Key Technologies Research And Application Of Sea Ice Numerical Forecast In The Bohai Sea

Active construction is under way on the occasion of the marine economic powerhouse inChina，rapid changes have happened in the ports’ construction, offshore oil development,shipping and marine aquaculture. Every winter, sea ice has different impact on ocean shipping,offshore production of oil and gas in the Bohai Sea. The oil platform once collapsed, ships weredamaged and shipping was interrupted under severe ice conditions in the history.With rapid economic development of the Bohai Sea, the period, resolution and product typeof old numerical ice forecasts cannot far meet the demand of China’s maritime economicactivities, especially for the offshore oil development. According to international trend and theurgent anti-icing needs on domestic marine engineering, offshore production and transport, thenumerical ice forecast system adapted to different temporal and spatial scales must be developedimmediately. The main direction of future development should be:1) to extend forecastingperiod from3-5days to more than7days;2) to improve the model spatial resolution frommesoscale to small-scale.Numerical ice forecast models of the Bohai Sea in the thesis have been developeddepending on research of historical ice conditions in respond to hydrometeorological andclimatic changes by large amounts of data analysis on sea ice freezing, melting and changes inthe Bohai Sea. During past winters, with the combination of ice reconnaissance, professionalanti-ice projects and field observation experiments, mass data have been acquired, including icekinematics and dynamics, ice surface characteristics, ice thermodynamic properties such as icethermohaline structure and hydrological, meteorological conditions which affect ice freezing,melting and moving. All these data provide observational basis for the determination of icemodel structure and the selection of physical parameters of ice models in the Bohai Sea.In order to provide the theoretical basis and reference data for developing ice-oceancoupled model, high-resolution ice model and the framework of numerical ice forecast system inthe Bohai Sea, basic theoretical knowledge of sea ice kinematics, dynamics, especially rheologyand thermodynamics has been summarized systematically with combination of sea iceobservations and data analysis.On the basis of synthetical research of ice dynamics, rheology, thermodynamics, radiationtransmission of ice-atmosphere interface, field observational data and analysis of satelliteremote sensing data, the parameters of the atmospheric and water drag coefficient on theice-atmosphere and ice-ocean interface, the albedo parameterization of ice surface, radiationattenuation coefficient within ice and the parameters of net long wave radiation on the ice-atmosphere interface and water-atmosphere interface are put forward and appliedrespectively to the development of high-resolution ice model and the ice-ocean coupled modelin the Bohai Sea and North Yellow Sea.An ice-ocean coupled model containing a sea ice module with ice thickness distributionfunction (including12categories for the Bohai Sea) and an ocean module (POM) has beendeveloped and the model region has been extended from the Bohai Sea to the northern YellowSea. By using this ice-ocean coupled model, the effect of tide to sea ice as well as the dynamicand thermodynamic interaction between the northern Yellow Sea and the Bohai Sea have beensuccessfully demonstrated, which can obviously enhance the accuracy of ice seasonal simulationand ice forecasts of ice-freezing day and ice-melting day.A nudging assimilation method of sea ice initial field has been applied to the ice-oceanmodel and carried out for1-winter seasonal simulation successfully, which can improve theaccuracy of sea ice numerical initial field and also the reanalysis field in the Bohai Sea andNorth Yellow Sea. This nudging assimilation method is not only simple and feasible, but alsoshows obvious effect, which can be applied to sea ice forecasts in the future.A high-resolution E-V-P ice forecast model for small region has been established firstly inthe Bohai Sea. Not only conventional variables such as ice thickness, ice concentration and icevelocity can be forecasted by this model, but other mechanical parameters such as icecompressive strength, ice drifting and drifting trajectories can also be successfully simulated andforecasted.In short, a sea ice forecasting system has been established including a high-resolution smallregional ice model, an ice-ocean coupled model, and a nudging assimilation method applied tothe sea ice numerical simulation for the first time in the Bohai Sea. All these work can greatlyenhance the sea ice forecast level in the Bohai Sea.