scholarly journals MODIS Sea Ice Thickness and Open Water–Sea Ice Charts over the Barents and Kara Seas for Development and Validation of Sea Ice Products from Microwave Sensor Data

2017 ◽  
Vol 9 (12) ◽  
pp. 1324 ◽  
Author(s):  
◽  
Keyword(s):  
Sea Ice ◽  
Open Water ◽  
Sensor Data ◽  
Ice Thickness ◽  
Sea Ice Thickness ◽  
Microwave Sensor ◽  
Barents And Kara Seas ◽  
Development And Validation

Early detection of the Weddell polynya re-opening using SAR imagery

2020 ◽  
Author(s):  
Adriano Lemos ◽  
Céline Heuzé
Keyword(s):  
Early Detection ◽  
Sea Ice ◽  
Open Water ◽  
Weddell Sea ◽  
Small Scale ◽  
Ice Thickness ◽  
Sar Images ◽  
Sea Ice Thickness ◽  
Sar Imagery ◽  
Microwave Sensors

<p>The sea ice thickness in the Weddell Sea during the austral winter normally exceeds 1 m, but in the case of a polynya, this thickness decreases to 10 cm or less. There are two theories as to why the Weddell Polynya opens: 1) comparatively warm oceanic water upwelling from its nominal depth of several hundred metres to the surface where it melts the sea ice from underneath; or 2) opening of a lead by a passing storm, lead which will then be maintained open either by the atmosphere or ocean and grow. The objective of this study is to estimate how long in advance the recent Weddell Polynya opening could have been detected by synthetic aperture radar (SAR) images due to the decrease of the sea ice thickness and/or early appearance of leads. We use high temporal and spatial resolution SAR images from the Sentinel-1 constellation (C-band) and ALOS2 (L-band) during the austral winters 2014-2018. We use an adapted version of the algorithm developed by Aldenhoff et al. (2018) to monitor changes in sea ice thickness over the polynya region. The algorithm detects the transition of the sea ice thickness through changes in small scale surface roughness and thus reduced backscatter, and allowing us to distinguish three different categories: ice, thin ice, and open water. The transition from ice to thin ice and then to open water indicates that the polynya is melted from under, whereas a direct transition from ice to open water will reveal leads. The high resolution and good coverage of the SAR imagery, and a combined effort of different satellites sensors (e.g. infrared and microwave sensors), opens the possibility of an early detection of Weddell Polynya opening.</p>

Progressing from 1D to 2D and 3D near-surface airborne electromagnetic mapping with a multisensor, airborne sea-ice explorer

Geophysics ◽  
2012 ◽  
Vol 77 (4) ◽  
pp. WB109-WB117 ◽  
Author(s):  
Andreas A. Pfaffhuber ◽  
Stefan Hendricks ◽  
Yme A. Kvistedal
Keyword(s):  
Sea Ice ◽  
Three Dimensional ◽  
Open Water ◽  
Ice Thickness ◽  
Receiver Coil ◽  
Differential Gps ◽  
Sea Ice Thickness ◽  
Near Surface ◽  
Level Ice ◽  
Ice Pressure

The polar ocean’s sea ice cover is an unconventional and challenging geophysical target. Helicopter electromagnetic (HEM) sea-ice thickness mapping is currently limited to 1D interpretation due to traditional procedures and systems. These systems are mainly sensitive to layered structures, ideally set for the widespread flat (level) ice type. Because deformed sea ice (e.g., pressure ridges) is 3D and usually also heterogeneous, ice thickness errors up to 50% can be observed for pressure ridges using 1D approximations for the interpretation of HEM data. We researched a new generation multisensor, airborne sea ice explorer (MAiSIE) to overcome these limitations. Three-dimensional finite-element modeling enabled us to determine that more than one frequency is needed, ideally in the range 1–8 kHz, to improve thickness estimates of grounded sea-ice pressure ridges that are typical of 3D sea ice structures. With the MAiSIE system, we found a new electromagnetic concept based on one multifrequency transmitter loop and a 3C receiver coil triplet with active digital bucking. The relatively small weight of the EM components freed enough payload to include additional scientific sensors, including a cross-track lidar scanner and high-accuracy inertial-navigation system combined with dual-antenna differential GPS. Integrating the 3D ice-surface topography obtained from the lidar with the EM data at frequencies from 500 Hz to 8 kHz in [Formula: see text]-, [Formula: see text]-, and [Formula: see text]-directions, significantly increased the accuracy of sea-ice pressure-ridge geometry derived from HEM data. Initial test flight results over open water showed the proof-of-concept with acceptable sensor drift and receiver sensitivity. Noise levels were relatively high (20–250 parts-per-million) due to unwanted interference, leaving room for optimization. The 20 ppm noise level at 4.1 kHz is sufficient to map level ice thickness with 10 cm precision for sensor altitudes below 13 m.

scholarly journals Deriving sea-ice thickness and ice types in the Sea of Okhotsk using dual-frequency airborne SAR (Pi-SAR) data

2002 ◽  
Vol 34 ◽  
pp. 429-434 ◽  
Author(s):  
Takeshi Matsuoka ◽  
Seiho Uratsuka ◽  
Makoto Satake ◽  
Akitsugu Nadai ◽  
Toshihiko Umehara ◽  
...  
Keyword(s):  
Sea Ice ◽  
Acoustic Doppler Current Profiler ◽  
Open Water ◽  
Ice Thickness ◽  
Dual Frequency ◽  
Backscattering Coefficient ◽  
Sea Ice Thickness ◽  
National Space ◽  
L Band ◽  
Airborne Sar

AbstractDual-frequency, multi-polarization airborne synthetic aperture radar (Pi-SAR; developed by the Communications Research Laboratory and National Space Development Agency of Japan) observations of the seasonal sea-ice region off the Okhotsk coast of Hokkaido, Japan, were carried out in February 1999 using X- and L-band radar frequencies with a resolution of 1.5 and 3.0 m. In conjunction with the SAR observations, the sea-ice thickness (draft) and velocity were measured by a moored Ice Profiling Sonar (IPS) and an Acoustic Doppler Current Profiler (ADCP). Tracks of the sea ice passing over the IPS were estimated from the time series of the ADCP ice-velocity and -direction data. Along these tracks, the SAR backscattering coefficient profiles were compared with the IPS ice-draft profiles. The results showed that the L-band SAR backs cattering profiles correlated well with the IPS ice-draft data, particularly in the thicker part (a few meters thick) of the rim of first-year ice, which had a large backscattering coefficient. Although the X-band SAR backscattering profiles did not correlate well with the IPS data, thin ice (<10 cm thick) showed a large backscattering coefficient. The L-band SAR and IPS data did not distinguish thin ice from open water.

scholarly journals Arctic sea-ice morphological characteristics in summer 1996

2001 ◽  
Vol 33 ◽  
pp. 165-170 ◽  
Author(s):  
P. Wadhams ◽  
N.R. Davis
Keyword(s):  
Sea Ice ◽  
Morphological Characteristics ◽  
Open Water ◽  
Arctic Sea Ice ◽  
Ice Thickness ◽  
Sea Ice Thickness ◽  
Thickness Profile ◽  
The North ◽  
Arctic Sea ◽  
Eurasian Basin

AbstractA sea-ice thickness profile obtained in September 1996 from the Greenland Sea and the Eurasian Basin, extending as far as the North Pole, has shown an unusually open ice cover with low mean drafts, large amounts of open water and little deep pressure ridging. Comparisons with data obtained from the same region in October 1976 show that mean ice draft has declined by 43% and that the decline can largely be ascribed to a loss of the thickest ice.

scholarly journals Atmospheric control of sea-ice thickness variability in the Amundsen Gulf, Canadian Beaufort Sea, and over the Labrador Shelf

2013 ◽  
Vol 54 (62) ◽  
pp. 227-240
Author(s):  
Simon J. Prinsenberg ◽  
Ingrid K. Peterson ◽  
J. Scott Holladay ◽  
Ryan J. Galley ◽  
Shannon Nudds
Keyword(s):  
Sea Ice ◽  
Open Water ◽  
Beaufort Sea ◽  
Ice Thickness ◽  
Late Winter ◽  
Sea Ice Thickness ◽  
Ice Growth ◽  
Northern Latitudes ◽  
Amundsen Gulf ◽  
The Difference

AbstractSea-ice thicknesses observed in Canadian coastal waters with helicopter-borne electromagnetic–laser sensors show large interannual variability caused by atmospheric fluctuations in two years for two areas where surveys were repeated, one in the Amundsen Gulf of the Canadian Beaufort Sea and one over the Labrador Shelf. For the Amundsen Gulf, the bimodal ice thickness peaks shifted by 40 cm to thinner thicknesses for the warmer winter of 2008 compared with 2004. The thinner ice in 2008 can be explained partially by reduced thermodynamic ice growth during the warmer winter of 2008. In addition, winds from the east were more persistent throughout the winter of 2008, increasing ice export from the Amundsen Gulf and thereby creating open-water areas where new ice growth in late winter produced the thinner ice classes. For the Labrador Shelf, the mean ice thicknesses of the warmer winter of 2011 (0.71 m) were much less than those of the near-normal winter of 2009 (1.60 m). Again the difference can be explained by the fact that along the entire Labrador Shelf the winter of 2011 was much warmer, reducing ice growth and resulting in thinner ice locally and thinner ice being transported into the survey region from northern latitudes. In addition, northwesterly winds occurred less frequently during the winter of 2011, reducing the transport of relatively thicker ice into the survey area from northern latitudes.

scholarly journals Trends in sea-ice variability on the way to an ice-free Arctic

2016 ◽  
Author(s):  
S. Bathiany ◽  
B. van der Bolt ◽  
M. S. Williamson ◽  
T. M. Lenton ◽  
M. Scheffer ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Sea Ice ◽  
Stochastic Systems ◽  
Open Water ◽  
Tipping Point ◽  
Arctic Sea Ice ◽  
Ice Thickness ◽  
Sea Ice Thickness ◽  
Arctic Sea ◽  
The Future

Abstract. It has been widely debated whether Arctic sea-ice loss can reach a tipping point, beyond which a large sea-ice area disappears abruptly. An important argument for this scenario is the destabilising role of the ice-albedo feedback. The theory of dynamical systems predicts a "slowing down" when a system destabilises towards a tipping point. In simple stochastic systems this can result in increasing variance and autocorrelation, potentially yielding an early warning of an abrupt change. Here we aim to establish whether the loss of Arctic sea ice would follow these conceptual predictions, an d which trends in sea ice variability can be expected from pre-industrial conditions toward an Arctic that is ice-free during the whole year. To this end, we apply a model hierarchy consisting of two box models and one comprehensive Earth system model. We find a consistent and robust decrease of the ice volume's annual relaxation time before summer ice is lost because thinner ice can adjust more quickly to perturbations. Thereafter, the relaxation time increases, mainly because the system becomes dominated by the ocean water's large heat capacity when the ice-free season becomes longer. Both trends carry over to the autocorrelation of sea ice thickness in time series. Also accounting for the geometric effect of increasing open-water formation efficiency for thinning ice, we obtain an increasing variability in sea-ice area fraction, but a decreasing variability in sea-ice thickness. These changes are robust to the nature and origin of climate variability in the models and hardly depend on the balance of feed backs. Therefore, characteristic trends can be expected in the future. As these trends are not specific to the existence of abrupt ice loss, the prospects for early warnings seem very limited. This result also has implications for statistical indicators in other systems whose effective "mass" changes over time, affecting the trend of their relaxation time. However, the robust relation between state and variability would allow an estimate of sea-ice variability from only short observations. This could help one to estimate the likelihood and persistence of extreme events in the future.

scholarly journals Revisiting Trans-Arctic Maritime Navigability in 2011–2016 from the Perspective of Sea Ice Thickness

2021 ◽  
Vol 13 (14) ◽  
pp. 2766
Author(s):  
Xiangying Zhou ◽  
Chao Min ◽  
Yijun Yang ◽  
Jack C. Landy ◽  
Longjiang Mu ◽  
...  
Keyword(s):  
Sea Ice ◽  
Transit Time ◽  
Open Water ◽  
The Arctic ◽  
Ice Thickness ◽  
Sea Ice Thickness ◽  
East Siberian Sea ◽  
Transportation Accessibility ◽  
Sea Ice Edge ◽  
Arctic Navigation

Arctic navigation has become operational in recent decades with the decline in summer sea ice. To assess the navigability of trans-Arctic passages, combined model and satellite sea ice thickness (CMST) data covering both freezing seasons and melting seasons are integrated with the Arctic Transportation Accessibility Model (ATAM). The trans-Arctic navigation window and transit time are thereby obtained daily from modeled sea ice fields constrained by satellite observations. Our results indicate that the poorest navigability conditions for the maritime Arctic occurred in 2013 and 2014, particularly in the Northwest Passage (NWP) with sea ice blockage. The NWP has generally exhibited less favorable navigation conditions and shorter navigable windows than the Northern Sea Route (NSR). For instance, in 2013, Open Water (OW) vessels that can only safely resist ice with a thickness under 15 cm had navigation windows of 47 days along the NSR (45% shorter than the 2011–2016 mean) and only 13 days along the NWP (80% shorter than the 2011–2016 mean). The longest navigation windows were in 2011 and 2015, with lengths of 103 and 107 days, respectively. The minimum transit time occurred in 2012, when more northward routes were accessible, especially in the Laptev Sea and East Siberian Sea with the sea ice edge retreated. The longest navigation windows for Polar Class 6 (PC6) vessels with a resistance to ice thickness up to 120 cm reached more than 200 days. PC6 vessels cost less transit time and exhibit less fluctuation in their navigation windows compared with OW vessels because of their ice-breaking capability. Finally, we found that restricted navigation along the NSR in 2013 and 2014 was related to the shorter periods of navigable days in the East Siberian Sea and Vilkitskogo Strait, with local blockages of thick ice having a disproportionate impact on the total transit. Shorter than usual navigable windows in the Canadian Arctic Archipelago and Beaufort Sea shortened the windows for entire routes of the NWP in 2013 and 2014.

scholarly journals Arctic Sea Ice Thickness Estimation Based on CryoSat-2 Radar Altimeter and Sentinel-1 Dual-Polarized SAR

2021 ◽  
Author(s):  
Juha Karvonen ◽  
Eero Rinne ◽  
Heidi Sallila ◽  
Petteri Uotila ◽  
Marko Mäkynen
Keyword(s):  
Sea Ice ◽  
Estimation Method ◽  
Texture Features ◽  
Arctic Sea Ice ◽  
Ice Thickness ◽  
Radar Altimeter ◽  
Sea Ice Thickness ◽  
Spatial Coverage ◽  
Barents And Kara Seas ◽  
Arctic Sea Ice Thickness

Abstract. We present a method to combine CryoSat-2 (CS-2) radar altimeter and Sentinel-1 synthetic aperture radar (SAR) data to obtain sea ice thickness (SIT) estimates for the Barents and Kara Seas. Our approach yields larger spatial coverage and better accuracy compared to estimates based on either CS-2 or SAR alone. The SIT estimation method developed here is based on interpolation and extrapolation of CS-2 sea ice thickness (SIT) utilizing SAR segmentation and segmentwise SAR texture features. The SIT results are compared to SIT data derived from the AARI ice charts, to ORAS5. PIOMAS and TOPAZ4 ocean-sea ice data assimilation system reanalyses, and to daily MODIS based ice thickness charts. Our results are directly applicable to the future CRISTAL mission and Copenicus programme SAR missions.

In-situ automatic observations of ice thickness of seas

2012 ◽  
Vol 19 (3) ◽  
pp. 583-592 ◽  
Author(s):  
Yinke Dou ◽  
Xiaomin Chang
Keyword(s):  
Sea Ice ◽  
New Technologies ◽  
Capacitive Sensor ◽  
Automatic Monitoring ◽  
Ice Thickness ◽  
In Situ Observation ◽  
Glacier Surface ◽  
Sea Ice Thickness ◽  
Surface Ice

Abstract Ice thickness is one of the most critical physical indicators in the ice science and engineering. It is therefore very necessary to develop in-situ automatic observation technologies of ice thickness. This paper proposes the principle of three new technologies of in-situ automatic observations of sea ice thickness and provides the findings of laboratory applications. The results show that the in-situ observation accuracy of the monitor apparatus based on the Magnetostrictive Delay Line (MDL) principle can reach ±2 mm, which has solved the “bottleneck” problem of restricting the fine development of a sea ice thermodynamic model, and the resistance accuracy of monitor apparatus with temperature gradient can reach the centimeter level and research the ice and snow substance balance by automatically measuring the glacier surface ice and snow change. The measurement accuracy of the capacitive sensor for ice thickness can also reach ±4 mm and the capacitive sensor is of the potential for automatic monitoring the water level under the ice and the ice formation and development process in water. Such three new technologies can meet different needs of fixed-point ice thickness observation and realize the simultaneous measurement in order to accurately judge the ice thickness.

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