Frequência de Ciclones tropicais em Moçambique e a sua relação com a precipitação

Abstract

The following is a summary of the work on the frequency of tropical cyclones in Mozambique and their relationship to rainfall. A statistical study of monthly precipitation values was carried out in 11 stations (map 1 in the annexes) for which there are results from observations of thirty years (1974-2003), as well as the statistics of tropical cyclones that affected the Mozambican coast during the same period, having drawn up tables in the annexes. The statistical treatment of the data used the analysis of frequency and correlation, having used the following parameters amplitude, number of classes, amplitude of classes, frequency of accumulation, relative frequency, mean, standard deviation and Pearson's correlation coefficient . With the results found, 22 graphs were drawn regarding the annual variation of precipitation and cyclones as well as the monthly variation of the same elements. Of the 76 tropical cyclones observed in the Mozambique Channel during the period under study, only 35 were felt on the coast or in the interior of the Mozambican territory. The results show that, in general, the distribution of precipitation and tropical cyclones is zonal; that is, it is asymmetric, comprising the North, Center and South zones. Precipitation in the central and northern regions of Mozambique is correlated with the occurrence of tropical cyclones. Tropical cyclones in Mozambique are observed from December to April. The cyclonic season in the South region varies from January to March and in the Center and North regions it varies from December to April. Tropical cyclones occur more frequently in the stations of Nampula, Pebane and Quelimane. In the South and Center regions the most frequent cyclones are category 3 and in the region and category 2 for the North region. The most frequent tropical cyclones in Mozambique are category 2 and 3, the least frequent are category 5. Tropical cyclones are not the only factor influencing rainfall in Mozambique. It is recommended that it would be interesting to continue the investigation of other atmospheric phenomena that may be linked to the occurrence of tropical cyclones. Since the frequency of tropical cyclones is small, it would be important to use long periods of study in order to obtain stable statistics.