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Presented  JOHANNESSEN O.M., Nansen Environmental and Remote Sensing         Project code:
by:        Center (NERSC) / Geophysical Institute, University of             PP.N3
           Bergen Edvard Griegsvei 3a N-5037 Solheimsvik, Norway,            PP2.N1
           T. +47 5529 7288, F. +47 5520 0050, 

Co         SANDVEN S., E. 
           MELENTYEV  V.V., Nansen International Environmental and Remote Sensing 
           Center (NIERSC) Korpusnaya str. 18, 197042 St. Petersburg, 
           Russia. F. +7 812 230 7994  

Keywords:  Sea ice, monitoring, ship routeing 

ICEWATCH Ice SAR Monitoring of the Northern Sea Route

Use of Synthetic Aperture Radar (SAR) images from satellites is a technology which is playing an increasingly important role in operational sea ice monitoring. SAR images, with a resolution of 100 m, can distinguish different ice types and map leads, polynyas, shear zones, landfast ice, drifting ice and location of the ice edge. The SAR is the only instrument which provide high resolution images different cloud and light conditions. The ERS-1 satellite, launched by the European Space Agency in 1991, is the first satellite which has provided extensive SAR coverage in most of the ice-covered areas in the worlds. The Russian Arctic Ocean is one of the most important areas for ice monitoring, because the ice conditions off the Siberian coast impose severe restrictions on sea transportation, ice navigation and offshore operations. The Russian icebreaker fleet, which assists all sea transportation in the area, uses an extensive ice monitoring and forecasting service in the navigation.

In several demonstration projects the Nansen Center in Bergen and St. Petersburg have used ERS-1 SAR images to monitor sea ice conditions in near realtime at different times of the year. The SAR images are used in combination with passive microwave data (SSM/I data) which provide large scale maps of ice extent and concentration at a resolution of about 30 km. The SAR images have shown good capability to map ice features which are important in ice navigation such as multiyear ice, firstyear ice, landfast ice, thin ice, leads/polynyas and areas of ridges. The demonstration projects have been supported by the European Space Agency, Murmansk Shipping Company and the INSROP program.

The expected result of the demonstration project will be a documentation that ERS SAR data plays an important role for improved mapping of the ice conditions along the Siberian coast. A longer term objective is to make SAR data from ERS-2 and ENVISAT available for the Russian Ice Service on an operational basis.


Presented  LEHNER S., DLR WT-DA-FE P.B. 11 16, D-82230                       Project code: 
by:        Oberpfaffenhofen Germany                                          AO2.D110
           T. +49 815 328 2895, F. +49 8153 2828 1445                        Commercial

Co         HASSELMANN K., Max-Planck-Institut fuer Meteorologie, Hamburg, 
authors:   BRUNS. T., SWA, Hamburg 

Keywords:  Ship routeing 

Test of a new onboard ship routing system

An onboard ship routeing system is being developed in cooperation between the MPI f. Meteorologie, the Dornier GmbH, the German Weather Service and the Hapag Lloyd AG. The new system, consisting of a Bellman-type cost optimization scheme combined with an interactive graphical interface, uses operational state-of-the-art ECMWF wave forecasts to enable a master to determine the most secure and economic route for his ship. ERS-1 SAR inverted wave mode spectra are assimilated into the global third generation wave model WAM to further improve the wave forecasts. In order to reduce the data for transmission the forecast spectra are partitioned into their dominant windsea and swell components (significant waveheights, directions and periods).

The ship routeing system was successfully tested onboard the container ship BONN EXPRESS during two cruises across the North Atlantic and Pacific Oceans. 10-day ECMWF wind and wave forecasts were transmitted once a day. Simultaneously, the master received route recommendations from the German Marine Weather Service. Optimal routes with respect to fuel consumption, speed and safety are intercompared with the recommended and the actual route. The results confirm the economic benefits of the optimization system. A future operational application is discussed.


Presented  FREMBGEN U., DORNIER GmbH, Satellite Systems,                     Project code:
by:        Earth Observation, D-88039 Friedrichshafen Germany                AO2.D110
           T. +49 754 585 732, F. +49 754 582 687                            Commercial


Keywords:  Ship routeing 

Marketing aspects for an operational onboard ship routeing system

A prototype for an onboard ship routeing system was successfully being tested on the container ship "BONN EXPRESS" of Hapag Lloyd during a far east cruise across the North Atlantic and North Pacific in summer this year. The main idea of operating the prototype was to investigate the economical and operational relevance the new routing system for a near future launch on the route consulting market.

For marketing activities the whole attention has to be given to the clientele. From interviews with ship owners and shipmasters we had to focus the following user requirements for the development of the prototype.

  • The system had to demonstrate a financial benefit.
    Therefore, the routing system was designed to use ECMWF wind and wave forecasts determining an optimal route with respect to:
    • in time arrivals at the ports of destination
    • non hazardous sea state conditions along the route.

    Both optimization criteria reflect the economical use of the system. In time arrivals keep the staying costs in the ports at minimum level while quiet sea state conditions may result in the reduction of fuel consumption by about 3 percent. As important as the short time benefits are the increasing of safety for the crew and cargo and the lifetime of the ship.

  • The system had to be available 24 hours per day.
    The ship masters must rely on that the forecast date will be updated at least once per day and that the transmission of the forecast data can be performed via Inmarsat at any time. Remote and landbased services had to be provided 24 hours per day.

  • The system had to fit the ship environment and its application had to be (very) simple.
    A graphical user interface was developed in order to enter navigational data for the optimization process and to visualize the forecast along the planned route.

The test phase in summer was too short to give a final analysis of the profitable use of the onboard routing system. Additional route consulting is therefore planned from November 95 to May 96, when strong low pressure systems create heavy sea state conditions in the northern hemisphere.


Presented  HEIMBACH P., Max-Planck Institut fuer Meteorlogie                Project code:
by:        Bundesstr.55, D-20146 Hamburg 13, Germany                        AO2.D110 
           T. +49 4041 173 377, +49 4041 173 298,               
           E. heimbach@dkrz.d400, W. 

Co         HASSELMANN S., 
authors:   BRÜNING C.
           HASSELMANN K.

Keywords:  Metocean 

The use of ERS SAR wave mode spectra for wind/wave assimilation into WAM and for statistical and dynamical comparison

The inversion algorithm to retrieve ocean wave spectra from the nonlinearly related observed ERS-1 SAR wave mode imagette spectra was improved. The cost function of the inverse problem was extended by a third term which minimizes the error in the azimuthal clutter cut-off wavelength.

For inverted wave spectra whose best estimate image spectra still differ essentially from the observed image spectra, an algorithm was developed which iteratively adjusts the input wave spectrum to the SAR inverted wave spectrum thus yielding a new input spectrum for a consecutive inversion. Therefore the inverted and first guess 2-dim. wave spectra are partitioned into their subsystems. These are reduced to their characteristic parameters (significant waveheight, mean wavelength, mean direction). Each first guess wave system is then modified to agree in the characteristic parameters with the inverted wave system thus yielding an improved input spectrum for a subsequent inversion.

The retrieved ERS-1 wave spectra from a three year period are compared with spectra, computed by the third generation WAM model (cycle 4). There is an overall good agreement. The distinction between windsea and swell however reveals an overestimation of the windsea and an underestimation of the swell systems of the WAM model as compared to ERS-1 SAR observations.

In addition to statistical analysis dynamical intercomparisons are performed by investigating the propagation paths of individual swell systems. This allows the identification of model shortcomings in the source function on large propagation scales.

A wind and wave data assimilation scheme was developed, assimilating 2-dim. SAR retrieved wave spectra into the WAM model. A field of analyzed characteristic parameters is created by optimal interpolation. First guess wave systems are adjusted to these parameters thus yielding a field of analyzed wave spectra. Wind field corrections are retrieved from the corrections in the windsea systems. Results are presented for a two month assimilation period.


Presented  BAUER E., Institut fur Meereskunde                                Project code:
by:        Troplowitzstr. 7, D-22529 Hamburg, Germany,                       AO2.D110
           T. +49 4041 236 518, F. +49 4041 235 713 

Co         HASSELMANN S., HASSELMANN K.                   
Keywords:  Wave forecasting 

An operational wave forecast system using wind and wave data

The Green's function assimilation method is developed for the operational assimilation of observed ocean wave spectra into the ocean wave model WAM. The observed ocean wave spectra are retrieved from ERS-1 SAR wave mode spectra by a non-linear inversion scheme. From differences between observed and modeled wave spectra the Green's function method yields corrections of wind speeds and directions with respect to the wind fields driving the wave model. The most effective position and time of a wind correction is determined by the spectral wave age. Energy deviations of the young wind waves are corrected by the local wind, and deviations of swell energy are corrected by the wind at the position and time of origin of the swell waves, respectively.

It can be shown, that deviations between wave spectra obtained from ERS-1 SAR wave mode data and modeled spectra, which are located along a propagation ray of a wave system, produce consistent wind corrections. In most cases wind corrections refer to strong storm cases. To further assess the calculated wind corrections various data are used for comparison. For the global validation the significant wave heights of the ERS-1 and the TOPEX altimeter are compared with wave heights retrieved from the ERS-1 SAR data, and the wind corrections are compared with the winds of the ERS-1 scatterometer. The assimilation of spectra from the ERS-1 wave mode data by the Green's function assimilation method clearly appears useful to detect errors in the wind field.


Presented  PARTINGTON K.C., GEC-Marconi Research Centre,                     Project code:
by:        Ice Applications Section West Hanning Field Road,                 PP.UK7/B/C/D
           CM28HN Great Baddow, UK 
           T. +44 1245 473 331, F. +44 1245 475 244, E.                             
Co         HODSON W., REES W.G., 
           GRAVES A., Matra Marconi Space, Anchorage Road, PO35PU                          
           Portsmouth, UK T. +44 1705 674 468, F. +44 1705 764 642  

           LARSEN M. 

Keywords:  Ship routeing, sea ice

Ship routeing with near real-time ERS-1 derived ice charts

UK Pilot Project 7 b/c/d was initiated in 1992 with the aim of promoting the commercialization of radar data for ship routing in polar waters. The project was funded by the British National Space Centre, managed by DRA Farnborough and involved BP, Canarctic Shipping, Nunaoil, SAIC and the University of Cambridge Scott Polar Research Institute, as well as GEC-Marconi Research Centre.

The project was completed in April 1995, and further demonstration activities are planned, notably with Radarsat and with bulletin board and ship-borne ice chart display and manipulation facilities. The pilot project demonstrated the technical feasibility of operational ice products from ERS-1 and provided a clear indication of how an operational ice service may be operated.

In this final presentation for the ERS-1 supported phase of the project, example products will be provided, a near real time demonstration described and the way forward discussed.


Presented  HÅKANSSON B., Swedish Meteorological and                          Project code:
by:        Hydrological Institute (SMHI) Research & Development              PP2.S2  
           Section, S-60176 Norrkoping, Sweden 
           T. +46 1115 8385, F. +46 1117 0207                                                            
Co         MOBERG M., SMHI, T. +46 1115 8318

Keywords:  Ship routeing, sea ice 

Potentials of SAR for sea ice ship routeing based on experiences obtained with ERS-1 SAR in the Baltic Sea

Seasonal ice cover occurs every winter in the Baltic Sea. Depending on the severity of the ice season, shipping is more or less obstructed. Substantial resources are allocated in Sweden to facilitate winter navigation in forms of a huge icebreaker fleet. In optimizing icebreaker operations a thorough knowledge of present and future ice conditions as well as weather forecasts is required. To meet this demand the Ice Service at SMHI are using all possible sources of information on the ice conditions as observers on the coast and on ships as well as remote sensing information from air and satellite.

As a part of the BEERS (Baltic Experiment for Ers-1) program, application experiments were carried out during two winter seasons using ERS-1 SAR imagery. The results obtained were encouraging, especially regarding the operational use onboard the icebreakers in matters of optimizing the route in the icefields when convoying and conveying route information to merchant ships going by there own. A considerable gain in optimization of icebreaker operations can be achieved with the additional information provided by the SAR imagery. Considering that the total cost for the icebreaker service during the winter 1993/94, which engaged up to six icebreakers simultaneously, was approx. 140 MSEK of which just bunker expenditures amounted to 20 MSEK, it is obvious that even minor improvements in icebreaker tactics will give a substantial cost reduction. In times with more dynamic ice conditions, access to SAR data can surely contribute even more in reducing costs.

With the forthcoming launch of Radarsat, SAR information can be accessible on an operational basis. Time and coverage are the crucial issues whether the usefulness of SAR information can be fully utilized for operational use. SAR sea ice data should cover all the area of interest once a day and the data should be available within 2 to 3 hours at the Ice Service Center. Experiences show that segmentation/classification of the imagery is not crucial for the interpretation onboard the icebreakers since this is done by highly skilled officers, but of course such derived SAR image products could be valuable complements in the future. Of great importance is, however, that the SAR imagery can be distributed within a reasonable transmission time and presented in a way onboard the icebreakers that suits navigational needs of the users.

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry