Unsteady state of glaciers (Chhota Shigri and Hamtah) and climate in Lahaul and Spiti region, western Himalayas: a review of recent mass loss

Abstract. The volume change of the Chhota Shigri Glacier (India, 32° 20 N, 77° 30' 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 ± 2.0 m w.e. (water equivalent) corresponding to −0.17 ± 0.09 m w.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 ± 1.8 m w.e. corresponding to −0.44 ± 0.16 m w.e. yr−1). Thus, we deduce a slightly positive or near-zero MB between 1988 and 1999 (+1.0 ± 2.7 m w.e. corresponding to +0.09 ± 0.24 m w.e. yr−1). Furthermore, satellite DEM differencing reveals that the MB of the Chhota Shigri Glacier (−0.39 ± 0.15 m w.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 ± 0.09 m w.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.

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Mass gain of glaciers in Lahaul and Spiti region (North India) during the nineties revealed by in-situ and satellite geodetic measurements

The Cryosphere Discussions ◽

10.5194/tcd-6-3733-2012 ◽

2012 ◽

Vol 6 (5) ◽

pp. 3733-3755 ◽

Cited By ~ 4

Author(s):

C. Vincent ◽

A. Ramanathan ◽

P. Wagnon ◽

D. P. Dobhal ◽

A. Linda ◽

...

Keyword(s):

Mass Loss ◽

Volume Change ◽

Western Himalaya ◽

North India ◽

Good Correspondence ◽

Chhota Shigri Glacier ◽

Geodetic Measurements ◽

Spiti Region ◽

Dem Differencing

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.

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Water accumulation as a function of temperature on specimens in an electron microscope cold stage

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100142219 ◽

1986 ◽

Vol 44 ◽

pp. 114-115 ◽

Cited By ~ 2

Author(s):

M.K. Lamvik ◽

D.A. Kopf ◽

S.D. Davilla ◽

J.D. Robertson

Keyword(s):

Electron Microscope ◽

Mass Loss ◽

Liquid Helium ◽

Liquid Nitrogen ◽

Liquid Nitrogen Temperature ◽

Liquid Helium Temperature ◽

Helium Temperature ◽

Cold Stage ◽

Water Accumulation ◽

Better Than

Last year we reported1 that there is a striking reduction in the rate of mass loss when a specimen is observed at liquid helium temperature. It is important to determine whether liquid helium temperature is significantly better than liquid nitrogen temperature. This requires a good understanding of mass loss effects in cold stages around 100K.

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Electron Beam-Induced Mass Loss in Freeze-Dried Tissue and Protein Samples

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010011917x ◽

1985 ◽

Vol 43 ◽

pp. 470-471

Author(s):

M.E. Cantino ◽

M.K. Goddard ◽

L.E. Wilkinson ◽

D.E. Johnson

Keyword(s):

Electron Beam ◽

Salivary Gland ◽

Mass Loss ◽

Counting Rate ◽

Dose Dependence ◽

X Ray ◽

Large Samples ◽

Freeze Dried ◽

Muscle Homogenate ◽

Large Muscle

Quantification in biological x-ray microanalysis depends on accurate evaluation of mass loss. Although several studies have addressed the problem of electron beam induced mass loss from organic samples (eg., 1,2). uncertainty persists as to the dose dependence, the extent of loss, the elemental constituents affected, and the variation in loss for different materials and tissues. in the work described here, we used x-ray counting rate changes to measure mass loss in albumin (used as a quantification standard), salivary gland, and muscle.In order to measure mass loss at low doses (10-4 coul/cm2 ) large samples were needed. While freeze-dried salivary gland sections of the required dimensions were available, muscle sections of this size were difficult to obtain. To simulate large muscle sections, frog or rat muscle homogenate was injected between formvar films which were then stretched over slot grids and freeze-dried. Albumin samples were prepared by a similar procedure. using a solution of bovine serum albumin in water. Samples were irradiated in the STEM mode of a JEOL 100C.

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Elemental mass loss in silicate minerals during x-ray analysis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100177155 ◽

1990 ◽

Vol 48 (4) ◽

pp. 804-805

Author(s):

P.E. Champness ◽

R.W. Devenish

Keyword(s):

Mass Loss ◽

Current Density ◽

Damage Mechanism ◽

Beam Current ◽

Single Chain ◽

Plagioclase Feldspar ◽

X Ray ◽

Alkali Ions ◽

Structural Order ◽

Sheet Silicate

It has long been recognised that silicates can suffer extensive beam damage in electron-beam instruments. The predominant damage mechanism is radiolysis. For instance, damage in quartz, SiO2, results in loss of structural order without mass loss whereas feldspars (framework silicates containing Ca, Na, K) suffer loss of structural order with accompanying mass loss. In the latter case, the alkali ions, particularly Na, are found to migrate away from the area of the beam. The aim of the present study was to investigate the loss of various elements from the common silicate structures during electron irradiation at 100 kV over a range of current densities of 104 - 109 A m−2. (The current density is defined in terms of 50% of total current in the FWHM probe). The silicates so far ivestigated are:- olivine [(Mg, Fe)SiO4], a structure that has isolated Si-O tetrahedra, garnet [(Mg, Ca, Fe)3Al2Si3AO12 another silicate with isolated tetrahedra, pyroxene [-Ca(Mg, Fe)Si2O6 a single-chain silicate; mica [margarite, -Ca2Al4Si4Al4O2O(OH)4], a sheet silicate, and plagioclase feldspar [-NaCaAl3Si5O16]. Ion- thinned samples of each mineral were examined in a VG Microscopes UHV HB501 field- emission STEM. The beam current used was typically - 0.5 nA and the current density was varied by defocussing the electron probe. Energy-dispersive X-ray spectra were collected every 10 seconds for a total of 200 seconds using a Link Systems windowless detector. The thickness of the samples in the area of analysis was normally 50-150 nm.

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