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The Polar Ice Prediction System (PIP) is a numerical ice forecasting system that has been implemented at the U.S. Navy Fleet Numerical Oceanographic Center (FNOC). The PIPS model is run as a 24-hr timestep out to 144 hours (6 days) on a 47 x 25 grid at a resolution of 127 Km. This grid covers the entire Arctic basin as well as the Greenland and Norwegian Seas. Graphic forecast products are transmitted via the Naval Environmental Display Systems to the Naval Polar Oceanographic Center (NPOC) for guidance in preparation of weekly ice forecasts. Primary products are ice drift, thickness, concentration and divergence. A two-phased evaluation of PIPS was conducted. The first extended from 15 Nov 1985 until 15 March 1986 while the second phase ran from 15 June until 15 Oct 1986. As well as covering periods of ice growth and decay, the model was initialized differently for the two phases. During Phase I, the model self-generated its initial concentration field from analysis atmospheric forcing fields. For Phase II, the digitized ice analysis prepared by NPOC was used to update the model each week. Primary products evaluated were ice drift, concentration and the location of the ice edge. Evaluation revealed that PIPS tends to predict too little ice in the Chukchi and East Siberian Seas while predicting excessive ice in the Greenland and Barents Seas. Ice drifts were compared to the drifts were compared to the drifts of buoys located on ice floes in the Arctic basin.

Contents: A Note on Estimating Melt Rate in the MIZ; Kinematics of Marginal Ice: MIZEX 83; On Estimating Ice Stress from MIZEX 83 Ice Deformation and Current Measurements; Crystal Structure of Fram Strait Sea Ice; MIZEX 84 Ice Surface Measurements from the FS Polarstern; 1984-85 Current Observations in the East Greenland Current: A Preliminary Description; An Ice/Air Feedback Mechanism for the Migration of the Marginal Ice Zone; The Planetary Boundary Layer in the Marginal Ice Zone; and An Air Ice Ocean Coupled Model for the Formation of Leads or Polynyas., Original contains color plates: All DTIC/NTIS reproductions will be in black and white. See also report dated Apr 86, AD-A169 070.

A dynamic-thermodynamic sea ice model is extended to include a full thermodynamic code and a complete multilevel ice thickness distribution. The variable thickness formulation includes a more realistic parameterization of ice ridging than used in previous models. Seasonal simulations have been performed using this model and the results have been analyzed with particular emphasis on examination of the ridge buildup results off the Canadian Archipelago and off the North Slope. This report presents a complete description of this model and discusses progress made on examining and testing the variable thickness extensions. Originator supplied keywords: Arctic Basin ice cover, Arctic Ocean, Mathematic models, Sea ice, Simulation modeling.

Contents: Drift Velocity During the Drift-Station Phase of MIZEX 83; MIZEX 83--BIO Buoy Data Summary; MIZEX 83 Mesoscale Sea Ice Dynamics--Initial Analysis; On the Rheology of a Broken Ice Field Due to Floe Collision; Heat and Mass Balance Observations During the MIZEX 83 Drift Program; Ocean Currents and Temperatures in the Center of Fram Strait During MIZEX 83; and Arctic Whitecapping--Preliminary results., See also Rept. nos. CRREL-SR-81-19, AD-A107 046 and CRREL-SR-83-12, AD-A134 872.

This monograph reviews essential aspects of sea ice dynamics on the geophysical scale and discusses the role of ice dynamics in air-sea-ice interaction. The review is divided into the following components: (a) a discussion of the momentum balance describing ice drift, (b) an examination of the nature of sea ice rheology on the geophysical scale, (c) an analysis of the relationship between ice strength and ice thickness characteristics, and (d) a discussion of the rle of ice dynamices in the atmosphere-ice-ocean system. Because of the unique, highly nonlinear nature of sea-ice interaction, special attention is given to the ramifications of ice interaction on sea ice motion and deformation. These ramifications are illustrated both by analytic solution and by numerical model results. In addition, the role of ice dynamics in the atmosphere-ice-ocean system is discussed in light of numerical modeling experiments, including a fully coupled ice-ocean model of the Arctic-Greenland-Norwegian seas.

The main goal of the marginal ice zone experiment (MIZEX) is to understand the processes that dictate the advance and retreat of the ice margin. Mechanistic model sensitivity studies can greatly aid in this goal by identifying the relative importance of different processes in the total system. In addition, more complete simulation models can be used both to test the adequacy of current understanding of the marginal ice zone and to serve as an integrating device for complex data sets. This volume contains the main results from a MIZEX modeling workshop held 18-20 October in Hanover, New Hampshire. Modelers interested in both Arctic and Antarctic sea ice were present. The purpose of the workshop was to determine the status of marginal ice zone modeling and to discuss different views on modeling processes in the MIZ. Results from full simulation models, mechanistic models, and empirical statistical models were presented and discussed. In addition, recommendations relevant to experimental measurements were made. The recommendations were divided into ocean, ice, and atmospheric categories; these were also the three main subject areas covered by the presentations. Overall, the workshop helped to identify areas where further simulations are needed to test our understanding and where knowledge of certain processes is lacking., See also Jun 81, AD-A107 046.

The report consists of an initial analysis of the ice kinematics field data from MIZEX-83 Greenland Sea Study. The data set consists of distance measurements accurate to 1-2 metres between Del Norte units at five sites, with one site being the ship. The data set represents a unique set of measurements of the deformation field of a series of interacting floes.

A semi-automatic procedure for transferring the location coordinates of a common set of ice features from the Earth coordinate system of one LANDSAT image to another is discussed. Errors in the transferral technique are examined using imagery over land and are found to be dominated by deviations (as large as 8 km) in the actual position of the center of the image from its states position. A least-squares strain program, which utilizes polar coordinates to eliminate spurious effects that may occur if the coordinate system of a given floe is used as the common coordinate system, is discussed. The use of uncontrolled aerial photography to measure sea ice strain results in errors of the order of 1%. (Author), Presented at International Symposium on Ice Problems (3rd), Held on 18-21 Aug 75 at Hanover, N.H.

A semi-automatic procedure for transferring the location coordinates of a common set of ice features from the Earth coordinate system of one LANDSAT image to another is discussed. Errors in the transferral technique are examined using imagery over land and are found to be dominated by deviations (as large as 8 km) in the actual position of the center of the image from its stated position. A least squares strain program which utilizes polar coordinates to eliminate spurious effects that may occur if the coordinate system of a given floe is used as the common coordinate system, is discussed. Errors in coordinate system rotation, center location, distortions and nonlinearities in the images caused errors in vorticity of the order of 0.5% and in strain of the order of 0.1% per day. Both these errors are less than typical sea ice vorticity and strain rate. (Author), Presented at the International Symposium on Remote Sensing of Environment (10th) 6-10 Oct 75.

Three surface elevation and ice thickness profiles obtained during the 1972 Arctic Ice Dynamics Joint Experiment on a multiyear ice floe were analyzed to obtain relationships between surface elevation, thickness and physical properties of the ice. It was found that for ice freeboards from 0.10 m to 1.05 m above sea level a linear relationship between ice density and freeboard could be postulated. The equation for the regression line is: Ice density = -194f' + 974 kg/cu m where f' is the ice freeboard plus snow depth in ice equivalent at the point in question. This statistical relationship is consistent with observed physical properties, which indicate that as the ice freeboard increases, ice salinity decreases and the higher freeboard or thicker ice therefore decreases in density. Using this variable density with freeboard relationship, a model was constructed to predict ice thickness, given ice freeboard and snow depth alone. This prediction is desirable, since snow depth and freeboard are relatively easy to obtain, whereas ice thickness can usually be obtained only by drilling through the ice. The model was compared with two other models. It was found that the variable density prediction model gave the best approximation to observed ice thickness, with a standard error between the measured and predicted value of about 0.4 m, compared with errors from 50 to 100% higher for the other two models.

Modeling studies were carried through with three types of ice rheologies: free drift, linear viscosity, and plasticity. It is suggested that ice thickness variations may be important to the dispersion of ice edge and lead to e.g. clustering of ice floes. Analytic linear viscous solutions show that variable ice strength rather than variable forcing is likely to produce sharp changes in ice velocity near the ice edge. Steady state ideal plastic solutions give a constant ice flow under constant forcing in the MIZ. In general, ice interaction has a rectifying effect on the flow pattern. Ice kinematics measurements were made with the Del Norte microwave trisponder system in MIZEX-83 Greenland Sea experiment. Differential ice motion was measured with four stations on the ice in the scale of 5 km at three-minute intervals. On several occasions, a rapid slip occurred in measured distances. Ice velocity fluctuations were typically of the order of 1 cm/s and large deformation rates a few per cent per hour. Various spectra of differential ice drift showed a moderate inertial peak and a red noise character at higher frequencies, up to about half-hour period. The maximum rate of shear was about twice as large as divergence from 12-h to about 2-h period., See also report dated 15 Sep 83, AD-A134 599.

Contents: Significance of the marginal ice zone; MIZ processes, models and scientific questions; Remote sensing; Strategy of the experiment; Collateral programs; Appendix A: Detailed plan of the air-ice-ocean experiment; Appendix B: Acoustics and MIZEX; Appendix C: Biological program; Appendix D: MIZEX organization., See also Part 1, AD-A107 046.

Contents: Mesoscale strain measurements on the Beaufort Sea pack ice; Structure of a multiyear pressure ridge; Top and bottom roughness of a multiyear ice floe; Airphoto analysis of ice deformation in the Beaufort Sea; Data on morphological and physical characteristics of sea ice in the Beaufort Sea.