| Summary: | 碩士 === 臺北市立教育大學 === 自然科學系碩士班 === 99 === The temporal and spatial characteristics of two types of El; Niño (Eastern Pacific
El Niño, EP-EL, and central Pacific El Niño, CP-EL) during 1950-2010 is explored by
analyzing HadiSST (Hadley Center Sea Ice and Sea Surface Temperature (SST) data set),
NCEP/NCAR reanalysis atmospheric data, and SODA(Simply Ocean Data Assimilation)
oceanic data. It shows that EP-EL is initiated in approximately April, near two month
earlier than CP-EL. Both types of El Niño peak in winter, while the EP-EL has larger
amplitude in mature phase and terminates to La Nina rapidly during the decaying phase
compared with CP-EL. The noticeable difference of atmospheric circulation anomalies
between EP-EL and CP-EL is that the anticyclone in WNP (Western North Pacific) is
well established during boreal autumn for EP-EL, when the Gill-type cyclonic
circulation in response to the central Pacific warm SST anomaly is still prominence for
the CP-EL.
The longitude-height section of atmospheric circulation reveals that the Indian
Ocean and the Pacific couple tightly during the developing stage for EP-EL, however the
air-sea coupling is insignificant for CP-EL. An eastward/westward propagation of
oceanic Kelvin/ Rossby wave is clearly identified during the lifecycle of EP-EL,
suggesting that the initiation and termination of EP-EL is closely related with the
thermocline-SST feedback process. The thermocline-SST feedback process is weak for
CP-EL.
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