Satellite and Oceanographic Observations of the Warm Coastal Current in the Chukchi Sea

Selected infrared images obtained by the NOAA satellites have increased our understanding of the formation and extent of the Alaskan Coastal Current, a movement of relatively warm water from the vicinity of Bering Strait northward along the Alaskan coast past Point Barrow and eventually into the Arctic Ocean where it disperses. Oceanographic measurements made from an icebreaker during the same period give spot checks on the depth of the warm layer, as well as the outline of a downward trend of the current when it is blocked by the ice. A study of satellite and oceanographic observations over a seven-year period, 1974-1980, reveals many interesting features of the flow and shows the annual variability. The northward flow and the shape of the ice edge are interrelated in that the flow is partially blocked by the ice and the ice is melted by the oncoming warm water. The solar-heated waters in Kotzebue Sound, Norton Sound, and along the coast to the south are seen as a major source of the heat in the coastal current.Key words: satellite, infrared, temperature, current, ice edge, eddies, oceanography, Chukchi Sea, Bering StraitMots clés: satellite, infra-rouge, température, courant, bord de la glace, remous, océanographie, mer Chukchi, détroit de Bérin

The influence of river discharge on the thawing of sea ice, Mackenzie River Delta: albedo and temperature analyses

Multi-temporal satellite images, field observations and field measurements were used to investigate the mechanisms by which sea ice melts offshore from the Mackenzie River Delta. Satellite data recorded between April and August 1986 were corrected to a map projection and calibrated such that albedo and temperature values could be compared. Three stages in the melting of sea ice were identified: flooding (overflows), insolation and melting by warm river water. The albedo values of overflows were as much as 1/7 that of ice values while the albedo of ice decreased by 1/3 over the summer. Approximately two weeks after the overflows develop, sea surface temperatures rise as the river-discharge peaks and becomes the dominant source of energy. By this process, ice removal in the delta regime is initiated two months earlier than adjacent coasts with minimal runoff. However, the net result is only a two-week acceleration of ice removal in the delta region

On the flow through Bering Strait: a synthesis of model results and observations

The article of record as published may be found at https://link.springer.com/chapter/10.1007/978-94-017-8863-2_7Bering Strait is the only ocean connection between the Pacific and the Arctic. The flow through this narrow and shallow strait links the Pacific and Arctic oceans and impacts oceanic conditions downstream in the Chukchi Sea and the Western Arctic. We present a model synthesis of exchanges through Bering Strait at monthly to decadal time scales, including results from coupled ice-ocean models and observations. Significant quantities of heat and freshwater are delivered annually into the southern Chukchi Sea via Bering Strait. We quantify seasonal signals, along with interannual variability, over the course of 26 years of multiple model integrations. Volume transport and property fluxes are evaluated among several high- resolution model runs and compared with available moored observations. High-resolution models represent the bathymetry better, and may have a more realistic representation of the flow through the strait, although in terms of fluxes and mean properties, this is not always the case. We conclude that, (i) while some of the models used for Arctic studies achieve the correct order of magnitude for fluxes of volume, heat and freshwater, and have significant correlations with observational results, there is still a need for improvement and (ii) higher spatial resolution is needed to resolve features such as the Alaska Coastal Current (ACC). At the same time, additional measurements with better spatial coverage are needed to minimize uncertainties in observed estimates and to constrain models. Bering Strait is the only ocean connection between the Pacific and the Arctic. The flow through this narrow and shallow strait links the Pacific and Arctic oceans and impacts oceanic conditions downstream in the Chukchi Sea and the Western Arctic. We present a model synthesis of exchanges through Bering Strait at monthly to decadal time scales, including results from coupled ice-ocean models and observations. Significant quantities of heat and freshwater are delivered annually into the southern Chukchi Sea via Bering Strait. We quantify seasonal signals, along with interannual variability, over the course of 26 years of multiple model integrations. Volume transport and property fluxes are evaluated among several high- resolution model runs and compared with available moored observations. High-resolution models represent the bathymetry better, and may have a more realistic representation of the flow through the strait, although in terms of fluxes and mean properties, this is not always the case. We conclude that, (i) while some of the models used for Arctic studies achieve the correct order of magnitude for fluxes of volume, heat and freshwater, and have significant correlations with observational results, there is still a need for improvement and (ii) higher spatial resolution is needed to resolve features such as the Alaska Coastal Current (ACC). At the same time, additional measurements with better spatial coverage are needed to minimize uncertainties in observed estimates and to constrain models.Department of Energy Earth System Modeling program (J. C. K and W. M.), National Science Foundation Office of Polar Programs (J. C. K, W. M., M. S., and J. Z.), and the Office of Naval Research (J. C. K and W. M.) for support of this research. We also thank the Arctic Ocean Model Intercomparison Project (J. C. K. and W. M.). At the National Oceanography Centre Southampton (Y.A. and B. d C.) the study was supported by the UK Natural Environment Research Council as a contribution to the Marine Centres’ Strategic Research Programme Oceans 2025.Support for this work was provided (in part) by NSF grants ARC-0632154, ARC-0855748, and the NOAA-RUSALCA program (R. W.). The mooring data used in this study was collected under funding from ONR, NSF, MMS, AOOS and NOAA-RUSALCA (R. W)