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Dust Responsible for Snowmelt in Western Himalayan Region

Dust Responsible for Snowmelt in Western Himalayan Region

Context:

A study published in the journal Nature Climate Change has found that the dust is responsible for snow-melt in the Western Himalayan Region.

Details:

  • The dust particles transported from Saudi Arabia that get deposited in the Western Himalayan Region i.e. Hindu Kush, Karakoram, and western Himalaya ranges have a large role to play in the melting of snow.
  • It is the first time the role of long-distance transported dust in elevational heterogeneity of snow melting in the Himalayas has been made.
  • The dust transported as elevated aerosol layers get deposited at 1-5 km elevation and the black carbon emission is mostly a surface phenomenon and influences the melting of snow from the surface to about 3 km elevation.

Key findings:

  • The authors of the study show that the relative impacts of dust and black carbon vary with a surface elevation of the snowpack.
  • The black carbon has a larger snow albedo darkening effect than dust due to larger mass absorption efficiency.
    • Albedo is the measurement of the reflectivity of an object. It is the measure of the diffuse reflection of solar radiation out of the total solar radiation received by an astronomical body. Every object has a different albedo.
  • The study found that the radiative effects of dust deposited on snow are comparable to black carbon in the Western Himalayan Region at higher elevations.
    • It is mainly because the deposition of dust by mass is 100-1,000 times more than black carbon.
  • As the elevation increases, the influence of dust becomes greater than black carbon and the phenomenon coincides with the maximum intensity of snowmelt reduction seen at 3-5 km elevation.

Black Carbon:

  • The study found out that black carbon mainly contributes to snowmelt at lower elevation while dust is the major contributor for snowmelt at a higher elevation.
  • The Westerlies transport dust particles as elevated aerosol layers at maximum intensities mostly during the pre-monsoon period  and it gets deposited at higher elevations in the western Himalayan region.
  • The annual contribution of dust to snowmelt is likely to increase in the future as the black carbon effect at lower elevation weakens with dwindling snowpack due to the effect of global warming.

Source: The Hindu