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Exercise 2: The influence of weather conditions on radar imagery  So far you have seen that the microwave backscatter varies a lot across the image and across the three dates. We will now look at the meteorological data of Ny Ålesund and try to interpret these microwave backscatter variations. Note in which meteorological situation the radar images were taken in terms of temperature and precipitation.
Based on what you read above, which ones are they?
Compare your findings with others in your class. a) The glaciers in the February image are relatively bright because the image was taken during a cold period after a significant snowfall. The dry and cold snow layer produces volume scatter. b) The glaciers in the September image look relatively bright because there is a lot of cold and dry snow that produces volume scattering. c) The glaciers in the June image look relatively dark, because the image was taken after onset of the snow-melting period (warmer temperatures) and the snow is presumably wet. d) Despite the snow on most glacier parts in the June image being wet and producing low microwave backscatter, in the upper parts of the small glaciers the surface still looks bright. This could be because the snowmelt has not yet reached the uppermost glacier parts, which are therefore still dry and cold and reflect a lot of microwave energy back to the sensor (volume scatter). e) The glaciers in the September image look medium bright because, after a long,warm period with lots of rain, much of the snow may have melted (excluding the upper glacier parts) and the rough ice surface produces medium backscatter.
f) On all images the upper parts of the small glaciers look brighter than the lower ones because the snow at high altitudes is very wet. Wet snow reflects a lot of microwave energy back to the sensor.
Last update: 23 January 2014
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