1086 A. Physical Oceanography OLR (1990) 37 (12)

In this study the seasonal asymmetric behavior of ice extent and changes in sea ice concentration are shown to be linked to the atmospheric convergence line (ACL) around Antarctica. The relative positions of the ACL characterized by the half-year cycle exert a strong influence upon the mean movement of the sea ice. It is also observed from the investigations of the areal concentration of the sea ice that a decrease in ice concentration prior to the sea ice retreat is needed for a rapid retreat. Kitami Inst. of Technol., Kitami, Hokkaido, 090 Japan.

90:6920 Gosink, J.P. and G.C. Baker, 1990. Salt fingering in

snbsea permafrost: some stability and energy considerations. J. geophys. Res, 95(C6):9575- 9583. Chem. and Thermal Syst., Natl. Sci. Foundation, 1800 G St. N.W., Washington, DC, 20550, USA.

and temporally varying sea ice covers. J. geophys. Res, 95(C6):9557-9567.

A simple two-stream, multilayer radiative transfer model in the 40~1000 nm wavelength region utilizes available experimental data on the optical properties of sea ice. The ice cover is characterized as a layered medium composed of selections from nine distinct snow and ice types. Three case studies are presented illustrating values of spectral albedo, transmittance, and transmitted photosynthetically active radiation for (I) a spatially inhomogeneous ice cover, (2) a uniform ice cover as it undergoes a melt cycle, and (3) a temporally changing spatially variable ice cover. Results indicate that small-scale horizontal variations in snow depth and ice thickness can cause light transmission to change over 3 orders of magnitude. Snow and Ice Br., U.S. Army Cold Regions Res. and Engng Lab., 72 Lyme Rd., Hanover, NH 03755, USA.

90:6921 Lemke, P., W.B. Owens and W.D. Hibler III, 1990.

A coupled sea ice-mixed layer-pycnocline model for the Weddell Sea. J. geophys. Res, 95(C6): 9513-9525.

This model prognostically determines the vertical oceanic heat flux from the mixed layer dynamics in contrast to earlier sea ice modeling where the oceanic heat flux was prescribed. In addition to the standard simulation, polynya and paleoclimate experiments were performed to investigate the effects of sea ice dynamics. Furthermore, the mixed layer-pycnoeline model is compared to the original Kraus-Turner approach. Alfred Wegener Inst. for Polar and Mar. Res., Bremerhaven, FRG.

90:6922 Owens, W.B. and P. Lemke, 1990. Sensitivity studies

with a sea ice-mixed layer--pycnociine model in the Weddell Sea. J. geophys. Res, 95(C6):9527- 9538.

The sensitivity of a dynamic-thermodynamic sea ice model coupled to a I-D mixed layer-pycnocline model to variations of dynamic and thermodynamic model parameters is investigated. Modifications of the model results due to the inclusion of a prognostic snow cover and the implementation of simplified sea ice rheologies are investigated. In these comparisons special emphasis is placed upon the ice-ocean boundary conditions (buoyancy fluxes) and the mixed layer properties. WHOI, Woods Hole, MA 02543, USA.

90:6923 Pcrovich, D.K., 1990. Thearetleal estimates of light

reflection and transmission by spatially complex

90:6924 Smith, S.D., R.D. Muench and C.H. Pease, 1990.

Polynyas and leads: an overview of physical processes and environment. J. geophys. Res~ 95(C6):9461-9479.

Polynyas and leads are openings in pack ice, the vents and windows to the polar oceans. In winter they are a major source of brine during freezing and a locus for gas exchange. Large sensible heat fluxes, together with evaporation and Iongwave radiation from a very small percentage of open water and thin ice, dominate regional heat budgets. In summer, solar radiation is absorbed by open water but is reflected from snow-covered pack ice. Experiments and models describing these processes are reviewed. Dept. of Fish. and Oceans, Bedford Inst. of Oceanogr., P.O. Box 1006, Dartmouth, NS B2Y 4A2, Canada.

90:6925 StOssel, Achim, Peter Lemke and W.B. Owens, 1990.

Coupled sea ice-mixed layer simulations for the Southern Ocean. J. geopl~s. Res, 95(C6):9539- 9555.

A coupled sea ice-mixed layer-pycnocline model for the Weddell Sea is extended to the entire sea ice area around Antarctica. Sensitivity runs were performed with a fixed mixed layer, without snow cover, with a different ice strength constant and a varying e- folding constant for the closing of leads, without dynamics, and without ocean currents. Since the atmospheric forcing fields, although derived from large historical data sets, differ considerably de- pending on the analysis technique, alternative wind, temperature, and precipitation forcing has been applied. Finally, the model has been forced with