A new index of glacier area change: a tool for glacier monitoring
A new index of glacier area change: a tool for glacier monitoring
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DOI：
10.3189/002214309789471030
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发表时间：
2009-01-01
影响因子：
3.4
通讯作者：
Bahr, David B.
中科院分区：
文献类型：
--
作者：
Dyurgerov, Mark;Meier, Mark F.;Bahr, David B.
自世纪中期以来，大多数冰川的面积和体积都在减少。这种面积的损失在时间和空间上并不均匀，直接观测很少，使得难以对冰川变化进行区域和全球估计。本文着重于制定一个监测冰川变化的单一指数，这一指数对遥感应用特别有用。我们结合联合收割机直接冰川质量平衡观测结果B，总冰川面积S和积累面积S-c来自地图或遥感图像。使用累积面积比（AAR = S-c/S），我们注意到观察到的AAR（时间平均）< AAR >与平衡状态AAR（0）之间的差异，平衡状态AAR（0）由B（AAR）回归得到的B = 0时的值确定。我们认为α（d）=（< AAR >- AAR（0））/ AAR（0）量化了目前观测到的冰川状态与其平衡状态之间的差异，并测量了S的动态响应相对于S-c的气候响应的延迟。使用1961-2004年期间所有可用的观测数据，热带冰川的α（d）约为-65%，这意味着随着S继续减少并“赶上”S-c，它们迅速萎缩。在同一时期，中纬度和极地冰川的α（d）负值较小。在所有纬度和地区的86个冰川中，只有11个在1961年至2004年期间的任何时候都显示出正α（d）。1961-2004年的平均值，α（d）为-15.1 +/-2.2%，< B >-360 +/- 42 mm a（-1）w.e.。AAR（0）的值范围在约40%和80%之间，但大部分平衡值在50%和60%之间。平均AAR（0）为57.9 +/- 0.9%，并随时间保持稳定（平衡AAR未随气候变化）。总的来说，观测到的负阿尔法（d）表明，即使全球温度保持不变，冰川也会持续退缩，并继续对海平面做出贡献。
Since the mid-19th century, most glaciers have been losing area and volume. This loss of area has not been homogeneous in time and space, and direct observations are sparse, making regional and global estimates of glacier change difficult. This paper focuses on developing a single index for monitoring glacier change, one that would be particularly useful for remote-sensing applications. We combine the results of direct glacier mass-balance observations B, total glacier area S and accumulation area S-c derived from maps or remotely sensed images. Using the accumulation-area ratio (AAR = S-c/S), we note the differences between observed AAR, time-averaged < AAR > and the equilibrium state AAR(0), as determined by its value at B = 0 from a regression of B(AAR). We suggest that alpha(d) = (< AAR > - AAR(0))/ AAR(0) quantifies the difference between the currently observed state of glaciers and their equilibrium state and measures the delay in the dynamic response of S relative to the climatic response of S-c. Using all available observations for the period 1961-2004, alpha(d) approximate to -65% for tropical glaciers, which implies their rapid shrinkage as S continues to decrease and 'catch up' with S-c. During the same period, mid-latitude and polar glaciers show less negative values Of alpha(d). Of 86 glaciers from all latitudes and regions, only 11 show positive alpha(d) at any time between 1961 and 2004. Averaged over 1961-2004, alpha(d) is -15.1 +/- 2.2%, and < B > is -360 +/- 42 mm a(-1) w.e. Values for AAR(0) range between about 40% and 80%, but the bulk of the equilibrium values are between 50% and 60%. The average AAR(0) is 57.9 +/- 0.9% and has remained stable over time (the equilibrium AAR has not changed with climate). Overall, the observed negative alpha(d) suggests a committed retreat of glaciers and their continuing contribution to sea level even if global temperature is held constant.