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<p>This study investigates how the South Pacific high (SPH) modulates surface turbulent heat fluxes—latent heat flux (LHF) and sensible heat flux (SHF)—over eastern Australia during austral summer (December–February, DJF) for 1988–2017. Using the center of action (COA) framework, interannual variability in SPH pressure, latitude, and longitude indices is quantified, and their effects on regional energy exchange are examined. Spatial correlation and composite diagnostics reveal that intensified SPH phases coincide with significant reductions in both LHF and SHF, caused by weakened near-surface humidity (air specific humidity <i>Q</i><sub>a</sub> and surface saturation specific humidity <i>Q</i><sub>s</sub>) and temperature (near-surface air temperature <i>T</i><sub>a</sub> and surface temperature <i>T</i><sub>s</sub>) gradients together with suppressed wind fields. These patterns indicate a stabilized boundary layer that limits evaporative cooling and favors surface warming. Compared with other teleconnection indices—the southern annular mode (SAM), Indian Ocean Dipole (IOD), and Niño 3.4—the SPH exerts a more spatially coherent and seasonally persistent influence on summer surface flux variability across the Coral and Tasman seas. The results identify the SPH as a key modulator of regional energy balance and a potential driver of Australia’s increasing summer heat-extreme risk under ongoing climate change, underscoring the need to include SPH dynamics in seasonal prediction and climate impact models.</p>

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Influence of the South Pacific high on surface turbulent heat fluxes and its implications for summer heat extremes over eastern Australia

  • 期刊论文

  • 发表日期：

    2026年1月1日

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  • Nasir Ilyas,
  • Muhammad Jawed Iqbal,
  • Maqsood Alam

摘要

This study investigates how the South Pacific high (SPH) modulates surface turbulent heat fluxes—latent heat flux (LHF) and sensible heat flux (SHF)—over eastern Australia during austral summer (December–February, DJF) for 1988–2017. Using the center of action (COA) framework, interannual variability in SPH pressure, latitude, and longitude indices is quantified, and their effects on regional energy exchange are examined. Spatial correlation and composite diagnostics reveal that intensified SPH phases coincide with significant reductions in both LHF and SHF, caused by weakened near-surface humidity (air specific humidity Qa and surface saturation specific humidity Qs) and temperature (near-surface air temperature Ta and surface temperature Ts) gradients together with suppressed wind fields. These patterns indicate a stabilized boundary layer that limits evaporative cooling and favors surface warming. Compared with other teleconnection indices—the southern annular mode (SAM), Indian Ocean Dipole (IOD), and Niño 3.4—the SPH exerts a more spatially coherent and seasonally persistent influence on summer surface flux variability across the Coral and Tasman seas. The results identify the SPH as a key modulator of regional energy balance and a potential driver of Australia’s increasing summer heat-extreme risk under ongoing climate change, underscoring the need to include SPH dynamics in seasonal prediction and climate impact models.