Preprints
https://doi.org/10.5194/acp-2021-158
https://doi.org/10.5194/acp-2021-158

  26 Mar 2021

26 Mar 2021

Review status: this preprint is currently under review for the journal ACP.

Shift in seasonal snowpack melt-out date due to light-absorbing particles at a high-altitude site in Central Himalaya

Johan Ström1, Jonas Svensson2,3, Henri Honkanen4, Eija Asmi2, Nathaniel B. Dkhar5, Shresth Tayal5,6, Ved P. Sharma5,6, Rakesh Hooda5,6, Outi Meinander2, Matti Leppäranta4, Hans-Werner Jacobi3, Heikki Lihavainen7,2, and Antti Hyvärinen2 Johan Ström et al.
  • 1Department of Environmental Science, Stockholm University, Stockholm, Sweden
  • 2Atmospheric Composition Research, Finnish Meteorological Institute, Helsinki, Finland
  • 3Université Grenoble-Alpes, CNRS, IRD, INP-G, IGE, Grenoble, 38000, France
  • 4Institute for Atmospheric and Earth System Research, Faculty of Science, University of Helsinki, Helsinki, Finland
  • 5The Energy and Resource Institute, (TERI) New Delhi, India
  • 6TERI School of Advanced Studies (TERI SAS), New Delhi, India
  • 7Svalbard Integrated Arctic Earth Observing System, Longyearbyen, Norway

Abstract. Snow darkening by deposited light-absorbing particles (LAP) has the potential to accelerate snowmelt and shift the snow melt-out date. Here we investigate the sensitivity of the seasonal snow cover duration to changes in LAP at a high altitude valley site in the Central Himalayas, India. First, the variation of the albedo of the seasonal snow was emulated using two seasons of automatic weather station (AWS) data and applying a constant, but realistic deposition of LAP to the snow. Then, the number of days with snowmelt were evaluated based on the estimated net energy budget of the seasonal snow cover and the derived surface temperature. The impact on the energy budget by LAP combined with the melt-day analysis resulted in very simple relations to determine the contribution of LAP to the number of days with snowmelt of the seasonal snow in Himalaya. Above a concentration of 1 ng g-1 (Elemental Carbon equivalent, ECeq, which in this study includes EC and the absorption equivalent EC contribution by other light absorbing particles, such as mineral dust) in new snow, the number of days with snowmelt can be estimated by; days=0.0109(log⁡(〖EC〗_eq )+1)PP±0.0033(log⁡(〖EC〗_eq )+1)PP, where PP is the seasonal precipitation in mm snow water equivalent. A change in ECeq by a factor of two corresponds to about 1/3 of a day per 100 mm precipitation. Although the change in the number of days with melt caused by the changes in ECeq is small, the estimated total change in the snow melt-out date by LAP can be significant. For our realistic base case scenario for the Sunderdhunga Valley, Central Himalayas, India, of ECeq=100 ng g-1 and PP=400 mm, this yields in an advancement of the melt-out date of about 13 days.

Johan Ström et al.

Status: open (until 21 May 2021)

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Johan Ström et al.

Johan Ström et al.

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Short summary
Snow darkening in the Himalaya results from the deposition of different particles. Here we assess the change in the seasonal snow cover duration due to the presence of mineral dust and black carbon particles in the snow of Sunderdhunga valley, Central Himalaya, India. With the use of in situ weather station data, the snow melt-out date is estimated to be shifted ~13 days earlier due to the presence of the particles in the snow.
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