Glaciology at Jan Mayen
Cecilie, Rolstad DenbyProject period: 2007-2011.
Staff: C. Rolstad, PhD student J. Hulth
Jan Mayen
The volcanic island Jan Mayen covers an area of 377 km2 and it is located at N 71°02’, W 8°12’. Twenty glacier covering an area of ~113 km2 are protruding the 2277 m high Beerenberg crater.
Mass balance
The glacier mass balance have never been monitored, except for Sørbreen glacier (area: ~15 km2), where the direct glaciological mass balance was measured in 1972 to 1974, and 1976 to 1977. In 2007 we initiated a mass balance field program here, including operation of automatic weather stations (AWS) at 330 and 880 m a.s.l. The geodetic mass balance of the glaciers is also determined. Read about the field work in 2010 at: Jan Mayen Arctic Expedition 2010.
AWS at Sørbreen, Jan Mayen.
Photo: John Hulth
Surface energy balance - distributed temperature-index melt model
Since 1921 the Norwegian Meteorological Institute has operated a meteorological station at 10 m a.s.l., 20 km southwest of Sørbreen. Radiosondes have been deployed twice a day, since 1949. Air temperature, humidity, air pressure and wind speed and direction are recorded at 10 meters intervals, to a height of 25 000-30 000 meters.
Temperature-index models often are forced by temperatures measured at a weather station on, or close to, the glacier, and a constant lapse rate is assumed as an estimate of the temperature distribution across the glacier surface. However, lapse rates vary in time and are not necessarily linear, especially on Arctic glaciers where inversion layers are common in the lower atmosphere. We explore the potential of using radiosonde data to improve the spatial distribution of air temperature and solar radiation in a grid-based temperature-index model. Radiosonde data are analyzed and compared with the meteorological data from the two AWSs on the glacier. An enhanced distributed temperature-index model is developed, driven by hourly temperature data from the main AWS on the glacier and potential clear-sky direct solar radiation. The radiosonde temperature observations are used to estimate the temperature lapse rate across the glacier surface. The radiosonde humidity profiles are used to calculate a radiation transmissivity index to compensate for elevation differences in the cloud cover. Both lapse rates and transmissivity indexes are calculated twice a day and interpolated to hourly time steps.
Preliminary results show that better spatial estimates of temperature lapse rate and solar radiation improve the accuracy of the melt modeling of this glacier since the ablation is highly affected by temperature inversion and the low-atmosphere cloud cover.
The project is conducted in cooperation with Prof. R. Hock, Geophysical Institute, University of Alaska, Fairbanks, USA & Department of Earth Sciences, Uppsala University, Sweden.
Publication
Hulth, J., C. Rolstad, K. Trondsen, and R. W. Rødby, 2010. Direct glaciological mass- and energy balance of Sørbreen, Jan Mayen, 2008. Annals of Glaciology 51 (55) 110-119.
Published: 15.04.00
Updated: 23.04.10
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Contact: Cecilie Rolstad (cecilie.rolstad@umb.no)