Meteorology Fieldwork September 2005
On September 1st, we received out first accumulating snowfall at sea level in Longyearbyen and the next week my Polar Meteorology and Climate class started fall fieldwork. All courses at UNIS include a fieldwork component and unless weather conditions are dire, we spend a lot of it outdoors. The 10 days of meteorology fieldwork coincided with the first cold air of the season, temperatures between 0 and -10°C and wind-chills around -20°C. Although not cold for Svalbard, it does take some time to adjust. Luckily we returned to the heated and well-equipped dormitories in Nybyen each evening so were only in the cold for 12-16 hours a day.
Despite the cold this was an exciting experience for me. My previous research experience has been using ground penetrating radar to image the interior of alpine glaciers and ice sheets with the St. Olaf Center for Geophysical Studies of Ice and Climate headed by Dr. Robert Jacobel. Thus the instruments, analysis, methodology and principles were all new to me and it was exciting to be in action collecting data so soon after coming to Svalbard.
My responsibility was the maintenance, operation, and analysis of data from a sonic anemometer. Basically this instrument measures deviation in the speed of a sound wave between two probes from the speed of a sound wave in dry air. This instrument has an extremely high sampling frequency and measures in three dimensions. These properties make it ideal to examine turbulence which is of great important in boundary layer meteorology and can have a large impact on aircraft, windmills, and skyscrapers. Understanding the turbulence in the boundary layer is also vital to understanding the thermodynamics near the earth’s surface and thus the daily diurnal variations in temperature that are standard in the middle-latitude regions that most of us call home. The Polar Regions are unique in that this diurnal variation vanishes during times of midnight sun and polar night. However, during this time, in early September, there are strong diurnal variations in turbulent fluxes, and thus our results were comparable to those in textbooks written about middle-latitudes.
In order to take meteorological measurement without interference from the ground you have to elevate the instruments above other objects on the ground to eliminate interference. We do this by using masts and measuring at several levels on the masts so we get an idea of how meteorological parameters vary with height. It is quite difficult to raise a 10 meter mast in winds of 20-25 m/s (around 50 mph) and prompts numerous quotations that are quite amusing in retrospect, such as:
“Pull harder. Don’t let the mast fall; we don’t want to destroy the instruments.”
“What about the students who are below the mast?”
“The instruments are quite expensive, and students are disposable. I mean we receive new students every year.”
“I need good ideas; very fast…my fingers are getting quite cold.”
“So what’s the best way to fasten the guide ropes again?”
“I am not really sure. I just make some loops until it looks like it won’t come undone, so they don’t really have to be that good.”
“But make sure you’re knots are good enough, we don’t want the mast to fall.”
“We need rocks. Lots of big rocks.”
In addition to the large mast we also set up several smaller, 3 meter, masts in the area of Adventdalen, Svalbard to get a spatial picture of boundary layer. The masts were set up at a variety of elevations ranging from sea level to over 1000 meters in elevation. We also took manual observations every 3 hours in order to have a secondary record. Finally we archived the satellite images and analyses from the days we were in the field so we would have an idea of both the local and synoptic meteorological situation.
In order to take measurements above 1000 meters, we planned to take a series of balloon profiles up to 1 km. We quickly learned that there were numerous frustrations with fieldwork through our experience with the balloon. First in order to launch the balloon winds had to be below 10 m/s (20 mph), otherwise we risked loosing the balloon and tether system and we couldn’t risk damaging this very expensive system. Secondly, a 5×2 meter bright orange balloon could interfere with local air travel so we could only launch with clearance from the local airport and when there were no planes or helicopters in the vicinity. Due to these restrictions, we were only able to launch four times during the 10 day period. Still we retrieved some valuable data on the boundary layer through these measurements.
The first episode of fieldwork was a fun and valuable learning experience. It showed that a large amount of ingenuity and cooperation are sometimes necessary to accomplish seemingly simple tasks, such as setting up a weather mast, when conditions aren’t ideal. Examining the data also showed that despite all your efforts, data collection isn’t perfect and you have to report the errors or incompleteness of your data when presenting your results to the public.
Click on the photo thumbnail for a larger version.
The weather balloon.
The 10 meter weather mast.
The sonic anemometer.
