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Seen from Space 2008

"The Gathering Place" in the Pacific, Oahu Island, Hawaii

  The Hawaiian Islands are located in the middle of the vast Pacific Ocean between Kure Atoll at latitude 28.5°N and the Island of Hawaii at 19°N. This archipelago consists of 137 islands, islets, and atolls. It extends some 2,450km in a gentle arc and represents the exposed peaks of the great undersea volcanic mountain range known as the Hawaiian-Emperor seamount chain. Magma erupted from cracks on the seabed and piled up over many years from 40 million to 25 million years ago. According to the plate tectonics theory, the chain of islands formed as the Pacific Plate moved slowly northwestward over a hotspot in the Earth's mantle at about 5 to 7.5cm per year. Oahu (Oʻahu in Hawaiian) has moved 354km westward from the place it was born.

Fig. 1. Oahu
Figure 1 depicts Oahu (west end of the island was not captured) in the State of Hawaii. It is the third largest island (1,545 km2) in the Hawaiian Islands. Koolau Mountain Range and Waianae Mountain Range run north and south on the east and west sides of the island, and the central plain extends between the two ranges. Pearl Harbor is visible in the innermost cove located at the south of the plain. The air gateway to the Hawaiian Islands, Honolulu International Airport, is visible to the east of the mouth of the bay, and beyond, the grayish downtown area extends from Honolulu Harbor (the sea gateway) to Waikiki Beach and Diamond Head.

Hawaii became the 50th state of the United States in 1959. The present population of Hawaii is 1.2 million of which 75% lives in Oahu and half of them live in Honolulu. Honolulu is the state capital and the largest city in Hawaii. The administrative area of Oahu extends up to Kure Atoll 2,253 km to the northwest, including islets and atolls (except Midway), which compose Honolulu City and Honolulu territory. Accordingly, Honolulu is the 11th largest city in the United States.

Whitecaps breaking on the beach are visible on the northern coast of the island. This is the famous "North Shore" where big waves, sometimes more than 15 m high, constantly crash ashore in winter, and many surfing events take place each year. The low-pressure area spawned during the Siberian winter creates big waves as it moves from Japan to the Aleutian Islands, and the waves travel all the way to the Hawaiian archipelago. Haleiwa Town in the center of the North Shore is always crowded with surfers and is where many Japanese immigrants settled and worked in the sugarcane and pineapple fields. Many shops and stores with Japanese signboards can be seen there.

Japanese immigration to Hawaii began in 1868 during the Meiji Restoration, according to a treaty between the Japanese government and the former Hawaiian government. From 1885 (the year when government-promoted immigration began) to 1894 (the year when the Republic of Hawaii was proclaimed), 29,000 Japanese settled in Hawaii. Private sector immigration continued until 1900 when Hawaii became a territory of the United States. There were 35,000 emigrants at that time, representing 40% of the total population of Hawaii. Until the blanket ban of immigration in 1924, it is estimated that 61,000 Japanese emigrants crossed the sea.

There are many cliffs on eastern Oahu where the Koolau Mountain Range pushes out to the sea. Easterly wet trade winds carry much rainfall to the mountain sides and create a rich flora of green vegetation. The ranch in a deep gorge in the Koolau Mountain Range, on the north of Kaneohe Bay on the east coast, is where the films "Jurassic Park" and "Godzilla" were shot.

Fig. 2. Vicinity of Honolulu
Oahu Island, Hawaii (kmz, 4.00MB, Low Resolution) as seen on Google Earth.
Figure 2 presents a close-up image of central Honolulu and its vicinity. The runway visible on the left of the figure is the Honolulu International Airport, and Honolulu Harbor is located to its east. The circular geological features visible at the center and at the lower right of the figure are the Punchbowl National Memorial Cemetery and Hawaii's symbolic Diamond Head, which are tuff hills made by volcanic ash deposit. Colonel Ellison Onizuka, NASA's Japanese-American astronaut from Hawaii, who died during the destruction of the Space Shuttle Challenger in 1986, was buried at Punchbowl.
Diamond Head is a rim of a beautiful 1,200-m-diameter conical volcanic crater. Kapiolani Park, named after the beloved wife of King Kamehameha, is located on the beach on the west of Diamond Head. To its west, is Waikiki, surrounded by Ala Wai Canal and beaches.

Photo. Vicinity of Waikiki
Buildings and hotels cluster on the flat land that extends about 3 km from Waikiki Beach to the foot of the Koolau Mountain Range. Residential houses climb up the slopes of the mountain, which faces the beach. A panoramic grand view of Diamond Head, Waikiki and the International Airport can be observed from the Tantalus Hill east of Punchbowl. The picture looking in the direction of Waikiki was taken from Tantalus Hill.



Explanation of the Images:


(Click the images twice to enlarge.)
Satellite: Advanced Land-Observing Satellite (ALOS) (Daichi)
Sensor: Advanced Visible and Near Infrared Radiometer-2 (AVNIR-2) (Figs. 1 and 3), and
Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM)(Fig. 2)
Date: 2113 (UTC) on December 23, 2006 (AVNIR-2), and 2112 (UTC) on August 7, 2006 (PRISM)
Ground resolution: 10m (AVNIR-2) and 2.5m (PRISM)
Map Projection: Universal Transversal Mercator (UTM)
Figs. 1 .
AVNIR-2 has four observation bands. The composite images are usually produced by assigning red to Band 3 (610 to 690nm), green to Band 2 (520 to 600nm), and blue to Band 1 (420 to 500nm). In Fig. 1, green is assigned to the sum of 90% of Band 2 and 10% of Band 4 (760 to 890nm), which improves the visibility of vegetation. The resulting image has natural coloring as if seen by the naked eye. Thus, the following colors designate ground objects.

Green: Forests
Light green: Farmland, grass fields or golf courses
Grey: City area or roads
Reddish brown: Harvested fields or bare land
Blue: Water surfaces

Figs. 2.
PRISM is an optical sensor for observing ground surfaces with visible and near-infrared signals in the 520 to 770 nano-meter (one-billionth of a meter) band. The acquired image is monochrome. PRISM has three independent optical systems (telescopes) to acquire images for nadir, forward, and backward views at the same time. Only the nadir image was used in this article.
The above AVNIR-2 composite image was then transformed into hue, saturation and intensity, and the intensity was replaced by the PRISM image. The hue, saturation and intensity data were then reversed into a color image. As a result, a virtual 2.5-m ground-resolution color image was obtained. This kind of high-resolution color image, composed by combining the higher resolution monochrome image and the lower resolution color image, is called a pan-sharpened image.

Related Sites:
ALOS Research and Application Page
A Cluster of Observatories on Volcanoes: The Island of Hawaii
JERS-1: Earth Visitors Guide: Hawaii (Mt. Mauna Loa)
Land, Seen from Space
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