SURFACE WIND PATTERNS IN THE NORTH COAST REGION OF BRAZIL

• Published in: Ciência e natura Vol. 38; no. IX WORKSHOP; p. 383
• Main Authors: Medeiros, Luiz Eduardo, Fisch, Gilberto, Iriart, Paulo, Felipe Denardin Costa, Oliveira, Dionnathan Willian, Schuch, Daniel
• Format: Journal Article
• Language: Portuguese
• Published: Santa Maria Universidade Federal de Santa Maria - Centro de Ciências Naturais e Exatas 01.01.2016
• ISSN: 0100-8307; 2179-460X

The atmospheric flow near the surface and in the planetary boundary layer (PBL) are investigated for the coastal part of Maranhão state. Near the coast in the PBL the flow is predominantly from the northeast quadrant with its meridional component increasing during the day and being from north-northeast and decreasing during the course of the night to be from east-northeast at early morning. The result of this is a small counterclockwise rotation but with no flow reversals. Through an analysis of extensive radiosonde data it is found that the flow above the PBL is predominantly southeasterly for the region. It is consequence of the outflow from the descending branch of the large-scale circulation of the Hadley cell. For stations further inland the flow is from approximately northeast during period between morning to noon but rotating clockwise to become from southeast-east (SEE) sector at early evening. The clockwise rotation continues in the afternoon and the wind becomes from south, and later southwest when in the evening it quickly becomes from north. The wind rotation during this period is mainly determined by an oscillating surface pressure gradient-force. During the night the local surface wind tendency is not controlled by the gradient-force probably because the air has to go against higher terrain and negative buoyancy becomes an important force of the momentum balance. The oscillating surface pressure-gradient-force is a response to a sea-breeze circulation. In the coast, we speculate that the flow does not reverse its meridional component because the surface pressure-gradient point south there for most of the time.