K. Kloster

Recent and future changes of the Arctic sea-ice cover

[1] The present and future state of the Arctic sea ice cover is explored using new observations and a coupled one dimensional air–sea–ice model. Updated satellite observations of Fram Strait ice-area export show an increase over the last four years, with 37% increase in winter 07–08. Atmospheric poleward energy flux declined since 1990, but advection of oceanic heat has recently increased. Simulations show that the ice area export is a stronger driver of thinning than the estimated ocean heat fluxes of 40 TW. Increased ocean heat transport will raise primarily Atlantic layer temperature. The ‘present 2007’ state of the Arctic ice could be a stable state given the recent high ice area export, but if ocean heat advection and ice export decrease, the ice cover will recover. A 2*CO2 scenario with export and oceanic heat flux remaining strong, forecasts a summer Arctic open ocean area of 95% around 2050. Citation: Smedsrud, L. H., A. Sorteberg, and K. Kloster (2008), Recent and future changes of the Arctic sea-ice cover, Geophys. Res. Lett., 35, L20503, doi:10.1029/ 2008GL034813.

Barents Sea seasonal ice zone features and processes from ERS 1 synthetic aperture radar: Seasonal Ice Zone Experiment 1992

Sea ice features and processes in the Barents Sea were studied during the Seasonal Ice Zone Experiment 1992 (SIZEX92), a dedicated ERS 1 satellite synthetic aperture radar (SAR) field campaign carried out in March 1992. SIZEX92 was based around the research vessels Polarsyssel and Hakon Mosby. In situ oceanographic, meteorological, and ice measurements were made, coordinated with low-altitude aerial observations and ERS 1 SAR data acquired in near real time. Fifty-eight low-and full-resolution SAR scenes were obtained during SIZEX92, which provided a validation data set for ERS 1 SAR backscatter under winter conditions in the Barents Sea. Analysis of SIZEX92 data has provided geophysical insights, including a better understanding of Barents Sea ice edge freezing processes and ice edge development in response to atmospheric forcings. In particular, areas of new ice formation were found to be related to bathymetric features through their influence on the circulation of Arctic and Atlantic water masses. ERS 1 SAR image sequences revealed rapid, mesoscale variations in new ice areas and the ice edge in response to wind conditions. In addition to geophysical insight, SIZEX92 demonstrated some of the technical capabilities and limitations of ERS 1 SAR to identify new ice areas, the ice edge, ice floes, and ice types. Mapping new ice areas using satellite SAR data may be considered the most promising new application. The limitations of ERS-1 SAR-derived ice classification and ice motion estimates in the marginal ice zone are identified.

Cover ERS-1/2 SAR monitoring of dangerous ice phenomena along the western part of Northern Sea Route

The Northern Sea Route ( NSR) as a part of the Arctic Ocean is very important for sea transportation to the Siberean coastal and river settlements, as well as for future transportation between Europe and the Paci® c Ocean countries. Recent opening of the gigantic oil and gas deposits on the Siberean shelf will require the build-up of a specialeet for eA cient marine oil and gas operations in this area. However, round-the-year navigation as well other marine operations (® shery, mining, oil and gas reconnaissance, etc. ) at the diA erent parts of the Arctic Ocean is a very complicated problem and an optimal choiceof the concrete sea route directions depends on numerous environmental factors. Environmental conditions which determine the high-latitude navigation in the North Pole area depend on seasonal and mean-annual distribution of water masses in the Arctic Ocean. An important factor which inuences marine operations in the Arctic Ocean is the presence of round-the-year ice. This is a complicated regional and global-scale process which depends on the location and properties of basic oceanic massif ice regime, on patterns of seasonal and mean-annual distribution of the basic massif s spurs, on the behaviour of the local ice massifs which in each area of the Arctic Ocean have their own characteristic features of the seasonal and mean-annual variability. The location and drift of the basic oceanic ice massifs spurs are variable para- meters. These spurs consist of the residual ® rst-year ice, and the second-year and multi-year pack iceoes. The thickness of this ice can be more than 3m and its invasion in the NSR area creates an especially dangerous situation for marine operations. Control of this phenomenon by all-weather remote sensing instruments is therefore extremely desirable. Another signi® cant factor which creates the favourable inuence for the ice navigation in the Arctic Ocean is the round-the-year presence of the vast recurring

Comparison of sea ice signatures in OKEAN and RADARSAT radar images for the northeastern Barents Sea

Sea ice signatures in near-simultaneous OKEAN real aperture radar (RAR) and RADARSAT synthetic aperture radar (ScanSAR) images have been analyzed and compared for the northeastern part of the Barents Sea in April 1998. Signatures of major sea ice types and features in these images have been identified and verified by in situ observations on board the nuclear icebreaker Sovetsky Soyuz. It is shown that both RAR and ScanSAR images can be used for detection of new, young, first year, and multiyear sea ice types, multiyear and fast ice boundaries, flaw polynyas, wide fractures, giant and vast ice floes, and large areas of rough ice. Backscatter signatures of the major sea ice types are analyzed and compared, and the backscattering differences between the ice types are estimated for both types of data. High-resolution ScanSAR images are found to be particularly suited for discrimination of narrow leads and level areas in compact sea ice. A study of the radar signatures of a flaw polynya to the north of Cape Zhelaniya was conducted using ERS SAR, RADARSAT ScanSAR, and OKEAN RAR over a period of 33 h. The backscatter from the polynya varied significantly between VV and HH polarization and as a consequence of changing physical properties due to freezing during the 33 h period. Access to satellite radar data for use in sea ice research will increase in the near future. Wide-swath SAR data are available from both RADARSAT and ENVISAT from 2003, and a new RAR satellite, SICH-M1, is planned for launch in 2004.

ICEWATCH-real-time sea ice monitoring of the Northern Sea Route using satellite radar technology

ICEWATCH is the first joint project in Earth observation between Russian Space Agency (RKA) and European Space Agency (ESA). The overall objective of the project is to implement satellite monitoring by combined use of ESA ERS SAR, RKA Okean SLR and other remote sensing data to support ice navigation in the Northern Sea Route (NSR), offshore industry and environmental studies. ERS-1 SAR images have been used in ice monitoring of the NSR in several demonstration campaigns since 1991. The experience from use of SAR data onboard Russian icebreakers to assist in ice navigation is very positive although ERS-1 can only provide data in selected parts of the NSR with a limited swath width of 100 km. In the ICEWATCH project a concept for integrating ERS SAR data in the Russian ice monitoring service is demonstrated where Okean SLR data are included. The system is currently tested in pilot demonstration phase before it is planned to become operational. In addition to data acquisition and interpretation techniques for data integration, ice classification and data transmission techniques have been tested. Also user requirements have been investigated, suggesting that there are many new and potential users of SAR ice information in the NSR. In future other radar satellites will also be used such as ESA ENVISAT which will be launched in 1999. The first results of ICEWATCH were presented at the Second ERS Applications Workshop in London in December 1995.

Near-real-time sea ice monitoring in the northern sea route using ERS-1 sar and DMSP SSM/I microwave data

Abstract Active and passive microwave sensor data from satellites are useful for studies of the sea ice in the polar regions, including the Eurasian Arctic. Their ability to acquire data regardless of darkness or cloudiness is an essential attribute in these regions. Here the scientific objective is to use the European Remote Sensing satellite (ERS-1) ERS-1 Synthetic Aperture Radar (SAR) data to investigate various sea ice phenomena and processes in the Kara Sea north of Russia. The technical objective is to assess the usefulness of ERS-1 SAR and Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave Imager (SSM/I) data for near-real-time monitoring of the ice conditions along the Northern Sea Route (the Northeast Passage) in support of navigation. The SAR data are seen to be very useful for small-scale ice studies, whereas the SSM/I data provide large-scale ice information, including the ice edge position. The SAR data are acquired in near real-time from the Tromso Satellite Station in order to transmit detailed sea ice maps to icebreakers operating in the Kara Sea. The use of SAR and SSM/I data in support of ice navigation there has been very successful.

Marginal ice zone signatures observed by the ERS-1 SAR during SIZEX '92

Coincident ship based X-, C-, and L-band scatterometer data and measurements of physical ice and snow properties were collected during ERS-1 synthetic aperture radar (SAR) overflights in the Barents Sea in March of 1992. One aspect of this Seasonal Ice Zone Experiment (SIZEX) concentrated on the marginal ice zone (MIZ), where a variety of sea ice types and open ocean conditions were encountered. A specific objective of SIZEX was to determine which MIZ ice types can be clearly discerned using ERS-1 SAR C-band imagery. First- and second-order statistics were generated to characterize ERS-1 ice signature. Comparing these statistics for each ice type, reveals that many of the ice types observed in the MIZ have comparable tones, as indicated by their means (i.e., multiyear and pancakes). However, the use of the SAR image texture may be used in conjunction with the tonal properties to successfully discern the various ice types and open water (all wind regimes) found in the MIZ.<<ETX>>

A comparative analysis of data on multiyear sea ice distribution in the Arctic as retrieved from satellite passive microwave radiometer and radar images

This study deals with a comparison of estimates on multiyear sea ice distribution in the Arctic, derived from SSM/I data using NORSEX algorithm and from satellite radar. Conducted analysis revealed qualitative correspondence of these estimates, as well as underestimation of SSM/S-derived values. The difference between these estimates can be explained by some inaccuracy in the input parameters, such as sea ice emissivities, air and ice temperatures, as well as by their spatial and temporal variations.

Iceberg identification in the Eurasian Arctic using SAR images

SAR studies on iceberg identification were conducted in Franz-Joseph Land, Novaya Zemlya, and Severnaya Zemlya. Field observations were used for SAR image interpretation.