Oahu Hawaii
915 of 1114

Oahu, Hawaii

January 17, 2006
This image shows an area, 56.5 km wide by 40.7 km long, covering the southern part of Oahu Island, the commercial center of Hawaii.

Oahu Island is home of the state capital, Honolulu, the worlds most famous beach, Waikiki and it is important to United States defense in the Pacific due to the presence of Pearl Harbor naval base.

The image results from a color composite where the red channel contains the VV polarized image, the green channel contains the VH polarized image and the blue channel contains the difference between the amplitude in VV and VH. The green color that dominates the image results from the extensive vegetation of the island (high VH backscatter due to volume scattering). Smooth surfaces, such as bare soils or area with low vegetation, appear in purplish tones.

The Koolau Range mountains chain runs from north to south on the east side of the island separating with sharp cliffs windward Oahu from the rest of the island. Shadow areas in the image created by the Koolau mountains are particularly large due to the high elevation angle in IS7 beam (approximately 40 deg.).

Pearl Harbor, marked by several inlets and bays, can be seen in the center of the image, with a large fleet of boats in the west side of the harbor. Runways of three airports are clearly visible, the Kalaeloa Airport (the former Barbers Point Naval Air Station) in cross form on the southwest coast, the Kaneohe Marine Corps airport on the east coast and the international airport on the southeast of Pearl Harbor. The cities appear in magenta and yellow tones depending whether they are densely populated (low VH backscatter) or not (equally high backscatter in VV and VH).

The principal cities are Kapolei seen in magenta color on the southwest coast, Honolulu on the east of the international airport and Waikiki further east, backed by the famous Diamond Head, an extinct volcano. On the other hand, the volcanically formed Hawaiian Islands are standing tall in the middle of the Pacific, in the path of the steady trade winds. When these westward winds encounter the islands, they are forced to split, creating areas of weak winds behind the islands (appear as black tones in the west side of Oahu) and strong winds (magenta-purple tones, high VV backscatter) on the islands flanks.

Technical Information:
  • Satellite: Envisat
  • Instrument: ASAR
  • Acquisition: 12-Apr-2003
  • Orbit nr: 05830
  • Center coordinates: lat. 21.45, lon. -157.95

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