International Journal of Marine Science, 2024, Vol.14, No.3, 218-230 http://www.aquapublisher.com/index.php/ijms 221 3.2 Ocean-atmosphere interactions The interactions between the ocean and atmosphere significantly contribute to the variability of circulation in the Indo-Pacific basin. Coupled ocean-atmosphere processes, such as those observed during glacial periods, amplify changes in the climate of the Indo-Pacific warm pool. For instance, the exposure of the Sahul shelf during glacial periods excited a positive feedback mechanism involving a stronger surface temperature gradient along the equatorial Indian Ocean and a weaker Walker circulation, leading to significant changes in ocean cooling and rainfall patterns (DiNezio et al., 2018). Furthermore, the Indo-Pacific Ocean Capacitor (IPOC) mode and the Pacific-Japan (PJ) pattern are examples of ocean-atmosphere interactions that influence regional climate variability, including the Indian Summer Monsoon Rainfall (ISMR) (Gnanaseelan and Chowdary, 2021). These interactions highlight the complex feedback mechanisms that drive circulation variability in the Indo-Pacific region. 3.3 Role of sea surface temperature Sea surface temperature (SST) is a critical factor in the variability of ocean circulation in the Indo-Pacific basin. Changes in SST can influence atmospheric circulation patterns, which in turn affect ocean currents. For example, the Indo-Pacific Warm Pool has experienced intensified warming, which is consistent with the strengthening of the Walker circulation (Wills et al., 2022). Additionally, the Indian Ocean has undergone substantial heat and freshwater changes, with rapid increases in SST and ocean heat content since the 2000s. These changes are linked to both anthropogenic forcing and natural multi-decadal variability associated with the Interdecadal Pacific Oscillation (Ummenhofer et al., 2021). The variability in SST, therefore, plays a pivotal role in modulating the circulation patterns and overall climate of the Indo-Pacific region. 4 Impact of Circulation Variability on Climate 4.1 Influence on regional climate patterns The variability in the Indo-Pacific Ocean basin circulation significantly influences regional climate patterns, particularly in the South Asian region. The Indo-Western Pacific Ocean Capacitor (IPOC) mode, for instance, induces a tripole pattern in precipitation anomalies over South Asia, characterized by strong positive precipitation anomalies over the western Ghats and Sundarbans-Bangladesh region, separated by negative anomalies over the monsoon trough region (Chowdary et al., 2019). This pattern is maintained by the anomalous western North Pacific (WNP) anticyclone and tropical Indian Ocean (TIO) warming, which affect local rainfall through mechanisms such as low-level convergence and orographic lift (Chowdary et al., 2019). Additionally, the South China Sea monsoon trough (SCSMT) exhibits interannual variability influenced by sea surface temperature anomalies (SSTAs) in the tropical Indo-Pacific, with different epochs showing varying key areas and mechanisms of influence (Zhang et al., 2020b). 4.2 Impact on global climate systems The Indo-Pacific warm pool (IPWP) plays a crucial role in global climate systems by affecting major atmospheric circulations such as the Hadley and Walker circulations. Warmer SSTs in the IPWP strengthen the upward branch of the Hadley circulation, while the Walker circulation is influenced by both natural variability and global warming trends (Kim et al., 2020). The El Niño/Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) are dominant modes of climate variability in the Indo-Pacific region, affecting global weather patterns through direct and indirect pathways (Behera, 2021). ENSO-induced basin-wide modes in the tropical Indian Ocean, for example, have delayed effects on climate variations in the western Pacific and adjacent Asian regions, acting like a capacitor (Behera, 2021). Furthermore, changes in sea level and SST variations in the Indo-Pacific are intrinsically linked, with climate variability modes such as ENSO, IOD, and Pacific Decadal Oscillation (PDO) significantly influencing sea level variability (Kumar et al., 2022). 4.3 Interaction with monsoon systems The interaction between Indo-Pacific circulation variability and monsoon systems is complex and multifaceted. The IPOC mode, for instance, has a strong impact on the South Asian summer monsoon rainfall, with the WNP anticyclone and TIO warming playing crucial roles in maintaining regional precipitation patterns (Chowdary et al.,
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