Information on the glacier velocity is imperative to understand the glacier ice volume, supraglacial feature evolution and glacier-climate interaction. The present study investigates annual velocities of the ablation zone (∼4500–4800 m asl) of Panchi Nala Glacier, western Himalaya through feature tracking. For this, multi-temporal Landsat (TM and OLI) and Sentinel −2 MSI images, acquired between 2000 and 2021, were correlated using the Co-registration of Optically Sensed Images and Correlation (COSI-Corr) tool. Results reveal a mean velocity of the ablation zone to be 10.6 ± 5.6 m/y during 2000–2021, with the highest (13.8 ± 4.6 m/y) and lowest velocity (8.9 ± 2.8 m/y) observed in 2005 and 2015, respectively. There is no significant trend in the velocity, rather it is highly heterogeneous on the inter-annual scale. Further, the influence of several factors such as slope, debris cover, altitude, annual average temperature and precipitation on the glacier velocity was investigated. Results indicate that the inter-annual heterogeneity in velocity is inversely correlated with the variation of summer precipitation implying that an increase in summer precipitation decreases the glacier velocity. The spatio-temporal velocity variations are also linked with the presence of supraglacial ponds, ice cliffs and heterogeneous debris distribution over the glacier. Findings indicate that, though annual glacier velocities have not changed significantly, their magnitudes are consistently low which coupled with consistent debris increase (19.74%) and gentle slope (8.2° over ablation zone) can promote rapid growth of supraglacial ponds and ice cliffs.

中文翻译：

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喜马拉雅山西部泮池那拉冰川消融区年流速变化趋势及控制因素

有关冰川速度的信息对于了解冰川冰量、冰上特征演化和冰川-气候相互作用至关重要。本研究通过特征跟踪研究了喜马拉雅山西部潘奇那拉冰川消融区（∼4500–4800 m asl）的年速度。为此，使用光学传感图像和相关性联合配准 (COSI-Corr) 工具对 2000 年至 2021 年期间获取的多时相 Landsat（TM 和 OLI）和 Sentinel −2 MSI 图像进行了关联。结果显示，2000年至2021年消融区的平均速度为10.6±5.6 m/y，其中2005年和2015年观测到的速度最高（13.8±4.6 m/y）和最低速度（8.9±2.8 m/y），分别。速度没有显着的趋势，而是在年际尺度上具有高度异质性。进一步研究了坡度、碎屑覆盖、海拔、年平均气温和降水量等因素对冰川速度的影响。结果表明，速度的年际异质性与夏季降水的变化呈负相关，这意味着夏季降水的增加会降低冰川的速度。时空速度变化也与冰川上池塘、冰崖和冰川上异质碎片分布的存在有关。研究结果表明，虽然年冰川速度没有显着变化，但其幅度始终较低，加上持续的碎屑增加（19.74％）和缓坡（消融区上方8.2°）可以促进冰上池塘和冰崖的快速生长。