Studies Of Surface Ice Flow On The Glaciers Austre Lovénbreen And Pedersenbreen, Svalbard, Arctic

The glacier is a product of certain climate，and function as indicators and records of the climateand environment changes. Ice flow is substantive characteristics for the existence and development ofthe glaciers and it is the key difference between glaciers and other ice in nature. Study of glaciermovement is a significant part of glacier research, which is the foundation of glacier change. Theglacier movement is related to its climate, glacier forms, mass balance, glacier temperature and glacierhydrology, and its study can provide parameters support for other part study of glacier. The glaciersAustre Lovénbreen and Pedersenbreen are located at Ny-lesund, Svalbard. Based on field observationin2005-2011of two glaciers, this thesis discusses the surge type glaciers in Svalbard, the ice flow andsurface strain rate on Austre Lovénbreen and Pedersenbreen, the methods to calculate the variations inglacier terminus, and the prediction model of Austre Lovénbreen glacier terminus variations. Theresults are as following:（1） The number of surge type is about13%-90%of the glaciers in Svalbard, and there is a varietyof reasons for the huge difference in the results. Austre Lovénbreen glacier has not surged while thePedersenbreen maybe surge between1962and1998.（2）The annual average horizontal velocities of Austre Lovénbreen and Pedersenbreen are2.14m·a^-1and6.28m·a^-1respectively. The average velocities of glaciers in summer are slightly higher thanthat in winter. From cross-sectional view on the glacier, the velocities are not symmetrical on bothsides of the glacier; the horizontal velocity along its mainstream line is much larger than that on bothsides of the glacier. From longitudinal profile on the glacier,based on the movement feature of theglacier, the Austre Lovénbreen can be divided into three regions from its origin to terminal，they arecompressional region, stretching region and compressional region in order.There is a multinomialrelationship between the glacier velocity and its elevation.（3） The glacier surface vertical velocities are0.76m·a^-1and0.90m·a^-1respectively. There is avertical velocity of0.14meter per month in summer phases and0.13meter per month in winter phaseson Austre Lovénbreen, and0.13meter per month in summer and0.09meter per month in winter onPedersenbreen.Along the mainstream line, there is a linear relation relationship between the vertical velocity and its elevation. In the composition of the vertical velocity on Austre Lovénbreen,change of surface mass balance makes the greatest contribution about64%, followed bycompensation flow and horizontal velocity. On Pedersenbreen, the change of surface mass balancemakes the greatest contribution about40%，followed by horizontal velocity and compensation flow.（4）The strain rate ε decreases firstly and then increases along the mainstream line direction onboth of the glaciers, and with a larger inter-annual variation. The surface stress rhombus monitornetwork is located at B2point on the glacier of Austre Lovénbreen, and shows a result that: along themainstream line direction, the ice is mainly affected by extrusion pressure in downstream of the glacier,in the direction perpendicular to the glacier mainstream line, the range of B2W is mainly affected bystretching pressure and B2E affected by extrusion pressure.（5）The rheological coefficients（A） is1.410m·Pa-3·a^-1of Austre Lovénbreen glacier, andthe average slip is1.77m/a at the bottom of the glacier, accounting for70%of the speed of the surfacemovement.（6） Based on glacial topographic maps and GPS monitoring data, four methods are summarized tocalculate the variations in glacier terminus, i.e., mainstream line method, centerline method, perimetermethod and character point method. Their operational procedures are put forward based on ARCGISplatform, and the advantages and disadvantages, as well as some attention points, are reviewed for themethods. It is recommended that the character point method with the shortest distances be used tocalculate glacier terminus variations, and the shortest distances be searched from the previous glacierfront edge to the latter. Those methods are applied to the glaciers Austre Lovénbreen andPedersenbreen located at Ny-lesund, Svalbard, and the calculation results indicate that its front edgehas been receding at an average rate of16.93m·a^-1and7.94m·a^-1respectively. The grey system theorywas used to build the prediction model of Austre Lovénbreen glacier terminus variations, and theexpression is as following:...