Diagnóstico e análise de ondas de calor e de frio em Minas Gerais.

Abstract

Climate change recorded in recent decades is associated with episodes of extreme temperature or precipitation. In the Brasil the biggest concern related to climate change are in health, agriculture, tourism and economy. Investigating the occurrence of extreme temperature such as warm and cold waves for climate and hydrological purposes is of great importance, as some regions of the Brasil, such as the South and Southeast, suffer several impacts due to high and low temperatures. This study aims to diagnose and analyze the number of days with warm and cold waves in the state of Minas Gerais in the period of 1961- 2015, using different methods of estimates as WMOI, SI and WSDI and CSDI (RClimdex). We used maximum and minimum temperature (Tmax) of the series of daily data (1961-2015) of 55 weather stations from the National Institute of Meteorology (INMET), for research and classification of cold and warm waves with basis of the five or more consecutive days of positive and negative anomaly maximum and minimum temperatures. In addition, methods for the analysis of seasonal and annual trends were applied from the Mann Kendall and Student's t test. When comparing the methods, the WMOI detected the largest number of days with waves warm and cold, in Minas Gerais, especially in the months of spring and summer. The SI method did not detect many warm waves in the summer and cold waves in the winter. The SI smooths the number of days with warm and cold waves in both seasonal and annual scale. With the use of the indexes WSDI and CSDI was detected amount similar to other indexes (WMOI and SI) heat waves and cold in annual scale. With result to spatial configurations of climatological means of the number of days of warm and cold waves. It observed increase of warm waves and reduction of cold waves. Trends calculated statistically significant 95%, which showed positive trends to an increase in heat waves and negative trends for the cold waves. As for the association of the influence of El Niño and La Niña it was observed that, on average, there are a greater number of days with warm waves in El Niño years and days with cold waves in La Niña years.