Few glaciological field data are available on
glaciers in the Hindu Kush–Karakoram–Himalayan (HKH... more Few glaciological field data are available on glaciers in the Hindu Kush–Karakoram–Himalayan (HKH) region, and remote sensing data are thus critical for glacier studies in this region. The main objectives of this study are to document, using satellite images, the seasonal changes of surface albedo for two Himalayan glaciers, Chhota Shigri Glacier (Himachal Pradesh, India) and Mera Glacier (Everest region, Nepal), and to reconstruct the annual mass balance of these glaciers based on the albedo data. Albedo is retrieved from Moderate Resolution Imaging Spectroradiometer (MODIS) images, and evaluated using ground based measurements. At both sites, we find high coefficients of determination between annual minimum albedo averaged over the glacier (AMAAG) and glacier-wide annual mass balance (Ba) measured with the glaciological method (R2 D0.75). At Chhota Shigri Glacier, the relation between AMAAG found at the end of the ablation season and Ba suggests that AMAAG can be used as a proxy for the maximum snow line altitude or equilibrium line altitude (ELA) on winteraccumulation- type glaciers in the Himalayas. However, for the summer-accumulation-type Mera Glacier, our approach relied on the hypothesis that ELA information is preserved during the monsoon. At Mera Glacier, cloud obscuration and snow accumulation limits the detection of albedo during the monsoon, but snow redistribution and sublimation in the post-monsoon period allows for the calculation of AMAAG. Reconstructed Ba at Chhota Shigri Glacier agrees with mass balances previously reconstructed using a positive degreeday method. Reconstructed Ba at Mera Glacier is affected by heavy cloud cover during the monsoon, which systematically limited our ability to observe AMAAG at the end of the melting period. In addition, the relation between AMAAG and Ba is constrained over a shorter time period for Mera Glacier (6 years) than for Chhota Shigri Glacier (11 years). Thus the mass balance reconstruction is less robust for Mera Glacier than for Chhota Shigri Glacier. However our method shows promising results and may be used to reconstruct the annual mass balance of glaciers with contrasted seasonal cycles in the western part of the HKH mountain range since the early 2000s when MODIS images became available.
ABSTRACT The volume change of Chhota Shigri Glacier (India, 32° N) between 1988 and 2010 has been... more ABSTRACT The volume change of Chhota Shigri Glacier (India, 32° N) between 1988 and 2010 has been determined using in-situ geodetic measurements. This glacier has experienced only a slight mass loss over the last 22 yr (-3.8 ± 1.8 m w.e.). Using satellite digital elevation models (DEM) differencing and field measurements, we measure a negative mass balance (MB) between 1999 and 2011 (-4.7 ± 1.8 m w.e.). Thus, we deduce a positive MB between 1988 and 1999 (+1.0 ± 2.5 m w.e.). Furthermore, satellite DEM differencing reveals a good correspondence between the MB of Chhota Shigri Glacier and the MB of an over 2000 km2 glaciarized area in the Lahaul and Spiti region during 1999-2011. We conclude that there has been no large ice wastage in this region over the last 22 yr, ice mass loss being limited to the last decade. This contrasts to the most recent compilation of MB data in the Himalayan range that indicates ice wastage since 1975, accelerating after 1990. For the rest of western Himalaya, available observations of glacier MBs are too sparse and discontinuous to provide a clear and relevant regional pattern of glacier volume change over the last two decades.
Surface digital elevation models (DEMs) and slope-related estimates of glacier thickness enable m... more Surface digital elevation models (DEMs) and slope-related estimates of glacier thickness enable modelling of glacier-bed topographies over large ice-covered areas. Due to the erosive power of glaciers, such bed topographies can contain numerous overdeepenings, which when exposed following glacier retreat may fill with water and form new lakes. In this study, the bed overdeepenings for �28000 glaciers (40775km2) of the Himalaya–Karakoram region are modelled using GlabTop2 (Glacier Bed Topography model version 2), in which ice thickness is inferred from surface slope by parameterizing basal shear stress as a function of elevation range for each glacier. The modelled ice thicknesses are uncertain (�30%), but spatial patterns of ice thickness and bed elevation primarily depend on surface slopes as derived from the DEM and, hence, are more robust. About 16000 overdeepenings larger than 104m2 were detected in the modelled glacier beds, covering an area of �2200km2 and having a volume of �120km3 (3–4% of present-day glacier volume). About 5000 of these overdeepenings (1800km2) have a volume larger than 106m3. The results presented here are useful for anticipating landscape evolution and potential future lake formation with associated opportunities (tourism, hydropower) and risks (lake outbursts).
Few glaciological field data are available on glaciers in the Hindu Kush–Karakoram–Himalayan (HKH... more Few glaciological field data are available on glaciers in the Hindu Kush–Karakoram–Himalayan (HKH) region, and remote sensing data are thus critical for glacier studies in this region. The main objectives of this study are to document, using satellite images, the seasonal changes of surface albedo for two Himalayan glaciers, Chhota Shigri Glacier (Himachal Pradesh, India) and Mera Glacier (Everest region, Nepal), and to reconstruct the annual mass balance of these glaciers based on the albedo data. Albedo is retrieved from Moderate Resolution Imaging Spectroradiometer (MODIS) images, and evaluated using ground based measurements. At both sites, we find high coefficients of determination between annual minimum albedo averaged over the glacier (AMAAG) and glacier-wide annual mass balance (Ba) measured with the glaciological method (R2 D 0.75). At Chhota Shigri Glacier, the relation between AMAAG found at the end of the ablation season and Ba suggests that AMAAG can be used as a proxy for the maximum snow line altitude or equilibrium line altitude (ELA) on winteraccumulation-type glaciers in the Himalayas. However, for the summer-accumulation-type Mera Glacier, our approach relied on the hypothesis that ELA information is preserved during the monsoon. At Mera Glacier, cloud obscuration and snow accumulation limits the detection of albedo during the monsoon, but snow redistribution and sublimation in the post-monsoon period allows for the calculation of AMAAG. Reconstructed Ba at Chhota Shigri Glacier agrees with mass balances previously reconstructed using a positive degreeday method. Reconstructed Ba at Mera Glacier is affected by heavy cloud cover during the monsoon, which systematically limited our ability to observe AMAAG at the end of the melting period. In addition, the relation between AMAAG and Ba is constrained over a shorter time period for Mera Glacier (6years) than for Chhota Shigri Glacier (11years). Thus the mass balance reconstruction is less robust for Mera Glacier than for Chhota Shigri Glacier. However our method shows promising results and may be used to reconstruct the annual mass balance of glaciers with contrasted seasonal cycles in the western part of the HKH mountain range since the early 2000s when MODIS images became available.
Some recent studies revealed that Himalayan
glaciers were shrinking at an accelerated rate since ... more Some recent studies revealed that Himalayan glaciers were shrinking at an accelerated rate since the beginning of the 21st century. However, the climatic causes for this shrinkage remain unclear given that surface energy balance studies are almost nonexistent in this region. In this study, a point-scale surface energy balance analysis was performed using in situ meteorological data from the ablation zone of Chhota Shigri Glacier over two separate periods (August 2012 to February 2013 and July to October 2013) in order to understand the response of mass balance to climatic variables. Energy balance numerical modelling provides quantification of the surface energy fluxes and identification of the factors affecting glacier mass balance. The model was validated by comparing the computed and observed ablation and surface temperature data. During the summer-monsoon period, net radiation was the primary component of the surface energy balance accounting for 80% of the total heat flux followed by turbulent sensible (13 %), latent (5 %) and conductive (2 %) heat fluxes. A striking feature of the energy balance is the positive turbulent latent heat flux, suggesting re-sublimation of moist air at the glacier surface, during the summer-monsoon characterized by relatively high air temperature, high relative humidity and a continual melting surface. The impact of the Indian Summer Monsoon on Chhota Shigri Glacier mass balance has also been assessed. This analysis demonstrates that the intensity of snowfall events during the summer-monsoon plays a key role on surface albedo (melting is reduced in the case of strong snowfalls covering the glacier area), and thus is among the most important drivers controlling the annual mass balance of the glacier. The summer-monsoon air temperature, controlling the precipitation phase (rain versus snow and thus albedo), counts, indirectly, also among the most important drivers.
Some recent studies revealed that Himalayan
glaciers were shrinking at an accelerated rate since ... more Some recent studies revealed that Himalayan glaciers were shrinking at an accelerated rate since the beginning of the 21st century. However, the climatic causes for this shrinkage remain unclear given that surface energy balance studies are almost nonexistent in this region. In this study, a point-scale surface energy balance analysis was performed using in situ meteorological data from the ablation zone of Chhota Shigri Glacier over two separate periods (August 2012 to February 2013 and July to October 2013) in order to understand the response of mass balance to climatic variables. Energy balance numerical modelling provides quantification of the surface energy fluxes and identification of the factors affecting glacier mass balance. The model was validated by comparing the computed and observed ablation and surface temperature data. During the summer-monsoon period, net radiation was the primary component of the surface energy balance accounting for 80% of the total heat flux followed by turbulent sensible (13 %), latent (5 %) and conductive (2 %) heat fluxes. A striking feature of the energy balance is the positive turbulent latent heat flux, suggesting re-sublimation of moist air at the glacier surface, during the summer-monsoon characterized by relatively high air temperature, high relative humidity and a continual melting surface. The impact of the Indian Summer Monsoon on Chhota Shigri Glacier mass balance has also been assessed. This analysis demonstrates that the intensity of snowfall events during the summer-monsoon plays a key role on surface albedo (melting is reduced in the case of strong snowfalls covering the glacier area), and thus is among the most important drivers controlling the annual mass balance of the glacier. The summer-monsoon air temperature, controlling the precipitation phase (rain versus snow and thus albedo), counts, indirectly, also among the most important drivers.
An attempt has been made to characterize the subglacial
pathways that transport the meltwaters fr... more An attempt has been made to characterize the subglacial pathways that transport the meltwaters from Chaturangi and Raktavarn glaciers through the lower ablation zone of the Gangotri glacier, Indian Himalaya, by means of dye tracer experiments. These inactive tributaries of the Gangotri glacier contribute significantly to the proglacial discharge, which is dominantly controlled by air temperature (0–20C at the measurement site) rather than rainfall (117 mm from June to September 2008). The breakthrough flow velocities, ranging from 0.6 to 1.7 ms–1 and dispersivity values varying between 2.1 and 17.5 m, decreased with bulk discharges in the proglacial stream (R2 = 0.66), indicating flow through highly efficient subglacial channels that develop during the melt season with increased meltwater influx. However, the dye return curves giving high velocities in a narrow range from 1.3 to 1.7 ms–1 as seasonal discharges were peaking, are interpreted as indicative of flow through pressurized channel/s. In general, the subglacial channels routing meltwater from these input points are arguably controlled by recharge hydrographs rather than channel geometry during the ablation season. Closely spaced dye tests need to be carried out to better understand the factors that control the diurnal and seasonal development of these hydrological pathways, which are important for downstream water management.
The volume change of the Chhota Shigri Glacier
(India, 32 20 N, 77 300 E) between 1988 and 201... more The volume change of the Chhota Shigri Glacier
(India, 32 20 N, 77 300 E) between 1988 and 2010 has
been determined using in situ geodetic measurements.
This glacier has experienced only a slight mass loss
between 1988 and 2010 (–3.8±2.0mw.e. (water equivalent)
corresponding to –0.17 pm 0.09mw.e. yr−1). Using
satellite digital elevation models (DEM) differencing and
field measurements, we measure a negative mass balance
(MB) between 1999 and 2010 (–4.8±1.8mw.e. corresponding
to –0.44±0.16mw.e. yr−1). Thus, we
deduce a slightly positive or near-zero MB between
1988 and 1999 (+1.0±2.7mw.e. corresponding to
+0.09±0.24mw.e. yr−1). Furthermore, satellite DEM
differencing reveals that the MB of the Chhota Shigri
Glacier (–0.39 pm 0.15mw.e. yr−1) has been only slightly
less negative than the MB of a 2110 km2 glaciarized area
in the Lahaul and Spiti region (–0.44±0.09mw.e. yr−1)
during 1999–2011. Hence, we conclude that the ice wastage
is probably moderate in this region over the last 22 yr, with
near equilibrium conditions during the nineties, and an ice
mass loss after. The turning point from balanced to negative
mass budget is not known but lies probably in the late
nineties and at the latest in 1999. This positive or near-zero
MB for Chhota Shigri Glacier (and probably for the surrounding
glaciers of the Lahaul and Spiti region) during at
least part of the 1990s contrasts with a recent compilation of
MB data in the Himalayan range that indicated ice wastage
since 1975. However, in agreement with this compilation,
we confirm more negative balances since the beginning of
the 21st century.
This study presents a reconstruction of the mass balance (MB) of Chhota Shigri glacier, Western H... more This study presents a reconstruction of the mass balance (MB) of Chhota Shigri glacier, Western Himalaya, India, and discusses the regional climatic drivers responsible for its evolution since
1969. The MB is reconstructed by a temperature-index and an accumulation model using daily air temperature and precipitation records from the nearest meteorological station, at Bhuntar
Observatory. The only adjusted parameter is the altitudinal precipitation gradient. The model is calibrated against 10 years of annual altitudinal MB measurements between 2002 and 2012 and
decadal cumulative MBs between 1988 and 2010. Three periods were distinguished in the MB series. Periods I (1969–85) and III (2001–12) show significant mass loss at MB rates of –0.36 +/-0.36 and –0.57 +/- 0.36mw.e. a–1 respectively, whereas period II (1986–2000) exhibits steady-state conditions with average MBs of –0.01 +/- 0.36 mw.e. a–1. The comparison among these three periods suggests that winter precipitation and summer temperature are almost equally important drivers controlling the MB pattern of Chhota Shigri glacier at decadal scale. The sensitivity of the modelled glacier-wide MB to temperature is –0.52 mw.e. a–1 C–1 whereas the sensitivity to precipitation is calculated as 0.16 mw.e. a–1 for a 10% change.
"Mass-balance and dynamic behaviour of Chhota Shigri glacier, western Himalaya, India, has been i... more "Mass-balance and dynamic behaviour of Chhota Shigri glacier, western Himalaya, India, has been investigated between 2002 and 2010 and compared to data collected in 1987–89. During the period 2002–10, the glacier experienced a negative glacier-wide mass balance of –0.670.40m w.e. a–1. Between 2003 and 2010, elevation and ice-flow velocities slowly decreased in the ablation area, leading to a 24–37% reduction in ice fluxes, an expected response of the glacier dynamics to its
recent negative mass balances. The reduced ice fluxes are still far larger than the balance fluxes calculated from the 2002–10 average surface mass balances. Therefore, further slowdown, thinning and terminus retreat of Chhota Shigri glacier are expected over the next few years. Conversely, the 2003/04
ice fluxes are in good agreement with ice fluxes calculated assuming that the glacier-wide mass balance is zero. Given the limited velocity change between 1987–89 and 2003/04 and the small terminus change between 1988 and 2010, we suggest that the glacier has experienced a period of near-zero or slightly positive mass balance in the 1990s, before shifting to a strong imbalance in the 21st century. This result challenges the generally accepted idea that glaciers in the Western Himalaya have been shrinking rapidly for the last few decades."
Few glaciological field data are available on
glaciers in the Hindu Kush–Karakoram–Himalayan (HKH... more Few glaciological field data are available on glaciers in the Hindu Kush–Karakoram–Himalayan (HKH) region, and remote sensing data are thus critical for glacier studies in this region. The main objectives of this study are to document, using satellite images, the seasonal changes of surface albedo for two Himalayan glaciers, Chhota Shigri Glacier (Himachal Pradesh, India) and Mera Glacier (Everest region, Nepal), and to reconstruct the annual mass balance of these glaciers based on the albedo data. Albedo is retrieved from Moderate Resolution Imaging Spectroradiometer (MODIS) images, and evaluated using ground based measurements. At both sites, we find high coefficients of determination between annual minimum albedo averaged over the glacier (AMAAG) and glacier-wide annual mass balance (Ba) measured with the glaciological method (R2 D0.75). At Chhota Shigri Glacier, the relation between AMAAG found at the end of the ablation season and Ba suggests that AMAAG can be used as a proxy for the maximum snow line altitude or equilibrium line altitude (ELA) on winteraccumulation- type glaciers in the Himalayas. However, for the summer-accumulation-type Mera Glacier, our approach relied on the hypothesis that ELA information is preserved during the monsoon. At Mera Glacier, cloud obscuration and snow accumulation limits the detection of albedo during the monsoon, but snow redistribution and sublimation in the post-monsoon period allows for the calculation of AMAAG. Reconstructed Ba at Chhota Shigri Glacier agrees with mass balances previously reconstructed using a positive degreeday method. Reconstructed Ba at Mera Glacier is affected by heavy cloud cover during the monsoon, which systematically limited our ability to observe AMAAG at the end of the melting period. In addition, the relation between AMAAG and Ba is constrained over a shorter time period for Mera Glacier (6 years) than for Chhota Shigri Glacier (11 years). Thus the mass balance reconstruction is less robust for Mera Glacier than for Chhota Shigri Glacier. However our method shows promising results and may be used to reconstruct the annual mass balance of glaciers with contrasted seasonal cycles in the western part of the HKH mountain range since the early 2000s when MODIS images became available.
ABSTRACT The volume change of Chhota Shigri Glacier (India, 32° N) between 1988 and 2010 has been... more ABSTRACT The volume change of Chhota Shigri Glacier (India, 32° N) between 1988 and 2010 has been determined using in-situ geodetic measurements. This glacier has experienced only a slight mass loss over the last 22 yr (-3.8 ± 1.8 m w.e.). Using satellite digital elevation models (DEM) differencing and field measurements, we measure a negative mass balance (MB) between 1999 and 2011 (-4.7 ± 1.8 m w.e.). Thus, we deduce a positive MB between 1988 and 1999 (+1.0 ± 2.5 m w.e.). Furthermore, satellite DEM differencing reveals a good correspondence between the MB of Chhota Shigri Glacier and the MB of an over 2000 km2 glaciarized area in the Lahaul and Spiti region during 1999-2011. We conclude that there has been no large ice wastage in this region over the last 22 yr, ice mass loss being limited to the last decade. This contrasts to the most recent compilation of MB data in the Himalayan range that indicates ice wastage since 1975, accelerating after 1990. For the rest of western Himalaya, available observations of glacier MBs are too sparse and discontinuous to provide a clear and relevant regional pattern of glacier volume change over the last two decades.
Surface digital elevation models (DEMs) and slope-related estimates of glacier thickness enable m... more Surface digital elevation models (DEMs) and slope-related estimates of glacier thickness enable modelling of glacier-bed topographies over large ice-covered areas. Due to the erosive power of glaciers, such bed topographies can contain numerous overdeepenings, which when exposed following glacier retreat may fill with water and form new lakes. In this study, the bed overdeepenings for �28000 glaciers (40775km2) of the Himalaya–Karakoram region are modelled using GlabTop2 (Glacier Bed Topography model version 2), in which ice thickness is inferred from surface slope by parameterizing basal shear stress as a function of elevation range for each glacier. The modelled ice thicknesses are uncertain (�30%), but spatial patterns of ice thickness and bed elevation primarily depend on surface slopes as derived from the DEM and, hence, are more robust. About 16000 overdeepenings larger than 104m2 were detected in the modelled glacier beds, covering an area of �2200km2 and having a volume of �120km3 (3–4% of present-day glacier volume). About 5000 of these overdeepenings (1800km2) have a volume larger than 106m3. The results presented here are useful for anticipating landscape evolution and potential future lake formation with associated opportunities (tourism, hydropower) and risks (lake outbursts).
Few glaciological field data are available on glaciers in the Hindu Kush–Karakoram–Himalayan (HKH... more Few glaciological field data are available on glaciers in the Hindu Kush–Karakoram–Himalayan (HKH) region, and remote sensing data are thus critical for glacier studies in this region. The main objectives of this study are to document, using satellite images, the seasonal changes of surface albedo for two Himalayan glaciers, Chhota Shigri Glacier (Himachal Pradesh, India) and Mera Glacier (Everest region, Nepal), and to reconstruct the annual mass balance of these glaciers based on the albedo data. Albedo is retrieved from Moderate Resolution Imaging Spectroradiometer (MODIS) images, and evaluated using ground based measurements. At both sites, we find high coefficients of determination between annual minimum albedo averaged over the glacier (AMAAG) and glacier-wide annual mass balance (Ba) measured with the glaciological method (R2 D 0.75). At Chhota Shigri Glacier, the relation between AMAAG found at the end of the ablation season and Ba suggests that AMAAG can be used as a proxy for the maximum snow line altitude or equilibrium line altitude (ELA) on winteraccumulation-type glaciers in the Himalayas. However, for the summer-accumulation-type Mera Glacier, our approach relied on the hypothesis that ELA information is preserved during the monsoon. At Mera Glacier, cloud obscuration and snow accumulation limits the detection of albedo during the monsoon, but snow redistribution and sublimation in the post-monsoon period allows for the calculation of AMAAG. Reconstructed Ba at Chhota Shigri Glacier agrees with mass balances previously reconstructed using a positive degreeday method. Reconstructed Ba at Mera Glacier is affected by heavy cloud cover during the monsoon, which systematically limited our ability to observe AMAAG at the end of the melting period. In addition, the relation between AMAAG and Ba is constrained over a shorter time period for Mera Glacier (6years) than for Chhota Shigri Glacier (11years). Thus the mass balance reconstruction is less robust for Mera Glacier than for Chhota Shigri Glacier. However our method shows promising results and may be used to reconstruct the annual mass balance of glaciers with contrasted seasonal cycles in the western part of the HKH mountain range since the early 2000s when MODIS images became available.
Some recent studies revealed that Himalayan
glaciers were shrinking at an accelerated rate since ... more Some recent studies revealed that Himalayan glaciers were shrinking at an accelerated rate since the beginning of the 21st century. However, the climatic causes for this shrinkage remain unclear given that surface energy balance studies are almost nonexistent in this region. In this study, a point-scale surface energy balance analysis was performed using in situ meteorological data from the ablation zone of Chhota Shigri Glacier over two separate periods (August 2012 to February 2013 and July to October 2013) in order to understand the response of mass balance to climatic variables. Energy balance numerical modelling provides quantification of the surface energy fluxes and identification of the factors affecting glacier mass balance. The model was validated by comparing the computed and observed ablation and surface temperature data. During the summer-monsoon period, net radiation was the primary component of the surface energy balance accounting for 80% of the total heat flux followed by turbulent sensible (13 %), latent (5 %) and conductive (2 %) heat fluxes. A striking feature of the energy balance is the positive turbulent latent heat flux, suggesting re-sublimation of moist air at the glacier surface, during the summer-monsoon characterized by relatively high air temperature, high relative humidity and a continual melting surface. The impact of the Indian Summer Monsoon on Chhota Shigri Glacier mass balance has also been assessed. This analysis demonstrates that the intensity of snowfall events during the summer-monsoon plays a key role on surface albedo (melting is reduced in the case of strong snowfalls covering the glacier area), and thus is among the most important drivers controlling the annual mass balance of the glacier. The summer-monsoon air temperature, controlling the precipitation phase (rain versus snow and thus albedo), counts, indirectly, also among the most important drivers.
Some recent studies revealed that Himalayan
glaciers were shrinking at an accelerated rate since ... more Some recent studies revealed that Himalayan glaciers were shrinking at an accelerated rate since the beginning of the 21st century. However, the climatic causes for this shrinkage remain unclear given that surface energy balance studies are almost nonexistent in this region. In this study, a point-scale surface energy balance analysis was performed using in situ meteorological data from the ablation zone of Chhota Shigri Glacier over two separate periods (August 2012 to February 2013 and July to October 2013) in order to understand the response of mass balance to climatic variables. Energy balance numerical modelling provides quantification of the surface energy fluxes and identification of the factors affecting glacier mass balance. The model was validated by comparing the computed and observed ablation and surface temperature data. During the summer-monsoon period, net radiation was the primary component of the surface energy balance accounting for 80% of the total heat flux followed by turbulent sensible (13 %), latent (5 %) and conductive (2 %) heat fluxes. A striking feature of the energy balance is the positive turbulent latent heat flux, suggesting re-sublimation of moist air at the glacier surface, during the summer-monsoon characterized by relatively high air temperature, high relative humidity and a continual melting surface. The impact of the Indian Summer Monsoon on Chhota Shigri Glacier mass balance has also been assessed. This analysis demonstrates that the intensity of snowfall events during the summer-monsoon plays a key role on surface albedo (melting is reduced in the case of strong snowfalls covering the glacier area), and thus is among the most important drivers controlling the annual mass balance of the glacier. The summer-monsoon air temperature, controlling the precipitation phase (rain versus snow and thus albedo), counts, indirectly, also among the most important drivers.
An attempt has been made to characterize the subglacial
pathways that transport the meltwaters fr... more An attempt has been made to characterize the subglacial pathways that transport the meltwaters from Chaturangi and Raktavarn glaciers through the lower ablation zone of the Gangotri glacier, Indian Himalaya, by means of dye tracer experiments. These inactive tributaries of the Gangotri glacier contribute significantly to the proglacial discharge, which is dominantly controlled by air temperature (0–20C at the measurement site) rather than rainfall (117 mm from June to September 2008). The breakthrough flow velocities, ranging from 0.6 to 1.7 ms–1 and dispersivity values varying between 2.1 and 17.5 m, decreased with bulk discharges in the proglacial stream (R2 = 0.66), indicating flow through highly efficient subglacial channels that develop during the melt season with increased meltwater influx. However, the dye return curves giving high velocities in a narrow range from 1.3 to 1.7 ms–1 as seasonal discharges were peaking, are interpreted as indicative of flow through pressurized channel/s. In general, the subglacial channels routing meltwater from these input points are arguably controlled by recharge hydrographs rather than channel geometry during the ablation season. Closely spaced dye tests need to be carried out to better understand the factors that control the diurnal and seasonal development of these hydrological pathways, which are important for downstream water management.
The volume change of the Chhota Shigri Glacier
(India, 32 20 N, 77 300 E) between 1988 and 201... more The volume change of the Chhota Shigri Glacier
(India, 32 20 N, 77 300 E) between 1988 and 2010 has
been determined using in situ geodetic measurements.
This glacier has experienced only a slight mass loss
between 1988 and 2010 (–3.8±2.0mw.e. (water equivalent)
corresponding to –0.17 pm 0.09mw.e. yr−1). Using
satellite digital elevation models (DEM) differencing and
field measurements, we measure a negative mass balance
(MB) between 1999 and 2010 (–4.8±1.8mw.e. corresponding
to –0.44±0.16mw.e. yr−1). Thus, we
deduce a slightly positive or near-zero MB between
1988 and 1999 (+1.0±2.7mw.e. corresponding to
+0.09±0.24mw.e. yr−1). Furthermore, satellite DEM
differencing reveals that the MB of the Chhota Shigri
Glacier (–0.39 pm 0.15mw.e. yr−1) has been only slightly
less negative than the MB of a 2110 km2 glaciarized area
in the Lahaul and Spiti region (–0.44±0.09mw.e. yr−1)
during 1999–2011. Hence, we conclude that the ice wastage
is probably moderate in this region over the last 22 yr, with
near equilibrium conditions during the nineties, and an ice
mass loss after. The turning point from balanced to negative
mass budget is not known but lies probably in the late
nineties and at the latest in 1999. This positive or near-zero
MB for Chhota Shigri Glacier (and probably for the surrounding
glaciers of the Lahaul and Spiti region) during at
least part of the 1990s contrasts with a recent compilation of
MB data in the Himalayan range that indicated ice wastage
since 1975. However, in agreement with this compilation,
we confirm more negative balances since the beginning of
the 21st century.
This study presents a reconstruction of the mass balance (MB) of Chhota Shigri glacier, Western H... more This study presents a reconstruction of the mass balance (MB) of Chhota Shigri glacier, Western Himalaya, India, and discusses the regional climatic drivers responsible for its evolution since
1969. The MB is reconstructed by a temperature-index and an accumulation model using daily air temperature and precipitation records from the nearest meteorological station, at Bhuntar
Observatory. The only adjusted parameter is the altitudinal precipitation gradient. The model is calibrated against 10 years of annual altitudinal MB measurements between 2002 and 2012 and
decadal cumulative MBs between 1988 and 2010. Three periods were distinguished in the MB series. Periods I (1969–85) and III (2001–12) show significant mass loss at MB rates of –0.36 +/-0.36 and –0.57 +/- 0.36mw.e. a–1 respectively, whereas period II (1986–2000) exhibits steady-state conditions with average MBs of –0.01 +/- 0.36 mw.e. a–1. The comparison among these three periods suggests that winter precipitation and summer temperature are almost equally important drivers controlling the MB pattern of Chhota Shigri glacier at decadal scale. The sensitivity of the modelled glacier-wide MB to temperature is –0.52 mw.e. a–1 C–1 whereas the sensitivity to precipitation is calculated as 0.16 mw.e. a–1 for a 10% change.
"Mass-balance and dynamic behaviour of Chhota Shigri glacier, western Himalaya, India, has been i... more "Mass-balance and dynamic behaviour of Chhota Shigri glacier, western Himalaya, India, has been investigated between 2002 and 2010 and compared to data collected in 1987–89. During the period 2002–10, the glacier experienced a negative glacier-wide mass balance of –0.670.40m w.e. a–1. Between 2003 and 2010, elevation and ice-flow velocities slowly decreased in the ablation area, leading to a 24–37% reduction in ice fluxes, an expected response of the glacier dynamics to its
recent negative mass balances. The reduced ice fluxes are still far larger than the balance fluxes calculated from the 2002–10 average surface mass balances. Therefore, further slowdown, thinning and terminus retreat of Chhota Shigri glacier are expected over the next few years. Conversely, the 2003/04
ice fluxes are in good agreement with ice fluxes calculated assuming that the glacier-wide mass balance is zero. Given the limited velocity change between 1987–89 and 2003/04 and the small terminus change between 1988 and 2010, we suggest that the glacier has experienced a period of near-zero or slightly positive mass balance in the 1990s, before shifting to a strong imbalance in the 21st century. This result challenges the generally accepted idea that glaciers in the Western Himalaya have been shrinking rapidly for the last few decades."
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Papers by MOHD. FAROOQ AZAM
glaciers in the Hindu Kush–Karakoram–Himalayan (HKH)
region, and remote sensing data are thus critical for glacier
studies in this region. The main objectives of this study are
to document, using satellite images, the seasonal changes of
surface albedo for two Himalayan glaciers, Chhota Shigri
Glacier (Himachal Pradesh, India) and Mera Glacier (Everest
region, Nepal), and to reconstruct the annual mass balance
of these glaciers based on the albedo data. Albedo is retrieved
from Moderate Resolution Imaging Spectroradiometer
(MODIS) images, and evaluated using ground based measurements.
At both sites, we find high coefficients of determination
between annual minimum albedo averaged over
the glacier (AMAAG) and glacier-wide annual mass balance
(Ba) measured with the glaciological method (R2 D0.75).
At Chhota Shigri Glacier, the relation between AMAAG
found at the end of the ablation season and Ba suggests that
AMAAG can be used as a proxy for the maximum snow
line altitude or equilibrium line altitude (ELA) on winteraccumulation-
type glaciers in the Himalayas. However, for
the summer-accumulation-type Mera Glacier, our approach
relied on the hypothesis that ELA information is preserved
during the monsoon. At Mera Glacier, cloud obscuration
and snow accumulation limits the detection of albedo during
the monsoon, but snow redistribution and sublimation in the
post-monsoon period allows for the calculation of AMAAG.
Reconstructed Ba at Chhota Shigri Glacier agrees with mass
balances previously reconstructed using a positive degreeday
method. Reconstructed Ba at Mera Glacier is affected
by heavy cloud cover during the monsoon, which systematically
limited our ability to observe AMAAG at the end of the
melting period. In addition, the relation between AMAAG
and Ba is constrained over a shorter time period for Mera
Glacier (6 years) than for Chhota Shigri Glacier (11 years).
Thus the mass balance reconstruction is less robust for Mera
Glacier than for Chhota Shigri Glacier. However our method
shows promising results and may be used to reconstruct the
annual mass balance of glaciers with contrasted seasonal cycles
in the western part of the HKH mountain range since the
early 2000s when MODIS images became available.
post-monsoon period allows for the calculation of AMAAG. Reconstructed Ba at Chhota Shigri Glacier agrees with mass balances previously reconstructed using a positive degreeday method. Reconstructed Ba at Mera Glacier is affected by heavy cloud cover during the monsoon, which systematically limited our ability to observe AMAAG at the end of the melting period. In addition, the relation between AMAAG and Ba is constrained over a shorter time period for Mera Glacier (6years) than for Chhota Shigri Glacier (11years). Thus the mass balance reconstruction is less robust for Mera Glacier than for Chhota Shigri Glacier. However our method shows promising results and may be used to reconstruct the annual mass balance of glaciers with contrasted seasonal cycles in the western part of the HKH mountain range since the early 2000s when MODIS images became available.
glaciers were shrinking at an accelerated rate since the beginning
of the 21st century. However, the climatic causes
for this shrinkage remain unclear given that surface energy
balance studies are almost nonexistent in this region. In this
study, a point-scale surface energy balance analysis was performed
using in situ meteorological data from the ablation
zone of Chhota Shigri Glacier over two separate periods
(August 2012 to February 2013 and July to October 2013)
in order to understand the response of mass balance to climatic
variables. Energy balance numerical modelling provides
quantification of the surface energy fluxes and identification
of the factors affecting glacier mass balance. The
model was validated by comparing the computed and observed
ablation and surface temperature data. During the
summer-monsoon period, net radiation was the primary component
of the surface energy balance accounting for 80% of
the total heat flux followed by turbulent sensible (13 %), latent
(5 %) and conductive (2 %) heat fluxes. A striking feature
of the energy balance is the positive turbulent latent heat
flux, suggesting re-sublimation of moist air at the glacier surface,
during the summer-monsoon characterized by relatively
high air temperature, high relative humidity and a continual
melting surface. The impact of the Indian Summer Monsoon
on Chhota Shigri Glacier mass balance has also been assessed.
This analysis demonstrates that the intensity of snowfall
events during the summer-monsoon plays a key role on
surface albedo (melting is reduced in the case of strong snowfalls
covering the glacier area), and thus is among the most
important drivers controlling the annual mass balance of the
glacier. The summer-monsoon air temperature, controlling
the precipitation phase (rain versus snow and thus albedo),
counts, indirectly, also among the most important drivers.
glaciers were shrinking at an accelerated rate since the beginning
of the 21st century. However, the climatic causes
for this shrinkage remain unclear given that surface energy
balance studies are almost nonexistent in this region. In this
study, a point-scale surface energy balance analysis was performed
using in situ meteorological data from the ablation
zone of Chhota Shigri Glacier over two separate periods
(August 2012 to February 2013 and July to October 2013)
in order to understand the response of mass balance to climatic
variables. Energy balance numerical modelling provides
quantification of the surface energy fluxes and identification
of the factors affecting glacier mass balance. The
model was validated by comparing the computed and observed
ablation and surface temperature data. During the
summer-monsoon period, net radiation was the primary component
of the surface energy balance accounting for 80% of
the total heat flux followed by turbulent sensible (13 %), latent
(5 %) and conductive (2 %) heat fluxes. A striking feature
of the energy balance is the positive turbulent latent heat
flux, suggesting re-sublimation of moist air at the glacier surface,
during the summer-monsoon characterized by relatively
high air temperature, high relative humidity and a continual
melting surface. The impact of the Indian Summer Monsoon
on Chhota Shigri Glacier mass balance has also been assessed.
This analysis demonstrates that the intensity of snowfall
events during the summer-monsoon plays a key role on
surface albedo (melting is reduced in the case of strong snowfalls
covering the glacier area), and thus is among the most
important drivers controlling the annual mass balance of the
glacier. The summer-monsoon air temperature, controlling
the precipitation phase (rain versus snow and thus albedo),
counts, indirectly, also among the most important drivers.
pathways that transport the meltwaters from
Chaturangi and Raktavarn glaciers through the lower
ablation zone of the Gangotri glacier, Indian Himalaya,
by means of dye tracer experiments. These inactive
tributaries of the Gangotri glacier contribute
significantly to the proglacial discharge, which is
dominantly controlled by air temperature (0–20C at
the measurement site) rather than rainfall (117 mm
from June to September 2008). The breakthrough
flow velocities, ranging from 0.6 to 1.7 ms–1 and
dispersivity values varying between 2.1 and 17.5 m,
decreased with bulk discharges in the proglacial
stream (R2 = 0.66), indicating flow through highly efficient
subglacial channels that develop during the melt
season with increased meltwater influx. However, the
dye return curves giving high velocities in a narrow
range from 1.3 to 1.7 ms–1 as seasonal discharges were
peaking, are interpreted as indicative of flow through
pressurized channel/s. In general, the subglacial
channels routing meltwater from these input points
are arguably controlled by recharge hydrographs
rather than channel geometry during the ablation season.
Closely spaced dye tests need to be carried out to
better understand the factors that control the diurnal
and seasonal development of these hydrological pathways,
which are important for downstream water
management.
(India, 32 20 N, 77 300 E) between 1988 and 2010 has
been determined using in situ geodetic measurements.
This glacier has experienced only a slight mass loss
between 1988 and 2010 (–3.8±2.0mw.e. (water equivalent)
corresponding to –0.17 pm 0.09mw.e. yr−1). Using
satellite digital elevation models (DEM) differencing and
field measurements, we measure a negative mass balance
(MB) between 1999 and 2010 (–4.8±1.8mw.e. corresponding
to –0.44±0.16mw.e. yr−1). Thus, we
deduce a slightly positive or near-zero MB between
1988 and 1999 (+1.0±2.7mw.e. corresponding to
+0.09±0.24mw.e. yr−1). Furthermore, satellite DEM
differencing reveals that the MB of the Chhota Shigri
Glacier (–0.39 pm 0.15mw.e. yr−1) has been only slightly
less negative than the MB of a 2110 km2 glaciarized area
in the Lahaul and Spiti region (–0.44±0.09mw.e. yr−1)
during 1999–2011. Hence, we conclude that the ice wastage
is probably moderate in this region over the last 22 yr, with
near equilibrium conditions during the nineties, and an ice
mass loss after. The turning point from balanced to negative
mass budget is not known but lies probably in the late
nineties and at the latest in 1999. This positive or near-zero
MB for Chhota Shigri Glacier (and probably for the surrounding
glaciers of the Lahaul and Spiti region) during at
least part of the 1990s contrasts with a recent compilation of
MB data in the Himalayan range that indicated ice wastage
since 1975. However, in agreement with this compilation,
we confirm more negative balances since the beginning of
the 21st century.
1969. The MB is reconstructed by a temperature-index and an accumulation model using daily air temperature and precipitation records from the nearest meteorological station, at Bhuntar
Observatory. The only adjusted parameter is the altitudinal precipitation gradient. The model is calibrated against 10 years of annual altitudinal MB measurements between 2002 and 2012 and
decadal cumulative MBs between 1988 and 2010. Three periods were distinguished in the MB series. Periods I (1969–85) and III (2001–12) show significant mass loss at MB rates of –0.36 +/-0.36 and –0.57 +/- 0.36mw.e. a–1 respectively, whereas period II (1986–2000) exhibits steady-state conditions with average MBs of –0.01 +/- 0.36 mw.e. a–1. The comparison among these three periods suggests that winter precipitation and summer temperature are almost equally important drivers controlling the MB pattern of Chhota Shigri glacier at decadal scale. The sensitivity of the modelled glacier-wide MB to temperature is –0.52 mw.e. a–1 C–1 whereas the sensitivity to precipitation is calculated as 0.16 mw.e. a–1 for a 10% change.
recent negative mass balances. The reduced ice fluxes are still far larger than the balance fluxes calculated from the 2002–10 average surface mass balances. Therefore, further slowdown, thinning and terminus retreat of Chhota Shigri glacier are expected over the next few years. Conversely, the 2003/04
ice fluxes are in good agreement with ice fluxes calculated assuming that the glacier-wide mass balance is zero. Given the limited velocity change between 1987–89 and 2003/04 and the small terminus change between 1988 and 2010, we suggest that the glacier has experienced a period of near-zero or slightly positive mass balance in the 1990s, before shifting to a strong imbalance in the 21st century. This result challenges the generally accepted idea that glaciers in the Western Himalaya have been shrinking rapidly for the last few decades."
glaciers in the Hindu Kush–Karakoram–Himalayan (HKH)
region, and remote sensing data are thus critical for glacier
studies in this region. The main objectives of this study are
to document, using satellite images, the seasonal changes of
surface albedo for two Himalayan glaciers, Chhota Shigri
Glacier (Himachal Pradesh, India) and Mera Glacier (Everest
region, Nepal), and to reconstruct the annual mass balance
of these glaciers based on the albedo data. Albedo is retrieved
from Moderate Resolution Imaging Spectroradiometer
(MODIS) images, and evaluated using ground based measurements.
At both sites, we find high coefficients of determination
between annual minimum albedo averaged over
the glacier (AMAAG) and glacier-wide annual mass balance
(Ba) measured with the glaciological method (R2 D0.75).
At Chhota Shigri Glacier, the relation between AMAAG
found at the end of the ablation season and Ba suggests that
AMAAG can be used as a proxy for the maximum snow
line altitude or equilibrium line altitude (ELA) on winteraccumulation-
type glaciers in the Himalayas. However, for
the summer-accumulation-type Mera Glacier, our approach
relied on the hypothesis that ELA information is preserved
during the monsoon. At Mera Glacier, cloud obscuration
and snow accumulation limits the detection of albedo during
the monsoon, but snow redistribution and sublimation in the
post-monsoon period allows for the calculation of AMAAG.
Reconstructed Ba at Chhota Shigri Glacier agrees with mass
balances previously reconstructed using a positive degreeday
method. Reconstructed Ba at Mera Glacier is affected
by heavy cloud cover during the monsoon, which systematically
limited our ability to observe AMAAG at the end of the
melting period. In addition, the relation between AMAAG
and Ba is constrained over a shorter time period for Mera
Glacier (6 years) than for Chhota Shigri Glacier (11 years).
Thus the mass balance reconstruction is less robust for Mera
Glacier than for Chhota Shigri Glacier. However our method
shows promising results and may be used to reconstruct the
annual mass balance of glaciers with contrasted seasonal cycles
in the western part of the HKH mountain range since the
early 2000s when MODIS images became available.
post-monsoon period allows for the calculation of AMAAG. Reconstructed Ba at Chhota Shigri Glacier agrees with mass balances previously reconstructed using a positive degreeday method. Reconstructed Ba at Mera Glacier is affected by heavy cloud cover during the monsoon, which systematically limited our ability to observe AMAAG at the end of the melting period. In addition, the relation between AMAAG and Ba is constrained over a shorter time period for Mera Glacier (6years) than for Chhota Shigri Glacier (11years). Thus the mass balance reconstruction is less robust for Mera Glacier than for Chhota Shigri Glacier. However our method shows promising results and may be used to reconstruct the annual mass balance of glaciers with contrasted seasonal cycles in the western part of the HKH mountain range since the early 2000s when MODIS images became available.
glaciers were shrinking at an accelerated rate since the beginning
of the 21st century. However, the climatic causes
for this shrinkage remain unclear given that surface energy
balance studies are almost nonexistent in this region. In this
study, a point-scale surface energy balance analysis was performed
using in situ meteorological data from the ablation
zone of Chhota Shigri Glacier over two separate periods
(August 2012 to February 2013 and July to October 2013)
in order to understand the response of mass balance to climatic
variables. Energy balance numerical modelling provides
quantification of the surface energy fluxes and identification
of the factors affecting glacier mass balance. The
model was validated by comparing the computed and observed
ablation and surface temperature data. During the
summer-monsoon period, net radiation was the primary component
of the surface energy balance accounting for 80% of
the total heat flux followed by turbulent sensible (13 %), latent
(5 %) and conductive (2 %) heat fluxes. A striking feature
of the energy balance is the positive turbulent latent heat
flux, suggesting re-sublimation of moist air at the glacier surface,
during the summer-monsoon characterized by relatively
high air temperature, high relative humidity and a continual
melting surface. The impact of the Indian Summer Monsoon
on Chhota Shigri Glacier mass balance has also been assessed.
This analysis demonstrates that the intensity of snowfall
events during the summer-monsoon plays a key role on
surface albedo (melting is reduced in the case of strong snowfalls
covering the glacier area), and thus is among the most
important drivers controlling the annual mass balance of the
glacier. The summer-monsoon air temperature, controlling
the precipitation phase (rain versus snow and thus albedo),
counts, indirectly, also among the most important drivers.
glaciers were shrinking at an accelerated rate since the beginning
of the 21st century. However, the climatic causes
for this shrinkage remain unclear given that surface energy
balance studies are almost nonexistent in this region. In this
study, a point-scale surface energy balance analysis was performed
using in situ meteorological data from the ablation
zone of Chhota Shigri Glacier over two separate periods
(August 2012 to February 2013 and July to October 2013)
in order to understand the response of mass balance to climatic
variables. Energy balance numerical modelling provides
quantification of the surface energy fluxes and identification
of the factors affecting glacier mass balance. The
model was validated by comparing the computed and observed
ablation and surface temperature data. During the
summer-monsoon period, net radiation was the primary component
of the surface energy balance accounting for 80% of
the total heat flux followed by turbulent sensible (13 %), latent
(5 %) and conductive (2 %) heat fluxes. A striking feature
of the energy balance is the positive turbulent latent heat
flux, suggesting re-sublimation of moist air at the glacier surface,
during the summer-monsoon characterized by relatively
high air temperature, high relative humidity and a continual
melting surface. The impact of the Indian Summer Monsoon
on Chhota Shigri Glacier mass balance has also been assessed.
This analysis demonstrates that the intensity of snowfall
events during the summer-monsoon plays a key role on
surface albedo (melting is reduced in the case of strong snowfalls
covering the glacier area), and thus is among the most
important drivers controlling the annual mass balance of the
glacier. The summer-monsoon air temperature, controlling
the precipitation phase (rain versus snow and thus albedo),
counts, indirectly, also among the most important drivers.
pathways that transport the meltwaters from
Chaturangi and Raktavarn glaciers through the lower
ablation zone of the Gangotri glacier, Indian Himalaya,
by means of dye tracer experiments. These inactive
tributaries of the Gangotri glacier contribute
significantly to the proglacial discharge, which is
dominantly controlled by air temperature (0–20C at
the measurement site) rather than rainfall (117 mm
from June to September 2008). The breakthrough
flow velocities, ranging from 0.6 to 1.7 ms–1 and
dispersivity values varying between 2.1 and 17.5 m,
decreased with bulk discharges in the proglacial
stream (R2 = 0.66), indicating flow through highly efficient
subglacial channels that develop during the melt
season with increased meltwater influx. However, the
dye return curves giving high velocities in a narrow
range from 1.3 to 1.7 ms–1 as seasonal discharges were
peaking, are interpreted as indicative of flow through
pressurized channel/s. In general, the subglacial
channels routing meltwater from these input points
are arguably controlled by recharge hydrographs
rather than channel geometry during the ablation season.
Closely spaced dye tests need to be carried out to
better understand the factors that control the diurnal
and seasonal development of these hydrological pathways,
which are important for downstream water
management.
(India, 32 20 N, 77 300 E) between 1988 and 2010 has
been determined using in situ geodetic measurements.
This glacier has experienced only a slight mass loss
between 1988 and 2010 (–3.8±2.0mw.e. (water equivalent)
corresponding to –0.17 pm 0.09mw.e. yr−1). Using
satellite digital elevation models (DEM) differencing and
field measurements, we measure a negative mass balance
(MB) between 1999 and 2010 (–4.8±1.8mw.e. corresponding
to –0.44±0.16mw.e. yr−1). Thus, we
deduce a slightly positive or near-zero MB between
1988 and 1999 (+1.0±2.7mw.e. corresponding to
+0.09±0.24mw.e. yr−1). Furthermore, satellite DEM
differencing reveals that the MB of the Chhota Shigri
Glacier (–0.39 pm 0.15mw.e. yr−1) has been only slightly
less negative than the MB of a 2110 km2 glaciarized area
in the Lahaul and Spiti region (–0.44±0.09mw.e. yr−1)
during 1999–2011. Hence, we conclude that the ice wastage
is probably moderate in this region over the last 22 yr, with
near equilibrium conditions during the nineties, and an ice
mass loss after. The turning point from balanced to negative
mass budget is not known but lies probably in the late
nineties and at the latest in 1999. This positive or near-zero
MB for Chhota Shigri Glacier (and probably for the surrounding
glaciers of the Lahaul and Spiti region) during at
least part of the 1990s contrasts with a recent compilation of
MB data in the Himalayan range that indicated ice wastage
since 1975. However, in agreement with this compilation,
we confirm more negative balances since the beginning of
the 21st century.
1969. The MB is reconstructed by a temperature-index and an accumulation model using daily air temperature and precipitation records from the nearest meteorological station, at Bhuntar
Observatory. The only adjusted parameter is the altitudinal precipitation gradient. The model is calibrated against 10 years of annual altitudinal MB measurements between 2002 and 2012 and
decadal cumulative MBs between 1988 and 2010. Three periods were distinguished in the MB series. Periods I (1969–85) and III (2001–12) show significant mass loss at MB rates of –0.36 +/-0.36 and –0.57 +/- 0.36mw.e. a–1 respectively, whereas period II (1986–2000) exhibits steady-state conditions with average MBs of –0.01 +/- 0.36 mw.e. a–1. The comparison among these three periods suggests that winter precipitation and summer temperature are almost equally important drivers controlling the MB pattern of Chhota Shigri glacier at decadal scale. The sensitivity of the modelled glacier-wide MB to temperature is –0.52 mw.e. a–1 C–1 whereas the sensitivity to precipitation is calculated as 0.16 mw.e. a–1 for a 10% change.
recent negative mass balances. The reduced ice fluxes are still far larger than the balance fluxes calculated from the 2002–10 average surface mass balances. Therefore, further slowdown, thinning and terminus retreat of Chhota Shigri glacier are expected over the next few years. Conversely, the 2003/04
ice fluxes are in good agreement with ice fluxes calculated assuming that the glacier-wide mass balance is zero. Given the limited velocity change between 1987–89 and 2003/04 and the small terminus change between 1988 and 2010, we suggest that the glacier has experienced a period of near-zero or slightly positive mass balance in the 1990s, before shifting to a strong imbalance in the 21st century. This result challenges the generally accepted idea that glaciers in the Western Himalaya have been shrinking rapidly for the last few decades."