title: Missing (in-situ) snow cover data hampers climate change and runoff studies in the Greater Himalayas.
abstract: The Himalayas are presently holding the largest ice masses outside the polar regions and thus (temporarily) store important freshwater resources. In contrast to the contemplation of glaciers, the role of runoff from snow cover has received comparably little attention in the past, although (i) its contribution is thought to be at least equally or even more important than that of ice melt in many Himalayan catchments and (ii) climate change is expected to have widespread and significant consequences on snowmelt runoff. Here, we show that change assessment of snowmelt runoff and its timing is not as straightforward as often postulated, mainly as larger partial pressure of H2O, CO2, CH4, and other greenhouse gases might increase net long-wave input for snowmelt quite significantly in a future atmosphere. In addition, changes in the short-wave energy balance - such as the pollution of the snow cover through black carbon - or the sensible or latent heat contribution to snowmelt are likely to alter future snowmelt and runoff characteristics as well. For the assessment of snow cover extent and depletion, but also for its monitoring over the extremely large areas of the Himalayas, remote sensing has been used in the past and is likely to become even more important in the future. However, for the calibration and validation of remotely-sensed data, and even more so in light of possible changes in snow-cover energy balance, we strongly call for more in-situ measurements across the Himalayas, in particular for daily data on new snow and snow cover water equivalent, or the respective energy balance components. Moreover, data should be made accessible to the scientific community, so that the latter can more accurately estimate climate change impacts on Himalayan snow cover and possible consequences thereof on runoff.
authors.affiliation: Meteodat GmbH, Technoparkstrasse 1, CH-8005 Zurich, Switzerland.
authors.forename: Mario
authors.initials: M
authors.lastname: Rohrer
authors.affiliation: Department of Geosciences, Geography, University of Fribourg, Chemin du Musée 4, CH-1700 Fribourg, Switzerland.
authors.forename: Nadine
authors.initials: N
authors.lastname: Salzmann
authors.affiliation: Institute for Environmental Sciences, University of Geneva, Chemin de Drize 7, CH-1227 Carouge, Geneva, Switzerland; Dendrolab.ch, Institute of Geological Sciences, University of Bern, Baltzerstrasse 1+3, CH-3012 Bern, Switzerland. Electronic address: markus.stoffel@unige.ch.
authors.forename: Markus
authors.initials: M
authors.lastname: Stoffel
authors.affiliation: Divecha Center for Climate Change, Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bangalore 560 012, India.
authors.forename: Anil V
authors.initials: AV
authors.lastname: Kulkarni
mesh_terms: D057231:Climate Change; D004784:Environmental Monitoring; D046448:Ice Cover; D007194:India; D012914:Snow; D014872:Water Movements; D062066:Water Resources / Q000706:statistics & numerical data; D014881:Water Supply / Q000706:statistics & numerical data
keywords: Climate change; Himalayas; In-situ measurements; Remote sensing; Snow cover