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Dynamical features of the global teleconnection pattern during the two types of El Niñoтезисы доклада
- Авторы: Gushchina D., Zheleznova I., Dewitte B.
- Сборник: Thesis of 11-th International conference on meteorology and oceanology of Southern Hemisphere
- Тезисы
- Год издания: 2015
- Место издания: Santiago
- Аннотация: It is now recognized that the two types of El Niño events, i.e. the eastern Pacific (EP) El Niño and Central Pacific (CP El Niño) events, have distinct teleconnection patterns in many regions of the world. Whereas most studies have focused on the teleconnection on temperature and precipitation, the details of changes in the main circulation cells due to the two types of El Niño have not been documented. These cells form the so-called “atmospheric bridges” providing a conduit for the transport of heat and moisture anomalies induced by El Niño outside the tropical Pacific. Here we use the NCEP/NCAR Reanalysis over 1950-2013 to document such changes using two circulation indexes: the velocity circulation along the latitude circle as a proxy of the intensity of the mean zonal circulation and the velocity circulation along the contours of the main atmosphere centers of action, which diagnoses the circulation anomalies within these centers. It is shown that the response in mean zonal circulation is more intense during CP El Niño event, which is interpreted as resulting from the localization of SST anomalies in the area of already strong deep convection. However the spatial structure of the zonal circulation anomalies is similar for the both types of El Niño. Therefore the difference in temperature and precipitation anomalies observed during the two types of El Niño results not from the change of mean zonal currents but from the different response to the CP and EP El Niño of the circulation in the atmosphere centers of action. The analysis reveals that (1) there is an hemispheric asymmetry in the response of the atmospheric circulation to the two types of El Niño, with CP El Niño events leading to a more pronounced change in the centers of action of the South Hemisphere than EP El Niño; (2) there is an earlier seasonal onset of the teleconnection circulation pattern in the middle and upper troposphere during CP El Niño events than during EP El Niño events. Changes in the Walker and Hadley circulation are also diagnosed and discussed.
- Добавил в систему: Гущина Дарья Юрьевна