Wednesday, May 12, 2010

European Trends in Nighttime Lights

The image above shows the monotonic trend in nighttime lights from 1992-2008. The data series is produced from the Operational Linescan System (OLS) sensor of the United States Defense Meteorological Satellite Program (DMSP). This sensor is very sensitive to light and has been used to create annual images of stable lights. The analysis was conducted using the Earth Trends Modeler by Ananya Baruah and Annalise Erkkinen -- two graduate students at Clark University. Trend monotonicity measures the degree to which data values are consistently increasing (red) or decreasing (blue). More extreme values indicate greater consistency in the trend. Areas that appear white are not necessarily dark. It simply means that the light levels are unchanging. Thus the central cores of Paris and London both appear white in this image.

What is remarkable about this image is the clear evidence of political boundaries. The increases in nighttime lights in Poland are extraordinary and are consistent with the fact that Poland's GDP increased over 500% from 1992 to 2008. However, an explanation based on the economy doesn't always work. For example, the UK and France experienced similar economic growth over this period, but opposite trends in the nighttime lights.

Do you have any insights on the trends evident in this image? If so, please leave a comment. Thanks

4 comments:

  1. Quite nice analysis. Do you think this could be used as an index of energy comsumption/footprint?
    This could be cross-checked with per capita energy consumption and also to measure naturalness of some large areas.
    Keep up with the good work.

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  2. The decrease in lights in certain countries that should have experience growth have had changes in laws regarding light polution.
    Perhaps are using better light shields to make sure the light being emmitted goes towards the ground; not the sky.

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  3. Yes, since a couple of years there are strict light pollution laws in The Netherlands, as it never became completely dark anymore anywhere in the Netherlands, nature got seriously confused. I guess other Northern European countries (Scandinavia, UK, Germany) have also introduced light pollotion laws. Southern European Countries are usually less quick with these kind of measures. And they can also often not afford such kind of laws.

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  4. Absolutely Leslie. You should be an engineer. Simple light shielding is certainly the answer.

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