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Increasingly precise data on radiation reflected from the Arctic sea area

Date:
October 6, 2011
Source:
Finnish Meteorological Institute
Summary:
Scientists have developed a new, globally unique method for estimating surface albedo in the Arctic sea area solely on the basis of microwave data. Its advantage over conventional optical methods is that neither clouds nor darkness interfere with measurements.
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The Finnish Meteorological Institute has developed a new, globally unique method for estimating surface albedo in the Arctic sea area solely on the basis of microwave data. Its advantage over conventional optical methods is that neither clouds nor darkness interfere with measurements.

The Finnish Meteorological Institute has developed a unique method for estimating surface albedo in the Arctic sea area. The method helps determine the amounts of solar radiation reflected from the Arctic sea area, information which is very important for climate change research. Albedo describes the ability of Earth's surface to reflect incoming radiation, and it is therefore associated with Earth's energy balance. Estimates of albedo affect the accuracy of model calculations pertaining to climate change, but they are also a good indicator of the change that has already taken place.

The surface albedo of Arctic regions is particularly important with respect to climate change, because changes in the extent of the ice cover in polar regions are crucial for albedo values. The albedo of the Arctic sea area is still relatively poorly known, but it has a major impact on climate model calculations. With global warming, the melting of sea ice reduces albedo values in the Arctic region. This means that more energy is absorbed in the region and more ice will melt. In other words, a decreasing albedo value will lead to climate feedback diminishing the albedo value further.

The world's only microwave-based method

When compared against the conventional optical method, the microwave-based method for estimating albedo has the advantage that neither cloudiness nor the low Sun angle in the Arctic region interfere with the measurements. For instance, it is possible to detect whether spring is coming unusually early; this is something that optical instruments do not necessarily reveal at that time of year.

Albedo indicates how much of the radiation reaching a body is reflected back. The whiter the reflecting surface is, the higher is its albedo. A black body does not reflect any incoming light, and so its albedo is zero. A planet's albedo is important in terms of thermal economy. Clouds and ice are good reflectors of solar radiation. About one third of radiation reaching Earth is immediately reflected back to space, while two thirds is absorbed by the atmosphere, soil and seas. This radiation is also reflected back, but more slowly.


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The above post is reprinted from materials provided by Finnish Meteorological Institute. Note: Materials may be edited for content and length.


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Finnish Meteorological Institute. "Increasingly precise data on radiation reflected from the Arctic sea area." ScienceDaily. ScienceDaily, 6 October 2011. <www.sciencedaily.com/releases/2011/10/111006085326.htm>.
Finnish Meteorological Institute. (2011, October 6). Increasingly precise data on radiation reflected from the Arctic sea area. ScienceDaily. Retrieved September 2, 2015 from www.sciencedaily.com/releases/2011/10/111006085326.htm
Finnish Meteorological Institute. "Increasingly precise data on radiation reflected from the Arctic sea area." ScienceDaily. www.sciencedaily.com/releases/2011/10/111006085326.htm (accessed September 2, 2015).

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