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Putrevu, Deepak
- L- and S-band Polarimetric Synthetic Aperture Radar on Chandrayaan-2 Mission
Abstract Views :261 |
PDF Views:99
Authors
Deepak Putrevu
1,
Sanjay Trivedi
1,
Anup Das
1,
Dharmendra Pandey
1,
Priyanka Mehrotra
1,
S. K. Garg
1,
Venkata Reddy
1,
Shalini Gangele
1,
Himanshu Patel
1,
Devendra Sharma
1,
R. Sijwali
1,
Nikhil Pandya
1,
Amit Shukla
1,
Gaurav Seth
1,
V. M. Ramanujam
1,
Raj Kumar
1
Affiliations
1 Space Applications Centre, Ahmedabad 380 015, IN
1 Space Applications Centre, Ahmedabad 380 015, IN
Source
Current Science, Vol 118, No 2 (2020), Pagination: 226-233Abstract
Dual-frequency Synthetic Aperture Radar (SAR) operating in L- and S-band frequencies is one of the primary payloads of the Chandrayaan-2 orbiter. This payload with the capability of imaging in dual frequency (L-band: 24 cm wavelength and S-band: 12 cm wavelength) with full polarimetric mode aims for unambiguous detection, characterization and quantitative estimation of water-ice in permanently shadowed regions over the lunar poles. The payload will address the ambiguities in interpreting high values of circular polarization ratio associated with water-ice observed during previous missions to the Moon through imaging in dual-frequency fully polarimetric SAR mode. Various improved system features such as wide range of resolutions and incidence angles, synchronized Land S-band operations, radiometer mode, are built into the instrument to meet the required science objectives, adhering to stringent mission requirements of low mass, power and data rates. Major scientific objectives of dual-frequency polarimetric SAR payload are: unambiguous detection and quantitative estimation of lunar polar water-ice; estimation of lunar regolith dielectric constant and surface roughness; mapping of lunar geological/morphological features and polar crater floors at high-resolution, and regional- scale mapping of regolith thickness and distribution.Keywords
Circular Polarization Ratio, Dual Frequency, Lunar Polar Water-ice, Synthetic Aperture Radar.Full Text
References
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- Mohan, S., Das, A. and Chakraborty, M., Investigation of polarimetric properties of lunar surface using Mini-SAR data. Curr. Sci., 2011, 101(2), 159–164.
- Mohan, S., Saran, S. and Das, A., Scattering mechanism-based algorithm for improved mapping of water-ice deposits in the lunar polar regions. Curr. Sci., 2013, 105(11), 1579–1587.
- Pieters, C. M. et al., Character and spatial distribution of OH/H2O on the surface of the Moon seen by M3 on Chandrayaan-1, Science, 2009, 326, 568–572.
- Spudis, P. D. et al., Evidence for water ice on the Moon: results for anomalous polar craters from the LRO Mini‐RF imaging radar, J. Geophys. Res.: Planets, 2013, 118, 2016–2029.
- Mishra, P., Kumar, S. and Singh, D., An approach for finding possible presence of water ice deposits on Lunar craters using MiniSAR data. IEEE J. Sel. Topics Appl. Earth Obs. Remote Sensing, 2015, 8(1), 30–38.
- Fa, W., Wieczorek, M. A. and Heggy, E., Modeling polarimetric radar scattering from the lunar surface: study on the effect of physical properties of the regolith layer. J. Geophys. Res., 2011, 116, E03005; doi:10.1029/2010JE003649.
- Pandey, D., Saran, S., Das, A. and Chakraborty, M., A simplistic approach to model radar backscatter from lunar regolith. In 44th Lunar and Planetary Science Conference (LPSC), Abstr. 1941, 2013.
- Pandey, D., Das, A., Saran, S. and Chakraborty, M., Scattering characteristics of lunar regolith with respect to dual-frequency SAR: preliminary simulation results. In LPSC XLIV, Abstr. 126, 2013.
- Putrevu, D., Das, A., Vachhani, J. G., Trivedi, S. and Misra, T., Chandrayaan-2 Dual-frequency SAR: further investigation into lunar water and regolith. Adv. Space Res., 2016, 57, 627–646.
- Campbell, B. A., Grant, J. A. and Maxwell, T., Radar penetration in Mars analog environments. In LPSC XXXIII, Abstr. #1616, 2002.
- Bell, W. S., Thomson, B. J., Dyar, M. D., Neish, C. D., Cahill, J. T. S. and Bussey, D. B. J., Dating small fresh lunar craters with Mini-RF radar observations of ejecta blankets. J. Geophys. Res., 2012, 117, E00h30.
- Desai J. Ami, Mohan, S. and Murty, S. V. S., Impact ejecta characterization for small-sized fresh and degraded lunar craters using radar data. Curr. Sci., 2016, 110(10), 1929–1938.
- Raney, R. K., Hybrid-polarity SAR architecture. IEEE Trans. Geosci. Remote Sensing, 2007, 45, 3397–3404.
- Chan, Y. K., Chung, B. K. and Chuah, H. T., Transmitter and receiver design of an experimental airborne synthetic aperture radar sensor. Progress. Electromagn. Res., 2004, 49, 203–218.
- Vijayan, S., Mohan, S. and Murty, S. V. S., Lunar regolith thickness estimation using dual frequency microwave brightness temperature and influence of vertical variation of FeO + TiO2. Planet. Space Sci., 2015, 105, 123–132.
- Changes in Antarctic Ice-Shelf Margins between 1997 and 2019 using Sentinel and Radarsat Data
Abstract Views :223 |
PDF Views:76
Authors
Affiliations
1 Physics Department, Gujarat University, Ahmedabad 380 009, IN
2 Space Applications Centre (ISRO), Ahmedabad 380 015, IN
1 Physics Department, Gujarat University, Ahmedabad 380 009, IN
2 Space Applications Centre (ISRO), Ahmedabad 380 015, IN
Source
Current Science, Vol 119, No 10 (2020), Pagination: 1633-1640Abstract
We have monitored the changes that have occurred over nine Antarctic ice shelves between 1997 and 2019 using Sentinel-1 and RADARSAT-1 images of Antarctica using change detection technique. The net loss of Antarctic ice shelves during the period was about 14,723 sq. km in surface area, corresponding to 1.21% area of ice shelves. The Ross and Filchner–Ronne ice shelves retreated significantly in terms of total area, while shelves in that Antarctic Peninsula, namely Wilkins and Larsen C retreated drastically in terms of percentage change.Keywords
Climate Change, Change Detection, Satellite, Ice-shelf Calving, Remote Sensing.Full Text
- Extraction of Antarctic Ice Features Using Hybrid Polarimetric RISAT-1 SAR Data
Abstract Views :81 |
PDF Views:59
Authors
Affiliations
1 Physics Department, Gujarat University, Ahmedabad 380 009, IN
2 Space Applications Centre, Ahmedabad 380 015, IN
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: 1445-1453Abstract
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
References
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- Dabboor, M. and Geldsetzer, T., On the classification of sea ice types using simulated Radarsat Constellation Mission (RCM) compact polarimetric SAR parameters. In Proceedings of the ASPRS 2014 Annual Conference, Louisville, Kentucky, USA, 2014, pp. 23–28.
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- Sabry, R. and Vachon, P. W., Advanced polarimetric synthetic aperture radar (SAR) and electro-optical (EO) data fusion through unified coherent formulation of the scattered EM field. Prog. Electromagn. Res., 2008, 84, 189–203.
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- Raney, R. K., Synthetic aperture radar hybrid-quadrature-polarity method and architecture for obtaining the stokes parameters of radar backscatter. US Patent 8,258,996, 2012.
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