Underlying images, credit EUMETSAT. Warning: 3371 x 1165 pixels (click for full size)
Image 2012 December 2nd (Sunday), 12 hours UT.
Meteosat 9 senses the full earth disc in 9 frequency bands, returning full data every 15 minutes. False colour data is published as a a visualisation, low resolution for full disc and much better resolution for some regions.
Full data needs an account and the means to take the data feed.
As part of an exercise I have constructed a good resolution image as above out of the regional fragments. This was done by hand as a proof of concept.
My motive is gaining a better intuitive understanding of circulation patterns with regard to the late Marcel Leroux’s MPH (Mobile Polar High, or AMP in the original French, Anticyclone Mobile Polar)
For the Arctic the concept is thin lens of cold air form at sea level as a temperature inversion from radiative loss to space. These lens slide out of the Arctic basin formed by the rim of high land, such as via the Bering straight, top of Canada, between Canada and Greenland and so on.
They then spiral down eastwards toward the tropics with warm air boiling around the rim and over the top. Lows form in the rim taking warm air and storms from lower latitudes toward the north. Is part of the general circulation cells.
That is simplistic.
There are some spectacular videos I will probably show soon which turn flat words into moving air, you can see the flows.
There is an older technology US geostationary satellite over the US but unfortunately this doesn’t really cover the Canada/Greenland gap although the Canadian weather service do their best to provide images.
That leaves polar orbit birds which give poor coverage, has to be stitched from different passes. Darkness at the pole doesn’t help.
In the above image Greenland is left of top on the rim of visibility, with the edge of Canada a little further around. Looks like a sea flowing out from there into a lake with a rim of cloud. The rim is taking warm moist air towards the UK. As I write this the forecast light rain has been falling as some of that moist air is moving east and meeting the Arctic air we have been experiencing, came from the other side of Greenland.
Another feature is the diagonal band of cloud across the Sahara. I’ve seen something similar many times on the RSS and UAH lower troposphere world plots, shows as a warm streak. Doesn’t show in the image I showed for October 2012.
I’m trying to work out what is a good selection of satellite images for following MPH progress. The above images were automatically downloaded, code already works and I could automatically stitch now I know how to do it. Quite possibly constructing something from separate channels will be better.
Whether this is a worthwhile little project which can be completed remains to be seen. I’ll learn something either way.
Blog readers are welcome to help.
Post by Tim Channon
Image source here