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Rao, V. V.
- Understanding Relationship between Melt/Freeze Conditions Derived from Spaceborne Scatterometer and Field Observations at Larsemann Hills, East Antarctica during Austral Summer 2015-16
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PDF Views:77
Authors
Affiliations
1 National Remote Sensing Centre (ISRO), Hyderabad 500 037, IN
2 Indian Institute of Space Science and Technology, Thiruvananthapuram 695 547, IN
1 National Remote Sensing Centre (ISRO), Hyderabad 500 037, IN
2 Indian Institute of Space Science and Technology, Thiruvananthapuram 695 547, IN
Source
Current Science, Vol 113, No 04 (2017), Pagination: 733-742Abstract
Snow fork and ground penetrating radar at 200 MHz were used for snow depth, wetness and density measurements towards understanding the relationship between melt/freeze conditions derived from spaceborne Advance Scatterometer (ASCAT) and Oceansat-2 Scatterometer (OSCAT), and field observations. The observations were acquired at Larsemann Hills, East Antarctica in austral summer of 2015-16 during the 35th Indian Scientific Expedition to Antarctica. The field observations of wetness correlated well with identified dry and percolation zones showcasing different behaviours of density and wetness. Ice firn was observed at 50-55 cm depth, even in dry zone. Melt onset and number of melt days based on ASCAT varied spatially and temporally over the years and correlated well with positive degree day (PDD) for automatic weather station data located at the Indian Antarctic station, Bharati. Backscatter measurements by OSCAT showed that winter backscatter reduced with accumulation for both dry and percolation zones, but increased in the later part of winter in the percolation zone. A positive but low correlation was observed between ASCAT backscatter to accumulation and the surface mass balance from regional atmospheric climate model (RACMO2.3). A high correlation of 0.78 was observed between reduction in backscatter due to liquid water content and PDD, which coincides with field observations of wetness. The observations serve as baseline to monitor melt conditions and stability of existing ice sheet.Keywords
Ground Penetrating Radar, Ice Firn, Snow-Fork, Scatterometer, Snowpack Characteristics.Full Text
References
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- Assessment of Colour Changes in Lonar Lake, Buldhana District, Maharashtra, India using Remote Sensing Data
Abstract Views :190 |
PDF Views:91
Authors
Affiliations
1 National Remote Sensing Centre, Indian Space Research Organisation, Hyderabad 500 037, IN
1 National Remote Sensing Centre, Indian Space Research Organisation, Hyderabad 500 037, IN
Source
Current Science, Vol 120, No 1 (2021), Pagination: 220-226Abstract
This communication presents results of a preliminary study to understand and assess the colour changes in Lonar lake, Buldhana district, Maharashtra, India, using remote sensing data of recent years (2019 and 2020). In addition, the study has utilized IMD gridded weather data and spectral profiles of algal pigments from the published literature. In order to verify whether the colour change is a cyclic event, long-term satellite data of Landsat 8-OLI and Sentinel 2-MSI sensors from 2014 onwards were analysed using spectral response in red and green bands. It was observed that even though a cyclic pattern exists, the colour change events occurred only during the 2019 and 2020 periods. The present analysis showed a change in colour of the lake from green to brown twice during April–June 2019. However, in 2020, there was a change in colour of the lake from green to brown and eventually to pinkish-red, which was not observed earlier. Rainfall and temperature were used to identify possible causes of abiotic stress on algae population of the lake. The study observed light rainfall and reduction in temperature just prior to the colour change event during both the years. In the absence of field data, the published literature on absorption spectra of different algal pigments was reviewed to identify pigments causing brown- and red-coloured appearance of the lake. Though cause of stress on the algae population is not known and is to be precisely identified by field surveys, the change in colour of Lonar lake appears to be caused by pigment(s), like phycoerythrin and carotenoids. However, this needs to be verified in the ground through water quality analysis.Keywords
Colour Changes, Lake Water, Pigments, Remote Sensing, Water Quality Analysis.Full Text
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