East‐west SST contrast over the tropical oceans and the post El Niño western North Pacific summer monsoon

Abstract

[1] The circulation and SST anomalies during the post El Niño Asian summer monsoon season were examined through data analysis and linear equatorial b plane model calculations. Over the Philippine Sea, a negative precipitation anomaly and low-level anti-cyclonic anomaly were found. Over the western equatorial Pacific, a low-level easterly anomaly prevailed. An east-west SST anomaly contrast dominated over the tropical Indian and Pacific Oceans, with positive anomalies over the Indian and western Pacific Oceans and negative anomalies over the central to eastern Pacific. The b plane model demonstrated that the anti-cyclonic anomaly over the Philippine Sea was a Rossby response to the negative precipitation anomaly found in this region. The easterly anomaly along the equator was part of a Kelvin response to the SST anomaly contrast. On the northern side of this anomalous easterly, a negative vorticity anomaly developed. This could induce the moist Rossby wave over the Philippine Sea. Citation: Terao, T., and T. Kubota (2005), East-west SST contrast over the tropical oceans and the post El Niño western North Pacific summer monsoon, Geophys. Res. Lett., 32, L15706,

Impacts of Rapid Warm-To-Cold ENSO Transitions on Summer Monsoon Rainfall over the Northeastern Indian Subcontinent

“…Terao and Kubota (2005) further calculated the solution of the simple linear equatorial b-model to show the Rossby response to a negative heating anomaly over the Philippine Sea extended westward up to the Indian subcontinent (Fig. 4b in Terao and Kubota (2005)), which is similar to the westward extension of anticyclonic circulation in the present paper (Figs. 6b, d).…”

“…These anomaly patterns seen in SST and the circulation fields are consistent with the analysis by Terao and Kubota (2005), but with higher statistical confidence since the period of the data used in the present paper is longer. Terao and Kubota (2005) further calculated the solution of the simple linear equatorial b-model to show the Rossby response to a negative heating anomaly over the Philippine Sea extended westward up to the Indian subcontinent (Fig. 4b in Terao and Kubota (2005)), which is similar to the westward extension of anticyclonic circulation in the present paper (Figs.…”

“…An east-west SST anomaly contrast developed in JJA in the rapid ENSO transition years. This east-west SST contrast is an important factor in the ENSO transition, as discussed in Section 1 (Terao and Kubota 2005;Xie et al 2009). To evaluate the SST anomaly contrast over the Indian Ocean and the central Pacific Ocean during the summer monsoon season, we defined dSST(IO-CP) as the difference between SST(IO) and SST(CP), the SST in JJA over the equatorial Indian Ocean (10°S̶10°N, 60°̶120°E) and central Pacific Ocean (10°S̶10°N, 150°E̶150°W).…”

“…Wang et al 2001). The suppression of WNPM after the El Niño termination was attributed to a zonal SST anomaly contrast developed over the equatorial Indian and Pacific Oceans toward summer (Terao and Kubota 2005;Xie et al 2009), with a positive SST anomaly over the Indian Ocean corresponding with the global SST warming during the mature phase of El Niño (Newell and Weare 1976;Weare 1979;Yulaeva and Wallace 1994;Klein et al 1999;Terao 2003, 2004;Du et al 2009) and a negative SST anomaly intensified over the central Pacific associated with the rapid transition to the cold phase of ENSO Vol. 91, No.…”

A Role of Zonal Gradient of SST between the Indian Ocean and the Western Pacific in Localized Convection around the Philippines

“…Wang et al (2000) reveals the importance of the local air-sea interaction on the precipitation over the East Asia. In addition to the influence of the local SST anomalies, the recent studies examine in situ versus remote SST influences on the variation of precipitation over the East Asia, especially around the Philippines (e.g., Nakazawa 2001; Terao and Kubota 2005). They argued that the East Asian summer monsoon is influenced not only by the local SST but also by the remote SST anomalies.…”