New evidence for enhanced ocean primary production triggered by tropical cyclone

Abstract

New evidence based on recent satellite data is presented to provide a rare opportunity in quantifying the long‐speculated contribution of tropical cyclones to enhance ocean primary production. In July 2000, moderate cyclone Kai‐Tak passed over the South China Sea (SCS). During its short 3‐day stay, Kai‐Tak triggered an average 30‐fold increase in surface chlorophyll‐a concentration. The estimated carbon fixation resulting from this event alone is 0.8 Mt, or 2–4% of SCS's annual new production. Given an average of 14 cyclones passing over the SCS annually, we suggest the long‐neglected contribution of tropical cyclones to SCS's annual new production may be as much as 20–30%.

Observed near‐surface flows under all tropical cyclone intensity levels using drifters in the northwestern Pacific

“…Many studies have been conducted on the upper ocean cooling, strong ocean currents, and the enhanced ocean primary production triggered by TCs [O'Brien and Reid, 1967;Price et al, 1994;Chu et al, 2000;Lin et al, 2003aLin et al, , 2003bSriver and Huber, 2007]. Under storms, energy transfer from atmosphere to ocean generally generates surface waves, near-inertial waves, and currents [Price, 1983;Price et al, 1994;D'Asaro, 1985;Nilsson, 1995;Wunsch, 1998;Alford, 2001Alford, , 2003Wang and Huang, 2004;Liu et al, 2008;Jaimes and Shay, 2010].…”

Cyclone‐induced mixing does not cool SST in the post‐monsoon north Bay of Bengal

“…Deepening of the ocean-mixed layer cools sea surface temperature (SST) by several degrees Celsius under the track of intense TCs (Price, 1981;Wentz et al, 2000;Lin et al, 2003). SST cooling is thought to inhibit cyclone intensification, preventing the storm from attaining its potential intensity (Emanuel, 1999).…”

Analysis of Water Properties and Geostrophic Currents in Fiji Waters Before and After Tropical Cyclone Gene

“…This increase can be associated with upwelling of nutrient rich waters due to divergence. The mixed layer depth and salinity increase enhances ocean primary (phytoplankton) production which is the base of ocean food chain and produces about half the world's oxygen [5] .…”

“…Phytoplankton, besides being the base of the ocean food chain, also produces about half the world's oxygen [5] . Like all plants, phytoplankton uses carbon dioxide, sunlight and nutrients to photosynthesize and multiply.…”

“…Lin et al [5] stated that primary production takes place in the top 50-150 m of the water column (euphotic zone) where there is abundant light for photosynthesis and the supply of nutrients is mostly from the pumping of nutrient-rich deep water to the euphotic zone through various mechanisms. Thus, the deepening of the mixed layer observed in both the profiles above showing lower temperatures and increased salinity can make the marine environment healthier.…”