Surface Forcing and Boundary-Layer Structure Over the Japan/East Sea
During Winter Cold-Air Outbreaks

Djamal Khelif (949-824-7437; dkhelif@uci.edu)
Carl A. Friehe (949-824-6159; cfriehe@uci.edu)      
University of California, Irvine CA 92697-3975

ABSTRACT:

    Preliminary results of air-sea interface fluxes and boundary layer
aircraft measurements made during the Winter 2000 Japan/East Sea (JES)
experiment are presented. They were obtained by the NPGS/CIRPAS Twin
Otter aircraft which was instrumented with wind , temperature, humidity,
IR sea temperature and aircraft motion and navigation sensors. Data were
recorded at up to 40 Hz rate for turbulent eddy correlation flux
calculations.  Thirteen research flights, up to 9.8 hours duration, were
flown from Misawa NAF, Japan, over the Japan/East Sea in conditions of
cold-air outbreaks.

    Structure of the boundary layer was mapped by following an
approximate streamline across the JES from the ``Flux Center'' near
Vladivostok to the west coast of Honshu.  One flight showed the dramatic
growth of the internal boundary layer (IBL) and a subsequent jump or
second IBL as the JES SST front was crossed.  The IBL warmed, moistened
and lost momentum along the streamline.  Another flight was
characterized by a deeper, well mixed boundary layer with winds
increasing along the streamline.

    A grid pattern at 100 feet with soundings to 5000 feet was also
flown to address the surface fluxes and their spatial variability and a
vertical stack pattern was flown to determine the flux divergence
profile in the boundary layer above the JES ``Flux Center''. Results
from these flights will also be presented.

This work was supported by ONR N00014-99-1-0205.