Snout Position Research Articles

Significant changes of area, length and terminus of Sikkim Himalayan glaciers within the Kanchenjunga national park from 1990 - 2022

In this study, we have investigated four glaciers, namely Zemu, Talung, Alukthang and Rathong within Kanchenjunga national park. This study evaluates physical and morphometric parameters (area, length, perimeter, area of accumulation zone, ablation zone length, snout position, thickness and specific mass balance) of multiple glaciers and to ascertain the poorly understood glaciers of western Sikkim region under Kanchenjunga national park. The principal objective of this research is to find out the changes of glacial mass and other physical parameters of the selected glaciers using multi sources digital elevation model data.Various techniques of statistics, including Mann-Kendall and Sen’s slope tests have been applied at different confidence interval. We have identified that climate change is responsible for the alterations of the physical characteristics of the glaciers. Result shows that during the study period, Zemu glacier has faced highest amount of deglaciation in terms of area (20.79 sq.km) along with maximum 30 meter elevation reduction, 24m increase of snout elevation and 200m retreat of terminus. Furthermore, it is observed that terminus of the each selected glaciers retreated during the study period. Rathong experienced maximum retreat rate, approximately 550m, and it is accompanied by a notable 163% increase in the ablation zone. Alukthang and Talung reduced their areas 0.56 and 4.06 sq.km respectively, along with 2.75m and 9.10m thickness respectively. Maximum 36.39m/y-1 flow rate has been observed over Zemu glacier. The flow rate of Talung, Rathong and Alukthang glacier is 26.4m/y-1, 34.1m/y-1, and 23.7m/y-1 respectively.

A novel, end-to-end framework for avoiding collisions between the patient's body and gantry in proton therapy.

Administration of external radiation therapy via proton therapy systems carries a risk of occasional collisions between the patient's body and gantry, which is increased by the snout placed near the patient for better dose distribution. Although treatment planning software (TPS) can simulate controlled collisions, the computed tomography (CT) data used for treatment planning are insufficient given that collisions can occur outside the CT imaging region. Thus, imaging the three-dimensional (3D) surface outside the CT range and combining the data with those obtained by CT are essential for avoiding collisions. To construct a prototype for 3D surface imaging and an end-to-end framework for preventing collisions between the patient's body and the gantry. We obtained 3D surface data using a light sectioning method (LSM). By installing only cameras in front of the CT, we achieved LSM using the CT couch motion and preinstalled patient-positioning lasers. The camera image contained both sagittal and coronal lines, which are unnecessary for LSM and were removed by deep learning. We combined LSM 3D surface data and original CT data to create synthetic Digital Imaging and Communications in Medicine (DICOM) data. Subsequently, we compared the TPS snout auto-optimization using the original CT data with the synthetic DICOM data. The mean positional error for LSM of the arms and head was 0.7±0.8 and 0.8±0.8mm for axial and sagittal imaging, respectively. The TPS snout auto-optimization indicated that the original CT data would cause collisions; however, the synthetic DICOM data prevented these collisions. The prototype system's acquisition accuracy for 3D surface data was approximately 1mm, which was sufficient for the collision simulation. The use of a TPS with collision avoidance can help optimize the snout position using synthetic DICOM data. Our proposed method requires no external software for collision simulation and can be integrated into the clinical workflow to improve treatment planning efficiency.

Sensitivity of Glaciers in the European Alps to Anthropogenic Atmospheric Forcings: Case Study of the Argentière Glacier

AbstractThis study aims to quantify the contribution of anthropogenic forcings on the retreat of the Argentière Glacier (European Alps). The glacier evolution is simulated over 1850–2014 following retrospective scenarios produced with the IPSL‐CM6‐LR climate model, with and without natural and anthropogenic forcings. The scenarios used to force an ice flow model are statistically downscaled, preserving the long‐term trends and the physical consistency between precipitation and temperature. Since the late 19th century, the regional aerosol cooling has partially counteracted the greenhouse gas‐induced warming, delaying the time of emergence of the anthropogenic signal. The anthropogenic signal emerged from natural variability in 1979 for temperature and surface melting, and in 2008 for the glacier mass, whereas its snout position in 2014 remains compatible with natural variability. From the total mass loss between 1850 and 2014, 66% [21%–111%] is attributed to anthropogenic activities.

The use of a mini-ridge filter with cyclotron-based pencil beam scanning proton therapy.

Pencil beam scanning (PBS) proton therapy allows for far superior dose conformality compared with passive scattering techniques. However, one drawback of PBS is that the beam delivery time can be long, particularly when treating superficial disease. Minimizing beam delivery time is important for patient comfort and precision of treatment delivery. Mini-ridge filters (MRF) have been shown to reduce beam delivery time for synchrotron-based PBS. Given that cyclotron systems are widely used in proton therapy it is necessary to investigate the potential clinical benefit of mini-ridge filters in such systems. To demonstrate the clinical benefit of using a MRF to reduce beam delivery time for patients with large target volumes and superficial disease in cyclotron-based PBS proton therapy. A MRF beam model was generated by simulating the effect of a MRF on our clinical beam data assuming a fixed snout position relative to the isocenter. The beam model was validated with a series of measurements. The model was used to optimize treatment plans in a water phantom and on six patient DICOM datasets to further study the effect of the MRF and for comparison with physician-approved clinical treatment plans. Beam delivery time was measured for six plans with and without the MRF to demonstrate the reduction achievable. Plans with and without MRF were reviewed to confirm clinical acceptability by a radiation oncologist. Patient-specific QA measurements were carried out with a two-dimensional ionization chamber array detector for one representative patient's plan optimized with the MRF beam model. Results show good agreement between the simulated beam model and measurements with mean and maximum deviations of 0.06mm (0.45%) and 0.61mm (4.9%). The increase in Bragg peak width (FWHM) ranged from 2.7mm at 226MeV to 6.1mm at 70 MeV. The mean and maximum reduction in beam delivery time observed per field was 29.1s (32.2%) and 79.7s (55.3%). MRFs can be used to reduce treatment time in cyclotron-based PBS proton therapy without sacrificing plan quality. This is particularly beneficial for patients with large targets and superficial disease such as in breast cancer where treatment times are generally long, as well as patients treated with deep inspiration breath hold (DIBH).

Glacier retreat analysis in the context of climate change impact over the Satopanth (SPG) and Bhagirathi-Kharak (BKG) glaciers in the Mana basin of the Central Himalaya, India: A geospatial approach

• Glacier retreat footprints over the Mana Basin. • Spatio-temporal changes in the snout/glacier over the period of 50 years. • Estimation of ice velocity using the SAR technique. • Negative trend in snow cover area and increase of temperature. This study explores the dynamics of the Satopanth (SPG) and Bhagirathi-Kharak (BKG) glaciers of the Mana basin in the Central Himalayan region of India under the scenario of climate change. The spatio-temporal changes in the glacier area, volume, and shift in snout positions during the period from 1968 to 2017 were assessed based on the CORONA photograph and satellite data . The study also intended to identify the common drifts in glacier areas for observing temporal and seasonal (during the winter-spring-summer transition) changes in the glacial landscapes and ably evaluate glacier velocity and ice-marginal lake stage. The ice velocity was found to vary from 0.117 md −1 to 0.165 md −1 for January to October months. It was found to have increased during the winter-spring-summer transition periods used to estimate the ice flow intensity and its phase information regular basis. Besides this, the linear trends of the MOD11A2 land surface temperature product were obtained and temperature variability has been analyzed from 2001 to 2020. The results show significant warming over the basin along with a significant negative trend in snow cover area during different seasons. The derived information is quite useful in analyzing the climate change footprints such as snowline movement, snow volume changes, and glacier mass balance-related studies.

Explaining the natural and anthropogenic factors driving glacier recession in Kashmir Himalaya, India.

Glaciers across the Kashmir Himalayan region are melting at an accelerated pace compared to other regions across the Himalayan arc. This study analyzed the recession patterns of nine glaciers in the Kashmir Himalaya region over 28years between 1992 and 2020 using satellite images and field measurements. The recession patterns were correlated with debris cover, topographic factors, and ambient black carbon (BC) concentration at glacier sites. HYSPLIT model was used to track the air mass sources at a 7-day time-step from September 1, 2014, to September 28, 2014, over the selected region. All nine glaciers revealed high recession as indicated by changes in the area (average recession: 20.8%) and snout position (~ 14m a-1). The relative percentage of debris on each glacier varied between ~ 0% (clean glacier) and 43%. Although the investigated glaciers lie in the same climatological regime, their topographical behavior is dissimilar with mean altitude ranging between 4000 and ~ 4700m asl and the average slope varying from 17 to 24°. All the investigated glaciers are north-facing except G3 (southerly aspect). Our results indicate anomalously high ambient BC concentrations, ranging from 500 to 1364ngm-3, at the glacier sites, higher than previously studied for glaciers in the Himalayas and neighboring Tibetan Plateau. The backward air-mass trajectory modeling indicated both local and global sources of particulate matter in the study area. A comparative analysis of BC measurements and glacier recession with the studies conducted across high Asia indicated the influence of BC in accelerating the melting of glaciers in the Kashmir region.

Clinical Flow Improvement by Direct Conversion of Proton Plans across Different Platforms

<h3>Purpose/Objective(s)</h3> For proton therapy plans, switching proton machines without re-optimization can greatly improve the clinical efficiency, when proton machines belong to different platforms. This study focused on machine switching efficiency between Proteus-1 and Proteus-plus platforms by modeling a Proteus-1 proton machine with built-in range shifter (P1RS) for direct recalculation of treatment plans between P1 and universal nozzle of Proteus-plus (P+US) systems. <h3>Materials/Methods</h3> For institutions with multiple platform proton machines (i.e., P+ to P1), re-planning is usually required if a patient needs to be moved from P+ to P1 machines due to their different spot sizes. This usually requires re-planning of the patient and creates significant time delay when one machine is down or overloaded. We are proposing commissioning a P1 machine model use built-in range shifter (P1RS) with snout position fixed at 45cm upstream from isocenter. The in-air spot size and PDD of the P1RS are compared to those of the P+US. The P+ patient plans are recalculated using P1RS machine directly with both pencil beam and Monte Carlo dose engines. <h3>Results</h3> The P1RS machine model has similar in-air spot size as those of P+US (see Table). There are noticeable differences between the PDDs of the two models. For patient plan with field size less than 20cm by 24cm, preliminary investigation of direct conversion of treatment plans between the two machine models indicates that it is feasible. <h3>Conclusion</h3> P1 model with a built-in range shifter can simulate a P+US system. Direct recalculation of treatment plan between the two systems is feasible with acceptable dosimetric differences and could increase machine switching capabilities and improve clinical flow efficiency.

Re-description of external morphology and factors affecting body and tail shape of the stone frog tadpoles

Ecological studies testing the preponderance of environmental filters on ontogeny to explain the variation in tadpole morphology are scarce for Neotropical anurans. We used tadpoles of the stone frog Limnomedusa macroglossa (Alsodidae): (1) to assess the variation in body and tail shape; (2) to examine the effect of streamlet depth and allometry on tadpole shape, and (3) to re-describe and compare the tadpole external morphology with closely related species. We obtained the body shape and size from 150 tadpoles. The re-description was based on 57 qualitative and 24 quantitative characters, from 19 tadpoles between stages 30 and 37 and 31 to 37, respectively. Allometry was the major factor influencing the lateral view of body shape: smaller tadpoles had round bodies and eyes and nostrils positioned more laterally in comparison with larger ones. Thus, the power of ontogenetic variations reported here makes the tadpole developmental “climax” period a questionable concept that deserves additional attention. The depth gradient of streamlets also affected the shape: in shallower environments, the tadpoles presented a decrease in height of the body, fins and tail muscles, and an increase in body width. These results may indicate adaptations allowing better swimming performance in lotic environments with intense water flow. The external morphological characterization of L. macroglossa presented here differed from that previously reported, mainly due to coloration, body shape, nostril, anal tube, tail, shape and position of nostrils and snout. Additionally, we presented unknown traits for this species, making comparisons with closely related species within the Alsodidae family.

Explaining the differential response of glaciers across different mountain ranges in the north-western Himalaya, India

The study investigated a group of 65 glaciers, selected from different mountain ranges in the north-western Himalaya, India to understand and explain their status and response to the changing climate, surface topography and glacier morphology. Two-date Landsat satellite images (1990 and 2014), ICESat altimetry data, HMA DEM and SRTM DEM were used to estimate the changes in glacier area, snout position, Equilibrium Line Altitude (ELA), glacier thickness and volume. The total area of the glaciers under consideration across the five ranges shrunk from 1106 ± 33.6 km2 in 1990 to 1073 ± 24.6 km2 in 2014 with the consequent reduction in the glacier volume from 219 ± 6.66 km3 in 1990 to 211 ± 4.85 km3 in 2014, a loss of 5.9 ± 0.09 Gt during 24-year observation period. Upward shift in ELA, ranging from 18 ± 17 m to 64 ± 17 m, was observed during the observation period. The glaciers across the study area are losing thickness in the range of −0.59 ± 0.22–1.18 ± 0.40 m a−1. The study revealed that the glaciers situated at altitudes <4500 m have witnessed higher glacier area loss (8.25 ± 1.3%) compared to those situated at altitudes >6000 m (2.72 ± 0.92%). The influence of size on glacier loss is indicated by the higher shrinkage observed for the glaciers <3 km2 in size (6.75 ± 1.63%) compared to the lower shrinkage of 2.17 ± 1.12% observed for the large-size glaciers (>30 km2). Significant differences in the glacier response were observed across the five ranges due to the unique topographic and climatic setting endemic to a particular mountain range.

Characterization of penumbra sharpening and scattering by adaptive aperture for a compact pencil beam scanning proton therapy system.

To quantitatively access penumbra sharpening and scattering by adaptive aperture (AA) under various beam conditions and clinical cases for a Mevion S250i compact pencil beam scanning proton therapy system. First, in-air measurements were performed using a scintillation detector for single spot profile and lateral penumbra for five square field sizes (3×3 to 18×18cm2 ), three energies (33.04, 147.36, and 227.16MeV), and three snout positions (5, 15, and 33.6cm) with Open and AA field. Second, treatment plans were generated in RayStation treatment planning system (TPS) for various combination of target size (3- and 10-cm cube), target depth (5, 10, and 15cm) and air gap (5-20cm) for both Open and AA field. These plans were delivered to EDR2 films in the solid water and penumbra reduction by AA was quantified. Third, the effect of the AA scattered protons on the surface dose was studied at 5mm depth by EDR2 film and the RayStation TPS computation. Finally, dosimetric advantage of AA over Open field was studied for five brain and five prostate cases using the TPS simulation. The spot size changed dramatically from 3.8mm at proton beam energy of 227.15MeV to 29.4mm at energy 33.04MeV. In-air measurements showed that AA substantially reduced the lateral penumbra by 30% to 60%. The EDR2 film measurements in solid water presented the maximum penumbra reduction of 10 to 14mm depending on the target size. The maximum increase of 25% in field edge dose at 5mm depth as compared to central axis was observed. The substantial penumbra reduction by AA produced less dose to critical structures for all the prostate and brain cases. Adaptive aperture sharpens the penumbra by factor of two to three depending upon the beam condition. The absolute penumbra reduction with AA was more noticeable for shallower target, smaller target, and larger air gap. The AA-scattered protons contributed to increase in surface dose. Clinically, AA reduced the doses to critical structures.

Applications of glacial geomorphological and lichenometric studies for reconstructing the Late Holocene glacial history of the Hoksar valley, Kashmir Himalaya, India

ABSTRACT In this study, the lichenometry studies of the Hoksar Glacier valley in Kashmir Himalaya, India supported by the extensive ground- and remote sensing-based glacial geomorphological mapping enabled the identification of the six episodes of glacier advances in the valley. Field-based geomorphologic evidence suggests that the glacial episode 1 (GEI) experienced the most extensive glaciation in the Hoksar valley extending ∼1 km down the valley (altitude 3565 m) from the current snout position of the Hoksar Glacier (altitude 3680m). Lichenometric dating of the moraines suggests that the GE1 episode is chronologically the oldest (∼480 ± 25 years) and GE6 episode the youngest (∼245 ± 10 years). The mean equilibrium line altitude (ELA) during the GE1 episode was calculated as 3755 ± 4 m compared to the observed present ELA position of 4060 ± 5 m, an upward shift of 305 m observed during the period. The spatio-temporal changes of the Hoksar Glacier during different episodes of the glacier advances until 2018 showed that the glacier area has shrunk from ∼212 ha during the GE1 to 100 ha at present losing an area of 112 ha (52%) during the period mainly as a result of the recent climate change. The recent observed glacier recession (1980–2018) is much higher (11 000 m2 a−1) compared to the past recession (1300 m2 a−1). The study provides valuable insights about the glacier recession in the Kashmir Himalayan region during the Late Holocene where knowledge about the past glacial history on a regional scale is generally poorly investigated.

Estimation of the recession rate of Gangotri glacier, Garhwal Himalaya (India) through kinematic GPS survey and satellite data

Snout monitoring of the Gangotri glacier (Uttarakhand, India) during the ablation season (May to September) in years 2005 and 2015 by using rapid static and kinematic GPS survey reveals that the retreating rate has been comparatively more declined than shown by the earlier studies. Our study is based on the individual measurement by the remote sensing, added by the ground observations by using Differential global positioning system (DGPS) to determine the precise recession rate of the glacier at sub-centimeter level of accuracy. The GPS dataset show that the total average retreat along the snout has been 102.57 ± 0.05 m from 2005 to 2015 with an average rate as 10.26 ± 0.05 m/yr. Additionally, the shift in snout position was also measured through multi-temporal satellite data from 1989 to 2016. The results indicate that the Gangotri glacier snout has retreated by 585.62 ± 38.30 m during this period with an average retreat of 26.75 ± 4.36 m/yr from 1989 to 1999, 21.58 ± 3.77 m/yr from 1999 to 2009 and 14.60 ± 4.81 m/yr from 2009 to 2016. Such a decline in retreat is further confirmed by the satellite data set. A close examination of meltwater discharge and retreating rate (r2 = 0.95) show that both parameters are strongly correlated. Therefore, we suggest that a consistent decrease in meltwater discharge from 1999 to 2015 is in agreement with decreasing trend of retreating rate during the recent years. To determine the possible causes of decreased retreating rate, a relationship between debris thickness and melt rate was also established by ablation stakes. Further, we infer that the declining trend in the glacier retreat is not only controlled by prevailing weather conditions (rainfall and air temperature) but is also governed by increased debris cover on the glacier surface which prevents the ice to melt.

End-to-end test to evaluate the comprehensive geometric accuracy of a proton rotating gantry using a cone-shaped scintillator screen detector.

In this study, we aim to evaluate the comprehensive geometric accuracy of proton rotating gantries by performing an end-to-end test using a cone-shaped scintillator screen detector, known as XRV-124. The XRV-124 comprises a cone-shaped sheet-like scintillator and charge-coupled device camera that detects the scintillation light. First, the results of the Winston-Lutz and end-to-end XRV-124 tests performed on a conventional linear accelerator were compared to confirm the reliability of the XRV-124, and the snout position dependency of the geometric accuracy was evaluated for the proton rotating gantry as a pre-verification process. Thereafter, an end-to-end test including computed tomography imaging and irradiation in 30° steps from 0° to 330° for two proton rotating gantries, which have the same specifications, was performed. The results of the pre-verification indicated that sufficient accuracy was obtained for the end-to-end test of the proton rotating gantry. The end-to-end test results showed a peak-to-peak deviation of up to 2mm for some of the coordinate axes. The two gantries exhibited almost similar results in terms of the absolute quantity; however, a few trends were different. Thus, the beam axis deviations were confirmed to be within the safety margin, as expected in clinical practice. Based on the results of this study, the XRV-124 can be used as a comprehensive end-to-end constancy test tool, as it enables a comparative verification of multiple rotating gantries and geometric accuracy verification of different treatment modalities.

Spatio-temporal changes in the six major glaciers of the Chitral River basin (Hindukush Region of Pakistan) between 2001 and 2018

Glaciers in the northern Pakistan are a distinctive source of freshwater for the irrigation, drinking and industrial water supplies of the people living in those regions and downstream. These glaciers are under a direct global warming impact as indicated in many previous studies. In this study, we estimated the glacier dynamics in terms of Equilibrium Line Altitude (ELA), mass balance and the snout position variation using remote sensing data between 2001 and 2018. Six glaciers, having area ≥ 20 km2 each, situated in the Chitral region (Hindukush Mountains) were investigated in this study. Digital Elevation Model (DEM) and available cloud-free continuous series of Landsat and Sentinel the entire study area was a retreat of -231 ± 140 m. No obvious relationship was found between the glacier variation trends and the available gauged climatic data possibly due to the presence of debris cover in ablation zones of all the studied glaciers which provides insulation and reduces the immediate climatic effects.

Spatio-temporal behaviour of Nehnar Glacier from 1962 to 2017, Jhelum basin, Kashmir Himalayas, India

ABSTRACT Nehnar glacier is located in the Sindh sub-basin of the Jhelum River in the Kashmir Himalayas. We studied the dynamic response of the glacier (area, snout, Equilibrium Line Altitude (ELA), specific mass balance, volume) using Survey of India (SOI) toposheets and Landsat imagery series from 1962 to 2017. The results show that this glacier has lost an area of 1.4 km2 (50.35%) during this period of 55 years. The snout position and ELA have risen significantly, with varying rates at different time intervals. The specific mass balance of the glacier changed from −2.3 cm water equivalent (w.e.) to −35.1 cm w.e. during this period, with a loss of glacier volume from 0.17 km3 to 0.07 km3. Annual mean maximum (Tmax) and mean minimum (Tmin) temperatures show significant increases, whereas an insignificant decrease in precipitation has been recorded from 1980 to 2016. The continuous glacier retreat will have a significant impact on streamflow, agriculture, and other sectors of the Kashmir Himalayas.

Sonapani Glacier Recession over a Century from 1906-2016, Chandra Basin, Himachal Himalaya

Abstract In this study, the changes in snout and area of Sonapani glacier located in Chandra river valley, Himachal Himalaya has been studied over a century from 1906 to 2016. The study used a Survey Map (1906), Corona KH4-B (1971), Landsat 5 TM (1989), Landsat 7 ETM+ (2000) and Google Earth (2016) data images. In order to validate the satellite data images and other field studies, field work was carried out during 2014 in this area. The Survey Map (SM) of the Glacier was prepared by the Geological Survey of India (GSI) in 1906 and hence, demarcated its earliest snout position. Thus, the SM has been used as the base map for overall change detection studies. The study indicated a total glacier retreat of 1820 m at a rate of 16.5 ma−1 over a time period of century from 1906 to 2016. During the different time intervals, the SG has indicated variable recessional patterns. For instance, the glacier has retreated by 991 m at a rate of 15 ma−1 during 1906-1971, 202 m at a rate of 11.2 ma−1 during1971-1989, 31 m at a rate 2.8 ma−1 during 1989-2000 and 596 m at rate of 37.3 ma−1 during 2000-2016. During the recent time period from 2000 to 2016, the rate of recession has increased rapidly. Due to this rapid recession of the glacier a major tributary towards the lower left side has also detached from it. The glacier also indicated an area loss of 29.7% (6.85 km2) from 1906 (23.9 km2) to 2016 (17.09 km2).

Retreating Rate of Chaturangi Glacier, Garhwal Himalaya, India Derived from Kinematic GPS Survey and Satellite Data

The regular monitoring of glaciers is important to determine their retreating rate and mass balance for overall glacier health. Chaturangi glacier, a major inactive tributary of the Gangotri glacier system was selected for the present study due to its dynamic nature and also because there are no previous records of its retreating rates. In order to reconstruct past retreating rates, total area loss, volume change and shift in snout position were measured through multi-temporal satellite data from 1989 to 2016 and kinematic GPS survey from 2015 to 2016. The results obtained from satellite data indicate that in the last 27 years Chaturangi glacier snout has retreated 1172.57 +/- 38.3 m (average = 45.07 +/- 4.31 m/year) with a total area and volume loss of 0.626 +/- 0.001 sq. km and 0.139 km(3) respectively. The field measurements through differential global positioning system survey revealed that the annual retreating rate was 22.84 +/- 0.05 m/year. The large variations in results derived from both the methods are probably because of higher difference in their accuracy. Nevertheless, the results derived from both the methods are in agreement that Chaturangi glacier is retreating at a considerable rate.

Dokriani glacier(Dingarh glacier) and its geological analysis

The study of geomorphological system not only gives information about environmental processes operating there but also relate them whith global environmental system. The geomorphological analysis of Dokriani glacier, Garhwal Himalaya shows five phases of glacial advancement and retreat in the form of well preserved lateral and terminal moraines. The observed retreat rate of glacier in last two decades is about 17.2 m/yr which represents its negative mass balance followed by change in snout position, area and surface height. The farthest glacier expansion of the valley represented as terminal moraine is situated at 8.3 km from present day snout. Whereas, the other sucsessive glacial stages has followed the similar fashion of glacial advancement due to climatic sensitiveness.

Retreat of Pindari glacier and detection of snout position using remote sensing technology

Pindari glacier is the source to Pindar River, one of the major tributary to the River Alaknanda. This study aims to assess the retreat of the Pindari glacier in four decades using visual interpretation of remote sensing data. The GPS technology (coordinates) was used to determine the latest snout position in 2014. The location of snout was marked using series of periodic Landsat imagery with manual digitization process. We marked the snow area and snout point for the different years by using satellite data. Further, these datasets were compared to measure the changes in the glacier position and the shift distances. The cumulative glacial retreat was recorded 1569.01 m with average glacier retreat rate of 51.23 m/year within the study duration (1976–2014). The glacier retreat rate/year was faster during 1976–94 than 1999–2014. The finding of the study may bring attention to the scientific society and trigger more vigorous study on quantifying glacier retreat in Pindari as well as other glaciers of the Himalaya.

Slowing down the retreat of the Morteratsch glacier, Switzerland, by artificially produced summer snow: a feasibility study

Many large valley glaciers in the world are retreating at historically unprecedented rates. Also in the Alps, where warming over the past decades has been more than twice as large as the global mean, all major glaciers have retreated over distances of several kilometers over the past hundred years. The Morteratsch Glacier, Pontresina, Switzerland, is a major touristic attraction. Due to strong retreat, the lowest part of the glacier is getting out of sight from the gravel road that provided direct access to the glacier front. The Community of Pontresina has commissioned a preparatory study to find out if it is possible to slow down the retreat of the Morteratsch Glacier in an environmentally friendly way. In this article, we report on the outcome of such a study, based on a modeling approach. Our analysis is based on a 20-year weather station record from the lower part of the glacier, combined with calculations with a calibrated ice-flow model. We arrive at the conclusion that producing summer snow in the ablation zone over a larger area (typically 0.5 to 1 km2) may have a significant effect on the rate of retreat on a timescale of decades. We consider various scenarios of climate change: (i) no change, (ii) a rise of the equilibrium-line altitude (ELA) by 1, 2, and 4 m/yr. Projections of glacier length are calculated until the year 2100. It takes about 10 years before snow deposition in the higher ablation zone starts to affect the position of the glacier snout. For the case of modest warming, the difference in glacier length between the snow and no-snow experiments becomes 400 to 500 m within two decades.