Utility of late summer transient snowline migration rate on Taku Glacier, Alaska
Utility of late summer transient snowline migration rate on Taku Glacier, Alaska
复制标题
DOI：
10.5194/tc-5-1127-2011
复制
发表时间：
2011-12
期刊：
影响因子：
--
通讯作者：
M. Pelto
中科院分区：
文献类型：
--
作者：
M. Pelto
抽象。在阿拉斯加的塔库冰川上，结合雪坑的雪水当量（SWE）和瞬态雪线（TSL）附近的探测的实地观测，用于量化质量平衡梯度。从1998-2010年在1000米的雪坑中测量的TSL和SWE得出的平衡坡度范围为2.6-3.8 mm m−1。从950 m-1100 m的探测样带直接测量SWE，并产生3.3-3.8 mm m−1的稍高的平衡梯度。在2004-2010年期间，在MODIS和Landsat 4和7专题成像仪图像中确定了Taku冰川上的TSL，以评估其上升速率的一致性和质量平衡评估消融的可靠性。例如，2010年7月28日的海平面为750米，8月5日为800米，8月14日为875米，8月30日为925米，9月20日为975米。2010年7月中旬至9月中旬，观测到的平均探测平衡梯度为3.3 mm m−1，加上TSL上升3.7 m d − 1，消融率为12.2 mm d −1。在消融季节的11个时期内，Taku冰川上该地区的TSL从750-1100 m上升，每个时期超过14天，表明TSL平均上升3.7 m天-1，上升率相对一致，范围为3.1至4.4 m天-1。如果图像或观察结果在消融季节结束时不可用，则该速率可用于确定最终ELA。2004-2010年期间，从TSL上升和观测到的平衡梯度确定的7 - 9月期间Taku冰川750-1100 m的平均消融量为11-13 mm day−1。在融化季节后期，从卫星图像中的TSL观测结果中估计BN的可能性，加上此类图像的频繁可用性，为多年来和许多冰川的有效质量平衡评估提供了一种手段。
Abstract. On Taku Glacier, Alaska a combination of field observations of snow water equivalent (SWE) from snowpits and probing in the vicinity of the transient snowline (TSL) are used to quantify the mass balance gradient. The balance gradient derived from the TSL and SWE measured in snowpits at 1000 m from 1998–2010 ranges from 2.6–3.8 mm m−1. Probing transects from 950 m–1100 m directly measure SWE and yield a slightly higher balance gradient of 3.3–3.8 mm m−1. The TSL on Taku Glacier is identified in MODIS and Landsat 4 and 7 Thematic Mapper images for 31 dates during the 2004–2010 period to assess the consistency of its rate of rise and reliability in assessing ablation for mass balance assessment. For example, in 2010, the TSL was 750 m on 28 July, 800 m on 5 August, 875 m on 14 August, 925 m on 30 August, and 975 m on 20 September. The mean observed probing balance gradient was 3.3 mm m−1, combined with the TSL rise of 3.7 m day−1 yields an ablation rate of 12.2 mm day−1 from mid-July to mid-Sept, 2010. The TSL rise in the region from 750–1100 m on Taku Glacier during eleven periods each covering more than 14 days during the ablation season indicates a mean TSL rise of 3.7 m day−1, the rate of rise is relatively consistent ranging from 3.1 to 4.4 m day−1. This rate is useful for ascertaining the final ELA if images or observations are not available near the end of the ablation season. The mean ablation from 750–1100 m during the July–September period determined from the TSL rise and the observed balance gradient is 11–13 mm day−1 on Taku Glacier during the 2004–2010 period. The potential for providing an estimate of bn from TSL observations late in the melt season from satellite images combined with the frequent availability of such images provides a means for efficient mass balance assessment in many years and on many glaciers.