Nutrient pumping/advection by propagating Rossby Waves in the Kuroshio Extension
Abstract
Ten years (1998–2007) of sea-level anomalies (SLA) from multiple satellite altimeters and chlorophyll-a
concentration from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) were used to detect eddy
pumping/advection of nutrients by the action of propagating Rossby waves in the Kuroshio Extension
(KE) region near 35oN after the seasonal SeaWiFS chlorophyll-a (Chl-a) concentrations cycles and
annual changes of altimeter SLA were eliminated. Spatial structure of Chl-a anomalies to the seasonal
cycle is examined in relation to altimeter eddy structure. Eddy propagation speeds and scales by the
Rossby waves are also identified. Chl-a structure is evident during the spring bloom period with a scale
around 460 km. Cold-core (cyclonic) rings correspond to areas of high Chl-a concentrations. Warm-core
(anticyclonic) rings relate to areas of low Chl-a concentration. Chl-a anomalies and SLA have an overall
modest negative correlation coefficient of r¼"0.45, which may imply the co-existence of both eddy
pumping and eddy advection mechanisms in the KE region. Swirl currents between eddies redistribute
surface chlorophyll concentrations and can spatially bias maximum and minimum concentration levels
off eddy center. The correlation coefficient has seasonal fluctuations. In the western KE region, it varies
from high negative correlation (r¼"0.70) in April and September (eddy pumping dominant) to low
negative correlation (r¼"0.33) in February and March (eddy advection dominant). In the eastern KE
region, it varies from high negative correlation (r¼"0.67) in February to low negative correlation
(r¼"0.42) in December. It is noted that the characteristic wavelengths of the SLA and Chl-a features,
and the seasonality of the correlation between these two variables have not been previously
documented.
Description
The article of record as published may be located at http://dx.doi.org/10.1016/j.dsr2.2010.04.007
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.Collections
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