IANIGLA   20881
INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
artículos
Título:
The Zonda event in Argentina. State of Climate in 2006, A. Arguez, Ed. Special Supplement to the Bulletin of American Meteorological Society
Autor/es:
FEDERICO A NORTE; ANA GRACIELA ULKE; SILVIA SIMONELL; MAXIMILIANO VIALE
Revista:
BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY
Editorial:
American Meteorological Society
Referencias:
Año: 2007 vol. 88 p. 94 - 94
ISSN:
0003-0007
Resumen:
The severe Zonda wind event of july 11 th. 2006 east of the Andes Cordillera (Argentine) by F. Norte*;G.Ulke**;S. Simonelli* and M.Viale* The zonda is a strong , warm and very dry wind associated to adiabatic compression upon descending the eastern slopes of the Andes in winter and spring time preferently.This wind exhibit the so called foehn effect.Although this phenomenom occurs on the entire length of the extratropical Andes it is most frequently detected near the cities of Mendoza and San Juan which represent the most important urban regions of western Argentina.(one million and a half inhabitans) There are defined four categories , based on the maximum zonda wind gust( The annual frequency distribution of severe and extreme severe zonda events is lower than eight percent of the annual total cases .. The Zonda wind event of july 11 th. 2006 reached categories Z3 and Z4 in the surrounding area of Mendoza and San Juan cities where wind speed were over 120 Km/h during two or three hours without interruption. The synoptic surface and upper air conditions were the typical associated with a severe zonda wind occurrence in the region: a surface cold front approaching to the central coast of Chile driven by a 500 hPa level trough, a deep low pressure surface system approximately over 55°S and 65°W, and a strong upper air jet stream. The main feature of the event is the sharp polar air advection from the south and a remarkable 500/1000 hPa thickness gradient. In Mendoza airport meteorological station(32º50S; 69ª 47W , 704 masl a persistent northern wind clearly showed the zonda since 18 UTC 11 July to 03 UTC 12 July and a marked wind speed increase occurred from 18 UTC 11 July reaching a maximum of 60 km/h at 22 UTC , with an extreme wind gust of 80 km/h at 22:25 UTC In San Juan airport meteorological station (31º 34S; 68º 25W, 598 masl), wind speed became more intense between 12 UTC and 18 UTC 11 July reaching a maximum of 45 km/h with an even stronger maximum (52 km/h) at 06 UTC 12 July. A distinguished increase in temperature and dryng was observed reaching 28.2 ºC, whereas the dewpoint temperature dropped to -6 ºC in Mendoza and 33 ºC and -15 ºC at San Juan The July 11th 2006 zonda event caused a great impact over the communiy.The Mendoza newspapers informed that hundred of residences were affected, many families must leave their homes, 159 country and 23 buldings fires were reported , a hospital was partially destroyed, 25 school buildings were affected, hundred of trees falling down, 50000 inhabitants without electric power and 1500 without telephonic service. Similar information appeared on San Juan newspapers *Programa Regional de Meteorología. Instituto Argentino de Nivología ,Glaciología y Ciencias Ambientales(IANIGLA) Consejo Nacional de Ciencia y Tecnologia(CONICET) **Departamento de Ciencias de la Atmósfera y los Océanos, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina