Oases in an Ocean Desert

Abstract

Western north Pacific Gyre is the most oligotrophic ocean in the world. Throughout the year its chlorophyll-a concentration is mostly < 0.05 mg/m3 with nutricline as deep as 200 m. It is an intriguing question whether this oligotrophic ocean desert can ever get ‘green’, i.e. is there any possibility for phytoplankton bloom occurrences? Using synergy of 5 types of remote sensing data including (a) ocean colour data (chlorophyll-a concentration and ocean colour spectra) from the NASA’s SeaWiFS (Sea-viewing Wide Field-of-view Sensor) satellite (O’Reilly et al., 1998) (b) aerosol data from the NASA MODIS (MODerate Resolution Imaging Spectro-radiometer, Kauffman et al., 2002) satellite, (c) SST data from the TRMM (Tropical Rainfall Measuring Mission, Wentz et al., 2000) satellite, (d) the Sea Surface Height Anomaly (SSHA) data from TOPEX/Poseidon and JASON-1 satellites (Fu et al., 1994), and (e) ocean surface wind vectors from the NASA QuikSCAT satellite (Liu et al., 1998), here we analysis one complete year (2003) of data. We found that indeed blooms can occur and the causes of bloom includes dust-storm deposition, typhoon-induced, and the passing of cold (cyclonic) ocean eddies.