Mass Balance Variation and Associative Climate Drivers for the Dongkemadi Glacier in the Central Tibetan Plateau

Abstract

Glacier mass balance is a critical parameter in assessing glacial changes and meltwater runoff associated with climate change. This study used a modified distributed surface energy balance model at 3 hr temporal and 100‐ × 100‐m spatial resolutions to reconstruct a 1960–2009 mass balance time series of the alpine Dongkemadi Glacier in the central region of the Tibetan Plateau. The modified distributed surface energy balance model was able to reasonably simulate glacier mass balance estimations. The average annual mass balance of the reconstructed long‐term time series was −0.125 m w.e. (meter water equivalent), and the cumulative mass balance was −6.245 m w.e. throughout 1960–2009. Simulation results revealed that the glacier mass balance was more readily influenced by changes in air temperature (−362 mm w.e. [millimeter water equivalent]) than changes in precipitation (+138 mm w.e.). Therefore, a decreasing trend in the annual mass balance mainly derived from increasing air temperature throughout the simulated study period, although increasing precipitation inhibited the glacier ablation trend to some extent. Throughout 1960–2009, the glacial ablation zone expanded as shown by an increase in the equilibrium line altitude. This study offers comprehensive information on an important glacier monitored under harsh environmental conditions while aiding in our understanding of glacial response to climate change, using a method that can be applied to other glaciers to which mass balance observations are limited.

Long‐Term Temporal Scale‐Dependent Warming Effects on the Mass Balance in the Dongkemadi Glacier, Tibetan Plateau

“…For daily precipitation, multiple regression analysis showed that only the Tuotuohe station was significant (p < 0.05), and the precipitation series was obtained using elevation gradients between the Tuotuohe station and the DKMD Glacier. Interpolated data agreed well with AWS observations during the operating period (p < 0.01) (Liang et al, 2019).…”

“…Changes in glacier area were examined based on the glacier volume-area scaling relationship (Liu et al, 2003). The calculation of glacial volume and area followed the procedure of Liang et al (2019). The formula used is as follows:…”

“…Accordingly, warming effects on glaciers are predicted to differ at different timescales. Up to now, quantitative studies on the response of glaciers to historical warming (e.g., Liang et al, 2019) or studies on glacial evolution under prospective warming conditions (e.g., Li et al, 2017) have been limited and have only been conducted on an annual scale. In other words, no studies have reported on the degree of glacier mass balance overestimation using annual warming rate.…”

“…Except for those in the eastern Pamir and central Karakorum, glaciers on the Tibetan Plateau have experienced phenomenal retreat under climate change conditions, shrinking in both area and length and becoming thinner due to surface mass loss (Yao et al, 2012). Using empirically based statistical methods (e.g., Liu et al, 2019; Mu et al, 2019) or a physically based energy balance model (Liang et al, 2019), studies on both continental (in the northwest and central regions) and maritime (in the southeast region) glacial recession in the Tibetan Plateau have shown that among climate factors, increases in air temperature have had the greatest impact on glacial shrinkage. Warming promotes glacier ablation, resulting in negative effects on the glacier mass balance.…”

“…In this context, a comprehensive exploration on how warming impact the glacier mass balance associated with warming rates over various timescales is necessary. Accordingly, this study aimed to do so by employing a modified distributed surface energy balance model (DSEBM; Hock & Holmgren, 2005; Liang et al, 2018) to the Dongkemadi (DKMD) Glacier situated in the central Tibetan Plateau (Figure 1), which is a typical continental glacier influenced by westerlies during the cold season and by the Indian Monsoon during the warm season, possessing an adequate amount of long‐term meteorological and mass balance observations (for details see Liang et al, 2019). Specifically, the objectives of this study were ( i ) to construct long‐term detrended air temperature series from 1960 to 2009 in the DKMD Glacier with warming rates at annual, seasonal, and monthly scales and statistically compare any differences; ( ii ) to investigate warming effects on the mass balance under different warming rates using the DSEBM as well as different detrended air temperature series (using annual, seasonal, and monthly scale warming rates); and ( iii ) to explain mechanisms associated with mass balance changes by analyzing changes in glacier energy factors at three different warming rates.…”