Short-Term Response of Chlorophyll-a Concentration to Change in Sea Surface Wind Field over Mesoscale Eddy

Abstract

Short-term biological responses to sea surface wind field over mesoscale eddies were investigated using hourly ocean color chlorophyll-a (chl-a) concentration data from the Geostationary Ocean Color Imager (GOCI), scatterometer wind data, and satellite sea surface temperature (SST) data. Four warm eddies were identified from SST fronts, by subjectively fitting ellipses to selected points, and anticyclonically rotating current vectors were estimated from sequential chl-a images. Scatterometer data confirmed wind speed strengthening by approximately 30% over anticyclonic eddies, regardless of wind direction, caused by stability changes in the marine atmospheric boundary layer. The modified wind speed field produced a characteristic pattern of wind stress curl and Ekman pumping (EKP) over the eddies, showing positive and negative values on the left and right sides of the upwind direction, respectively. The EKP field was divided into three components: eddy current-induced, relative vorticity gradient-induced, and crosswind SST-induced terms. Short-term changes in the chl-a concentration showed a positive relation with EKP variations over most eddies. SST-induced EKP played a significant role in the eddies for 76% of the total variations, which is much higher than that in other oceans. This study emphasizes the significant effect of SST distribution and the biological responses to changes in an EKP field in relation to air-sea interactions and feedback processes in the East Sea (Sea of Japan).

Surface chlorophyll anomalies induced by mesoscale eddy-wind interactions in the northern Norwegian Sea

“…where r a is the air density (1.25 kg m -3 ) and u rel is relative wind speed to a surface water mass, which is derived from scatterometry data (Gaube et al, 2013;Gaube et al, 2014;Park et al, 2019). C D is the speed-dependent drag coefficient, which was determined following Anderson (1993) and Park et al (2019):…”

MESI: A Multiparameter Eddy Significance Index

“…Due to mesoscale eddies' apparent role in primary productivity and phytoplankton blooms, tracking and monitoring of CEs in conjunction with ocean color observations of chlorophyll‐a (Chl‐a) is becoming increasingly common, with researchers and fisheries taking advantage of satellite observations to determine where fish are the most likely to be found based on these phytoplankton blooms (Leterme & Pingree, 2008; McGillicuddy, 2016; Park et al., 2020; Pegliasco et al., 2015; Y. Zhang et al., 2019). Eddies are also known to transport harmful algal blooms (Leterme & Pingree, 2008; McGillicuddy, 2016; Santana et al., 2020), coral and fish larvae (Bakun, 2006; McGillicuddy, 2016), and even have impacts on ocean acidification (Hauri et al., 2009).…”

“…Due to mesoscale eddies' apparent role in primary productivity and phytoplankton blooms, tracking and monitoring of CEs in conjunction with ocean color observations of chlorophyll-a (Chl-a) is becoming increasingly common, with researchers and fisheries taking advantage of satellite observations to determine where fish are the most likely to be found based on these phytoplankton blooms (Leterme & Pingree, 2008;McGillicuddy, 2016;Park et al, 2020;Pegliasco et al, 2015;Y. Zhang et al, 2019).…”

A Machine Learning Algorithm for Himawari-8 Total Suspended Solids Retrievals in the Great Barrier Reef

“…Its success provided a useful case for the future development of global GEO ocean colour missions [14]; however, none of the missions proposed for launching within the next decade were designed for observing Australian waters. Nevertheless, GEO satellites are globally operated for meteorological observations and recent technological advances have leveraged their capabilities for collecting data over the oceans, allowing more dynamic processes to be observed from space [15][16][17]. The next-generation GEO meteorological sensors are equipped with an increased number of bands in the visible spectrum (2 or 3 instead of only 1 band) combined with improved radiometric sensitivity (signal-to-noise ratio) and onboard calibration capabilities [9].…”