Influência dos fenômenos El Niño e La Niña nos veranicos do Estado de Minas Gerais

• Autor(a) principal: Minuzzi, Rosandro Boligon
• Data de Publicação: 2003
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5273
• topic: Climatologia; Minas Gerais; El nino; Corrente; La nina; Precipitação; Meteorologia; Climatology; Minas Gerais; El nino; Current; La Nina; Precipitation; Meteorology; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA

The daily precipitation data referring to 134 localities in the State of Minas Gerais, supplied by the Agência Nacional de Águas (ANA), were analyzed in order to characterize the rainy period (RP), as well as the event and duration of the dry spells occurring over the climatic events El Niño (EN) and La Niña (LN). At first, the beginning of the rainy periods (BRP) and the precipitation amount of the rainy period were analyzed, respectively based on the averages and normalized standard deviations of three annual series: El Niño, La Niña and neutral years. The influence of these phenomena on each 15-day period over the months from November to February were analyzed, by using the average and the standardized precipitation rate, as well as the behavior of each RP based on precipitation anomalies. For both analyses, seven stations were chosen according to the climatically homogeneous areas in Minas Gerais. Then, the frequency of dry spells was determined to intervals with four durations in these three series, and the dry spell was defined as a period with at least three dry consecutive days (precipitation ≤ 1 mm) during the rainy period. The method of Regression Analysis was used to relate the duration of the rainy period (RPD) and, or, BRP with the dry spells lasting from three to six days (A) and from seven to ten days (B), as well as the BRP and the total precipitation amount during RP with the dry spells classified as classes A and B, respectively. The results obtained for the influence of the EN and LN phenomena were georeferrenced by the interpolation method that materialized them into thematic maps generated by the Geographic Information System (GIS). The thematic maps were obtained, by involving of Minas Gerais State Digital Elevation Model (DEM) with the classification concerning to the total precipitation and RPD with the average frequencies of the dry spells. A characteristic of La Niña is to cause rains below the average on an extensive part of the State, as well as on half-Northeastern over events El Niño, and rains above the average on half- Southwestern Minas Gerais. The dry spells caused by LN on the North-Northeastern part of the State are due to the periods lasting more than 15 days, whereas on the South-Southwestern are due to the dry spells lasting from three to six days. Similarly, the dry spells on North-Northeastern of Minas Gerais during El Niño events, and the rains above the average on the half-Southwestern of the State cause an influence of the dry spells lasting three to six days.