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Summary of Proposal LAN0122

TitleSnow and Glacier Characteristics and Interferometry studies of Gangotri glacier region using TERRA SAR-X
Investigator Venkataraman, Gopalan - Indian Institute of Technology, Bombay, Centre of studies in Resource Engineering
Team Members
Sr. Research Scienit Rao, Y. S - Indian Institute of Technology Bombay, Centre of studies in resource engineering
Asst. Director Snehmani, A - Snow and Avalanche Study Establishment, DRDO
Summary The proposed study will form part of the ongoing project)2005 may-2008 may)sponsored by Dept. of science and Technology,Govt. of India.Wherein ENVISAT ASAR data is being used.Hence the proposed study will be supplementing the results to be obtained for this project.The study area will be (1)Gangotri glacier region,Uttarkashi District,Uttaranchal state,India. (2)Manali-Dhundi region,Kulu District,Himachal Pradesh state,India.We proposed to use the X-Band SAR data for the first two objectives relating to the 1st test site and the 3rd objective relating to 2nd test site. Objectives: (1)Multi temporal SAR data analysis and interpretation to delineate distinct zones and glacier facies. (2)SAR Interferometry technique to decipher the movement of glacier during the period of observation. (3)To evaluate the dual polarization data for estimating snow pack characteristics like density, thickness,wetness and particle size.Further the data will be evaluated for mapping snow cover and identification of different snow types like wet snow,moist snow,dry snow,fresh snow and dirty snow. Methodology: Multi temporal SAR data of early summer,late summer and winter seasons will be used to generate composite.This composite will be used for mapping different facies of Gangotri glacier. This methodology is based on the principle that different zones have typical backscatter signatures related to the snow pack characteristics influenced by the balance of accumulation and melt at different altitudes.In addition to the composite the backscatter coefficient value along with corressponding elevation data will be extracted for various glacier zones in all three SAR images .The analysis and plotting of these values and the interpretation of the combined SAR composit help in delineation of various glacier zones. Differential SAR interferometry technique is useful to measure the movement of glaciers and ice sheets.The concept of differential SAR interferometry technique involves the use of two or threepasses of data to generate interferograms.When we use two passes of data we will require the DEM of the study area derived through other means.When we use data of 3 satellite passes,one interferogram is generated using passes 1&2 and another interferogram is generated using passes 1&3(or passes 2&3)as the case may be. These two interferograms are differenced to give rise to differential interferograms.This differential interferogram represents the movement of the glacier during the period of observation. With the help of dual polarization data,we will try to map the snow cover and thus assess the capabilities of different polarization for snow cover mapping we will assess the capabilities of VV,HH,HV and VH polarization for discriminating different types of snow as well.With the help of collection of data relating to snow wetness,snow density,snow thickness and grain size we will attempt to develop empirical models for estimating snow pack characteristics. Data requirements:We will require different data types for different objectives.For glacier zone mapping we will require data in image mode scanSAR data with incidence angle more than 30deg and less than 50deg.For Interferometry work we will require single look complex data of ascending and descending passes(separately)with incidence angle more than 30deg and less than 50deg.For snow cover mapping and to study snow pack characteristics. we will require single as well as dual polarization with incidence angle more than 30deg and less than 50deg. The deliverable will include: 1.Glacier facies map of Gangotri glacier. 2.Gangotri glacier movement estimation during the period of observation. 3.Snow cover map and development of empirical models to estimate snow pack characteristics of Manali-Dhundi region.

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