Re: Volcano lake turns from blue to red

Aidan Karley wrote:

Which would suggest
the possibility, at least, of there being colour gradients visible on satellite
and/or aerial photography that could indicate localisation of the input, flow
rates and concentrations, *without* putting people at prolonged risk.

ASTER, perhaps?

"Alain Bernard recently processed a 26 January 2006 nighttime ASTER
(Advanced Spaceborne Thermal Emission and Reflection Radiometer) image.
Figure 25 shows the ASTER product called AST_04 (TIR-thermal infrared
radiometer, 8.12-11.65 µm wavelengths-band 10) unprocessed image of
Aoba with Lakes Voui and Lakua. The TIR bands, with a spatial
resolution of 90 m, give the ability to detect small thermal anomalies
(a few degrees C), perform thermal mapping, and monitor temporal
variations in the lake surface temperature. As shown in figure 26, Lake
Voui's temperature in early January 2006 dropped by ~ 10°C to a mean
of 25.4°C (down from 35.7°C one month earlier). Temperature
differences between Voui and Lakua dropped to 4.3°C, reaching almost
to the background levels observed in July 2005 (see plot "Temperature
data from Lake Voui at Aoba, October 1998-December 2005 . . ."; BGVN
30:11). There is still a strong thermal anomaly of 46.1°C inside the
new island (figure 13)."
--
http://www.volcano.si.edu/world/volcano.cfm?vnum=0507-03=&volpage=var&VErupt=Y&VSources=Y&VRep=Y&VWeekly=N#bgvn_3101

The shorter URL, same page: http://tinyurl.com/n4j44

Nothing more recent than late January of this year. I wanted to find
an image of this blue water they were talking about to see if they just
meant it in the ordinary way, that is, clear water under a blue sky;
however, the lake in the images at the above page seems to have an
unusual blue color. If it's not a photographic effect, one wonders
what causes it. And if the water on the island is still blue, perhaps
it's something that is temperature dependent.

Barb
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"Small earthquake in Chile. Not many dead."
Claud Cockburn 1904-81: winning entry for a dullest headline
competition at /The Times; In Time of Trouble/ (1956) (Little Oxford
Dictionary of Quotations)

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