1028 A. Physical Oceanography OLR(1987)34(12)

marine ice-stream/ice-shelf. The upstream distance in the ice stream from the grounding line is estimated and found to be relatively insensitive to the basal sliding velocity and the rheological con- stant of ice. A potentially important feedback mechanism between ice stream and ice shelf is associated with buoyancy corrections to the lon- gitudinal deviatoric stress field. Dept. of Geolog. Sci., Northwestern Univ., Evanston, IL 60201, USA.

87:6739 Thorndike, A.S., 1987. A random discontinuous

model of sea ice motion. J. geophys. Res., 92(C6):6515-6520.

The rate of sea ice pack opening (exposing warm ocean to cold atmosphere and controlling air-sea heat exchange in the Arctic and ice mass production) can be estimated from observations of ice motion, using a model which accounts for the random manner of ice breakage into rigid pieces. In a region of many cracks, some will be opening while others are closing, and total openings will exceed the average divergence. This random model imagines a Poisson distribution of leads and Gaussian relative displacements at cracks. Total opening relative to average deformation, and the influence of the region's size and number of points used to determine average deformation are determined. Dept. of Phys., Univ. of Puget Sound, 1500 North Warner, Tacoma, WA 98416, USA.

87:6740 Waiters, J.M., C. Ruf and C.T. Swift, 1987. A

microwave radiometer weather-ctmrectiug sea ice algorithm. J. geophys. Res., 92(C6):6521-6534.

The algorithm uses six SMMR channels to assess multi- and first-year sea ice fractions in variable atmospheric and sea surface conditions. It accepts error in auxiliary parameters (surface temperature, wind speed, atmospheric water vapor, and cloud liquid water content) and uses the radiative transfer equation to eliminate false retrievals without dis- carding data. Dept. of Electrical and Computer Engng, Univ. of Massachusetts, Amherst, MA 01003, USA.

A240. Optical properties

87:6741 Aas, Eyvind, 1987. Two-stream irradiance model for

deep waters. Appl. Opt., 26(11):2095-2101 Univ. of Oslo, Inst. of Geophys., P.O. Box 1022 Blindern, 0315 Oslo 3, Norway.

87:6742 Dirks, R.W.J. and D. Spitzer, 1987. Solar radiance

distribution in deep natural waters including fluorescence effects. Appl. Opt., 26(12):2427- 2430.

The limit values for large depths of the upward and downward distribution functions for (diffuse) fluo- rescence emitting wavelengths are examined. Even in strong fluorescence emissions these functions do not always correspond to a diffuse radiance field. A model is proposed to describe the depth dependence of the distribution functions. Netherlands Inst. for Sea Res., P.O. Box 59, 1790 AB Den Burg, Texel, Netherlands.

87:6743 Hoge, F.E., C.W. Wright and R.N. Swift, 1987.

Radiance-ratio algorithm wavelengths for remote oceanic chlorophyll determination. Appl. Opt., 26(11):2082-2094 NASA Goddard Space Flight Center, Wallops Flight Facility, Wallops Island, VA 23337, USA.

87:6744 Rorslett, Bjorn, 1987. Statistics of the underwater

light field: an eml~kal model. Int. Revue ges. Hydrobiol., 72(1): 1-25.

The underwater light field is described as a sto- chastic process, with vertical attenuation as a random variable. The vertical attenuation integral is a Normal process with uncorrelated increments. Attenuation processes within a water body are quite independent of incoming irradiance. Relative light intensity at any depth can be approximated by a Lognormal random variable. Based upon this Lognormal variable, and the mean value of the incident irradiance, the irradiance delivered at any depth and its statistical distribution can be esti- mated. Norwegian Inst. for Water Res., Oslo, Norway.

A260. Acoustics

87:6745 Angell, T.S., R.E. Kleinman and G.F. Roach, 1987.

An inverse transmission problem for the Helm- hoitz equation. Inverse Problems, 3(2):149-180. Dept. of Math. Sci., Univ. of Delaware, Newark, DE 19716, USA.

87:6746 Griffiths, L.J. and K.M. Buckley, 1987. Qulcecent

pattern control in linearly constrained adaptive arrays. IEEE Trans. Acoust. Speech Signal