Review of "Satellite-based sea ice thickness changes in the Laptev Sea from 2002 to 2017: Comparison to mooring observations" by Hans Jakob Belter et al.

Abstract. The gridded sea ice thickness (SIT) climate data record (CDR) produced by the European Space Agency (ESA) Sea Ice Climate Change Initiative Phase 2 (CCI-2) is the longest available, Arctic-wide SIT record covering the period from 2002 to 2017. SIT data are based on radar altimetry measurements of sea ice freeboard from the Environmental Satellite (ENVISAT) and CryoSat-2 (CS2). The CCI-2 SIT has previously been validated with in situ observations from drilling, airborne remote sensing, electromagnetic (EM) measurements and upward-looking sonars (ULSs) from multiple ice-covered regions of the Arctic. Here we present the Laptev Sea CCI-2 SIT record from 2002 to 2017 and use newly acquired ULS and upward-looking acoustic Doppler current profiler (ADCP) sea ice draft (VAL) data for validation of the gridded CCI-2 and additional satellite SIT products. The ULS and ADCP time series provide the first long-term satellite SIT validation data set from this important source region of sea ice in the Transpolar Drift. The comparison of VAL sea ice draft data with gridded monthly mean and orbit trajectory CCI-2 data, as well as merged CryoSat-2–SMOS (CS2SMOS) sea ice draft, shows that the agreement between the satellite and VAL draft data strongly depends on the thickness of the sampled ice. Rather than providing mean sea ice draft, the considered satellite products provide modal sea ice draft in the Laptev Sea. Ice drafts thinner than 0.7 m are overestimated, while drafts thicker than approximately 1.3 m are increasingly underestimated by all satellite products investigated for this study. The tendency of the satellite SIT products to better agree with modal sea ice draft and underestimate thicker ice needs to be considered for all past and future investigations into SIT changes in this important region. The performance of the CCI-2 SIT CDR is considered stable over time; however, observed trends in gridded CCI-2 SIT are strongly influenced by the uncertainties of ENVISAT and CS2 and the comparably short investigation period.

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Review of "Satellite-based sea ice thickness changes in the Laptev Sea from 2002 to 2017: Comparison to mooring observations"

10.5194/tc-2019-307-rc1 ◽

2020 ◽

Author(s):

Anonymous

Keyword(s):

Sea Ice ◽

Ice Thickness ◽

Laptev Sea ◽

Sea Ice Thickness ◽

The Laptev Sea

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Satellite-based sea ice thickness changes in the Laptev Sea from 2002 to 2017: Comparison to mooring observations

10.5194/tc-2019-307 ◽

2020 ◽

Cited By ~ 1

Author(s):

Hans Jakob Belter ◽

Thomas Krumpen ◽

Stefan Hendricks ◽

Jens A. Hoelemann ◽

Markus A. Janout ◽

...

Keyword(s):

Sea Ice ◽

Source Region ◽

European Space Agency ◽

The Arctic ◽

Ice Thickness ◽

Laptev Sea ◽

Validation Data ◽

Data Set ◽

Sea Ice Thickness ◽

The Laptev Sea

Abstract. The gridded sea ice thickness (SIT) climate data record (CDR) produced by the European Space Agency (ESA) Sea Ice Climate Change Initiative Phase 2 (CCI-2) is the longest available, Arctic-wide SIT record covering the period from 2002 to 2017. SIT data is based on radar altimetry measurements of sea ice freeboard from the Environmental Satellite (ENVISAT) and CryoSat-2 (CS2). The CCI-2 SIT has previously been validated with in situ observations from drilling, airborne electromagnetic (EM) measurements and Upward-Looking Sonars (ULS) from multiple ice-covered regions of the Arctic. Here we present the Laptev Sea CCI-2 SIT record from 2002 to 2017 and use newly acquired ULS and upward-looking Acoustic Doppler Current Profiler (ADCP) sea ice draft data (VAL) for validation of the gridded CCI-2 and additional satellite SIT products. The ULS and ADCP time series provide the first long-term satellite SIT validation data set from this important source region of sea ice in the Transpolar Drift. The comparison of VAL sea ice draft data with gridded monthly mean and orbit trajectory CCI-2 data, as well as merged CryoSat-2/SMOS (CS2SMOS) sea ice draft shows that the agreement between the satellite and VAL draft data strongly depends on the thickness of the sampled ice. Rather than providing mean sea ice draft the considered satellite products provide modal sea ice draft in the Laptev Sea. Ice thinner than the modal draft is overestimated, while thicker ice is increasingly underestimated by all satellite products investigated for this study. This tendency of the satellite SIT products to better agree with modal sea ice draft and underestimate thicker ice needs to be considered for all past and future investigations into SIT changes in this important region. The performance of the CCI-2 SIT CDR is considered stable over time, however, observed trends in gridded CCI-2 SIT are strongly influenced by the uncertainties of ENVISAT and CS2 and the comparably short investigation period.

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Stages of sea ice development in the Laptev sea

Arctic and Antarctic Research ◽

10.30758/0555-2648-2017-0-4-5-15 ◽

2017 ◽

pp. 5-15 ◽

Cited By ~ 1

Author(s):

S. V. Hotchenkov

Keyword(s):

Sea Ice ◽

Ice Cover ◽

Ice Thickness ◽

Winter Period ◽

First Year ◽

Laptev Sea ◽

Partial Concentration ◽

Fast Ice ◽

Drifting Ice ◽

The Laptev Sea

Variability of the stages of sea ice development in the Laptev Sea is assessed with 10-days periodicity for the autumn — winter period on a basis of AARI digital ice charts for 1997–2017. Difference in formation of the stages of ice development (ice thickness) was revealed between the drifting and fast ice, which is manifested in an earlier appearance of the first-year ice for the fast ice area and in its partial concentration. On average, the ice cover of the Laptev Sea is by 60 % composed of thick first-year ice, most of which is formed within the fast ice area — 38%, while the area of drifting ice is 1,5 times larger.

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Comparison of MODIS-based thin-ice thicknesses with ice draft measurements in the Laptev Sea & Chukchi Sea

10.5194/egusphere-egu21-7909 ◽

2021 ◽

Author(s):

Andreas Preußer ◽

H. Jakob Belter ◽

Yasushi Fukamachi ◽

Günther Heinemann

Keyword(s):

Sea Ice ◽

Chukchi Sea ◽

Reanalysis Data ◽

Arctic Sea Ice ◽

Balance Model ◽

Ice Thickness ◽

Laptev Sea ◽

Data Set ◽

In Situ Data ◽

The Laptev Sea

Acquiring information about the thickness of thin Arctic sea-ice is an important aspect of assessing atmosphere &#8211; sea-ice &#8211; ocean interactions, as the ice thickness directly relates to the magnitude of energy fluxes at the sea-ice interfaces. In winter, these fluxes are linked to sea-ice formation and hence accompanying processes such as physically induced upper-ocean convection and turbulent mixing of the lower atmospheric boundary layer. It remains a big challenge to validate satellite-derived thin-ice thicknesses, first and foremost due to the lack of suitable in-situ data in these remote areas.In order to address this issue, we here present the first insight into a comparison between high-resolution (2km) MODIS thermal infrared satellite data (available for 2002/2003 to 2017/2018) and comprehensive time series of ice-draft data obtained from moored Ice Profiling Sonar (IPS) data. The IPS data set comprises winter-seasons 2009/2010 to 2011/2012 in the Chukchi Sea and winter-seasons 2013/2014 to 2014/2015 in the Laptev Sea. For the MODIS data set, a 1D energy balance model serves as the base for deriving thin-ice thicknesses (0 to 50 cm) from ice-surface temperature swath-data and ERA-Interim atmospheric reanalysis data. In order to facilitate the comparison, the 1Hz IPS ice-draft data is first empirically converted to ice thickness and afterwards resampled to 5-minute modal-values to find matching MODIS swath data.It shows that the agreement between the MODIS and IPS ice-thickness data largely depends on the thickness of the ice sampled by the IPS. We found the highest agreement for ice thickness values below 20 cm, which tend to appear more frequently at the Chukchi Sea mooring location. More generally, we notice that MODIS seems to overestimate ice thicknesses up to approximately 40 cm. For thicker ice, the limitations of the MODIS ice-thickness retrieval result in an underestimation.

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A combined approach of remote sensing and airborne electromagnetics to determine the volume of polynya sea ice in the Laptev Sea

The Cryosphere Discussions ◽

10.5194/tcd-7-441-2013 ◽

2013 ◽

Vol 7 (1) ◽

pp. 441-473 ◽

Cited By ~ 2

Author(s):

L. Rabenstein ◽

T. Krumpen ◽

S. Hendricks ◽

C. Koeberle ◽

C. Haas ◽

...

Keyword(s):

Sea Ice ◽

Thickness Distribution ◽

Growth Conditions ◽

Ice Age ◽

The Arctic ◽

Ice Thickness ◽

Laptev Sea ◽

Volume Estimate ◽

Sea Ice Thickness ◽

Level Ice

Abstract. A combined interpretation of synthetic aperture radar (SAR) satellite images and helicopter electromagnetic (HEM) sea-ice thickness data has provided an estimate of sea-ice volume formed in Laptev Sea polynyas during the winter of 2007/08. The evolution of the surveyed sea-ice areas, which were formed between late December 2007 and middle April 2008, was tracked using a series of SAR images with a sampling interval of 2–3 days. Approximately 160 km of HEM data recorded in April 2008 provided sea-ice thicknesses along profiles that transected sea-ice varying in age from 1–116 days. For the volume estimates, thickness information along the HEM profiles was extrapolated to zones of the same age. The error of areal mean thickness information was estimated to be between 0.2 m for younger ice and up to 1.55 m for older ice, with the primary error source being the spatially limited HEM coverage. Our results have demonstrated that the modal thicknesses and mean thicknesses of level ice correlated with the sea-ice age, but that varying dynamic and thermodynamic sea-ice growth conditions resulted in a rather heterogeneous sea-ice thickness distribution on scales of tens of kilometers. Taking all uncertainties into account, total sea-ice area and volume produced within the entire surveyed area were 52 650 km2 and 93.6 ± 26.6 km3. The surveyed polynya contributed 2.0 ± 0.5% of the sea-ice produced throughout the Arctic during the 2007/08 winter. The SAR-HEM volume estimate compares well with the 112 km3 ice production calculated with a high resolution ocean sea-ice model. Measured modal and mean-level ice thicknesses correlate with calculated freezing-degree-day thicknesses with a factor of 0.87–0.89, which was too low to justify the assumption of homogeneous thermodynamic growth conditions in the area, or indicates a strong dynamic thickening of level ice by rafting of even thicker ice.

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Spatial and Temporal Variations in the Extent and Thickness of Arctic Landfast Ice

Remote Sensing ◽

10.3390/rs12010064 ◽

2019 ◽

Vol 12 (1) ◽

pp. 64 ◽

Cited By ~ 3

Author(s):

Zixuan Li ◽

Jiechen Zhao ◽

Jie Su ◽

Chunhua Li ◽

Bin Cheng ◽

...

Keyword(s):

Sea Ice ◽

Coastal Areas ◽

Arctic Sea Ice ◽

Ice Thickness ◽

Laptev Sea ◽

Maximum Extent ◽

Arctic Sea ◽

Landfast Ice ◽

The Mean ◽

The Laptev Sea

Analyses of landfast ice in Arctic coastal areas provide a comprehensive understanding of the variations in Arctic sea ice and generate data for studies on the utilization of the Arctic passages. Based on our analysis, Arctic landfast ice mainly appears in January–June and is distributed within the narrow straits of the Canadian Archipelago (nearly 40%), the coastal areas of the East Siberian Sea, the Laptev Sea, and the Kara Sea. From 1976–2018, the landfast ice extent gradually decreased at an average rate of −1.1 ± 0.5 × 104 km2/yr (10.5% per decade), while the rate of decrease for entire Arctic sea ice was −6.0 ± 2.4 × 104 km2/yr (5.2% per decade). The annual maximum extent reached 2.3 × 106 km2 in the early 1980s, and by 2018, the maximum extent decreased by 0.6 × 106 km2, which is an area approximately equivalent the Laptev Sea. The mean duration of Arctic landfast ice is 44 weeks, which has gradually been reduced at a rate of −0.06 ± 0.03 weeks/yr. Regional landfast ice extent decreases in 16 of the 17 subregions except for the Bering Sea, making it the only subregion where both the extent and duration increases. The maximum mean landfast ice thickness appears in the northern Canadian Archipelago (>2.5 m), with the highest increasing trend (0.1 m/yr). In the Northeast Passage, the mean landfast ice thickness is 1.57 m, with a slight decreasing trend of −1.2 cm/yr, which is smaller than that for entire Arctic sea ice (−5.1 cm/yr). The smaller decreasing trend in the landfast ice extent and thickness suggests that the well-known Arctic sea ice decline largely occurred in the pack ice zone, while the larger relative extent loss indicates a faster ice free future in the landfast ice zone.

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A combined approach of remote sensing and airborne electromagnetics to determine the volume of polynya sea ice in the Laptev Sea

The Cryosphere ◽

10.5194/tc-7-947-2013 ◽

2013 ◽

Vol 7 (3) ◽

pp. 947-959 ◽

Cited By ~ 2

Author(s):

L. Rabenstein ◽

T. Krumpen ◽

S. Hendricks ◽

C. Koeberle ◽

C. Haas ◽

...

Keyword(s):

Sea Ice ◽

Thickness Distribution ◽

Growth Conditions ◽

Ice Age ◽

The Arctic ◽

Ice Thickness ◽

Laptev Sea ◽

Volume Estimate ◽

Sea Ice Thickness ◽

Level Ice

Abstract. A combined interpretation of synthetic aperture radar (SAR) satellite images and helicopter electromagnetic (HEM) sea-ice thickness data has provided an estimate of sea-ice volume formed in Laptev Sea polynyas during the winter of 2007/08. The evolution of the surveyed sea-ice areas, which were formed between late December 2007 and middle April 2008, was tracked using a series of SAR images with a sampling interval of 2–3 days. Approximately 160 km of HEM data recorded in April 2008 provided sea-ice thicknesses along profiles that transected sea ice varying in age from 1 to 116 days. For the volume estimates, thickness information along the HEM profiles was extrapolated to zones of the same age. The error of areal mean thickness information was estimated to be between 0.2 m for younger ice and up to 1.55 m for older ice, with the primary error source being the spatially limited HEM coverage. Our results have demonstrated that the modal thicknesses and mean thicknesses of level ice correlated with the sea-ice age, but that varying dynamic and thermodynamic sea-ice growth conditions resulted in a rather heterogeneous sea-ice thickness distribution on scales of tens of kilometers. Taking all uncertainties into account, total sea-ice area and volume produced within the entire surveyed area were 52 650 km2 and 93.6 ± 26.6 km3. The surveyed polynya contributed 2.0 ± 0.5% of the sea-ice produced throughout the Arctic during the 2007/08 winter. The SAR-HEM volume estimate compares well with the 112 km3 ice production calculated with a~high-resolution ocean sea-ice model. Measured modal and mean-level ice thicknesses correlate with calculated freezing-degree-day thicknesses with a factor of 0.87–0.89, which was too low to justify the assumption of homogeneous thermodynamic growth conditions in the area, or indicates a strong dynamic thickening of level ice by rafting of even thicker ice.

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Winter sea ice export from the Laptev Sea preconditions the local summer sea ice cover

10.5194/tc-2017-28 ◽

2017 ◽

Author(s):

Polona Itkin ◽

Thomas Krumpen

Keyword(s):

Sea Ice ◽

Ice Cover ◽

Sensitivity Study ◽

Late Winter ◽

Laptev Sea ◽

Sea Ice Extent ◽

Ice Dynamics ◽

Sea Ice Thickness ◽

Statistical Connection ◽

The Laptev Sea

Abstract. Recent studies based on satellite observations have shown that there is a high statistical connection between the late winter (Feb-May) sea ice export out the Laptev Sea, and the ice coverage in the following summer. By means of airborne sea ice thickness surveys made over pack ice areas in the southeastern Laptev Sea, we show that years of offshore directed sea ice transport have a thinning effect on the late winter sea ice cover, and vice versa. Once temperature rise above freezing, these thin ice zones melt more rapidly and hence, precondition local anomalies in summer sea ice cover. The preconditioning effect of the winter ice dynamics for the summer sea ice extent is confirmed with a model sensitivity study where we replace the inter-annual summer atmospheric forcing by a climatology. In the model, years with high late winter sea ice export always result in a reduced sea ice cover, and vice versa. We conclude that the observed tendency towards an increased ice export further accelerates ice retreat in summer. The mechanism presented in this study highlights the importance of winter ice dynamics for summer sea ice anomalies in addition to atmospheric processes acting on the ice cover between May and September. Finally, we show that ice dynamics in winter not only precondition local summer ice extent, but also accelerate fast ice decay.

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