Annual Report - 1998

PRINCIPAL INVESTIGATOR:

 

Stephen R. Okkonen

Institute of Marine Science

University of Alaska Fairbanks

 

PROGRESS:

 

The general goal of this research has been to employ spectral and least squares methods to analyze GEOSAT and TOPEX satellite altimeter measurements of sea surface height anomalies in the Bering Sea to describe the distribution and variability of mesoscale eddy-like features in the space-time domain.

The analyses of the altimeter data has been completed. A draft of the manuscript summarizing this research is currently being prepared.

 

SCIENTIFIC ACCOMPLISHMENTS:

 

The region of principal interest and effort for the present study is the shelf break region in the central Bering Sea, a region of high primary productivity and along which flows the Bering Slope Current (Figure 1). The altimeter data reveal mesoscale activity occurring near the shelf break region during the entirety of the data record (Figure 2). The observed mesoscale features exhibit a component of propagation along the shelf break. Other analyses of the data reveal both on-shelf and off-shelf components of propagation. Those features exhibiting an on-shelf component of propagation are interpreted to be topographic planetary waves, whereas, the mesoscale features which are observed to propagate into the central Aleutian Basin are interpreted to be baroclinic planetary waves. The topographic planetary waves have a representative wavelength and period of about 100 km and 2-3 months, respectively. The baroclinic planetary waves are characterized by wavelengths of hundreds of kilometers and periods of hundreds of days. Shorter period activity typically occurs nearer the shelf break than does longer period activity (Figure 3). The eddy field undergoes a seasonal modulation such that greatest amplitudes typically occur in the spring and summer months (Figure 4).

 

APPLICATIONS:

 

A summary of this research was presented at the SEBSCC PI Workshop, 15 - 16 December 1997, Battelle Seattle Conference Center, Seattle Washington.

 

An oral summary this research will be presented at the PICES Symposium, October 1998, in Fairbanks, Alaska.

 

A follow-up proposal to this research was submitted, in collaboration with Dr. Phyllis Stabeno, for SEBSCC Phase II.

 

STEPS TO COMPLETION:

 

All that remains is the completion of the manuscript describing this research and its submission for review and publication. It is anticipated that the draft manuscript will be ready for submission by late August 1998.