The observed sea surface height (SSH)-sea surface temperature (SST) in east equatorial Indian Ocean (EEIO) shows a significant asymmetric relation between the positive and negative SSH anomalies during boreal autumn. Whether or not the thermocline- SST feedback is responsible for the negative SST skewness in the EEIO is explored by diagnosing various air-sea feedback processes and a mixed layer heat budget. Our analysis based on observations suggests that the SSH-subsurface temperature relation is approximately symmetric between the positive and negative episode, which is significantly different from the asymmetric SSH-SST relation. This implies that the observed SSH-SST asymmetry is not attributed to the ocean thermocline feedback. A further analysis of the SST-precipitation, precipitation-wind stress and wind stress-SSH relations demonstrates that the asymmetry arises from asymmetric atmospheric heating/wind responses to the SST anomaly. A mixed layer heat budget analysis reveals that the ratio of the mixed-layer temperature tendency between the positive and negative events keeps approximately unchanged with and without vertical temperature advection, suggesting that the thermocline-feedback is not crucial for generating the negative SST skewness in the EEIO.
關聯:
Geophysical Research Letters，Vol. 37, Issue 11，Pages L11702
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