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OBSERVATIONS-MODELLING OF AIR-SEA-ICE INTERACTION NORTH OF EUROPE

Objective

TO UNDERSTAND THE SEA-ICE SEASONAL AND INTERANNUAL CYCLE.

THE GENERAL APPROACH FOR THIS PROJECT IS : 1. FROM OBSERVATIONS SUCH AS AVERAGE SURFACE WIND FIELDS, SURFACE OCEAN CURRENTS SST AND SEA-ICE EXTEND AND AIR-OCEAN FLUXES, TO INFER FORCING FUNCTIONS TO DRIVE OCEAN-ICE MODELS. 2. TO CONTROL FROM OBSERVATIONS SUCH AS SEA-ICE CONCENTRATION MOTIONS, DEFORMATIONS THICKNESS DISTRIBUTIONS AND ICE FLUXES THROUGH THE STRAITS, HOW WELL MODELS ARE GOOD AT REPRODUCING AND PREDICTING MAIN FEATURES AND EVENTUALLY TO APPLY NECESSARY CORRECTIONS. IN THAT CONTEXT, REMOTE SENSING INFORMATIONS FROM SAR IN PARTICULAR WILL BE OF UPMOST IMPORTANCE IN COMBINATION WITH IN SITU DATA AND OTHER SATELLITE INFORMATIONS AS STATED BY THE PIPOR GROUP. (PROGRAM FOR INTERNATIONAL POLAR OCEANS RESEARCH).A. TO OBSERVE SIMULTANEOUSLY ICE MOTIONS, SURFACE WINDS AND CURRENTS, SEA-ICE GROWTH AND DECAY, CONCENTRATION AND THICKNESS DISTRIBUTION.REGARDING SEA-ICE MOTIONS AND SURFACE CURRENTS. WE WILL MOSTLY RELY ON LAGRAGIAN TECHNICS SUCH AS ARGOS BUOYS AND SOFAR FLOATS FOR IN SITU OBSERVATIONS, AND HIGH RESOLUTION REMOTE SENSING.CONCERNING SURFACE WINDS, IN A FIRST APPROACH, WE SHALL CONSIDER GEOSTROPHIC WINDS PRODUCED FROM SURFACE ATMOSPHERIC PRESSURE MEASURED AT BUOYS LOCATIONS AND LAND STATIONS ON NORTH COAST OF GREENLAND AND ON SVALBARD. REGARDING SEA-ICE GROWTH AND DECAY ARGOS BUOYS WILL BE EQUIPED WITH THERMISTOR CHAIN GOING ACROSS THE ICE FROM WHICH WE CAN DEDUCE LOCALLY ICE THICKNESS VARIATIONS AND HEAT FLUXES AT THE ICE-OCEAN INTERFACE. SEA-ICE CONCENTRATION AND THICKNESS DISTRIBUTION WILL BE DEDUCED TEMPORARILY FROM REMOTE-SENSING OBSERVATIONS SUCH AS VISIBLE (SPOT) INFRARED (AVHRR AND LATER ON, MORE REGULARLY, FROM ACTIVE AND PASSIVE MICROWAVE (SAR ON ERSI - SSM/I ON DMSP). IN ADDITION THICKNESS DISTRIBUTION WILL BE IMPROVED BY ADDING INVERTED ECHO SOUNDERS ON SOFAR FLOATS (NEUTRALLY BUOYANT DRIFTING FLOATS).B. TO DEVELOP A HIERARCHY OF ICE-OCEAN COUPLED MODELS DEDICATED TO PRECISE ESTIMATIONS OF ICE-OCEAN FLUXES OF MOMENTUM, HEAT AND SALT UNDER PROPER ATMOSPHERIC FORCING RESULTING FROM A DETAILED ANALYSIS OF METEOROLOGICAL OBSERVATIONS. THE MAIN FEATURES OF THESE ICE-OCEAN MODELS USING TENSORIAL COORDINATES TO AVOID INCOHERENCY ON GRID SCALING WILL BE : A 3D STRATIFIED OCEAN MODEL USING PRIMITIVE EQUATATIONS ALREADY EXISTING AT LODYC COUPLED WITH A MIXED LAYER MODEL TAKING CARE OF A NON HOMOGENEOUS SURFACE LAYER RELATED TO VARIABLE SEA-ICE CONCENTRATIONS. THE "HETEROGENEOUS" MIXED LAYER MODEL WILL COMPUTE THE TEMPERATURE AND THICKNESS OF THE MIXED LAYER. IT WILL ALSO CONSIDER A SALT BALANCE DUE TO THE MELTING-FREEZING CYCLES AND INCORPORATE THE SURFACE HETEROGENCEITY INTO THE COMPUTATION THROUGH A 2D DIFFUSION MODEL. THE MIXED LAYER MODEL WILL BE COUPLED, ITS A SEA-ICE DYNAMICAL-THERMODYNAMICAL MODEL.THE WIND FORCING ON AN ICE EDGE WILL BE ANALYSED BOTH BY ANALYTICAL AND NUMERICAL MODELLING DEPENDING UPON THE ORIENTATION OF THE WIND RELATIVE TO THE ICE EDGE AND DEPENDING UPON THE GEOMETRY OF THE EDGE.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Centre National de la Recherche Scientifique (CNRS)
Address
23 Rue Du Maroc
75940 Paris
France

Participants (6)

CENTRE NATIONAL DE RECHERCHE METEOROLOGIQUE
LAB METEOROLOGIE DYNAMIQUE
RIJKSUNIVERSITEIT
SCOTT POLAR RESEARCH INSTITUTE
United Kingdom
Address
Lensfield Rd
CB2 1ER Cambridge
UCL
UK METEOROLOGICAL OFFICE