scholarly journals Estimation of sea-ice thickness and volume in the Sea of Okhotsk based on ICESat data

2018 ◽  
Vol 59 (76pt2) ◽  
pp. 101-111 ◽  
Author(s):  
Sohey Nihashi ◽  
Nathan T. Kurtz ◽  
Thorsten Markus ◽  
Kay I. Ohshima ◽  
Kazutaka Tateyama ◽  
...  
Keyword(s):  
Sea Ice ◽  
Sea Of Okhotsk ◽  
Heat Budget ◽  
Ice Thickness ◽  
Sea Ice Thickness ◽  
The Sea Of Okhotsk ◽  
Ice Volume ◽  
Ice Concentration ◽  
Ice Production ◽  
Hydrostatic Balance

ABSTRACTSea-ice thickness in the Sea of Okhotsk is estimated for 2004–2008 from ICESat derived freeboard under the assumption of hydrostatic balance. Total ice thickness including snow depth (htot) averaged over 2004–2008 is 95 cm. The interannual variability of htot is large; from 77.5 cm (2008) to 110.4 cm (2005). The mode of htot varies from 50–60 cm (2007 and 2008) to 70–80 cm (2005). Ice thickness derived from ICESat data is validated from a comparison with that observed by Electromagnetic Induction Instrument (EM) aboard the icebreaker Soya near Hokkaido, Japan. Annual maps of htot reveal that the spatial distribution of htot is similar every year. Ice volume of 6.3 × 1011 m3 is estimated from the ICESat derived htot and AMSR-E derived ice concentration. A comparison with ice area demonstrates that the ice volume cannot always be represented by the area solely, despite the fact that the area has been used as a proxy of the volume in the Sea of Okhotsk. The ice volume roughly corresponds to that of annual ice production in the major coastal polynyas estimated based on heat budget calculations. This also supports the validity of the estimation of sea-ice thickness and volume using ICESat data.

scholarly journals Creation of a Heat and Salt Flux Dataset Associated with Sea Ice Production and Melting in the Sea of Okhotsk

2012 ◽  
Vol 25 (7) ◽  
pp. 2261-2278 ◽  
Author(s):  
Sohey Nihashi ◽  
Kay I. Ohshima ◽  
Noriaki Kimura
Keyword(s):  
Spatial Distribution ◽  
Sea Ice ◽  
Sea Of Okhotsk ◽  
Heat Budget ◽  
Salt Flux ◽  
The Sea Of Okhotsk ◽  
Ice Melt ◽  
Budget Analysis ◽  
Coastal Polynya ◽  
Ice Production

Abstract Sea ice formation, its transport, and its melting cause the redistribution of heat and salt, which plays an important role in the climate and biogeochemical systems. In the Sea of Okhotsk, a heat and salt flux dataset is created in which such sea ice processes are included, with a spatial resolution of ~12.5 km. The dataset is based on a heat budget analysis using ice concentration, thickness, and drift speed from satellite observations and the ECMWF Interim Re-Analysis (ERA-Interim) data. The salt flux calculation considers both salt supplied to the ocean from sea ice production and freshwater supplied when the ice melts. This dataset will be useful for the validation and boundary conditions of modeling studies. The spatial distribution of the annual fluxes shows a distinct contrast between north and south: significant ocean cooling with salt supply is shown in the northern coastal polynya region, while ocean heating with freshwater supply is shown in the south. This contrast suggests a transport of freshwater and negative heat by ice advection. The annual fluxes also show ocean cooling with freshwater supply in the Kashevarov Bank (KB) region and the central and eastern Sea of Okhotsk, suggesting the effect of warm water advection. In the ice melt season, relatively prominent ice melting is shown in the coastal polynya region, probably due to large solar heating of the upper ocean. This indicates that the polynya works as a “meltwater factory” in spring, contrasting with its role as an “ice factory” in winter. In the coastal polynya region, the spatial distribution of phytoplankton bloom roughly corresponds with the ice melt region.

scholarly journals Observation of sea-ice thickness fluctuation in the seasonal ice-covered area during 1992−99 winters

2001 ◽  
Vol 33 ◽  
pp. 449-456 ◽  
Author(s):  
Kazutaka Tateyama ◽  
Hiroyuki Enomoto
Keyword(s):  
Sea Ice ◽  
Bering Sea ◽  
Sea Of Okhotsk ◽  
Retrieval Algorithm ◽  
Ice Thickness ◽  
The Sea Of Okhotsk ◽  
Ice Volume ◽  
Fast Ice ◽  
Ice Floes ◽  
The Bering Sea

AbstractSea-ice fluctuations in the Sea of Okhotsk and the Bering Sea during the winters of 1992−99 were investigated by using the Special Sensor Microwave/ Imager dataset and a new ice-property retrieval algorithm This algorithm can distinguish between ice types such as fast ice floes, young ice and new ice, in an area covered by concentrations of >80% ice, and also has improved display resolution because it uses one of the 85 GHz channels. The ice thicknesses derived from the ice-thickness parameter of the new algorithm were compared with ship-based ice-thickness measurements, and were assumed to be 1−10, 11−34, 35−85 and 86−120 cm for new ice, young ice, floes (first-year ice) and fast ice, respectively. The results showed that ice volume can be small even if the ice area is large, due to thinness of the ice (e.g. in 1999 in the Sea of Okhotsk). A significant out-of-phase response, i.e. ice volume is larger in the Sea of Okhotsk when ice volume is smaller in the Bering Sea, was observed. The period of this see-saw showed two different time-scales, which were short (1 week) and long (2−4 weeks).

scholarly journals Modeled Trends in Antarctic Sea Ice Thickness

2014 ◽  
Vol 27 (10) ◽  
pp. 3784-3801 ◽  
Author(s):  
Paul R. Holland ◽  
Nicolas Bruneau ◽  
Clare Enright ◽  
Martin Losch ◽  
Nathan T. Kurtz ◽  
...  
Keyword(s):  
Sea Ice ◽  
The Arctic ◽  
Ice Thickness ◽  
Sea Ice Concentration ◽  
Sea Ice Thickness ◽  
Ice Volume ◽  
Antarctic Sea Ice ◽  
Ice Concentration ◽  
Order Of Magnitude ◽  
Concentration Changes

Abstract Unlike the rapid sea ice losses reported in the Arctic, satellite observations show an overall increase in Antarctic sea ice concentration over recent decades. However, observations of decadal trends in Antarctic ice thickness, and hence ice volume, do not currently exist. In this study a model of the Southern Ocean and its sea ice, forced by atmospheric reanalyses, is used to assess 1992–2010 trends in ice thickness and volume. The model successfully reproduces observations of mean ice concentration, thickness, and drift, and decadal trends in ice concentration and drift, imparting some confidence in the hindcasted trends in ice thickness. The model suggests that overall Antarctic sea ice volume has increased by approximately 30 km3 yr−1 (0.4% yr−1) as an equal result of areal expansion (20 × 103 km2 yr−1 or 0.2% yr−1) and thickening (1.5 mm yr−1 or 0.2% yr−1). This ice volume increase is an order of magnitude smaller than the Arctic decrease, and about half the size of the increased freshwater supply from the Antarctic Ice Sheet. Similarly to the observed ice concentration trends, the small overall increase in modeled ice volume is actually the residual of much larger opposing regional trends. Thickness changes near the ice edge follow observed concentration changes, with increasing concentration corresponding to increased thickness. Ice thickness increases are also found in the inner pack in the Amundsen and Weddell Seas, where the model suggests that observed ice-drift trends directed toward the coast have caused dynamical thickening in autumn and winter. Modeled changes are predominantly dynamic in origin in the Pacific sector and thermodynamic elsewhere.

scholarly journals Direct observations of sea-ice thickness and brine rejection off Sakhalin in the Sea of Okhotsk

2009 ◽  
Vol 29 (11-12) ◽  
pp. 1541-1548 ◽  
Author(s):  
Yasushi Fukamachi ◽  
Kunio Shirasawa ◽  
Anatoliy M. Polomoshnov ◽  
Kay I. Ohshima ◽  
Ervin Kalinin ◽  
...  
Keyword(s):  
Sea Ice ◽  
Sea Of Okhotsk ◽  
Ice Thickness ◽  
Sea Ice Thickness ◽  
The Sea Of Okhotsk ◽  
Direct Observations ◽  
Brine Rejection

scholarly journals Standardization of electromagnetic–induction measurements of Sea-ice thickness in polar and Subpolar Seas

2006 ◽  
Vol 44 ◽  
pp. 240-246 ◽  
Author(s):  
K. Tateyama ◽  
K. Shirasawa ◽  
S. Uto ◽  
T. Kawamura ◽  
T. Toyota ◽  
...  
Keyword(s):  
Sea Ice ◽  
Sea Of Okhotsk ◽  
Electromagnetic Induction ◽  
Sea Water ◽  
Chukchi Sea ◽  
The Arctic ◽  
Average Error ◽  
Ice Thickness ◽  
Sea Ice Thickness ◽  
The Sea Of Okhotsk

AbstractElectromagnetic–induction (EM) instruments can be used to estimate Sea-ice thickness because of the large contrast in the conductivities of Sea ice and Sea water, and are currently used in investigations of Sea-ice thickness. In this Study we analyze Several Snow, ice and Sea-water Samples and attempt to derive an appropriate formula to transform the apparent conductivity obtained from EM measurements to the total thickness of Snow and ice for all regions and Seasons. This was done to Simplify the EM tuning procedure. Surface EM measurement transects with the instrument at varying heights above the ice were made in the Chukchi Sea, off East Antarctica, in the Sea of Okhotsk and in Saroma-ko (lagoon). A Standardized transformation formula based on a one-dimensional multi-layer model was developed that also considers the effects of water-filled gaps between deformed ice, a Saline Snow Slush layer, and the increase in the footprint Size caused by increasing the instrument height. The overall average error in ice thickness determined with the Standardized transform was <7%, and the regional average errors were 2.2% for the Arctic, 7.0% for the Antarctic, 6.5% for the Sea of Okhotsk and 4.4% for Saroma-ko.

scholarly journals Sea-ice drift characteristics revealed by measurement of acoustic Doppler current profiler and ice-profiling sonar off Hokkaido in the Sea of Okhotsk

2011 ◽  
Vol 52 (57) ◽  
pp. 1-8 ◽  
Author(s):  
Yasushi Fukamachi ◽  
Kay I. Ohshima ◽  
Yuji Mukai ◽  
Genta Mizuta ◽  
Masaaki Wakatsuchi
Keyword(s):  
Sea Ice ◽  
Sea Of Okhotsk ◽  
Acoustic Doppler Current Profiler ◽  
Ice Thickness ◽  
Coastal Station ◽  
Turning Angle ◽  
The Sea Of Okhotsk ◽  
Ice Drift ◽  
Current Profiler ◽  
Sea Ice Drift

AbstractIn the southwestern part of the Sea of Okhotsk off Hokkaido, sea-ice drift characteristics are investigated using the ice and water velocities obtained from a moored upward-looking acoustic Doppler current profiler (ADCP) during the winters of 1999–2001. Using hourly-mean values of these data along with the wind data measured at a nearby coastal station, the wind factor and turning angle of the relative velocity between the ice and water velocities with respect to the wind are calculated assuming free drift under various conditions. Since the simultaneous sea-ice draft data are also available from a moored ice-profiling sonar (IPS), we examine the dependence of drift characteristics on ice thickness for the first time. As ice thickness increases and wind decreases, the wind factor decreases and the turning angle increases, as predicted by the theory of free drift. This study clearly shows the utility of the moored ADCP measurement for studying sea-ice drift, especially with the simultaneous IPS measurement for ice thickness, which cannot be obtained by other methods.

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