Premium
Asymmetry of the Bjerknes positive feedback between the two types of El Niño
Author(s) -
Zheng Fei,
Fang XiangHui,
Yu JinYi,
Zhu Jiang
Publication year - 2014
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl062125
Subject(s) - asymmetry , anomaly (physics) , equator , amplitude , geology , positive feedback , physics , sea surface temperature , climatology , geodesy , condensed matter physics , latitude , quantum mechanics , engineering , electrical engineering
Corresponding to the pronounced amplitude asymmetry for the central Pacific (CP) and eastern Pacific (EP) types of El Niño, an asymmetry in the strength of the Bjerknes positive feedback is found between these two types of El Niño, which is manifested as a weaker relationship between the zonal wind anomaly and the zonal gradient of sea surface temperature (SST) anomaly in the CP El Niño. The strength asymmetry mainly comes from a weaker sensitivity of the zonal gradient of sea level pressure (SLP) anomaly to that of diabatic heating anomaly during CP El Niño. This weaker sensitivity is caused by (1) a large cancelation induced by the negative SST‐cloud thermodynamic feedback to the positive dynamical feedback for CP El Niño, (2) an off‐equator shift of the maximum SLP anomalies during CP El Niño, and (3) a suppression of the mean low‐level convergence when CP El Niño events occur more often.