scholarly journals Contrasted surface mass balances of debris-free glaciers observed between the southern and the inner parts of the Everest region (2007–15)

2017 ◽  
Vol 63 (240) ◽  
pp. 637-651 ◽  
Author(s):  
SONAM FUTI SHERPA ◽  
PATRICK WAGNON ◽  
FANNY BRUN ◽  
ETIENNE BERTHIER ◽  
CHRISTIAN VINCENT ◽  
...  
Keyword(s):  
Vertical Gradient ◽  
High Elevation ◽  
Area Ratio ◽  
Horizontal Gradient ◽  
Mass Balances ◽  
Surface Mass ◽  
Maximum Elevation ◽  
Accumulation Area Ratio ◽  
Inner Parts ◽  
Cyclonic Storms

ABSTRACTThree debris-free glaciers with strongly differing annual glaciological glacier-wide mass balances (MBs) are monitored in the Everest region (central Himalaya, Nepal). The mass budget of Mera Glacier (5.1 km2in 2012), located in the southern part of this region, was balanced during 2007–15, whereas Pokalde (0.1 km2in 2011) and West Changri Nup glaciers (0.9 km2in 2013), ~30 km further north, have been losing mass rapidly with annual glacier-wide MBs of −0.69 ± 0.28 m w.e. a−1(2009–15) and −1.24 ± 0.27 m w.e. a−1(2010–15), respectively. An analysis of high-elevation meteorological variables reveals that these glaciers are sensitive to precipitation, and to occasional severe cyclonic storms originating from the Bay of Bengal. We observe a negative horizontal gradient of annual precipitation in south-to-north direction across the range (≤−21 mm km−1, i.e. −2% km−1). This contrasted mass-balance pattern over rather short distances is related (i) to the low maximum elevation of Pokalde and West Changri Nup glaciers, resulting in years where their accumulation area ratio is reduced to zero and (ii) to a steeper vertical gradient of MB for glaciers located in the inner arid part of the range.

scholarly journals SPATIO-TEMPORAL VARIABILITY OF CARBOHYDRATE AND CHLOROPHYLL CONTENT IN THE COFFEE CANOPY

2019 ◽  
Vol 14 (3) ◽  
pp. 366
Author(s):  
Paula Tristão Santini ◽  
Lorena Gabriela Almeida ◽  
Kamila Rezende Dázio de Souza ◽  
João Paulo Rodrigues Alves Delfino Barbosa ◽  
José Donizeti Alves
Keyword(s):  
Chlorophyll Content ◽  
Soluble Sugars ◽  
Vertical Direction ◽  
Vertical Gradient ◽  
Horizontal Gradient ◽  
Coffee Plant ◽  
Chloroplast Pigments ◽  
Spatio Temporal ◽  
Inner Parts ◽  
Plagiotropic Branches

The spatial variability of the total chlorophyll content and carotenoids content, starch and soluble sugars of coffee canopy were mapped throughout the day. Therefore, evaluations were carried out in a ‘Catuaí Vermelho’ coffee plant with 1.7 meters height. A vertical gradient (from the apex to the base of the plant canopy) and a horizontal gradient (plagiotropic branches) were established to analyze different positions of the canopy. Thus, in the vertical direction, four heights were analyzed in the plant: top, upper, middle and lower regions. In the horizontal gradient, the plagiotropic branches were divided into three parts: basal, median and apical. Collection of leaf samples was performed on the east and west sides of the canopy, at 9 a.m., totaling 24 collection points at each time. Higher content of photosynthetic pigments and concentration of sugars were observed in the western face and in the inner parts of the coffee tree. The content of chloroplast pigments and sugars of an individual coffee leaf diverge considerably from other leaves, which requires caution when scaling estimates at the global canopy level. The analysis of some punctual leaves does not serve to discriminate the overall dynamics of a canopy.

scholarly journals Long-range terrestrial laser scanning measurements of annual and intra-annual mass balances for Urumqi Glacier No. 1, eastern Tien Shan, China

2019 ◽  
Vol 13 (9) ◽  
pp. 2361-2383 ◽  
Author(s):  
Chunhai Xu ◽  
Zhongqin Li ◽  
Huilin Li ◽  
Feiteng Wang ◽  
Ping Zhou
Keyword(s):  
Mass Balance ◽  
Long Range ◽  
Tien Shan ◽  
Glacier Mass Balance ◽  
Surface Mass Balance ◽  
Mass Balances ◽  
Surface Mass ◽  
Mass Conversion ◽  
Geodetic Mass Balance

Abstract. The direct glaciological method provides in situ observations of annual or seasonal surface mass balance, but can only be implemented through a succession of intensive in situ measurements of field networks of stakes and snow pits. This has contributed to glacier surface mass-balance measurements being sparse and often discontinuous in the Tien Shan. Nevertheless, long-term glacier mass-balance measurements are the basis for understanding climate–glacier interactions and projecting future water availability for glacierized catchments in the Tien Shan. Riegl VZ®-6000 long-range terrestrial laser scanner (TLS), typically using class 3B laser beams, is exceptionally well suited for repeated glacier mapping, and thus determination of annual and seasonal geodetic mass balance. This paper introduces the applied TLS for monitoring summer and annual surface elevation and geodetic mass changes of Urumqi Glacier No. 1 as well as delineating accurate glacier boundaries for 2 consecutive mass-balance years (2015–2017), and discusses the potential of such technology in glaciological applications. Three-dimensional changes of ice and firn–snow bodies and the corresponding densities were considered for the volume-to-mass conversion. The glacier showed pronounced thinning and mass loss for the four investigated periods; glacier-wide geodetic mass balance in the mass-balance year 2015–2016 was slightly more negative than in 2016–2017. Statistical comparison shows that agreement between the glaciological and geodetic mass balances can be considered satisfactory, indicating that the TLS system yields accurate results and has the potential to monitor remote and inaccessible glacier areas where no glaciological measurements are available as the vertical velocity component of the glacier is negligible. For wide applications of the TLS in glaciology, we should use stable scan positions and in-situ-measured densities of snow–firn to establish volume-to-mass conversion.

scholarly journals Characterization of Snow and Ice Reflectance Zones On Glaciers Using Landsat Thematic Mapper Data

1987 ◽  
Vol 9 ◽  
pp. 104-108 ◽  
Author(s):  
D.K. Hall ◽  
J.P. Ormsby ◽  
R.A. Bindschadler ◽  
H. Siddalingaiah
Keyword(s):  
Surface Temperature ◽  
Area Ratio ◽  
Thematic Mapper ◽  
Landsat Thematic Mapper ◽  
Ablation Area ◽  
Thematic Mapper Data ◽  
Glacier System ◽  
Accumulation Area Ratio ◽  
Snow And Ice

Landsat Thematic Mapper (TM) data have been analyzed to study the reflectivity characteristics of three glaciers: the Grossglockner mountain group of glaciers in Austria and the McCall and Meares Glaciers in Alaska, USA. The ratio of TM band 4 (0.76–0.90 μm) to TM band 5 (1.55–1.75 μm) was found to be useful for enhancing reflectivity differences on the glaciers. Using this ratio, distinct zones of similar reflectivity were noted on the Grossglockner mountain group of glaciers and on the Meares Glacier; no distinct zones were observed on the McCall Glacier. On the TM subscene containing the Grossglockner mountain group of glaciers, 28.2% of the glacierized area was determined to be in the zone corresponding most closely to the ablation area, and 71.8% with the location of the accumulation area. Using these measurements, the glacier system has an accumulation area ratio (AAR) of approximately 0.72. Within the accumulation area, two zones of different reflectivity were delineated. Radiometric surface temperatures were measured using TM band 6 (10.4–12.5 μm) on the Grossglockner mountain group of glaciers and on the Meares Glacier. The average radiometric surface temperature of the Grossglockner mountain group of glaciers decreased from 0.9 ± 0.34 °C in the ablation area, to −0.9 ± 0.83 C in the accumulation area.

scholarly journals Equilibrium-Line Altitudes and Paleoenvironment in the Merchants Bay Area, Baffin Island, N.W.T., Canada

1985 ◽  
Vol 31 (109) ◽  
pp. 205-213 ◽  
Author(s):  
Fred F. Hawkins
Keyword(s):  
Area Ratio ◽  
Equilibrium Line ◽  
Storm Tracks ◽  
Lateral Moraine ◽  
Baffin Island ◽  
Statistical Comparison ◽  
Bay Area ◽  
The North ◽  
Simple Geometry ◽  
Accumulation Area Ratio

AbstractThe fiordlands south of Merchants Bay contain an extensive, well-preserved moraine record of a late Foxe advance of local valley glaciers. This has allowed accurate reconstruction of former glacier margins and computation of former equilibrium-line altitudes (ELAs) by a variety of methods. Statistical comparison of three methods (maximum lateral-moraine elevation, median elevation, and accumulation area ratio (AAR)) shows that different techniques can give different results for the same glaciers. Lateral moraines gave estimates that were too low, probably due to post-glacial erosion or to non-deposition. Median elevations and the AAR method produced statistically similar results but only for glaciers of simple geometry. The median-elevation method fails to take into account variations in valley morphology and glaciological parameters, and so is not reliable in all situations. The AAR method is supported by empirical evidence and is the best of the three methods for estimating former ELAs.Analysis of trend surfaces of present and late Foxe ELAs shows changes in elevation and orientation through time due to changing environmental factors. Present ELAs are strongly influenced by local factors, southerly storm tracks, and warm maritime conditions. Paleo-ELAs do not show this influence, suggesting that Davis Strait may have been ice-covered during the late Foxe stade and that storm tracks were from the north.

scholarly journals Monitoring glacier albedo as a proxy to derive summer and annual surface mass balances from optical remote-sensing data

2018 ◽  
Vol 12 (1) ◽  
pp. 271-286 ◽  
Author(s):  
Lucas Davaze ◽  
Antoine Rabatel ◽  
Yves Arnaud ◽  
Pascal Sirguey ◽  
Delphine Six ◽  
...  
Keyword(s):  
Mass Balance ◽  
Surface Albedo ◽  
In Situ Measurements ◽  
Surface Mass Balance ◽  
Mass Balances ◽  
Equilibrium Line Altitude ◽  
Surface Mass ◽  
Minimum Surface ◽  
Summer Minimum

Abstract. Less than 0.25 % of the 250 000 glaciers inventoried in the Randolph Glacier Inventory (RGI V.5) are currently monitored with in situ measurements of surface mass balance. Increasing this archive is very challenging, especially using time-consuming methods based on in situ measurements, and complementary methods are required to quantify the surface mass balance of unmonitored glaciers. The current study relies on the so-called albedo method, based on the analysis of albedo maps retrieved from optical satellite imagery acquired since 2000 by the MODIS sensor, on board the TERRA satellite. Recent studies revealed substantial relationships between summer minimum glacier-wide surface albedo and annual surface mass balance, because this minimum surface albedo is directly related to the accumulation–area ratio and the equilibrium-line altitude. On the basis of 30 glaciers located in the French Alps where annual surface mass balance data are available, our study conducted on the period 2000–2015 confirms the robustness and reliability of the relationship between the summer minimum surface albedo and the annual surface mass balance. For the ablation season, the integrated summer surface albedo is significantly correlated with the summer surface mass balance of the six glaciers seasonally monitored. These results are promising to monitor both annual and summer glacier-wide surface mass balances of individual glaciers at a regional scale using optical satellite images. A sensitivity study on the computed cloud masks revealed a high confidence in the retrieved albedo maps, restricting the number of omission errors. Albedo retrieval artifacts have been detected for topographically incised glaciers, highlighting limitations in the shadow correction algorithm, although inter-annual comparisons are not affected by systematic errors.

The Annual Balance of North Cascade Glaciers, Washington, U.S.A., Measured and Predicted Using An Activity-Index Method

1988 ◽  
Vol 34 (117) ◽  
pp. 194-199 ◽  
Author(s):  
Mauri S. Pelto
Keyword(s):  
Mass Balance ◽  
Activity Index ◽  
Prediction Method ◽  
Climatic Conditions ◽  
Area Ratio ◽  
Index Method ◽  
The North ◽  
Snow Line ◽  
Accumulation Area Ratio ◽  
Annual Balance

AbstractThe annual balance has been measured for ten North Cascade glaciers in 1983–84, 1984–85, 1985–86, and 1986–87 (1984, 1985, 1986, and 1987). Based on these data, an annual balance prediction method was designed and tested. Comparison of measured versus predicted annual balances indicates an accuracy of ±0.22–0.30 m. The method is based on annual measurement of the accumulation area ratio (AAR), and determination of the perennially constant activity index and area-altitude distribution on each glacier. The accumulation area ratio is determined from aerial and ground photographs at the end of the ablation season. The activity index is identified from observation of the rise of the snow line with time, compared to measured snow depths above the snow line. The AAR-activity index method was used to calculate the annual balance of 47 North Cascade glaciers in 1984, 1985, 1986, and 1987. The mean balance during the 4 year period was —0.33 m.From the mass-balance records, it is apparent that North Cascade glaciers can be divided into six climatic sensitivity groups. Each glacier type responds differently to specific climatic conditions. The mass-balance variation for glaciers of the same type is small.Since 1977, warmer, drier climatic conditions have prevailed in the North Cascades, resulting in the retreat of 42 of the 47 glaciers examined.

scholarly journals The climate sensitivity of Antarctic blue-ice areas

1995 ◽  
Vol 21 ◽  
pp. 157-161 ◽  
Author(s):  
Richard Bintanja ◽  
Michiel R. Van Den Broeke
Keyword(s):  
Mass Balance ◽  
Time Scales ◽  
Climate Sensitivity ◽  
High Elevation ◽  
Surface Mass Balance ◽  
Snow Surface ◽  
Local Climate ◽  
Surface Mass

On time-scales of less than about 100 years, when the ice topography can be considered stationary, the extent of Antarctic blue-ice areas is governed mainly by the surface mass balance. In and near high-elevation blue-ice areas, ablation is due entirely to sublimation. An estimate of the mass-balance profile ranging from a blue-ice area to the adjacent snow surface is presented. By considering changes in sublimation induced by variations in local climate, the deviation from the mass-balance profile is evaluated. It is concluded that even for considerable changes in local climate these deviations remain relatively small and have only little effect on the extent of a blue-ice area. This can be attributed mainly to the steep mass-balance profile.

scholarly journals The geodetic mass balance of Eyjafjallajökull ice cap for 1945–2014: processing guidelines and relation to climate

2019 ◽  
Vol 65 (251) ◽  
pp. 395-409 ◽  
Author(s):  
JOAQUÍN M. C. BELART ◽  
EYJÓLFUR MAGNÚSSON ◽  
ETIENNE BERTHIER ◽  
FINNUR PÁLSSON ◽  
GUðFINNA AÐALGEIRSDÓTTIR ◽  
...  
Keyword(s):  
Mass Balance ◽  
Robust Statistics ◽  
Winter Precipitation ◽  
Summer Temperature ◽  
Aerial Photographs ◽  
Mass Balances ◽  
Stereo Images ◽  
Surface Mass ◽  
Ice Cap ◽  
Static Sensitivity

ABSTRACTMass-balance measurements of Icelandic glaciers are sparse through the 20th century. However, the large archive of stereo images available allows estimates of glacier-wide mass balance ($\dot{B}$) in decadal time steps since 1945. Combined with climate records, they provide further insight into glacier–climate relationship. This study presents a workflow to process aerial photographs (1945–1995), spy satellite imagery (1977–1980) and modern satellite stereo images (since 2000) using photogrammetric techniques and robust statistics in a highly automated, open-source pipeline to retrieve seasonally corrected, decadal glacier-wide geodetic mass balances. In our test area, Eyjafjallajökull (S-Iceland, ~70 km2), we obtain a mass balance of $<![CDATA[ $ \dot{\curr B}_{\curr 1945}^{\curr 2014} \curr = -0.27 \pm 0.03\,{\rm \curr m\ w}{\rm. \curr e}{\rm.} {\rm \curr a}^{{\rm \ndash \curr 1}}$, with a maximum and minimum of $\dot{\curr B}_{\curr 1984}^{\curr 1989} \curr = 0.77 \curr \pm 0.19\,{\rm \curr m\ \curr w}{\rm\curr . e}{\rm\curr .} {\rm\curr a}^{{\rm\curr \ndash 1}}$ and $\dot{\curr B}_{\curr 1994}^{\curr 1998}\curr = -1.94 \curr \pm 0.34\,{\rm \curr m\ w}{\rm\curr . e}{\rm\curr .} {\rm \curr a}^{{\rm\curr \ndash 1}}$, respectively, attributed to climatic forcing, and $\dot{\curr B}_{\curr 2009}^{\curr 2010} \curr = -3.39{\rm \;} \curr \pm {\rm \;} \curr 0.43\,{\rm \curr m\ w}{\rm\curr . e}{\rm\curr .} {\rm\curr a}^{{\rm\curr \ndash 1}}$, mostly caused by the April 2010 eruption. The reference-surface mass balances correlate with summer temperature and winter precipitation, and linear regression accounts for 80% of the mass-balance variability, yielding a static sensitivity of mass balance to summer temperature and winter precipitation of − 2.1 ± 0.4 m w.e.a–1K–1 and 0.5 ± 0.3 m w.e.a–1 (10%)–1, respectively. This study serves as a template that can be used to estimate the mass-balance changes and glaciers' response to climate.

scholarly journals Quantifying mass balance processes on the Southern Patagonia Icefield

2015 ◽  
Vol 9 (1) ◽  
pp. 25-35 ◽  
Author(s):  
M. Schaefer ◽  
H. Machguth ◽  
M. Falvey ◽  
G. Casassa ◽  
E. Rignot
Keyword(s):  
Mass Balance ◽  
Reanalysis Data ◽  
Ice Thickness ◽  
Surface Mass Balance ◽  
Mass Balances ◽  
Surface Mass ◽  
Mass Losses ◽  
Southern Patagonia ◽  
Spatially Distributed ◽  
The Individual

Abstract. We present surface mass balance simulations of the Southern Patagonia Icefield (SPI) driven by downscaled reanalysis data. The simulations were evaluated and interpreted using geodetic mass balances, measured point balances and a complete velocity field of the icefield for spring 2004. The high measured accumulation of snow of up to 15.4 m w.e. yr−1 (meters water equivalent per year) as well as the high measured ablation of up to 11 m w.e. yr−1 is reproduced by the model. The overall modeled surface mass balance was positive and increasing during 1975–2011. Subtracting the surface mass balance from geodetic balances, calving fluxes were inferred. Mass losses of the SPI due to calving were strongly increasing from 1975–2000 to 2000–2011 and higher than losses due to surface melt. Calving fluxes were inferred for the individual glacier catchments and compared to fluxes estimated from velocity data. Measurements of ice thickness and flow velocities at the glaciers' front and spatially distributed accumulation measurements can help to reduce the uncertainties of the different terms in the mass balance of the Southern Patagonia Icefield.

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