Observed Global Increases in Tropical Cyclone-Induced Ocean Cooling and Primary Production

Abstract

Tropical cyclones provide an important source of ocean mixing, bringing cold, nutrient-rich water to the surface and triggering phytoplankton blooms. Here, we show significant increases in global tropical cyclone-induced sea surface temperature cooling and surface chlorophyll-a concentration of 0.05°C and 3.7 × 10−3 mg m−3 per decade over the past 20–35 years. The trends have been driven primarily by an increase in the intensity of strong tropical cyclones. The increase in chlorophyll-a concentration has been, on average, 1.6% per decade in oligotrophic areas during the tropical cyclone season, in contrast to a decrease of 0.1% per decade during the other months. This tropical cyclone-induced increase has partially mitigated the overall decline in primary production under climate change.