The subpolar front forms an important physical and biological boundary at approximately 40° N in the Japan/East Sea, separating seasonally stratified southern waters from northern waters which exhibit deep wintertime mixed layers and only weak summertime stratification. Energetic meanders and active eddy generation mark the frontal region, with remotely sensed sea surface temperature and ocean color revealing strong temperature and chlorophyll contrasts associated with these features. The front may also be a region of watermass formation and subduction, influencing stratification beneath the seasonal pycnocline and thus the general circulation within the basin. Wintertime outbreaks of cold, dry Siberian air extending offshore from the continent provide strong atmospheric forcing over the subpolar front and are likely to exert a strong influence on watermass formation and southward spreading.
This program involves several principal investigators with diverse, but interrelated, interests.
SeaSoar Surveys and Hydrographic/Bio-Optical Profiling
(C. M. Lee, B. H. Jones, K. H. Brink)
This study seeks to understand the processes that control physical and bio-optical variability in the Japan/East Sea. Specifically, we are interested in:
The upper ocean response to strong wintertime atmospheric forcing.
Watermass formation, subduction and spreading.
Dynamics of the subpolar front.
Characterizing cross-front and cross-shelf bio-optical transitions.
These objectives fit into the framework of our long-term scientific efforts to understand:
Physical and biological responses of the upper ocean to atmospheric forcing and how these penetrate to the interior.
Dynamics and biological influences of instabilities and secondary circulations associated with upper ocean fronts.
Physical and bio-optical transitions between coastal and central basin waters.
Atmospheric Observations (C. E. Dorman)
The atmospheric program seeks to:
Characterize the lower atmosphere over the Japan/East Sea.
Examine the role played by the marine boundary layer in determining air-sea heat fluxes in the Japan/East Sea.
Satellite Characterization of Bio-Optical and Thermal Variability (R. A. Arnone, R. W. Gould)
The primary remote sensing objectives are:
Examine the relationships between thermal and ocean color (bio-optical) features in the Japan/East Sea, focusing on the region of the Subpolar Front;
Examine the spatial and temporal variability of the spring bloom in the Japan/East Sea, during both the formation and dissipation phases;
Collect ground truth reflectance, absorption, and scattering measurements to calibrate/ validate the SeaWiFS sensor and optical algorithms.