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Jayaprasad, P.

Breaking of Larsen C from Antarctica

Abstract Views :442 | PDF Views:108

Authors

P. Jayaprasad ¹, Touseef Ahmad ¹, Saroj Maity ¹, Arundhati Misra ¹

Affiliations
1 Advanced Microwave and Hyperspectral Technique Development Group, Earth, Ocean, Atmosphere, Planetary Sciences and Applications Area, Space Applications Centre, ISRO, Ahmedabad 380 015, IN

Source

Current Science, Vol 114, No 05 (2018), Pagination: 961-962

Abstract

A huge portion of the Larsen C ice shelf (~50,000 km²) in Antarctic Peninsula calved away to an iceberg of area ~6,200 km² between 10 and 12 July 2017. Larsen C is the fourth largest ice shelf in Antarctica, after Filchner-Ronne, Ross and Amery ice shelves. Unusual rift propagation at Larsen C ice shelf has excited the scientific community during the last six months. The calved area is ~1.6 times the area of Goa and ~4 times the area of Delhi.

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References

Cook, A. J. and Vaughan, D. G., Cryosphere, 2010, 4(1), 77–98.

Khazendar, A., Rignot, E. and Larour, E., Geophys. Res. Lett., 2012, 38, L09502; doi:10.1029/2011GL046775.

McGrath Daniel, Konrad Steffen, Ted Scambos, Harihar Rajaram, Gino Casassa and Jose Luis Rodriguez Lagos, Ann. Glaciol., 2012, 58(60); doi:10.3189/2012AoG60A005.

Mueller, R. D., Padman, L., Dinniman, M. S., Erofeeva, S. Y., Fricker, H. A. and King, M. A., J. Geophys. Res., 2012, 117, C05005; doi:10.1029/2011JC0 07263.

Assessment of Cryospheric Parameters Over the Himalaya and Antarctic Regions using SCATSAT-1 Enhanced Resolution Data

Abstract Views :245 | PDF Views:78

Authors

Sandip R. Oza ¹, Rajashree V. Bothale ², D. Ram Rajak ¹, P. Jayaprasad ¹, Saroj Maity ¹, Praveen K. Thakur ³, Naveen Tripathi ¹, Arpit Chouksey ³, I. M. Bahuguna ¹

Affiliations
1 Space Applications Centre, ISRO, Ahmedabad 380 015, IN
2 National Remote Sensing Centre, ISRO, Hyderabad 500 037, IN
3 Indian Institute of Remote Sensing, ISRO, Dehradun 248 001, IN

Source

Current Science, Vol 117, No 6 (2019), Pagination: 1002-1013

Abstract

Antarctica is the focus of scientific studies considering the largest reservoir of terrestrial water in the form of ice and doubling of ice area during winter due to sea-ice growth. The third pole – Himalaya is equally important due to the large extent of snow and ice cover outside the polar regions, which is a major source of water for the Asian countries. At present, the Ku-band scatterometer observing global cryosphere is the SCATSAT-1 launched by India. This article describes the study carried out on different cryospheric parameters using high-resolution (~2.2 km) scatterometer data in the Antarctica and Himalaya. Impact of seasonal variations in snow/ice and ice calving on the backscatter over Antarctica is discussed in detail. A procedure developed for the estimation of sea-ice extent, which yielded overall accuracy of 89%, has been presented and successfully applied for daily monitoring of the Antarctic ice extent for 2017. Surface melting using backscatter and brightness temperature data has been discussed and the contrast between large-sized and small-sized Antarctic ice shelves during the austral summer period of summer 2017–18 is highlighted. The higher average surface melt observed around majority of east Antarctic ice shelves, particularly near the Indian station ‘Maitri’, is of particular interest. Typical surface melting patterns observed over the third largest Antarctic ice shelf, Amery, are discussed in detail. Over northwest Himalaya, derived changes in snow water equivalent (ΔSWE) shows a good correlation between observed and calculated SWE variations. The present study demonstrates that simultaneous availability of high-resolution brightness temperature and backscatter data from SCATSAT-1 provides a unique opportunity to study the polar and mountain cryosphere.

Keywords

Calving, Scatterometer, Sea-ice, Snow Water Equivalent, Surface Melt.

Full Text

References

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Changes in Antarctic Ice-Shelf Margins between 1997 and 2019 using Sentinel and Radarsat Data

Extraction of Antarctic Ice Features Using Hybrid Polarimetric RISAT-1 SAR Data

Abstract Views :81 | PDF Views:59

Authors

Esha Shah ¹, P. Jayaprasad ², Raghav Mehra ², Deepak Putrevu ², Arundhati Misra ², M. E. James ¹

Affiliations
1 Physics Department, Gujarat University, Ahmedabad 380 009, IN
2 Space Applications Centre, Ahmedabad 380 015, IN

Source

Current Science, Vol 124, No 12 (2023), Pagination: 1445-1453

Abstract

Compact polarimetry has gained popularity due to its advantages, such as larger swath, simple architecture and low power consumption. The backscattered signal and scattering decomposition vary for different targets based on their electrical, geometrical and structural properties. As of now, the potential of hybrid polarimetric synthetic aperture radar (SAR) data for exploring Antarctic ice features is not fully explored. Here, we present a comprehensive polarimetric feature analysis and classification results of the hybrid polarimetric dataset acquired by RISAT-1 near the Indian Antarctic research station Maitri. The single-look complex images have been subjected to polarimetric data processing for extracting Antarctic ice features using POLSARPRO software. The polarimetric coherence matrix is generated and then filtered to eliminate speckles. Raney m–χ decomposition technique has been utilized to understand the scattering mechanism of the targets. The decomposed RGB image is classified using Wishart-supervised classification, and classification accuracy is assessed using a confusion matrix. It is found that the comparatively simple hybrid polarimetric SAR provides sufficient information to detect and discriminate various Antarctic ice features. Features such as rifts, ice–rises, ice shelves and icebergs are clearly discriminated using Wishart-supervised classification. It is also found that the overall accuracy of the classification of study areas varies between 80% and 97%, suggesting a good classification outcome.

Keywords

Classification Accuracy, Confusion Matrix, Hybrid Polarimetry, Ice Features, m–χ Decomposition, Synthetic Aperture Radar Data.

Full Text

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