Solar eclipse had an economic impact

Solar eclipse had an economic impact

Top image: Maximum eclipse of 93% occurred at 11:41 over Longyearbyen on 1 August 2008. Photo: Stig Foss/UNIS.

The solar eclipse on 1 August 2008 had quite an impact on Svalbard, not only visually, but also meteorologically. The eclipse was the cause of a three day fog so thick that all air-traffic to and from Svalbard was grounded, according to an article recently published in Meteorology and Atmospheric Physics.

27 July 2010
Text: Eva Therese Jenssen

In the morning of 1 August 2008 the sun disappeared behind the moon, the largest eclipse event in Norway in over 50 years. The totality eclipse band started in Arctic Canada and proceeded over northern Greenland, parts of northern Svalbard, Novaya Zemlya and Siberia to finally end in the inner parts of China.

This meant that most of the passage in the Arctic was over unpopulated areas, however, from Longyearbyen, the main settlement in Svalbard, the solar eclipse could be observed with a maximum coverage of 93 %.

This caused a temperature decrease over land between 0.3 and 1.5ºC. But it also had a significant social and economic impact for people in Svalbard.

First study so far north
Solar eclipses are fascinating events. For the public in general, it is a fascinating optical show. For meteorologists, an eclipse is an excellent opportunity to study what effects a sudden decrease in radiation has on meteorological parameters and the weather.

There are very few studies of solar eclipses from the Arctic and the Antarctic, and the 2008 eclipse was, as far as we know, the first eclipse to be observed by scientists at such a high latitude as 78 degrees N, according to Dr. Anna Sjöblom, associate professor in meteorology at UNIS and author of a paper recently published about the eclipse.

The eclipse took place when the midnight sun is still shining in Longyearbyen, so it provided a rare opportunity for us to observe the effects of a sudden decrease in solar radiation after several months of continuous sunlight both day and night, Sjöblom says.

During a 48-hour period prior, during and after the eclipse, complimentary measurements were made both over land and over water in Isfjorden.

The two main measurement sites were in Adventdalen, about 10 km inland from Isfjorden, and at Vestpynten, a locality close the coastline of the fjord and in the vicinity of the airport.

In addition, data from three standard weather stations around Longyearbyen (Gruvefjellet, Janssonhaugen and at the Svalbard global seed vault) were used.

Direct connection to the eclipse
Simultaneous observations done over land and over the Isfjorden showed that the eclipse, and the consequent drop in temperature, triggered downslope winds in the valleys surrounding the fjord, thereby creating low-level clouds over the water, says Dr. Sjöblom.

During the actual eclipse, the cloud cover over land consisted of a thin layer of Cirrostratus (sheet-like, high-level clouds composed of ice crystals). This made the eclipse extra spectacular to watch since the clouds created a halo around the sun.

At the same time there were no clouds over Isfjorden, but soon after the end of the eclipse low Stratocumulus clouds (large dark, rounded clouds) appeared at the shorelines of the fjord.

– This cloud development had direct connection with the solar eclipse since the clouds appeared along the coastline immediately after the eclipse. As it was still midnight sun season, no sunset occurred that could otherwise have caused the surface to cool in a similar way, explains Sjöblom.

Triggered long lasting fog
The Stratocumulus clouds continued to grow during the day, gradually covering all of Isfjorden and later in the evening drifted in over Longyearbyen and Adventdalen.

– This suggests that the surface cooling over land was enough to start a downslope air flow from the mountains and glaciers surrounding Isfjorden, which resulted in that, when the cool air reached the fjord, the humidity increased and low-level clouds formed, says Sjöblom.

At midnight, the whole area around Longyearbyen was covered in thick fog, which lasted for three whole days. The consequence was that the air traffic to and from the archipelago was grounded, causing significant economical impact not only for the airline companies that could not fly in to Longyearbyen, but also the local tourist industry which lost money when there was no air traffic.

Prepare for 2015
Reports of solar eclipses causing trouble for the airline industry are not common, but cloud and fog development have been observed other places in the world right after an eclipse. But this is the first time we have seen such a result so far north, according to Sjöblom.

The next big solar eclipse event will be 20 March 2015, when the totality will be a 100 %. Upper atmospheric scientists and meteorologists are already preparing for this event, which can be seen only in the High Arctic.

– If there is now cloud cover, I believe the eclipse can have major consequences on the local weather, given that there is winter and snow on the ground when the eclipse occurs, Sjöblom says.

Reference:
Sjöblom, Anna: “A solar eclipse seen from the High Arctic during the period of midnight sun: effects on the local meteorology”. Meteorology and Atmospheric Physics, vol. 107, No. 3-4, August, 2010, doi: 10.1007/s00703-010-0070-3.

Partial solar eclipse

The partial solar eclipse on 1 August 2008 was monitored closely outside UNIS. Photo: Sebastien Barrault/UNIS.

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