Total Water Storage and Satellites

High Mountain Asia's hydrological cycle is dominated by changes in glaciers that affect water resources and impact 1.9 billion people living in or directly downstream of (1.6 billion) densely populated areas of India, Nepal, Bhutan, Pakistan, and many others, and significantly contributes to sea-level rise. Previous records indicate sustained HMA glacier mass loss since ~1850, with accelerated loss in recent decades attributed to atmospheric warming based on various glacier measurement techniques, and recently with data from the Gravity Recovery and Climate Experiment (GRACE) and other satellite imagery. 

During my master's degree, I investigated the mass and energy balance study of three glaciers in the Central Himalayas in the High Mountain Asia or the Himalayas using in-situ measurements and an energy balance model. In this, three debris-free glaciers with strongly differing annual glaciological glacier-wide mass balances (MBs) are monitored in the Everest region (central Himalaya, Nepal), where the mass budget of Mera Glacier (5.1 km ² in 2012), located in the southern part of this region, Pokalde (0.1 km ² in 2011) and West Changri Nup glaciers (0.9 km ² in 2013), ~30 km further north are examined. The main objectives of this study are to (i) present results from extensive MB measurements performed on debris-free Mera, Pokalde, and West Changri Nup glaciers in the Everest region since 2007, and (ii) identify the drivers explaining the MB differences between these glaciers using previously unpublished meteorological data recorded at the glacier elevations. A special focus is directed to the West Changri Nup Glacier whose measuring network is described for the first time. In addition, new data are presented from the Mera and Pokalde glaciers for 2012–15 to extend the MB time series previously reported until 2012 by Wagnon and others (2013). I was able to produce the longest time series of mass balance changes using in-situ observation (See below). 

Fig. 1. Annual (histograms) and cumulative (line with dots) MBs of Mera (blue), Pokalde (green) and Changri Nup (red) glaciers, respectively. The inset shows the annual centered MB (i.e. annual Ba – 2010–15 mean Ba) for every glacier, over the period 2010–15.

During my Ph.D., I expanded my local-scale, in-situ glacier mass analysis to the regional scale. This research aimed to investigate the impacts of climate warming and monsoon intensity changes on regional-scale total water storage and glacier mass change. To achieve this, I utilized gravity data sources such as the Gravity Recovery and Climate Experiment and Follow-up Mission Data (GRACE/FO), along with other hydrological data, including in-situ groundwater measurements, soil moisture, snow cover, and surface water. Our unique approach involved estimating and removing groundwater data from 6171 in-situ measurements, providing valuable insights into ice mass changes using GRACE/FO data, and processing signals to understand the relation with changing precipitation patterns. 

Related Publications

1. Sherpa, S. F., Wagnon, P., Brun, F., Bertheir, E., Vincent, C., Lejeune, Y., Arnaud Y., Kayastha, R.B., Sinisalo, A. (2017). Contrasted surface mass balances of debris-free glaciers observed between the southern and the inner parts of the Everest region (2007–15). Journal of Glaciology, 1-15. doi:10.1017/jog.2017.30.

2. Vincent, C., Wagnon, P., Shea, J. M., Immerzeel, W. W., Kraaijenbrink, P., Shrestha, D., Soruco, A., Arnaud, Y., Brun, F., Berthier, E., and Sherpa, S. F. (2016). Reduced melt on debris-covered glaciers: investigations from Changri Nup Glacier, Nepal. The Cryosphere, 10, 1845-1858, https://doi.org/10.5194/tc-10-1845-2016.

Manuscript Submitted and in Prep.

3. Sherpa, S.F., & Werth, S., (Under Review). Accelerated Melting of High Mountain Asia Glaciers Due to Increased South Asian Monsoon Intensity.

Conference Abstracts #Talk 

1. Sherpa, S.F., Werth, S. & Shirzaei, M. (2021). Association between Changes in Glacier Mass and Climate Seasonality Revealed from GRACE/FO in High Mountain Asia. Poster presented at American Geophysical (AGU) Conference, December 13, 2021, New Orleans, USA. 

2. #Sherpa, S.F., & Werth, S. et al., (2019). Climate Sensitivity of the Glacier Mass Budget of High Mountain Asia Based on Satellite Gravimetry. In AGU Conference, High Mountain Asia’s Cryosphere Research to Address Climate, Hydrology, Geodynamics, and Hazards session. December 12, 2019, San Francisco, USA.

3. #Sherpa S.F., Myint, S. (2018). Space-Time Analysis of Variation of Snow and Ice in Nepal, Himalaya from 2001-2016, International Symposium on Timescales, Processes and Glacier Dynamics International Glaciological Society, in Buffalo, New York, USA.

Also, see below for follow-up work on Mera Glacier (glacier very close to my heart)

• Wagnon, P., Brun, F., Khadka, A., Berthier, E., Shrestha, D., Vincent, C., ... & Jomelli, V. (2021). Reanalysing the 2007–19 glaciological mass-balance series of Mera Glacier, Nepal, Central Himalaya, using geodetic mass balance. Journal of Glaciology, 67(261), 117-125.