The blog has moved to syngron.com
|Monthly sunshine hours in Germany with global scale.|
Recently I saw this surprising map comparing the sunshine hours of Europe with the US:
Any location in the US apparently has much more sunshine than any location in Germany! Actually this makes sense if you check the latitude boundaries of the US and Europe but it was never that clear to me.
This made me wonder how the distribution is in Germany and there are already a couple of maps done for that which are easily found with a fast internet search.
But then I stumbled upon some nice datasets from the German Weather Service (DWD, Deutscher Wetterdienst). They actually provide monthly raw data of sunshine hours for all of their weather stations online :
Free weather data from the DWD (mean data of 30 year period)
I used the Table A, Sunshine hours (Sonnenscheindauer), years 1981-2010.
The data from there can be easily converted into a CSV file by copying it in a spreadsheet software (e.g. Libreoffice) and save it as CSV.
To further process the data I used python which makes it straight forward to read CSV files and plot map data with the Basemap library. To create an evenly distributed grid of data from the not evenly distributed measurement points I use the matplotlib.mlab.griddata function and to plot the data on that grid the contourf function. The code provided in this gist (attention, in the gist the latitude and longitude are switched!) helped a lot.
My final script can be found here: https://raw.github.com/syngron/misc/master/DWD_sunshine_hours_Germany.py
The output of the script is shown in the pictures.
The first one uses a global scale which makes it nice to see the obvious changes over the seasons of whole Germany.
The second one is even more interesting, here each month has ist own scale and you can clearly see the regional differences per month. An interesting point is, that in the summer months the sunlight seems to be much more evenly distributed apart from the hole in the mid-west. In the winter month the most southern parts (the region is actually the Allgäu) seems to get much more sunshine then the whole rest. Probably this is related to the high altitudes there, the Allgäu stations are just over the clouds :)