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Posts tagged Chile

Comparative Vegetation Index East and West of the Andes

26.6S 68.9W

March 21st, 2013 Category: Vegetation Index

Argentina – March 21st, 2013

The Normalized Difference Vegetation Index (NDVI) is a simple graphical indicator that can be used to analyze satellite data, and assess whether the target being observed contains live green vegetation or not.

Live green plants absorb solar radiation in the photosynthetically active radiation (PAR) spectral region, which they use as a source of energy in the process of photosynthesis. Leaf cells have also evolved to scatter (i.e., reflect and transmit) solar radiation in the near-infrared spectral region. Hence, live green plants appear relatively dark in the PAR and relatively bright in the near-infrared.

The pigment in plant leaves, chlorophyll, strongly absorbs visible light (from 0.4 to 0.7 µm) for use in photosynthesis. The cell structure of the leaves, on the other hand, strongly reflects near-infrared light (from 0.7 to 1.1 µm). The more leaves a plant has, the more these wavelengths of light are affected, respectively.

Since early instruments of Earth Observation acquired data in visible and near-infrared, it was natural to exploit the strong differences in plant reflectance to determine their spatial distribution in these satellite images. Here, the color contrast shows a stark difference in the vegetation index between arid Chile and western Bolivia, which appear brown to yellow (low vegetation index), and more fertile Argentina, which appears green (high vegetation index).

Volcanic Eruption in Chile – January 21st, 2013

40.6S 72.5W

January 21st, 2013 Category: Image of the day, Volcanoes

Chile – January 20th, 2013

A cloud of what appears to be ash from a volcanic eruption blows westward over Chile, towards the Pacific Ocean. The ash appears to be emanating from one of the four different volcanoes that constitute the volcanic group known as the Puyehue-Cordón Caulle Volcanic Complex: the Cordillera Nevada caldera, the Pliocene Mencheca volcano, Cordón Caulle fissure vents and the Puyehue stratovolcano. However, reports of volcanic activity in Chile indicate that activity is currently limited to the Copahue and Villarrica volcanoes, meaning that the cloud in this image may be the result of other phenomena, such as wildfires.

Lakes in Argentine and Chilean Patagonia

49.5S 72.6W

November 18th, 2012 Category: Lakes, Mountains

Chile and Argentina – November 16th, 2012

Several lakes can be seen by the Andes Mountains and Chile-Argentina border in this image of Patagonia. The northernmost is known as Lake General Carrera (Chilean side) or Lake Buenos Aires (Argentine side). It has a surface of 1,850 km² of which 970 km² are in Chile and 880 km² in Argentina, making it the biggest lake in Chile, and the fourth largest in Argentina. The lake is of glacial origin and drains to the Pacific Ocean on the west through the Baker River.

Visible to its south, also dark blue in color, is known as Cochrane Lake in Chile and Pueyrredón Lake in Argentina. The Argentine portion of the lake has a surface of 150 km2, while the portion in Chile covers 175 km2. It is a glacier fed lake.

Continuing southward, three light blue lakes can be seen: Lake O’Higgins/San Martín (the former name is used in Chile, the latter in Argentina), Viedma Lake and Argentino Lake. All three are glacial lakes, and their milky color is due to rock flour suspended in their waters.

Sediments Along Coast of Argentine Patagonia – September 28th, 2012

50.5S 70.7W

September 28th, 2012 Category: Image of the day, Lakes, Sediments

Argentina – September 24th, 2012

Sediments line the coast of the Argentine provinces of Santa Cruz and Tierra del Fuego, both part of Patagonia, from the San Jorge Gulf to the Mitre Peninsula.

Visible parallel to the west coast are the Andes Mountains, along the border with Chile. Visible by the mountains are several bright blue glacial lakes (from north to south): Lake O’Higgins/San Martín (the former name is used in Chile, the latter in Argentina), Viedma Lake and Argentino Lake.

Spine of the Andes and Salt Flats in Argentina

38.7S 62.9W

June 18th, 2012 Category: Salt Flats

Argentina - June 5th, 2012

While the spine of the Andes Mountains, running along the Chile-Argentina border, appears bright white due to snowfall, it is not the only bright white feature on the South American landscape nearby: several salt flats are visible to the east, in Argentina. Visible near the foothills of the Andes are the Salinas Grandes, a salt desert in the Córdoba and Santiago del Estero provinces of the Sierras de Córdoba that covers an area of 3,200 mi² (8,290 km²). Further east, salt flats can be seen by the northern shores of the Mar Chiquita, an endorheic salt lake that is the largest of the naturally occurring saline lakes in Argentina. Here, some dust (probably salt and other minerals) can be seen blowing off the Mar Chiquita salt flats and southward over the lake.

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