Regional-scale meteorological characteristics of the Vento Norte phenomenon observed in Southern Brazil

• Published in: Environmental fluid mechanics (Dordrecht, Netherlands : 2001) Vol. 22; no. 4; pp. 819 - 837
• Main Authors: da Rosa, Cinara Ewerling, Stefanello, Michel, Facco, Douglas Stefanello, Roberti, Débora Regina, Rossi, Fábio Diniz, Nascimento, Ernani de Lima, Degrazia, Gervásio Annes
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.08.2022; Springer Nature B.V
• Subjects: Air temperature; Atmospheric diffusion; Classical Mechanics; Climatology; Cold season; Earth and Environmental Science; Earth Sciences; Elevation; Environmental Physics; Gusts; Gusty winds; Hydrogeology; Hydrology/Water Resources; Maximum winds; Meteorological data; Meteorological observations; Morning; Oceanography; Original Article; Temperature variations; Weather forecasting; Weather stations; Wind; Winds; Brazil; Regional meteorology; Downslope windstorms; Topography effect; Vento Norte
• ISSN: 1567-7419; 1573-1510
• DOI: 10.1007/s10652-022-09855-4

The sudden increase in air temperature associated with strong gusty winds of northerly direction is a phenomenon occasionally observed during the cold season in the central region of Rio Grande do Sul ( RS ) state, located in extreme southern Brazil. This geophysical flow, which is known as Vento Norte ( VNOR ; Portuguese for “North Wind”), promotes temperature variations that depart significantly from the local cold-season climatology. In this study, eleven years of surface meteorological observations collected at seven weather stations distributed over central RS  are employed to investigate the regional extension of the effects of the VNOR  windstorm. The analysis revealed that the sharp increase in temperature and in wind magnitude caused by VNOR  is observed over a rather wide region of central RS . However, it is in the vicinities of the city of Santa Maria, located just south of an abrupt drop in terrain elevation, that the most intense VNOR  effects are observed suggesting a downslope enhancement of the windstorm. A detailed investigation of the meteorological data also showed that the duration of the VNOR  windstorm is well correlated with the magnitude of the maximum wind gusts, with the most intense VNOR  events also lasting longer. VNOR  events occur more frequently in the period between the morning (0700 LST) and early afternoon (1400 LST). The onset of the windstorm is detected predominantly during overnight and morning hours, with 70% of VNOR  cases initiating between 0000 and 1000 LST. Regarding the VNOR  demise, 66% of the windstorms dissipate between early afternoon and early evening hours (1200–1900 LST). Results from this study are applicable in the areas of atmospheric diffusion and local weather forecasting.