R98229029 CHC

Outline

ENSO– EP and CP ENSO

ACW– ACW– ENSO and ACW

GEW– GEW– ACW and GEW– ENSO and GEW– ENSO and GEW and ACW

Indian Ocean– ENSO and Indian Ocean– IOD– ENSO and IOD

ENSO

Kao and Yu, 2009

ENSO - EP ENSO

Kao and Yu, 2009

ENSO - CP ENSO

Kao and Yu, 2009

ENSO

EP– Before 1977 : 2 yr– After 1977 : 4 yr

CP– Before 1977 : 2 yr– After 1977 : 2 yr

ACW

ACW

El Nino prior to 1977 deriving from eastward phase propagating of SST/SLP wave propagating eastward across the subtropical South Pacific Ocean , leading the equator ward propagating along the west coast of South America.

After 1977, the evolution of the 1983, 1987, 1992 El Nino initiated by the slow eastward propagating of a couple SST/SLP wave propagating eastward along the tropical Pacific Ocean from the Warm Pool north of Australia.

(Wang, 1995)

ENSO and ACW

Covarying warm SST and low SLP anomalies in the western and central subtropical South Pacific during the year prior to El Nino, finding them propagating eastward into the eastern tropical Pacific Ocean during the following El Nino year.

(Van Loon and Shea, 1985/1987)

Observing interannual SIE anomalies in the eastern Indian and western Pacific sector of Southern Ocean leading El Nino by 1 to 2 years.

(Simmonds and Jacka, 1995; Yuan and Martinson, 2000)

ENSO and ACW

ACW propagate slowly eastward across the tropical Indian and western and central Pacific oceans, influencing the phase and magnitude of El Nino in the eastern equatorial Pacific Ocean during following year.

(Yasunari, 1987; Wang, 1995; Tourre amd White, 1997; White amd Cayan, 2000)

GEW

The GEW appears to be initiated in the western tropical Indian Ocean by zonal atmospheric teleconnections associated with the tropical standing mode of ENSO.

(Tourre and White, 1997)

GEW

Before 1977, the warm phase of the GEW propagated only as far east as the central equatorial Pacific Ocean, where it was diverted northward, propagating eastward into the Caribbean Sea between 10N and 20N, associated with the northward displacement or expansion of the ACW into the subtropical

South Pacific Ocean. After 1977, when the ACW receded to the middle and high latit

ude South Pacific Ocean, the warm phase of the GEW penetrated all the way into the eastern equatorial Pacific Ocean.(White and Annis, 2004)

GEW and ACW

Atmospheric and oceanic teleconnections link the ACW in the Southern Ocean and the GEW in the tropical Indo-Pacific Ocean.

(White and Peterson, 1996; White and Cayan, 2000)

Oceanic teleconnection provides appositive feedback to the GEW in the Warm Pool north of Australia, producing a resonant interaction between the GEW and ACW that reinforce the amplitudes of both via a global feedback loop in the southern hemisphere that takes ~4 years to complete. Thus it comes as no surprise that the GEW and ACW are linked to one another over most of the southern hemisphere.

(White et al., 2002)

GEW and ACW

The tropical standing mode of ENSO initiating anomalous Hadley cell activity in the western Pacific Ocean, with anomalous divergence in the subtropical limb initiating quasi-stationary Rossby waves in the mean upper level Westerly Wind. These quasi-stationary Rossby waves allow the tropical standing mode of ENSO to penetrate its influence into the eastern Pacific and western Atlantic sectors of the Southern Ocean along a great circle route extending from the subtropical ocean north of New Zealand through Drake Passage.

(Karoly, 1989)

ENSO and GEW

GEW propagate eastward across the Indo-Pacific Ocean alone the mean path of the ITCZ, providing a delayed positive feedback to El Nino/La Nina in the eastern equatorial Pacific Ocean.

(White and Cayan, 2000)

ENSO and ACW and GEW

Before 1977, El Nino was initiated by covarying warm ST and low SLP anomalies in ACW propagating equator ward along the eastern boundary to the equator.

After 1977 El Nino was initiated by covarying warm ST and low SLP anomalies in GEW/ACW propagating eastward across the tropical Indian and western and central Pacific Ocean.

(White and Annis, 2004)

ENSO and Indian Ocean

Indian Ocean climate variability might have an important influence on the ENSO variance and frequency.

(e.g., Yu et al. 2002; Wu and Kirtman 2004; Behera et al. 2006)

CP-ENSO is significantly reduced in a CCSM3 experiment where the Indian Ocean coupling is turned off.

(Yu, 2009)

IOD

Intensity of the IOD is represented by anomalous SST gradient between the western equatorial Indian Ocean(50E‐70E and 10S‐10N) and the south eastern equatorial Indian Ocean (90E‐110E and 10S‐0N)

IOD

IOD

ENSO and IOD

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