Metrics of hurricane-ocean interaction: vertically-integrated or vertically-averaged ocean temperature?

[摘要] The ocean thermal field is often represented in hurricane-ocean interactionby a metric termed upper Ocean Heat Content (OHC), the vertical integral ofocean temperature in excess of 26°C. High values of OHC have proven usefulfor identifying ocean regions that are especially favorable for hurricaneintensification. Nevertheless, it is argued here that a more direct androbust metric of the ocean thermal field may be afforded by a verticalaverage of temperature. In the simplest version, dubbed T₁₀₀,the averaging is from the surface to 100 m, a typical depth of verticalmixing by a category 3 hurricane. OHC and T₁₀₀ are wellcorrelated over the deep open ocean in the high range of OHC, ≥75 kJ cm⁻².They are poorly correlated in the low range of OHC, ≤50 kJ cm⁻², in part because OHC is degenerate when evaluated on cool oceanregions, ≤26°C. OHC and T₁₀₀ can be qualitativelydifferent also over shallow continental shelves: OHC will generally indicatecomparatively low values regardless of the ocean temperature, whileT₁₀₀ will take on high values over a shelf that is warm andupwelling neutral or negative. In so far as the ocean thermal field alone isconcerned, these warm, shallow continental shelves would appear to be asfavorable for hurricane intensification as are warm, deep ocean regions.

[学科分类] 海洋学与技术