Variations in snowpack melt on the Greenland ice sheet based on passive-microwave measurements
Variations in snowpack melt on the Greenland ice sheet based on passive-microwave measurements
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DOI：
10.3189/s0022143000017755
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发表时间：
1995
影响因子：
3.4
通讯作者：
T. Mote;M. Anderson
中科院分区：
文献类型：
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作者：
T. Mote;M. Anderson
利用一个简单的微波发射模型，模拟了格陵兰冰盖各地点与积雪融化条件相关的37 GHz亮度温度。模拟值被用作阈值，并与每日网格化的SMMR和SSM/I被动微波数据进行比较，以揭示经历融化的区域。在1979 - 1991年的日、月和季节（5 - 8月）的基础上检查了被划分为融化区域的空间范围。融化覆盖的典型季节周期表现为4月下旬开始融化，5月中旬至7月中旬融化面积迅速增加，7月下旬至8月中旬融化范围迅速减少，9月下旬停止融化。每日融化范围的季节平均值表明，在13年期间，融化覆盖率明显增加，每年约增加3.8%（在95%置信区间显著）。这种增加主要是由7月和8月期间冰盖西部和西南部融化覆盖的统计上显著的积极趋势所主导。研究发现，6月和7月微波衍生熔化范围与表面消融率测量值之间存在显著的线性相关关系，而8月则不存在，因此在使用8月微波衍生熔化范围时必须谨慎。尽管如此，从微波数据中获得的关于格陵兰冰盖积雪融化变动性的知识，对于探测北极的气候变化和研究气候变化对冰盖的影响应该是有用的。
Abstract A simple microwave-emission model is used to simulate 37 GHz brightness temperatures associated with snowpack-melt conditions for locations across the Greenland ice sheet. The simulated values are utilized as threshold values and compared to daily, gridded SMMR and SSM/I passive-microwave data, in order to reveal regions experiencing melt. The spatial extent of the area classified as melting is examined on a daily, monthly and seasonal (May-August) basis for 1979–91. The typical seasonal cycle of melt coverage shows melt beginning in late April, a rapid increase in the melting area from mid-May to mid-July, a rapid decrease in melt extent from late July through mid-August, and cessation of melt in late September. Seasonal averages of the daily melt extents demonstrate an apparent increase in melt coverage over the 13 year period of approximately 3.8% annually (significant at the 95% confidence interval). This increase is dominated by statistically significant positive trends in melt coverage during July and August in the west and southwest of the ice sheet. We find that a linear correlation between microwave-derived melt extent and a surface measure of ablation rate is significant in June and July but not August, so caution must be exercised in using the microwave-derived melt extents in August. Nevertheless, knowledge of the variability of snowpack melt on the Greenland ice sheet as derived from microwave data should prove useful in detecting climate change in the Arctic and examining the impact of climate change on the ice sheet.