Distúrbios ondulatórios de leste: estudo de casos que afetaram a costa leste do NEB.

Abstract

In this study, we analyzed events Easterly Waves Disturbances (EWDs) that reached the coast of Northeastern Brazil during the months of May, June, July and August of the years 2005-2008. We used data from Reanalysis of the National Centers for Environmental Prediction - National Center for Atmosphere Research (NCEPNCAR) to find values of the instability index K, and the relative vorticity and divergence to identify their behavior during the passage of the disturbances. The results revealed that EWDs are associated with a high precipitation on the east coast of the Northeast, in the five cases examined rainfall exceeded 80 mm and it was negative relative vorticity (cyclonic) in low and middle levels there are upward movements characterizing in the atmosphere. It was observed that the K index for all months of the five cases EWDs indicate an extremely unstable atmosphere and events in the days of the index values were above 30 ° C (30 K), a value that may indicate a likelihood of 60 to 80% of rainfall events. It was concluded that the EWDs identified from the diagrams Hovmöller meridional wind show wave patterns in the months investigated. The EWDs showed an average period of about three days, propagation speed of about 10 m / s and a wavelength of 3227 km.