Microwave and Millimetre Wave Radar and Imaging
Generation and Validation of Digital Elevation Model using ERS - SAR Interferometry Remote Sensing Data
by Vinay Sehgal
SHELTON PADUA, VINAY K. SEHGAL, K.S. SUNDARA SARMA
Jour. Agric. Physics, Vol. 7, pp. 8-13 (2007)
Topographic information of landmass is very important in many scientific disciplines and military and industrial... more Topographic information of landmass is very important in many scientific disciplines and military and industrial sectors. Radar Interferometry with Synthetic Aperture Radar (SAR) is considered to be one of the most modern techniques for acquiring topographic information. A study was conducted using ERS-1/2 SAR tandem data to generate the Digital Elevation Model (DEM) of a part of Sind river basin, Madhya Pradesh. The performance of mapping procedure was ascertained by checking the altitude of obvious features with conventional topographic maps. When the checkpoints were taken from Survey of India(SOI) toposheet, a root mean square error (RMSE) of 2.7m was obtained. The elevation accuracy was also found to be associated with the land cover type of the area.
Download (.pdf) A Marine Radar Wind Sensor
Journal of Atmospheric and Oceanic Technology, 1629–1642, 2007; Heiko Dankert and Jochen Horstmann
A new method for retrieving the wind vector from radar-image sequences is presented. This method, called WiRAR, uses a... more A new method for retrieving the wind vector from radar-image sequences is presented. This method, called WiRAR, uses a marine X-band radar to analyze the backscatter of the ocean surface in space and time with respect to surface winds. Wind direction is found using wind-induced streaks, which are very well aligned with the mean surface wind direction and have a typical spacing above 50 m. Wind speeds are derived using a neural network by parameterizing the relationship between the wind vector and the normalized radar cross section (NRCS). To improve performance, it is also considered how the NRCS depends on sea state and atmospheric parameters such as air–sea temperature and humidity. Since the signal-to-noise ratio in the radar sequences is directly related to the significant wave height, this ratio is used to obtain sea state parameters. All radar datasets were acquired in the German Bight of the North Sea from the research platform FINO-I, which provides environmental data such as wind measurements at different heights, sea state, air–sea temperatures, humidity, and other meteorological and oceanographic parameters. The radar-image sequences were recorded by a marine X-band radar installed aboard FINO-I, which operates at grazing incidence and horizontal polarization in transmit and receive. For validation WiRAR is applied to the radar data and compared to the in situ wind measurements from FINO-I. The comparison of wind directions resulted in a correlation coefficient of 0.99 with a standard deviation of 12.8°, and that of wind speeds resulted in a correlation coefficient of 0.99 with a standard deviation of 0.41 m s−1. In contrast to traditional offshore wind sensors, the retrieval of the wind vector from the NRCS of the ocean surface makes the system independent of the sensors’ motion and installation height as well as the effects due to platform-induced turbulence.