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Archive for December, 2009

Volcanoes of La Réunion – December 31st, 2009

20.9S 55.4E

December 31st, 2009 Category: Image of the day, Volcanoes

La Réunion - December 11th, 2009

La Réunion - December 11th, 2009

This orthorectified image portrays the island of La Reunion, which is 63 kilometres (39 mi) long, 45 kilometres (28 mi) wide, and covers 2,512 square kilometres (970 sq mi). It is similar to the island of Hawaii insofar as both are located above hotspots in the Earth’s crust.

On the eastern end of the island, the Piton de la Fournaise shield volcano rises to more than 2,631 metres (8,630 ft) above sea level. It is sometimes considered a sister to Hawaiian volcanoes because of the similarity of climate and volcanic nature. The volcano is very active, having erupted more than 100 times since 1640, and is thus monitored constantly.

Another volcano, the Piton des Neiges is located northwest of the Piton de la Fournaise. It is the highest point on the island at 3,070 metres (10,100 ft) above sea level. Collapsed calderas and canyons can also be observed southwest of the mountain. Unlike its active neighbor, the Piton des Neiges is extinct.

Vegetation Index of Southeastern Coastal USA

35.2N 80.8W

December 31st, 2009 Category: Climate Change

USA - December 20th, 2009

USA - December 20th, 2009

This FAPAR image shows the Fraction of Absorbed Photosynthetically Active Radiation of the east coast of the  southern USA, including the states of (from top to bottom) Virginia, North Carolina, South Carolina, Georgia and Florida.

In FAPAR images, the color spectrum over land runs from red (1.0), to green, to yellow and white (0.0). Here, most of the land visible is light green, indicating good to average photosynthetic activity. The land in Florida appears slightly darker green than that in the other states, indicating a somewhat higher vegetation index.

Phytoplankton in Nutrient-Rich Waters of the Bay of Arguin, Mauritania

19.7N 16.4W

December 31st, 2009 Category: Phytoplankton

Mauritania - December 16th, 2009

Mauritania - December 16th, 2009

The Bay of Arguin, or Banc d’Arguin, is a bay on the Atlantic shore of Mauritania. It is south of Cap Blanc, north of Cap Timiris, and contains the islands of Arguin (above center) and Tidra (below). The bay also contains the 12,000 km² Banc d’Arguin National Park. Here, its waters appear greenish due to nutrient-rich offshore waters teeming with phytoplankton.

The bay is an area of shallow water and tidal flats between the Sahara and the upwelling system off the Mauritanian coast. Hydrographically the Banc d’Arguin can be characterized as a large-scale negative estuary with higher salinities near the shore. It is concluded that ultimately the Banc d’Arguin ecosystem is fueled by nutrients and organic matter derived from the upwelling area.

The inner part of the Banc d’Arguin system is dominated by a detritus-based benthic foodweb in which seagrasses are the principal primary producers. Little of the seagrass production seems to be exported to other parts of the system or other areas. Zooplankton and zoobenthos biomasses are relatively low, but nevertheless support high densities of consumers. Aquatic birds are especially numerous.

Sari and the Alborz Mountains, Northern Iran

36.5N 53.0E

December 31st, 2009 Category: Snapshots

Iran - December 14th, 2009

Iran - December 14th, 2009

This orthorectified image stretches from the southern coast of the Caspian Sea to the northern slopes of the Alborz Mountains in Iran. The large white patch is the city of Sari, the provincial capital of Mazandaran. Its population is estimated to be 261,293, as of 2006, and it has a land area of 5,089 square kilometers.

The Alborz Mountains in northern Iran stretch from the borders of Armenia in the northwest to the southern end of the Caspian Sea, and end in the east at the borders of Turkmenistan and Afghanistan. The tallest mountain in the Middle East, Mount Damavand, is located in the range.

The Alborz mountain range forms a barrier between the south Caspian and the Qazvin-Tehran plateau. It is only 60-130 km wide and consists of sedimentary series dating from Upper Devonian to Oligocene, prevalently Jurassic limestone over a granite core.

Vegetation Index of Western Mexico

24.9N 108.2W

December 30th, 2009 Category: Climate Change

Mexico - December 20th, 2009

Mexico - December 20th, 2009

This FAPAR image highlights the great contrast between the high Fraction of Absorbed Photosynthetically Active Radiation along a narrow coastal strip of western Mexico and the low fraction of the country’s arid interior. In FAPAR images, the color spectrum over land ranges from red (1.0), to green, to yellow and white (0.0).

Here, some agricultural areas on the coastal plains in the bottom right corner appear red, indicating high photosynthetic activity. The rest of the coastal plains and the forested peaks of some mountains further inland are green, indicating good activity. The rest of the land visible here, however, is yellow to white, showing the low photosynthetic activity of the desert regions.