but their determi- nation is limited due to the high level of interannual variability and the relative shortness of the available records (King 1994). An analysis of the annual mean temperature made by Raper et al. (1984), using sev- eral meteorological stations all around Antarctica, Pesq Antárt Bras (2004) 4