[SQM] ecological light pollution paper, and worldwide SQM database

Christopher Kyba christopher.kyba at wew.fu-berlin.de
Thu Mar 3 14:09:07 UTC 2011

Hi Chuck,

Thanks for your email, and especially sharing the data!  If I put our
results in the same table, and re-arrange by clear sky brightness:

Location                Clear   Cloudy

Rural Berlin            21.0    19.9      <- Europe
Madison                 20.23   18.86
Grissom                 19.47   17.50
Horizon                 19.32   17.58
Discovery               19.23   17.39
Free University         19.0    16.5     <- Europe
Prairie Vista           18.71   16.41
Elsie Rogers            18.63   16.88
Walt Disney             18.12   16.30

You can see the results aren't monotonic.  See the attached plot that
shows the amplification factor for each site - the Berlin sites have
an "x" inside the "o".

This indicates that the cloud amplification factor depends upon local
factors (maybe it's a nice function of population density?), and it
shows why we need to repeat the cloud amplification study but using
diverse locations.


On Thu, Mar 3, 2011 at 2:35 PM, Chuck Bueter <bueter at nightwise.org> wrote:
> Hi, Chris and all,
> In 2009 our community participated in Globe at Night, with over 3,400 students from 14 schools submitting observations during clear nights (http://www.LetThereBeNight.com).  The boundaries covered about 140 square miles ranging from fringe urban, through suburban, and rural.  Concurrently we had teams of students from each school go back to their respective schools after astronomical twilight every night for two weeks, cloudy or clear.  At school, each team took five measurements from each of three SQMs and averaged the numbers.  For the reasons you cite below, we wanted to use the meters to know more about (and quantify) how bright the night was rather than how dark it was.
> The table below shows the average SQM values from surprisingly clear nights and the average values from the cloudy nights, while it omits the data from partly cloudy nights.  Sure, it wasn't a rigid experiment, but it certainly was indicative that the nights with clear skies and abundant light pollution are considered good nights for the nocturnal kingdom, for it can only go downhill from there.  In nature the moon admittedly creates bright nightscapes at times that alters movement, feeding and mating, but the moon eventually goes away.  However, the light pollution on cloudy nights is both amplified and incessant.  There's no escape.
> School                  Clear   Cloudy
> Discovery               19.23   17.39
> Elsie Rogers            18.63   16.88
> Grissom                 19.47   17.50
> Horizon                 19.32   17.58
> Madison                 20.23   18.86
> Prairie Vista           18.71   16.41
> Walt Disney             18.12   16.30
> Chuck Bueter
> bueter at nightwise.org
> On Mar 3, 2011, at 5:39 AM, Christopher Kyba wrote:
>> Hello all,
>> I wanted to make you aware of a paper our group just published, "Cloud
>> Coverage Acts as an
>> Amplifier for Ecological Light Pollution in Urban Ecosystems."  It was
>> published in the online open access journal PLoS ONE, and is available
>> here: http://dx.plos.org/10.1371/journal.pone.0017307
>> We find that overcast nights in Berlin are 10.1 times brighter than
>> clear nights, and the bottom line of the paper is that if you are
>> interested in the biological, ecosystem, or human health consequences
>> of light pollution, then the sky brightness on overcast nights is
>> actually more important than that for clear nights.  We end the paper
>> with a call for the establishment of an international database of
>> continuous SQM-LE readings.
> [snip]
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