-
Abstract
It has long been acknowledged that there are two types of El Ni~no events, i.e., the eastern Pacific El
Ni~no (EE) and the central Pacific El Ni~no (CE), according to the initial position of the anomalous warm
water and its propagation direction. In this paper, the oceanic and atmospheric evolutions and the possible
mechanisms of the two types of El Ni~no events were examined. It is found that all the El Ni~no events, CE
or EE, could be attributed to the joint impacts of the eastward advection of warm water from the western
Pacific warm pool (WPWP) and the local warming in the equatorial eastern Pacific. Before the occurrence of
CE events, WPWP had long been in a state of being anomalous warm, so the strength of eastward advection
of warm water was much stronger than that of EE, which played a major role in the formation of CE. While
for the EE events, most contribution came from the local warming of the equatorial eastern Pacific. It is
further identified that the immediate cause leading to the difference of the two types of El Nieno events was
the asynchronous variations of the Southern Oscillation (SO) and the Northern Oscillation (NO) as defined
by Chen in 1984. When the transition from the positive phase of the NO (NO+) to NO- was prior to that
from SO+ to SO-, there would be eastward propagation of westerly anomalies from the tropical western
Pacific induced by NO and hence the growth of warm sea surface temperature anomalies in WPWP and
its eastward propagation. This was followed by lagged SO-induced weakening of southeast trade winds and
local warming in the equatorial eastern Pacific. These were conducive to the occurrence of the CE. On the
contrary, the transition from SO+ to SO- leading the transition of NO would favor the occurrence of EE
type events.
-
-
Citation
PENG Jingbei, ZHANG Qingyun, CHEN Lieting. 2011: Connections Between Different Types of El Ni~no and Southern/Northern Oscillation. Journal of Meteorological Research, 25(4): 506-516.
PENG Jingbei, ZHANG Qingyun, CHEN Lieting. 2011: Connections Between Different Types of El Ni~no and Southern/Northern Oscillation. Journal of Meteorological Research, 25(4): 506-516.
|
PENG Jingbei, ZHANG Qingyun, CHEN Lieting. 2011: Connections Between Different Types of El Ni~no and Southern/Northern Oscillation. Journal of Meteorological Research, 25(4): 506-516.
PENG Jingbei, ZHANG Qingyun, CHEN Lieting. 2011: Connections Between Different Types of El Ni~no and Southern/Northern Oscillation. Journal of Meteorological Research, 25(4): 506-516.
|
Export: BibTex EndNote
Article Metrics
Article views:
PDF downloads:
Cited by: