scholarly journals Climate at the Equilibrium Line of Glaciers

1992 ◽  
Vol 38 (130) ◽  
pp. 397-411 ◽  
Author(s):  
Atsumu Ohmura ◽  
Peter Kasser ◽  
Martin Funk
Keyword(s):  
Mass Balance ◽  
Climate Models ◽  
Equilibrium Line ◽  
Total Precipitation ◽  
Net Radiation ◽  
Specific Mass ◽  
Free Atmosphere ◽  
Long Wave ◽  
Annual Total ◽  
Meteorological Observations

AbstractThe relationships between temperature, precipitation and radiation on glacier equilibrium lines are investigated, using 70 glaciers for which the mass balance and meteorological observations have been carried out for sufficiently long periods. It is found that the characteristic climate at glacier equilibrium lines can be described using the summer 3 months’ temperature in a free atmosphere, annual total precipitation, and the sum of global and long-wave net radiation. All of these are measured at or very near the equilibrium-line altitudes. Then, it is shown how the shift of the equilibriumline will occur as a result of a climatic change. Finally, the effect of the shift of the equilibrium line on the annualmean specific mass balance is analytically derived and compared with observations. The present results make it possible to identify the altitudes in climate models where glacierization should begin, and to evaluate the mass-balance changes as a result of possible future changes in the climate.

scholarly journals Climate at the Equilibrium Line of Glaciers

1992 ◽  
Vol 38 (130) ◽  
pp. 397-411 ◽  
Author(s):  
Atsumu Ohmura ◽  
Peter Kasser ◽  
Martin Funk
Keyword(s):  
Mass Balance ◽  
Climate Models ◽  
Equilibrium Line ◽  
Total Precipitation ◽  
Net Radiation ◽  
Specific Mass ◽  
Free Atmosphere ◽  
Long Wave ◽  
Annual Total ◽  
Meteorological Observations

AbstractThe relationships between temperature, precipitation and radiation on glacier equilibrium lines are investigated, using 70 glaciers for which the mass balance and meteorological observations have been carried out for sufficiently long periods. It is found that the characteristic climate at glacier equilibrium lines can be described using the summer 3 months’ temperature in a free atmosphere, annual total precipitation, and the sum of global and long-wave net radiation. All of these are measured at or very near the equilibrium-line altitudes. Then, it is shown how the shift of the equilibriumline will occur as a result of a climatic change. Finally, the effect of the shift of the equilibrium line on the annualmean specific mass balance is analytically derived and compared with observations. The present results make it possible to identify the altitudes in climate models where glacierization should begin, and to evaluate the mass-balance changes as a result of possible future changes in the climate.

scholarly journals Historical Spatial and Temporal Climate Trends in Southern Ontario, Canada

2017 ◽  
Vol 56 (10) ◽  
pp. 2767-2787 ◽  
Author(s):  
Hussein Wazneh ◽  
M. Altaf Arain ◽  
Paulin Coulibaly
Keyword(s):  
Climate Models ◽  
Global Climate ◽  
Global Climate Models ◽  
Climate Indices ◽  
Total Precipitation ◽  
Southern Ontario ◽  
Temperature And Precipitation ◽  
Annual Total ◽  
Precipitation Indices ◽  
Temperature Indices

AbstractSpatial and temporal trends in historical temperature and precipitation extreme events were evaluated for southern Ontario, Canada. A number of climate indices were computed using observed and regional and global climate datasets for the area of study over the 1951–2013 period. A decrease in the frequency of cold temperature extremes and an increase in the frequency of warm temperature extremes was observed in the region. Overall, the numbers of extremely cold days decreased and hot nights increased. Nighttime warming was greater than daytime warming. The annual total precipitation and the frequency of extreme precipitation also increased. Spatially, for the precipitation indices, no significant trends were observed for annual total precipitation and extremely wet days in the southwest and the central part of Ontario. For temperature indices, cool days and warm night have significant trends in more than 90% of the study area. In general, the spatial variability of precipitation indices is much higher than that of temperature indices. In terms of comparisons between observed and simulated data, results showed large differences for both temperature and precipitation indices. For this region, the regional climate model was able to reproduce historical observed trends in climate indices very well as compared with global climate models. The statistical bias-correction method generally improved the ability of the global climate models to accurately simulate observed trends in climate indices.

scholarly journals Calculation of Mass Balance of Glaciers by Remote-Sensing Imagery Using Similarity of Accumulation and Ablation Isoline Patterns

1987 ◽  
Vol 33 (115) ◽  
pp. 363-368 ◽  
Author(s):  
A.N Krenke ◽  
V.M Menshutin
Keyword(s):  
Remote Sensing ◽  
Mass Balance ◽  
Satellite Imagery ◽  
Equilibrium Line ◽  
Glacier Mass Balance ◽  
Specific Mass ◽  
Mean Values ◽  
Remote Sensing Imagery ◽  
Air Temperatures ◽  
One Year

Abstract An investigation of the combined heat, ice, and water balances was carried out in the Marukh glacier basin (west Caucasus) in 1966–67 to 1976–77, according to the International Hydrological Decade programme. Averaged glacier mass balance for these 11 years appears to be −55 g cm−2 year−1 according to stake measurements, and −51 g cm−2 year−1 according to geodetic measurements. The variability of accumulation is estimated as C v = 0.15 and of ablation as C v = 0.11. Thus, the variation in accumulation governs the oscillations in glacier balance. The inner nourishment of the glacier was also taken into account. The glacier mass balance is closely related to the relation between the accumulation and ablation areas. The “transient” values of both figures during the whole period of ablation can be used for this relation. The forms of the accumulation and ablation fields are similar from year to year and from one 10 day period to another. The areas of the accumulation and ablation zones are very different from one year to another. On the contrary, the average specific balance for each zone changes very little. One can use these features for the construction of accumulation, ablation, and specific mass-balance maps from satellite imagery. Mean values for the mass-balance terms occur in the vicinity of the equilibrium line. They can be calculated by using the air temperatures. Deviations from the means in different areas of the glacier determine the typical fields of the mass-balance terms.

scholarly journals Estimating equilibrium-line altitude (ELA) from glacier inventory data

2009 ◽  
Vol 50 (53) ◽  
pp. 127-132 ◽  
Author(s):  
R.J. Braithwaite ◽  
S.C.B. Raper
Keyword(s):  
Mass Balance ◽  
Climate Models ◽  
Equilibrium Line ◽  
Strongly Correlated ◽  
Inventory Data ◽  
Equilibrium Line Altitude ◽  
Glacier Inventory ◽  
Geographical Variations ◽  
The World ◽  
Balanced Budget

AbstractA glacier’s most fundamental altitude is the equilibrium-line altitude (ELA) because it divides the glacier into ablation and accumulation areas. The best parameterization of the ELA for glacier inventory is the balanced-budget ELA. We discuss direct estimation of balanced-budget ELA from mass-balance data for individual glaciers, and indirect estimation of balanced-budget ELA from simple topographic parameters available from the World Glacier Inventory (WGI), i.e. the area-median and maximum and minimum altitudes. Mass balance and ELA for individual glaciers are usually strongly correlated and we calculate balanced-budget ELA from the regression equation linking the two. We then compare balanced-budget ELA with area-median and mid-range altitudes for the 94 glaciers for which we have all the necessary data. The different ELA estimates agree well enough (±82 to ±125 m) to describe geographical variations in ELA and for application of glacier–climate models to glacier inventory data. Mid-range and area-median altitudes are already available for tens of thousands of glaciers in the current WGI and should be evaluated in future inventories.

scholarly journals Climatic Shift of the Equilibrium Line: Kuhn's Concept Applied to the Greenland Ice Cap

1985 ◽  
Vol 6 ◽  
pp. 76-78 ◽  
Author(s):  
Walter Ambach
Keyword(s):  
Heat Balance ◽  
Sensible Heat Flux ◽  
Equilibrium Line ◽  
Net Radiation ◽  
Ice Cap ◽  
Long Wave ◽  
Altitudinal Shift ◽  
Downward Radiation ◽  
Climatic Disturbances ◽  
The Heat Transfer Coefficient

The shift of the equilibrium line in response to climatic disturbances is calculated for the International Glaciological Greenland Expedition (EGIG) profile of the Greenland Ice Cap. Data of heat balance studies carried out during EGIG 1959 and EGIG 1967 are used according to Kuhn’s algorithm. The following parameters are applied; the heat transfer coefficient of the sensible heat flux; the effective emissivity of the atmosphere for long wave downward radiation; a factor relating net radiation to cloudiness; the duration of the ablation season; the altitudinal temperature gradient; the altitudinal accumulation gradient. The altitudinal shift of the equilibrium line results for the EGIG profile + 77m/°C and -4 m per 1/10 cloudiness with 35d of ablation. Changes in heat balance by formation of superimposed ice are taken into account.

scholarly journals Climatic Shift of the Equilibrium Line: Kuhn's Concept Applied to the Greenland Ice Cap

1985 ◽  
Vol 6 ◽  
pp. 76-78 ◽  
Author(s):  
Walter Ambach
Keyword(s):  
Heat Balance ◽  
Sensible Heat Flux ◽  
Equilibrium Line ◽  
Net Radiation ◽  
Ice Cap ◽  
Long Wave ◽  
Altitudinal Shift ◽  
Downward Radiation ◽  
Climatic Disturbances ◽  
The Heat Transfer Coefficient

The shift of the equilibrium line in response to climatic disturbances is calculated for the International Glaciological Greenland Expedition (EGIG) profile of the Greenland Ice Cap. Data of heat balance studies carried out during EGIG 1959 and EGIG 1967 are used according to Kuhn’s algorithm. The following parameters are applied; the heat transfer coefficient of the sensible heat flux; the effective emissivity of the atmosphere for long wave downward radiation; a factor relating net radiation to cloudiness; the duration of the ablation season; the altitudinal temperature gradient; the altitudinal accumulation gradient.The altitudinal shift of the equilibrium line results for the EGIG profile + 77m/°C and -4 m per 1/10 cloudiness with 35d of ablation. Changes in heat balance by formation of superimposed ice are taken into account.

scholarly journals Calculation of Mass Balance of Glaciers by Remote-Sensing Imagery Using Similarity of Accumulation and Ablation Isoline Patterns

1987 ◽  
Vol 33 (115) ◽  
pp. 363-368
Author(s):  
A.N Krenke ◽  
V.M Menshutin
Keyword(s):  
Remote Sensing ◽  
Mass Balance ◽  
Satellite Imagery ◽  
Equilibrium Line ◽  
Glacier Mass Balance ◽  
Specific Mass ◽  
Mean Values ◽  
Remote Sensing Imagery ◽  
Air Temperatures ◽  
One Year

AbstractAn investigation of the combined heat, ice, and water balances was carried out in the Marukh glacier basin (west Caucasus) in 1966–67 to 1976–77, according to the International Hydrological Decade programme. Averaged glacier mass balance for these 11 years appears to be −55 g cm−2 year−1 according to stake measurements, and −51 g cm−2 year−1 according to geodetic measurements. The variability of accumulation is estimated as Cv = 0.15 and of ablation as Cv = 0.11. Thus, the variation in accumulation governs the oscillations in glacier balance. The inner nourishment of the glacier was also taken into account. The glacier mass balance is closely related to the relation between the accumulation and ablation areas. The “transient” values of both figures during the whole period of ablation can be used for this relation. The forms of the accumulation and ablation fields are similar from year to year and from one 10 day period to another. The areas of the accumulation and ablation zones are very different from one year to another. On the contrary, the average specific balance for each zone changes very little. One can use these features for the construction of accumulation, ablation, and specific mass-balance maps from satellite imagery. Mean values for the mass-balance terms occur in the vicinity of the equilibrium line. They can be calculated by using the air temperatures. Deviations from the means in different areas of the glacier determine the typical fields of the mass-balance terms.

scholarly journals Analysis of meteorological data and the surface energy balance of McCall Glacier, Alaska, USA

2005 ◽  
Vol 51 (174) ◽  
pp. 451-461 ◽  
Author(s):  
E.J. Klok ◽  
M. Nolan ◽  
M.R. Van Den Broeke
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Mass Balance ◽  
Forest Fires ◽  
Surface Energy Balance ◽  
Meteorological Data ◽  
Heat Fluxes ◽  
Turbulent Heat ◽  
Net Radiation ◽  
Specific Mass

AbstractWe report on analysis of meteorological data for the period 27 May–20 August 2004, from two automatic weather stations on McCall Glacier, Alaska, USA, aimed at studying the relationship between climate and ablation. One station is located on a mountain ridge and the other in the ablation area where we also analyzed the energy balance. The weather station on the glacier measured an average temperature of 5.3°C (at 2 m height above surface) and wind speed of 3.1 m s−1 (at 3 m height). A sonic height ranger and ablation stakes indicate a specific mass balance of –1.94 ± 0.09 m w.e between 15 June and 20 August. The specific mass balance calculated from the surface energy balance, –2.06 ± 0.18 m w.e., is in close correspondence to this. The latter is the sum of 0.12 m w.e. of snowfall, 0.003 m w.e. of deposition and –2.18 m w.e. of melt. Net radiation contributes 74% of the melt energy. Compared to ablation measurements in the early 1970s, summer ablation was large. This increase is explained by a combination of a relatively higher net radiation, a lower albedo and larger turbulent heat fluxes that led to more energy being available for melting. No single meteorological variable can be isolated as being the principal reason for the high ablation, however. The lower ice albedo (0.19) is possibly due to ash deposits from forest fires.

scholarly journals Cumulus over the Tibetan Plateau in the Summer Based on CloudSat–CALIPSO Data

2016 ◽  
Vol 29 (3) ◽  
pp. 1219-1230 ◽  
Author(s):  
Yunying Li ◽  
Minghua Zhang
Keyword(s):  
Tibetan Plateau ◽  
Climate Models ◽  
Surface Wind ◽  
Lower Atmosphere ◽  
The Tibetan Plateau ◽  
Shallow Convection ◽  
Free Atmosphere ◽  
Northern Summer ◽  
Static Energy ◽  
Fine Resolution

Abstract Cumulus (Cu) can transport heat and water vapor from the boundary layer to the free atmosphere, leading to the redistribution of heat and moist energy in the lower atmosphere. This paper uses the fine-resolution CloudSat–CALIPSO product to characterize Cu over the Tibetan Plateau (TP). It is found that Cu is one of the dominant cloud types over the TP in the northern summer. The Cu event frequency, defined as Cu occurring within 50-km segments, is 54% over the TP in the summer, which is much larger over the TP than in its surrounding regions. The surface wind vector converging at the central TP and the topographic forcing provide the necessary moisture and dynamical lifting of convection over the TP. The structure of the atmospheric moist static energy shows that the thermodynamical environment over the northern TP can be characterized as having weak instability, a shallow layer of instability, and lower altitudes for the level of free convection. The diurnal variation of Cu with frequency peaks during the daytime confirms the surface thermodynamic control on Cu formation over the TP. This study offers insights into how surface heat is transported to the free troposphere over the TP and provides an observational test of climate models in simulating shallow convection over the TP.

scholarly journals Map-based methods for estimating glacier equilibrium-line altitudes

2003 ◽  
Vol 49 (166) ◽  
pp. 329-336 ◽  
Author(s):  
Katherine C. Leonard ◽  
Andrew G. Fountain
Keyword(s):  
Mass Balance ◽  
Sea Level ◽  
Equilibrium Line ◽  
Topographic Maps ◽  
Kinematic Waves ◽  
The Mean

AbstractWe examine the validity of two methods for estimating glacier equilibrium-line altitudes (ELAs) from topographic maps. The ELA determined by contour inflection (the kinematic ELA) and the mean elevation of the glacier correlate extremely well with the ELA determined from mass-balance data (observed ELA). However, the range in glacier elevations above sea level is much larger than the variation in ELA, making this correlation unhelpful. The data were normalized and a reasonable correlation (r2 = 0.59) was found between observed and kinematic ELA.The average of the normalized kinematic ELAs was consistently located down-glacier from the observed ELA, consistent with theory. The normalized mean elevation of the glacier exhibited no correlation and suggests that the toe–headwall altitude ratio is not a good approximation for the ELA. Kinematic waves had no effect on the position of the kinematic ELA. Therefore, topographic maps of glacier surfaces can be used to infer the position of the ELA and provide a method for estimating past ELAs from historic topographic maps.

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