Estudo da variação multi – temporal da temperatura, precipitação e humidade relativa do ar na cidade de Quelimane e sua relação com os índices oceânicos 1981 - 2016

Abstract

The main objective of this research was to study the multi-temporal variation of the meteorological variables (temperature, precipitation and humidity of the air) in the city of Quelimane and to relate to the oceanic indexes of the Pacific. The multi-temporal (seasonal, inter-annual, decadal) evaluation of the meteorological variables was through the monthly, annual and decadal averages for each time series, and to relate to the oceanic indexes was through the use of two analysis approaches: In the first approach, seasonal averages (for every three months) were calculated and the normal climatological means (without occurrence of the indices) and averages corresponding to the years when the climatic indexes were above the + 0.5 ° (El-Niño) threshold and below the -0.5 º (La-Niña) threshold were determined. In the second approach, the anomalies of the annual precipitation and humidity averages were calculated for the years classified as El-Niño or La-Niña. Results revealed that the city of Quelimane presents a rainy summer and a dry winter, with an annual dry rainfall rate varying between 2000 mm and 860 mm with a maximum amplitude of 970.5 mm and a minimum of 35.1 mm. The precipitation has two distinct seasons: rainy season runs between December and April, with values between 110 and 300 mm, January being the wettest month and the dry season presenting values between 10 and 80 mm with the minimum observed in the month of September. The annual temperature variation is characterized by a period of high temperatures (summer) with temperatures varying between 26 and 28 °C, extending between October and April and a period of low temperatures, with values between 21 and 24 °C during the months of May and September. The highest values of relative humidity occur between January and July and vary between 81 and 83%, with the maximum observed in March. The period of low relative humidity is between August and December, with values ranging from 74 to 78 % with the lowest occurring in October. For the period 1981-2016 the coldest year was the year 1981 with an average annual temperature of about 24 °C and the hottest were the years 2007 and 2009 with average annual temperature of about 26.2°. The coldest decade was the 1980s with an average temperature of about 24.9 ° C and the hottestHilário Isaías Tamele Júnior Licenciatura em Oceanografia UEM-ESCMC x decade was the 2000s with an average temperature of about 25.8 °C. The temperature showed a tendency to increase, at an average rate of 0.011 °C. The years 1983, 1987 and 1992 were the driest years of the period 1981-2016 with cumulative annual precipitation of about 200 mm. The year 1981 was the rainiest, with cumulative annual precipitation of about 2000 mm. The rainiest decade was the 1980s with cumulative annual rainfall averaging about 1800 mm. The driest decade was the decade of 2000, with accumulated annual precipitation average of about 1200 mm. During the period under analysis, precipitation showed a tendency to decrease at an average rate of -9. 36 mm / year. The 1980s were the least wet decade for the period 1981-2016, with an average relative humidity of about 80%. The 2000s was the wettest decade with an average relative humidity of about 88%. Relative humidity showed a trend at an average rate of 0.086% per year. The temperature variation was not related to the variation of the temperature of the Pacific Ocean. The rainfall was inversely related to the temperature variation in the Niño-3.4 region of the Pacific Ocean, and during the warm period of the temperature in the Niño-3.4 region, precipitation tended to present values below the historical average, mainly in the quarters September-October -November to May-June-July.