High resolution observations of the Terra Nova Bay polynya using COSMO-SkyMed X-SAR and other satellite imagery

Ciappa, Achille; Pietranera, L.

doi:10.1016/j.jmarsys.2012.12.004

Cited by 23 publications

(40 citation statements)

References 28 publications

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“…The mean annual extent of the open water area was at lower side of the known range (around 900-1000 km 2 ) but in good agreement with previous visible and infrared satellite observations. A very good agreement was also found with MODIS derived TNBP estimates reported by previous studies [30,48] for sea ice seasons 2010 and 2011.…”

Section: Discussionsupporting

confidence: 89%

“…This case study is described in detail in Section 4.2. As for 2011 ( Figure 3b), a general agreement is found with TNBP extent fluctuations on 17-27 July (days 198 to 208) and 9-21 September (days 252 to 264) provided by Figure 4 in [30], through MODIS IST products and X-band VV-polarized CSK SAR imagery. In particular, position and magnitude of the relative peak detected on 23 July (around 2100 Km 2 ) perfectly correspond to our estimations; the peak on 15-16 September also corresponds but its extent is not comparable, probably due to the limited number of MODIS clear-sky scenes available for our procedure during those days.…”

Section: Terra Nova Bay Polynya Variability During Wintertime 2010 Ansupporting

confidence: 82%

“…Suspect IST scenes are pointed out in order to allow a visual check and the possibility of discarding them (less than 7%). As we expected, in most cases this happens during the closing phase when the TNBP is characterized by the presence of large areas of thin ice produced during subsequent katabatic events [30,42].…”

Section: The Polynya Extent Estimation Techniquesupporting

confidence: 59%

“…However, Kern et al [10] demonstrated that TNBP extent, location and orientation can change very fast, suggesting that openings and closings occur on timescales shorter than 24 h, usually in response to the regime of the katabatic events [36]. Ciappa and Pietranera [30] also suggested that fluctuations of the open water area can occur within very short time intervals, in the order of hours, and peaks of areal growing rate may exceed 300 km 2 per hour during extreme katabatic events.…”

Section: Remote Sensing Of the Terra Nova Bay Polynyamentioning

confidence: 99%

“…Unfortunately, their passages and swath widths are very limited, and they are not suitable for long-term monitoring [8]. Hence, they are mainly used to observe polynyas in local areas and short periods, and to validate algorithms derived for PMW [28,29] and TIR [30] products. Correctly, Hollands and Dierking [6] argued that the concurrent use of complementary sensors (optical, thermal, radar) represents the best approach to improve future satellite observation strategies over polynyas.…”

Section: Introductionmentioning

confidence: 99%

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A New Approach for Monitoring the Terra Nova Bay Polynya through MODIS Ice Surface Temperature Imagery and Its Validation during 2010 and 2011 Winter Seasons

et al. 2018

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Polynyas are dynamic stretches of open water surrounded by ice. They typically occur in remote regions of the Arctic and Antarctic, thus remote sensing is essential for monitoring their dynamics. On regional scales, daily passive microwave radiometers provide useful information about their extent because of their independence from cloud coverage and daylight; nonetheless, their coarse resolution often does not allow an accurate discrimination between sea ice and open water. Despite its sensitivity to the presence of clouds, thermal infrared (TIR) Moderate Resolution Imaging Spectroradiometer (MODIS) provides higher-resolution information (typically 1 km) at large swath widths, several times per day, proving to be useful for the retrieval of the size of polynyas. In this study, we deal with Aqua satellite MODIS observations of a frequently occurring coastal polynya in the Terra Nova Bay (TNB), Ross Sea (Antarctica). The potential of a new methodology for estimating the variability of this polynya through MODIS TIR during the 2010 and 2011 freezing season (April to October) is presented and discussed. The polynya is observed in more than 1600 radiance scenes, after a preliminary filter evaluates and discards cloudy and fog-contaminated scenes. This reduces the useful MODIS swaths to about 50% of the available acquisitions, but a revisit time of less than 24 h is kept for about 90% of the study period. As expected, results show a high interannual variability with an opening/closing fluctuation clearly depending on the regime of the katabatic winds recorded by the automatic weather stations Rita and Eneide along the TNB coast. Retrievals are also validated through a comparison with a set of 196 co-located high-resolution ENVISAT ASAR images. Although our estimations slightly underestimate the ASAR derived extents, a good agreement is found, the linear correlation reaching 0.75 and the average relative error being about 6%. Finally, a sensitivity test on the applied thermal thresholds supports the effectiveness of our setting.

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Section: Discussionsupporting

confidence: 89%

Section: Terra Nova Bay Polynya Variability During Wintertime 2010 Ansupporting

confidence: 82%

Section: The Polynya Extent Estimation Techniquesupporting

confidence: 59%