Geodetic glacier mass balance (1975–1999) in the central Pamir using the SRTM DEM and KH-9 imagery

Yushan Zhou,Xiaoli Ding,Zhiwei Li,Jia Li,Rong Zhao

doi:10.1017/jog.2019.8

Yushan Zhou, Xiaoli Ding + Show 3 more

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https://doi.org/10.1017/jog.2019.8

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Abstract

ABSTRACTMultiple studies on regional glacier mass balance in the Pamir Mountains have been conducted using the geodetic method, but they were rarely extended to the period before 2000. In this study, we used KH-9 imagery acquired in 1975 to generate the historical DEM for the central Pamir, and then obtained the glacier elevation change by comparing this with the SRTM C-band DEM. The penetration depth of the C-band radar was corrected for different glacier surfaces, i.e. 2.96, 1.68 and 0 m for firn/snow cover, bare ice and debris-covered areas, respectively. The final results suggest that the central Pamir glaciers, overall, experienced a near-zero mass balance of −0.03 ± 0.24 m w.e. a−1 for 1975–99. Due to glacier surge activity, the elevation change patterns of individual glaciers were highly variable, and their mass balances varied from −0.12 ± 0.26 to 0.63 ± 0.20 m w.e. a−1. The mean mass budgets of the surge-type glaciers and non-surge-type glaciers were 0.03 ± 0.14 and −0.05 ± 0.28 m w.e. a−1, respectively. Concurring with previous studies, we conclude that the central Pamir glaciers may have been in a state of approximately balanced mass budget or slight mass deficit from the mid-1970s to the mid-2010s.

Highlights

Glacier mass balance, as one of the most direct and reliable indicators of climate change, can quantitatively reveal whether there has been mass gain or loss in a glacier system (Bolch and others, 2011; Gardelle and others, 2013)
The penetration difference estimate we obtained is close to that of Holzer and others (2015) in the bare ice areas (i.e. 1.68 versus 1.50 ± 0.90 m), but is lower than that in the firn/snow areas (2.96 versus 4.30 ± 0.90 m). The latter represents the average of the penetration depth estimation over three regions (Karakoram, Hindu Kush and Jammu Kashmir), which were calculated by extrapolating the ICESat trend to the moment of SRTM acquisition, theoretically reflecting an absolute penetration depth
Based on the early KH-9 stereo images and the 1 arc-second C-band SRTM DEM, this study evaluated the glacier mass change for 1975–99 in the central Pamir by employing the approach of DEM differencing

Summary

Introduction

As one of the most direct and reliable indicators of climate change, can quantitatively reveal whether there has been mass gain or loss in a glacier system (Bolch and others, 2011; Gardelle and others, 2013). Over the entire Pamir, field-based measurements of mass balance (i.e. the glaciological method) have mainly concentrated on several small glaciers that are easy to reach, revealing a highly variable pattern of mass change in both space and time. The use of ICESat laser altimetry products revealed a surface lowering of −0.13 ± 0.22 m a−1 for 2003–09 (Gardner and others, 2013) and −0.48 ± 0.14 m a−1 for 2003–08 (Kääb and others, 2015) The discrepancy between these results is mainly due to the fact that the surface elevation of the Pamir glaciers is highly variable at the inter-annual scale (Brun and others, 2017). The difference in the penetration depth correction of SRTM C-band radar

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