Abstract

BISCHOFF, Susana A  and  VARGAS, Walter M. Climatic properties of the daily 500 HPA circulation ECWMF reanalysis data over southern southamerica during 1980-1988. Meteorologica [online]. 2006, vol.31, n.1-2, pp.3-10. ISSN 1850-468X.

Several properties of atmospheric circulation over South America using ECMWF reanalyzed daily circulation anomaly maps at 500 hPa over the period 1980-1988 are analyzed. Reanalysis are particularly useful in this region due to the scarce radiosonde measurements. The properties analyzed here are selected in a way that they describe the different circulation conditions over the region to obtain a statistical diagnosis for objective forecast. The most frequent circulation types were obtained in a previous paper by applying correlation matrices between fields. In this paper that matrix was used to obtain other properties of the circulation types such as persistence, "opposites types", uncommon types and those providing information independent of the sample ("quasi orthogonal types"). Uncommon circulation types whose occurrence probability ranges from 6 to 10% are relevant in May, July, August, September, October and December. Types which correlate with each other with negative coefficients compose the group of "opposites types". This would allow constructing a partial time series of circulation types. The physical standpoint means that the two types represented respond to opposite dynamic and thermodynamic conditions.

Keywords : Circulation types; Persistence; Extreme circulation patterns.

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