Main features associated to the precipitation in Madeira and the Atmospheric rivers in the winter seasons.

Abstract

This study presents the main features about 10-year daily accumulated precipitation analysis over the Madeira's highlands, as well as the relationships between this precipitation and the meridional water vapor transport occurring in narrow corridors, also known as atmospheric rivers (ARs). The ARs were visually identified in the total precipitable water vapor field extracted from the Atmospheric Infrared Sounder (AIRS) data, and over a domain covering the North Atlantic Ocean. When needed, ECMWF Analysis were also used as support. The daily precipitation during the study period evidenced generally dry summers, whereas the highest values of daily accumulated precipitation being recorded mainly during the winter, but also occurring during autumn and spring seasons. Moist air emanating mainly from the Caribbean Sea flows northward or eastward intersecting, on some occasions, the Madeira Island throughout the winter seasons, but frequently already in a dissipation stage. In fact, the moist environment created by the ARs can favor the precipitation development, but it is not the sole factor favoring the high rainfall amounts over the Madeira island.