Appendix D 

 Iceberg Reconnaissance Using ENVISAT 



LTJG Nicolas A. Jarboe 



Introduction 



Using satellite-borne sensors to locate icebergs has interested the International Ice Patrol (HP) 

 since the first weather satellite was put in orbit in 1960. The first satellites could detect large 

 cloud systems, but it was not until the 1972 launch of the Earth Resources Technology Satellite 

 that IIP started to consider satellite imagery for iceberg detection. With a spatial resolution of 

 approximately 80 meters, this visual sensor could detect sea ice as well as medium and large 

 icebergs, but could not see through fog and clouds. Consequently, IIP did not use this system for 

 iceberg reconnaissance. In 1975, an internal assessment was conducted on remote sensing as it 

 applied to IIP. That report (Super & Osmer, 1975) expressed HP's interest in using satellites to 

 perform its mission; thus, IIP eagerly awaited the projected 1978 launch of the ocean monitoring 

 satellite SEASAT-A, which had an L-band synthetic-aperture radar with 25-meter resolution. 

 However, SEASAT's three-and-a-half-month lifetime prevented the sensor from realizing its 

 promise. 



In early 1996. IIP began considering satellites for operational iceberg reconnaissance by testing 

 the target detection capability of the Canadian satellite RADARSAT. RADARSAT has a 

 synthetic-aperture radar with a C-band horizontal-polarization microwave radar instrument that 

 can gather ocean-surface data day or night and is virtually unaffected by fog or weather. In July 

 of 1997, IIP conducted a validation flight of RADARSAT data to determine the satellite's ability 

 to detect icebergs. This study concluded that RADARSAT could detect targets 15 meters or 

 greater, but it could not classify targets or distinguish between an iceberg and a ship; furthermore, 

 the satellite imagery was very costly (Andrews, 1997). Fortunately, however, the European Space 

 Agency's satellite, ENVISAT— an advanced synthetic aperture radar (ASAR) capable of dual 

 polarization — was launched in 2002 and has the potential to distinguish between icebergs and 

 ships. 



During the 2003 and 2004 ice seasons, IIP participated in the Global Monitoring for Environment 

 and Security program, which was sponsored by the European Space Agency and European 

 Commission. Ice Patrol was an end user of ice products from the Northern View team, which was 

 led by the Newfoundland-based organization C-CORE. Ice Patrol cooperated with C-CORE to 

 evaluate ENVISAT's ability to detect and classify targets on the ocean's surface. ENVISAT 

 ASAR is a C-band active-microwave radar that possesses dual alternating polarization in both HH 

 and HV modes. ENVISAT ASAR has various incident-swath (IS) modes ranging from ISl 

 through IS7. Table 1 shows the incidence angle and swath width for each IS mode. IS4 through 

 IS7 modes at 30-meter resolution are suitable for iceberg detection; however, the probability of 

 target detection increases in IS6 and IS7 modes, which are recommended for iceberg detection 

 (Lane, Randell, Youden, & Power, 2003). 



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