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The Norwegian Meteorological Institute, DNMI is responsible for the Norwegian National Ice Service. Daily ice maps based on subjective analysis of SSM/I, ERS-scatterometer and AVHRR data are produced and distributed to users. The data are also used as input to DNMI's operational weather and ocean models. At present DNMI makes use of the HIRLAM (High Resolution Limited Area Model) in its operational weather forecast services. For forecasting of oceanographic variables DNMI uses a version of the POM model (Princeton Ocean Model). DNMI has contributed to its development since 1988. Recently an in-house developed sea-ice model based upon the elastic-viscous-plastic rheology has been coupled to DNMI's POM version.
Sea ice analysis and forecast projects and techniques under development at DNMI are here briefly discussed in order to offer the opportunity for international collaboration in future works.
As a part of the EUMETSAT Ocean and Sea Ice SAF (Satellite Application Facilities) DNMI, together with the Danish Meteorological Institute, DMI is responsible for development of the High Latitude Sea Ice Products. The aim is to produce gridded products with 10 km horizontal resolution daily based on multi sensor analysis of satellite observations from passive and active microwave measurements and from additional information from optical sensors.
The idea of the multi sensor analysis is to develop a tool for combined use of information from different sea ice parameters from different sensors. The starting point is well-known sea ice variables based on both physical knowledge and well-established empirical relations. The scientific challenge in making a combined product from the available sensors, AVHRR, SSM/I and scatterometer, is to obtain a single reliable ice product from the various observations involving different and possibly contradicting information. For doing this, it is necessary to use an algorithm that takes into account the uncertainties in the ice classification of the various instruments. It is therefore essential not only with an ice estimate, but also with knowledge of the uncertainty involved. A general tool for combining various data sources containing uncertain information is given by the Bayesian (inverse method) approach. Using this approach, several measured variables can be combined to yield an optimal estimate. In the SAF development project the multi sensor method has been developed to analyse ice cover and ice types.
The SAF development project started in 1997 and will continue until April 2002 with a pre-operational phase starting in April 2001. The EUMETSAT SAF program also includes a visiting scientist program. More information is found on "programs under development" on the EUMETSAT web site http://www.eumetsat.de/en/ ore directly on the Ocean and Sea Ice web site: http://www.meteorologie.eu.org/safo/
Sea Ice Modeling and Data AssimilationA DNMI developed ice model based upon the elastic-viscous-plastic rheology has been coupled to DNMI's operational ocean model. The work is part of an ongoing project on regional climate modeling, where the purpose is to investigate regional impact of global climate changes. The aim is also to make the coupled ice-ocean model operational and use it in DNMI's model based nowcast/forecast system.
In co-operation with DMI (coordinator), the Nansen Environmental and Remote Sensing Centre (NERSC), the Institute of Marine Research, Bergen, the Icelandic Meteorological Institute, the Danish Hydraulic Institute and the Swedish Meteorological and Hydrological Institute, DNMI is in the process of proposing a new project within the EU 5th framework programme to develop the necessary components of ice-ocean observations and operational forecast mode. This includes a development of an assimilation procedure to produce an initial ice cover. The assimilation system will take advantage of the ongoing development of a multi sensor ice analysis within the SAF Ocean & Sea Ice project. The plan is to extend this analysis to take into account first guess information from the ice model forecast and to develop a method for multivariate coupling to the ocean model. The possibilities of utilizing ENVISAT ASAR-data global mode available by the end of 2001 will also be investigated.
The area north of Svalbard and the Hinlopen strait is a popular area for shrimp fishing and cruise traffic. It is also an area with difficult ice conditions due to strong tide current and strong winds. This has resulted in several cases of ships being grounded and ships being in the ice. For environmental reasons the governor at Svalbard have tried to close the area for ship traffic parts of the year, but such a decision has been met with heavy protests from the fishing organisations. DNMI has together with the Nansen Environmental and Remote Sensing Centre, Norwegian Polar Institute (NP) and Tromsø Satellite Station (TSS) applied the Norwegian government for financial support to develop a fine scale ice-forecasting model for the area. A high-resolution coupled ice/ocean model is going to be developed during a two years period and it is planned to use SAR data for initials the model.
To demonstrate to the Norwegian government the facility to use SAR data in sea ice analyses DNMI is, together with TSS and NP, trying to establish a demonstration project in March 2000. In the project we are planning to use both ERS and Radarsat data.
Lars-Anders Breivik
Norwegian Meteorological Institute
P.O.Box 43, Blindern
N-0313 Oslo
e-mail l.a.breivik@dnmi.no
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