The atmospheric circulation on the synoptic scale during the culmination phase of the El-Niño − Southern Oscillation events (1997−1998)

Abstract. For the classification of the synoptic processes in the tropical Pacific using daily data, criteria were proposed for identifying the different evolutional phases of the equatorial westerly wind zone. The criteria are based on the location, extent and activity of the westerly wind zone on the 850 hPa isobaric surface. According to this classification all the observed variants of the westerly wind regime above the tropical Pacific can be divided into three classes: normal, active, and break. For each class one specific pattern of tropical atmospheric circulation centers and divergent wind velocity potential in the lower and upper troposphere are found.

Using the singular value decomposition method (SVD) the connection between the atmospheric circulation and sea surface temperature (SST) of equatorial Pacific is investigated.