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  • 1
    Publication Date: 2015-07-01
    Description: Data from the Seasonal Ice Zone Observing Network (SIZONet) acquired near Barrow, Alaska, during the 2009/10 ice season allow novel comparisons between measurements of ice thickness and velocity. An airborne electromagnetic survey that passed over a moored Ice Profiling Sonar (IPS) provided coincident independent measurements of total ice and snow thickness and ice draft at a scale of 10 km. Once differences in sampling footprint size are accounted for, we reconcile the respective probability distributions and estimate the thickness of level sea ice at 1.48 +/- 0.1 m, with a snow depth of 0.12 +/- 0.07 m. We also complete what we believe is the first independent validation of radar-derived ice velocities by comparing measurements from a coastal radar with those from an under-ice acoustic Doppler current profiler (ADCP). After applying a median filter to reduce high-frequency scatter in the radar-derived data, we find good agreement with the ADCP bottom-tracked ice velocities. With increasing regulatory and operational needs for sea-ice data, including the number and thickness of pressure ridges, coordinated observing networks such as SIZONet can provide the means of reducing uncertainties inherent in individual datasets.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 2
    Publication Date: 2022-05-25
    Description: © The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Deep Sea Research Part I: Oceanographic Research Papers 102 (2015): 43-54, doi:10.1016/j.dsr.2015.04.004.
    Description: Over the past few decades, sea ice retreat during summer has been enhanced in the Pacific sector of the Arctic basin, likely due in part to increasing summertime heat flux of Pacific-origin water from the Bering Strait. Barrow Canyon, in the northeast Chukchi Sea, is a major conduit through which the Pacific-origin water enters the Arctic basin. This paper presents results from 6 repeat high-resolution shipboard hydrographic/velocity sections occupied across Barrow Canyon in summer 2010. The different Pacific water masses feeding the canyon – Alaskan coastal water (ACW), summer Bering Sea water (BSW), and Pacific winter water (PWW) – all displayed significant intra-seasonal variability. Net volume transports through the canyon were between 0.96 and 1.70 Sv poleward, consisting of 0.41–0.98 Sv of warm Pacific water (ACW and BSW) and 0.28–0.65 Sv of PWW. The poleward heat flux also varied strongly, ranging from 8.56 TW to 24.56 TW, mainly due to the change in temperature of the warm Pacific water. Using supplemental mooring data from the core of the warm water, along with wind data from the Pt. Barrow weather station, we derive and assess a proxy for estimating heat flux in the canyon for the summer time period, which is when most of the heat passes northward towards the basin. The average heat flux for 2010 was estimated to be 3.34 TW, which is as large as the previous record maximum in 2007. This amount of heat could melt 315,000 km2 of 1-meter thick ice, which likely contributed to significant summer sea ice retreat in the Pacific sector of the Arctic Ocean.
    Description: MI, TK, YF, KO and DS were supported by Green Network of Excellence Program (GRENE Program), Arctic Climate Change Research Project ‘Rapid Change of the Arctic Climate System and its Global Influences’ by Ministry of Education, Culture, Sports, Science and Technology Japan. RP was supported by grant ARC-1203906 from the US National Science Foundation. CA was supported by grant ARC-1023331 from the US National Science Foundation and by the Cooperative Institute for the North Atlantic Region (NOAA Cooperative AgreementNA09OAR4320129) with funds provided by the US National Oceanographic and Atmospheric Administration through an Interagency Agreement between the US Bureau of Ocean and Energy Management and the National Marine Mammal Laboratory. SV was supported by the Department of Fisheries and Oceans Canada. MI and TK were supported by the Japan Agency for Marine-Earth Science and Technology. MI, TK, YF and KO were supported by Grant no. 2014-23 from Joint Research Program of the Institute of Low Temperature Science, Hokkaido University. YF and KO were supported by grants-in-aid 20221001 for scientific research from the Ministry of Education, Culture, Sports, Science and Technology of Japan. JTM was supported by grant PLR-1041102 from the US National Science Foundation.
    Keywords: Polar oceanography ; Arctic Ocean ; Chukchi Sea ; Heat fluxes ; Volume transports ; Water properties
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 3
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    American Geophysical Union (AGU)
    In:  EPIC3Journal of Geophysical Research: Oceans, American Geophysical Union (AGU), 124(8), pp. 5503-5528, ISSN: 2169-9275
    Publication Date: 2022-11-02
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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  • 4
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    PANGAEA
    In:  Supplement to: Preußer, Andreas; Ohshima, Kay I; Iwamoto, Katsushi; Willmes, Sascha; Heinemann, Günther (2019): Retrieval of Wintertime Sea Ice Production in Arctic Polynyas Using Thermal Infrared and Passive Microwave Remote Sensing Data. Journal of Geophysical Research: Oceans, https://doi.org/10.1029/2019JC014976
    Publication Date: 2023-11-24
    Description: A precise knowledge of wintertime sea-ice production in Arctic polynyas is not only required to enhance our understanding of atmosphere - sea-ice - ocean interactions, but also to verify frequently utilized climate and ocean models. In this study, a high-resolution (2km) MODIS thermal infrared satellite data set featuring spatial and temporal characteristics of 17 Arctic polynya regions (see attached overview map) for the winter seasons 2002/2003 to 2017/2018 is directly compared to a similar data set based on AMSR-E passive microwave data (available for 2002/2003 to 2010/2011). The MODIS data set is purely based on a 1D energy balance model, where thin-ice thicknesses (up to 20cm) are directly derived from ice-surface temperature swath data and ERA-Interim atmospheric reanalysis data on a quasi-daily basis. A gap-filling approach is applied to account for cloud and data gaps in the MODIS composites. Estimation of the thin-ice thickness in the AMSR-E data set is based on an empirical approach that utilizes a distinct polarization ratio (PR) - ice thickness relationship. More detailed information on the retrieval of the data can be found in the referenced publication.
    Keywords: AMSR-E; Arctic; Area; Beaufort shelf; BSH; CAA; Canadian Arctic Archipelago; Cape Bathurst Polynya; CATS; CATS - The Changing Arctic Transpolar System; CBP; CHU; Chukchi Sea; DATE/TIME; derived from AMSR-E passive microwave data; derived from MODIS remote sensing data; East-Siberian Fast-ice; East Siberian Sea; ESF; ESS; Event label; FJL; Franz Josef Land; GLN; Greenland North; KAR; Kara Sea; LAP; Laptev Sea; Latitude of event; Longitude of event; MODIS; Nares Strait/Lincoln Sea; NEWP; North-East Water polynya; North Water polynya; NOW; NSL; Optional event label; Polynya; remote sensing; Sea ice; Sea ice production; Severnaya Zemlya North; STO; Storfjorden polynya; SVA; Svalbard archipelago; SZN; Western Novaya Zemlya; WNZ
    Type: Dataset
    Format: text/tab-separated-values, 103054 data points
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  • 5
    ISSN: 1573-868X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Step-like thermohaline structure was observed near icebergs trapped by fast ice in Lützow-Holm Bay, Antarctica. The structure was developed within the draft depth of the icebergs. The typical vertical distance between the succeeding step surfaces is 20–30 m, and the temperature and salinity differences across the step surface are about 0.05–0.06 deg and 0.06–0.10 psu, respectively. The structure appears to be generated by a sea-water/iceberg interaction, and is explainable by a simple model in which an ice wall is placed in the ocean linearly stratified by vertical salinity gradient.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-868X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Coastal polynyas off East Queen Maud Land in Antarctica are examined using NOAA AVHRR infrared data. From image analyses, two locations of coastal polynyas in this region are identified; one in Breid Bay and the other along the shelf break. The areal coverage of the Breid Bay polynya is significantly related to the strength of katabatic winds, which maintain their strength over the coastal sea due to land topography favoring for their confluence, thereby being capable of removing newly formed ice. Land fast ice in the eastern part of the bay also plays an additional role in the formation mechanism. It is also found that the areal coverage of coastal polynyas in this region fluctuate coherently. Moreover, these fluctuations correspond to the synoptic index, which measures the strength of the offshore wind, with their peaks closely associated with the areal peaks. These facts strongly suggest the influence of synoptic scale weather on the formation and maintenance of polynyas in this region.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-868X
    Keywords: Ice band ; ice streamer ; coastal polynya ; sea ice ; Antarctic Ocean ; MESSR MOS-1/1b
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Meso- or submeso-scale features of the Antarctic sea ice are investigated using the MOS-1/1b MESSR Images (spatial resolution of approximately 50 m) received at Syowa Station. Particular attention is paid to the ice bands and ice streamers in coastal polynyas. In the Antarctic Ocean, ice bands can be often seen not only at the ice edge but also in the ice interior zone throughout the year and they extend for hundreds of kilometers in the latitudinal direction. It is found that the width and spacing of ice bands tend to decrease from winter to summer. The width of ice band is about 2–6 km in August and September, and 0.1–0.7 km in December. The spacing of ice bands is about 3–10 km in August and September, and 0.1–2 km in December. In coastal polynyas, ice streamers, which are composed of new ice, are sometimes observed. In general, the row of the streamers is spaced at 0.5–2 km with a width of 0.1–1.0 km.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-868X
    Keywords: Funka Bay ; cold air outbreaks ; water circulation ; horizontal wind shear ; wind stress curl ; bathymetry torque
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Horizontal wind fields over Funka Bay during cold air outbreaks were simulated using a 3-D meso-scale atmospheric model. The simulated wind fields over the bay have a positive curl in the north and a negative curl in the south. These wind fields were used to simulate the current in Funka Bay using a barotropic ocean model. The simulated current pattern was composed of two vortices—one with anti-clockwise vorticity in the north and the other with clockwise vorticity in the south—and was in the opposite direction to that simulated by the uniform wind fields. This is because the wind stress curl effect on the vorticity production in Funka Bay opposes and overwhelms the bathymetry torque effect during cold air outbreaks. These results show that the non-uniformity of the wind fields caused by the land topography around a shallow lake or bay cannot be neglected in simulating its currents.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of oceanography 56 (2000), S. 643-654 
    ISSN: 1573-868X
    Keywords: Okhotsk Sea ; Soya Warm Current Water ; East Sakhalin Current Water ; seasonal variation ; water mass exchange ; sea level ; steric height ; Ekman convergence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract A new grid data set for the southwestern part of the Okhotsk Sea was compiled by using all the available hydrographic data from the Japan Oceanographic Data Center, World Ocean Atlas 1994 and the other additional data sources with the resolution of about 10 km. We examine the seasonal variations of areas and volumes of Soya Warm Current Water (SWCW) and East Sakhalin Current Water (ESCW) and show that the exchanges of these water masses drastically occur in April and November. The peculiar variation of sea level in this region is also related with the water mass exchange. Sea level at the Hokkaido coast of the Okhotsk Sea reaches its minimum in April about two months later than in the case of ordinary mid-latitude ocean, and its maximum in December besides the summer peak. The winter peak of sea level in December is caused by the advent of fresh and cold ESCW which is accumulated at the subsurface layers (20–150 m) through the Ekman convergence by the prevailing northerly wind. Sea level minimum in April is caused by the release of the convergence and the recovery of dense SWCW that is saline and much colder than that in summer.
    Type of Medium: Electronic Resource
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  • 10
    Publication Date: 2022-03-08
    Description: Precise knowledge of wintertime sea ice production in Arctic polynyas is not only required to enhance our understanding of atmosphere‐sea ice‐ocean interactions but also to verify frequently utilized climate and ocean models. Here, a high‐resolution (2‐km) Moderate Resolution Imaging Spectroradiometer (MODIS) thermal infrared satellite data set featuring spatial and temporal characteristics of 17 Arctic polynya regions for the winter seasons 2002/2003 to 2017/2018 is directly compared to an akin low‐resolution Advanced Microwave Scanning Radiometer‐EOS (AMSR‐E) passive microwave data set for 2002/2003 to 2010/2011. The MODIS data set is purely based on a 1‐D energy‐balance model, where thin‐ice thicknesses (≤ 20 cm) are directly derived from ice‐surface temperature swath data and European Centre for Medium‐Range Weather Forecasts Re‐Analysis‐Interim atmospheric reanalysis data on a quasi‐daily basis. Thin‐ice thicknesses in the AMSR‐E data set are derived empirically. Important polynya properties such as areal extent and potential thermodynamic ice production can be estimated from both pan‐Arctic data sets. Although independently derived, our results show that both data sets feature quite similar spatial and temporal variations of polynya area (POLA) and ice production (IP), which suggests a high reliability. The average POLA (average accumulated IP) for all Arctic polynyas combined derived from both MODIS and AMSR‐E are 1.99×105 km2 (1.34×103 km3) and 2.29×105 km2 (1.31×103 km3), respectively. Narrow polynyas in areas such as the Canadian Arctic Archipelago are notably better resolved by MODIS. Analysis of 16 winter seasons provides an evaluation of long‐term trends in POLA and IP, revealing the significant increase of ice formation in polynyas along the Siberian coast.
    Type: Article , PeerReviewed
    Format: text
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