Active Role of the ITCZ and WES Feedback in Hampering the Growth of the Expected Full-Fledged El Nino in 2014

作者：Maeda Shuhei^*; Urabe Yusuke; Takemura Kazuto; Yasuda Tamaki; Tanimoto Youichi

来源：SOLA, 2016, 12(0): 17-21.

DOI：10.2151/sola.2016-004

We investigated features of the atmosphere and ocean to seek a possible candidate that suppressed the growth of the El Nino event in 2014. In the boreal summer-fall season, equatorially antisymmetric sea surface temperature (SST) anomalies with a positive (negative) sign to the north (south) of the equator prevailed in the central and eastern tropical Pacific. In association with the SST anomalies, cumulus convective activity was enhanced in the region of the climatological Intertropical Convergence Zone (ITCZ). Anomalous southerly surface winds flowing across the equator toward the ITCZ induced upward latent heat flux anomalies and lowered SST in the near-equatorial region. These coherent spatial patterns between SST, wind, and latent heat flux anomalies suggested that the wind-evaporation-SST (WES) feedback sustained the suppression of the El Nino growth. A linear baroclinic model experiment indicated that the enhanced convective heating in the ITCZ also contributed to sustain the anomalous surface southerlies across the equator by the intense meridional atmospheric circulation over the equator. These results indicate that the anomalous southerlies across the equator sustained by the WES feedback and intense convective heating in the ITCZ contributed to the suppression of the El Nino growth.

• 出版日期2016
• 单位中国气象科学研究院