HR: 1340h
AN: OS13A-1014    [Abstracts]
TI: Central Pacific and Eastern Pacific Types of ENSO
AU: * Kao, H
EM: hkao@uci.edu
AF: Department of Earth System Science, University of California, Irvine, 3200 Croul Hall, Earth System Science, University of California, Irvine, Irvine, CA 92697, United States
AU: Yu, J
EM: jyyu@uci.edu
AF: Department of Earth System Science, University of California, Irvine, 3200 Croul Hall, Earth System Science, University of California, Irvine, Irvine, CA 92697, United States
AB: n this study, surface ocean observational and subsurface ocean assimilation data are examined to demonstrate that there exits two distinct types of El Nino Southern Oscillation (ENSO): a traditional eastern Pacific (EP) -type of ENSO and a less-studied central Pacific (CP) -type of ENSO. The EP-type of ENSO is characterized by a sea surface temperature (SST) anomaly centers in the eastern tropical Pacific, westward propagation, basin-wide thermocline variation, shallower thermocline, more sensible to the subsurface processes and remote surface wind response. In contrast, the CP-type of ENSO is characterized by local air-sea interaction with its SST, surface wind, and SST anomalies confined mostly in the central Pacific. The underlying generation mechanisms, spatial structures and evolutions of these two types of ENSO will be discussed. Advanced indices based on SST and ocean heat content (OHC) are developed to better separate these two types of ENSO. It is found that since 1958 until 2001, all the strong El Nino events are EP-type of ENSO while all the strong La Ninas are CP-type of ENSO. Also, a CP type of La Nina usually comes after a EP-type of El Nino. The indices defined based on OHC can not only demonstrate the independence and relationships between these two types of ENSO but also capture the ENSO events better than single Nino SST index. This study suggests that more insights of ENSO dynamics may be obtained using ENSO indices defined with subsurface ocean information.
DE: 4223 Descriptive and regional oceanography
DE: 4231 Equatorial oceanography
DE: 4260 Ocean data assimilation and reanalysis (3225)
DE: 4522 ENSO (4922)
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting