Journal of Earth System Science ( IF 1.3 ) Pub Date : 2022-09-30 , DOI: 10.1007/s12040-022-01962-6 Ankit Pandey , Purushottam Kumar Garg , Harish Chandra Nainwal , Bhanu Prakash Rathore , Ish Mohan Bahuguna
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Abstract
We examined the two neighbouring Raj Bank and Kosa glaciers of the upper Dhauliganga catchment of Uttarakhand, central Himalaya, India, to assess their variability towards climate change. We performed the analysis of multiple satellite images for the period of 1962–2019 and field-based GNSS data obtained during 2018–2019. Length change, area change, debris cover area, and snowline altitude (SLA) were obtained using that. During the last 57 years (1962–2019), the Raj Bank and Kosa glaciers lost 2.43% (0.32 km2 or 0.006 km2 a−1) and 4.54% (0.45 km2 or 0.008 km2 a−1) area; and for the same time span, their frontal retreat was estimated 639.39 m (11.22 m a−1) and 206.71 m (3.69 m a−1), respectively. The study also depicts that from 1968 to 2019, the Raj Bank glacier shows a significant increase in the debris cover area of 4.41%, while in the Kosa glacier, it was 4.08% only. Between 1968 and 2017, the SLA of the Raj Bank and Kosa glaciers shifted on an average by 82 and 71 m upwards, respectively. Loss in glacial area, enhanced debris cover area, and shift in SLA are the indicators of ice volume loss under the present climatic scenario.
Research highlights
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Our findings show that both the neighbouring glaciers (Raj Bank and Kosa) not only losing their area and length, but also show an upshifts of the SLAs during the last 57 years (1962-2019).
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The debris cover areas of the glaciers are also increased during the study period.
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The retreat rate of the Raj Bank glacier was found higher compared to the Kosa glacier.
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During the above-mentioned study period, length wise a reduction of 6.2% and 1.8% was observed in the Raj bank and Kosa glaciers, while both the glaciers lost about 2.43% and 4.54% area respectively from 1962 to 2019.
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Besides global warming, we observed that the role of local topographical factors (i.e. altitude, size, slope, aspect and debris cover) have significant impact on glacial dynamics.
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The frontal retreat and area loss of both the glaciers suggest negative mass balance in response to the ongoing temperature rise.
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The observed heterogeneity in various glacier parameters of these two neighbouring glaciers is probably topographically induced.
中文翻译：
1962 年至 2019 年印度喜马拉雅中部道利甘加盆地两个相邻冰川（Raj Bank 和 Kosa）的比较评估
摘要
我们检查了印度喜马拉雅中部北阿坎德邦上道利甘加流域的两个相邻的 Raj Bank 和 Kosa 冰川，以评估它们对气候变化的可变性。我们对 1962-2019 年期间的多个卫星图像和 2018-2019 年期间获得的基于现场的 GNSS 数据进行了分析。使用它获得长度变化、面积变化、碎片覆盖面积和雪线高度（SLA）。在过去 57 年（1962-2019 年）中，Raj Bank 和 Kosa 冰川减少了 2.43%（0.32 km 2或 0.006 km 2 a -1）和 4.54%（0.45 km 2或 0.008 km 2 a -1）面积；在同一时间跨度内，它们的正面后退估计为 639.39 m（11.22 ma -1) 和 206.71 m (3.69 ma -1 )。该研究还描绘，从 1968 年到 2019 年，Raj Bank 冰川的碎片覆盖面积显着增加了 4.41%，而在 Kosa 冰川，仅为 4.08%。1968 年至 2017 年间，Raj Bank 和 Kosa 冰川的 SLA 平均分别向上移动了 82 和 71 m。冰川面积的减少、碎片覆盖面积的增加和 SLA 的变化是当前气候情景下冰量损失的指标。
研究亮点
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我们的研究结果表明，邻近的冰川（Raj Bank 和 Kosa）不仅失去了面积和长度，而且在过去 57 年（1962-2019 年）中显示出 SLA 的上升趋势。
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在研究期间，冰川的碎片覆盖面积也有所增加。
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与科萨冰川相比，发现拉杰银行冰川的退缩率更高。
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在上述研究期间，拉吉河岸和科萨冰川的长度分别减少了 6.2% 和 1.8%，而从 1962 年到 2019 年，这两个冰川的面积分别减少了约 2.43% 和 4.54%。
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除了全球变暖，我们观察到当地地形因素（即海拔、大小、坡度、坡向和碎片覆盖）对冰川动力学的影响很大。
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两条冰川的正面退缩和面积损失表明，由于持续的温度升高，质量出现负平衡。
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在这两个相邻冰川的各种冰川参数中观察到的异质性可能是地形引起的。
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