Hydro-meteorological Correlations of Himalayan Glaciers: A Review

This review manuscript addresses hydro-meteorological correlations of various glaciers situated in the Himalayan region. Meteorological parameters influence the discharge pattern of the glacier. A strong correlation has been observed between discharge and air temperature of the studied Himalayan glaciers. Whereas, other meteorological parameters such as wind speed and wind direction etc. were not significantly correlated with the meltwater runoff of different glaciers in this region. In general, variability (Cv) in discharge from the various Himalayan glaciers such as Chhota Shigri and Gangotri glaciers follow the variability (Cv) in the temperature of these glaciers. Maximum variability (Cv) in meltwater runoff from the Chhota Shigri glacier has been reported in the month of September, which might be due to the fast decline in stream runoff and air temperature of the study area during the month of September. A strong relationship has been observed between suspended sediment concentration and temperature of the majority of studied Himalayan glaciers. Such type of result shows that the suspended sediment concentration in the glacial meltwater has increased with rising air temperature in this region.

Efficiency of artificial neural networks for glacier ice-thickness estimation: a case study in western Himalaya, India

Knowledge of glacier volume is crucial for ice flow modelling and predicting the impacts of climate change on glaciers. Rugged terrain, harsh weather conditions and logistic costs limit field-based ice thickness observations in the Himalaya. Remote-sensing applications, together with mathematical models, provide alternative techniques for glacier ice thickness and volume estimation. The objective of the present research is to assess the application of artificial neural network (ANN) modelling coupled with remote-sensing techniques to estimate ice thickness on individual glaciers with direct field measurements. We have developed two ANN models and estimated the ice thickness of Chhota Shigri Glacier (western Himalaya) on ten transverse cross sections and two longitudinal sections. The ANN model estimates agree well with ice thickness measurements from a ground-penetrating radar, available for five transverse cross sections on Chhota Shigri Glacier. The overall root mean square errors of the two ANN models are 24 and 13 m and the mean bias errors are ±13 and ±6 m, respectively, which are significantly lower than for other available models. The estimated mean ice thickness and volume for Chhota Shigri Glacier are 109 ± 17 m and 1.69 ± 0.26 km3, respectively.

Modelling mass changes of Dokriani (Central Himalaya) and Chhota Shigri (Western Himalaya) glaciers, India using energy balance approach

<p>Processes controlling the glacier wastage in the Himalaya are still poorly understood. In the present study, a surface energy-mass balance model is applied to reconstruct the long-term mass balances over 1979-2020 on two benchmark glaciers, Dokriani and Chhota Shigri, located in different climatic regimes. The model is forced with ERA5 reanalysis data and calibrated using field-observed point mass balances. The model is validated against available glacier-wide mass balances. Dokriani and Chhota Shigri glaciers show moderate wastage with a mean value of –0.28 and –0.34 m w.e. a<sup>-1</sup>, respectively over 1979-2020. The mean winter and summer glacier-wide mass balances are 0.44 and –0.72 m w.e. a<sup>-1</sup> for Dokriani Glacier and 0.53 and –0.85 m w.e. a<sup>-1</sup> for Chhota Shigri Glacier, respectively, showing a higher mass turn over on Chhota Shigri Glacier. Net radiation flux is the major component of surface energy balance followed by sensible and latent heat fluxes on both the glaciers. The losses through sublimation is around 10% to the total ablation. Surface albedo is one of the most important drivers controlling the annual mass balance of both Dokriani and Chhota Shigri glacier. Summer mass balance (0.76, p<0.05) mainly controls the annual glacier-wide mass balance on Dokriani Glacier whereas the summer (0.91, p<0.05) and winter (0.78, p<0.05) mass balances together control the annual glacier-wide mass balance on Chhota Shigri Glacier.</p>

Interrelationships among mass balance, meteorology, discharge, and surface velocity on Chhota Shigri Glacier over 2002-2019 using in-situ measurements

<p>Interrelationships among mass balance, meteorology, discharge, and surface velocity on Chhota Shigri Glacier over 2002-2019 using in-situ measurements</p><p> </p><p> </p><p>Arindan MANDAL<sup>1</sup>, AL. RAMANATHAN<sup>1*</sup>, Mohd. Farooq AZAM<sup>2</sup>, Thupstan ANGCHUK<sup>1</sup>, Mohd. SOHEB<sup>1</sup>, Naveen KUMAR<sup>1</sup>, Jose George POTTAKKAL<sup>3</sup>, Sarvagya VATSAL<sup>1</sup>, Somdutta MISHRA<sup>1</sup>, Virendra Bahadur SINGH<sup>1,4</sup></p><p><sup> </sup></p><p><sup>*</sup>Corresponding author email: [email protected]</p><p>The Himalayan glaciers contribute significantly to regional water resources. However, limited field observations restrict our understanding of glacier dynamics and behavior. Here, we investigated the long-term in-situ mass balance, meteorology, ice velocity, and discharge of the Chhota Shigri Glacier over the past two decades. With 17 years of uninterrupted glacier-wide mass balance datasets, Chhota Shigri Glacier is one of the most studied glaciers in the Hindu-Kush Himalayan region in terms of mass balance record. The mean annual glacier-wide mass balance was negative, -0.46±0.40 m w.e. a<sup>-1</sup> during 2002-2019 corresponding to a cumulative wastage of about -8 m w.e. Mean winter mass balance was 1.15 m w.e. a<sup>-1</sup> and summer mass balance was -1.35 m w.e. a<sup>-1 </sup>over 2009-2019. Surface ice velocity has decreased on average by 25-42% in the lower and middle ablation zone (below 4700 m a.s.l.) since 2003; however, no substantial change was observed at higher altitudes. The decrease in velocity suggests that the glacier is adjusting its flow in response to negative mass balance. The summer discharge begins to rise from May and peaks in July, with a contribution of 43%, followed by 38% and 19% in August and September, respectively. The discharge pattern closely follows the air temperature. The long-term observation on the Chhota Shigri — a benchmark — glacier, shows a mass wastage that corresponds to the glacier’s slowdown in the past two decades.</p><p> </p><p> </p>

Osmium isotope and trace elements reveal melting of Chhota Shigri Glacier, western Himalaya, insensitive to anthropogenic emission residues

The western Himalaya glaciers seasonally melt, in part, controlled by the presence of ice surface impurities in the form of dust, organic, and inorganic particles. The hitherto knowledge that dark-colored impurities on the ice surface are a mechanistic driver of heat absorption and thus enhancing ice mass wasting makes understanding the concentrations, origin, and pathways of emission residues on the glacier surface a global concern to conserve the Himalayan ice mass that provides water to more than one billion people. Yet, the source, origin, and pathways of metal impurities on the ice surface of Himalayan glaciers remain poorly constrained. Here, we present major and trace element geochemistry, rhenium-osmium (Re-Os) isotopes composition of cryoconite – a dark-colored aggregate of mineral and organic materials – on the ablation zone of the Chhota Shigri Glacier (CSG) considered as a benchmark glacier for process understanding in the western Himalaya. We find that the cryoconite possesses elemental ratios and crustal enrichment factor that reveal a predominant crustal source. Further, the 187Os/188Os composition in cryoconite varies from non-radiogenic (0.36) to radiogenic (1.31) compositions. Using a three-component isotope mixing model we show that the Os in cryoconite is dominantly derived from local rocks with negligible input from anthropogenic Os sources. Given that the CSG has limited debris cover (~ 3.4 %) and the near absence of anthropogenically derived particles; our results suggests that dark-colored surficial deposits of anthropogenic dust particles are not one of the significant drivers of glacier melting in the western Himalaya, as observed elsewhere.