The Glacier Mass Balance And Its Relationship With Climate Change Of Austre Lovénbreen And Pedersenbreen, Svalbard, Arctic

Glaciers are sensitive indicator of climate change. Svalbard's special geographic location makes it to be one of the most rapidly place to response to climate change in the Arctic. The research in this area may help to understand the relationship between the Arctic glaciers and global climate change. The glaciers Austre Lovénbreen and Pedersenbreen are the research objects, which are observed from 2005 by us in Svalbard. The latest (2005-2010) variation characteristics of mass balance, equilibrium line altitude etc., the relationship with climate change and the sensitivity to climate change are analyzed. Furthermore, the characteristics of mass balance of other major glaciers monitored by WGMS in this region are discussed, the main results are as follows:(1)The major glaciers'variation characteristics in Svalbard between 1987-2007 are:①there is no significant long-term fluctuations regularity in the annual net mass balance of glaciers and the equilibrium line altitude, but they show the similar trends. Most of the observed glaciers'mass balance is negative, the cumulative mass balance continues to fall, and the accelerating trend is decreasing, which reflects the same response to climate change of the glaciers in this area.②the average mass balance of the five glaciers are -0.55 m w.e ./ a, -0.43 m w.e ./ a, -0.12 m w.e ./ a, -0.37 m w.e ./ a and-0.65m w.e ./ a, and the average equilibrium line altitude are 441m, 407m, 565m, 349 mand 423m respectively. The equilibrium line altitude and the net mass balance show a high negative correlation during the observation period.(2) During the period of 2005-2010, the characteristics of mass balance and equilibrium line altitude etc. of Austre Lovénbreen and Pedersenbreen as follows:① the variation of annual net mass balance of the two glaciers showed the same trend, but there is no obvious trend. The average annual net mass balance are -0.15 m w.e./a and 0.11m w.e./a, there is a big difference.②the accumulated value of the mass balance of the two glaciers are very different. Austre Lovénbreen always shows a negative mass balance state between 2005 and 2010, but Pedersenbreen shows a negative mass balance from 2005 to 2007, then it shows all positive, and the growth trend is accelerating.③the average equilibrium line altitude of them are 399.2m and 444.32m respectively. There is a high negative correlation between the equilibrium line altitude and mass balance, the interannual changes are both large. The sensitivity of annual net mass balance to equilibrium line altitude are -0.51m w.e. / 100m and-0.47m w.e. / 100m, remain stable. Accumulation area ratio and net mass balance show the same trend.④the average annual ablation volume are -1.11 m w.e. /a and -1.01m w.e. /a, the value of Pedersenbreen is smaller. The average accumulations are 0.97 m w.e. / a and 1.12m w.e. / a, and the maximum accumulation occurs in the same year.⑤Pedersenbreen's average annual surface velocity is significantly greater than Austre Lovénbreen. The movement direction of points in the surface of glacier is found to converge to the central line of glaciers or be parallel to it.⑥The interannual retreat of Austre Lovénbreen vary greatly, the average value is 11.63m / a. The largest amount of retreat is generally located in the central of the glacier, and the minimum one have not significantly fixed position.(3)The characteristics of climate change in Ny-?lesund and the relationship between the variation of Austre Lovénbreen and Pedersenbreen glaciers show that:①The annual daily average temperature did not change significantly in Ny-?lesund. The daily temperature vary greatly in winter, while it luffing smaller in summer.②The feature of precipitation is less precipitation in summer, and more precipitation in winter. The annual total precipitation has a big change.③There is no simple linear correlation between the mass balance , the equilibrium line altitude and daily temperatures and annual snowfall. The ablation sensitivity to daily temperatures increase of +1℃are 0.53 m w.e. / a and 0.55m w.e. / a. The accumulation sensitivity to snowfall increase of +10% are 0.17 m / a and 0.26m / a respectively. 31.9% and 21.3% of annual snowfall are needed to offset the loss of mass balance induced by daily temperatures increase of +1℃. So, the major weather conditions influence the mass balance of Austre Lovénbreen is daily temperatures, as for Pedersenbreen is annual snowfall.④The equilibrium line altitude sensitivity to daily temperatures increase of +1℃are 185.10 m / a and 77.53m / a, and to annual snowfall increase of 10% are -19.97 m / a and-32.87m / a. 92.7% and 23.6% of annual snowfall are needed to offset the change of equilibrium line altitude influenced by the temperatures increase of +1℃.So, the temperatures seems to be the main impact on equilibrium line altitude.