08 May 2023
 | 08 May 2023
Status: this preprint is open for discussion.

Intraseasonal and interannual variability of sea temperature in the Arabian Sea Warm Pool

Na Li, Xueming Zhu, Hui Wang, Shouwen Zhang, and Xidong Wang

Abstract. The Arabian Sea Warm Pool (ASWP) is a part of the Indian Ocean Warm Pool, formed in the Arabian Sea before the onset of the Indian Ocean summer monsoon. The ASWP has a significant impact on climate change in the Indian Peninsula and globally. In this study, we examined the Intraseasonal and interannual variability of sea temperature in the Arabian Sea Warm Pool using the latest 5-day SODA reanalysis dataset. We quantified the contributions of sea surface heat flux, advection, and vertical entrainment to the sea surface temperature using mixed-layer heat budget analysis. We also used a lead lag correlation method to examine the relationship between the interannual variability of the ASWP and various large-scale modes in the Indo-Pacific Ocean. We found that the ASWP formed in April and decayed in June. Its formation and decay processes were asymmetrical, with the decay rate being twice as fast as the formation rate. During the ASWP development phase, the sea surface heat flux had the largest impact on the mixed layer temperature with a contribution of up to 85 %. Its impact was divided into the net heat flux at the sea surface (0.41–0.50 °C/5 day) and the short-wave radiation loss penetrating the mixed layer (from –0.08 °C/5 day to –0.17 °C/5 day). During the decay phase, the cooling effect of the vertical entrainment (from –0.05 °C/5 day to –0.18 °C/5 day) on the temperature variation increased and dominated the temperature variation jointly with the sea surface heat flux. We also found that the ASWP has strong interannual variability related to the consistent warming of the Indian Ocean basin. The lead lag correlation indicated that ASWP had a good synchronous correlation with the Indian Ocean Dipole. ASWP had the largest correlation coefficient at a lag of 5–7 months of niño3.4 index, showing the characteristics of modulation by ENSO. The ASWP was more significant (insignificant) in the following year before the summer monsoon after an El Niño (La Niña) event that peaked in the previous winter.

Na Li et al.

Status: open (until 03 Jul 2023)

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Na Li et al.

Na Li et al.


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Short summary
Observations of the sea surface temperature in the Arabian Sea show exceptional warming before the onset of the Indian Ocean summer monsoon. The sea surface temperature change is mainly caused by sea surface heat flux, horizontal advection, and vertical entrainment. Here, we quantify the contribution of those factors to the Arabian Sea warm pool using heat budget analysis and highlight how large-scale ocean modes control its change.