Analysis of Difference Between Direct and Geodetic Mass Balance Measurements at South Cascade Glacier, Washington

Net mass balance has been measured since 1958 at South Cascade Glacier using the 'direct method,' e.g. area averages of snow gain and firn and ice loss at stakes. Analysis of cartographic vertical photography has allowed measurement of mass balance using the 'geodetic method' in 1970, 1975, 1977, 1979–80, and 1985–97. Water equivalent change as measured by these nearly independent methods should give similar results. During 1970–97, the direct method shows a cumulative balance of about −15 m, and the geodetic method shows a cumulative balance of about −22 m. The deviation between the two methods is fairly consistent, suggesting no gross errors in either, but rather a cumulative systematic error. It is suspected that the cumulative error is in the direct method because the geodetic method is based on a non-changing reference, the bedrock control, whereas the direct method is measured with reference to only the previous year's summer surface. Possible sources of mass loss that are missing from the direct method are basal melt, internal melt, and ablation on crevasse walls. Possible systematic measurement errors include under-estimation of the density of lost material, sinking stakes, or poorly represented areas.     

Measurements and Models of the Mass Balance of Hintereisferner

This paper summarizes the methods applied to determine the mass balance of Hintereisferner and several other glaciers in the Tyrolean Alps since 1952. On an annual basis the direct glaciological method was applied with fixed date measurements on 10–15 accumulation pits and 30–90 ablation stakes on 9 km².
Indirect mass balance determination from equilibrium line altitude, accumulation area ratios or representative stakes, yield fair results and some exceptions could be related to anomalous meteorological conditions.
Monthly or more frequent stake readings supplied time series of ablation at various altitudes and slope aspects that served as basis for the calibration of energy and mass balance models. Of various models developed, two are presented in this paper. Both are based on degree days, one using daily values from a valley station to predict the mean annual balance of the entire glacier, while the other calculates day-to-day changes at 50-m grid points on the glacier.
The geodetic method has been applied for longer periods and yields results consistent with those of the glaciological method. The balance velocity calculated from recent ice thickness soundings and accumulation measurements is significantly less than observed velocity.     

Mass Balance Measurements on the Lemon Creek Glacier, Juneau Icefield, Alaska 1953–1998

Annual balance measurements on the Lemon Creek Glacier, Alaska conducted by the Juneau Icefield Research Program (JIRP) from 1953 through 1998 provide a continuous 46 year record. This is one of the nine American glaciers selected in a global monitoring network during the International Geophysical year, 1957/58. These data have been acquired primarily by employing consistent ground methods, conducted on similar annual dates and calculated using comparable methodology. The results have been until now fairly precise, but of uncertain accuracy. An adjunct comparison of topographic surface maps of the glacier made in 1957 and 32 years later in 1989 provides a rough determination of glacier surface elevation changes which are clearly of less precision than the compilation of annual ground data. Airborne surface profiling in 1995, and global positioning system leveling transects in 1996–1998 update the record of surface elevation changes over the past decade. The mean glacier ice thickness reductions suggested by these methods from 1957–1989, from 1957–1995 and from 1957–1998 are ?13.2 m, ?16.4 m, and ?21.7 m, respectively. It is of interest that the geodetic interpretations agree fairly well with the trend of sequential balances from ground-level stratigraphic measurements. To date, however, the infrequent mapping methods in this study have yielded specific balances averaging between 5 and 11% less than those resulting from our annual on-site glaciological monitoring. For future studies this can be an important factor. The ground data are, therefore, the ones in which we have most confidence. These show cumulative ice losses of ?13.9 m (12.7 m water equivalent w.e.) from 1957–1989, of ?19.0 m (?17.1 m w.e.) from 1957–1995, of ?24.4 m (22 m w.e.) from 1957–1998, and ?24.7 m (22.2 m w.e.) for the total cumulative loss over the full 46 years between 1953 and 1998. Although the balance trend has been increasingly negative it averages ?0.48 m/a in w.e. or 0.52 m of ice loss per year. To refine the reliability of density determinations in this data set the effects of internal accumulation from refrozen meltwater producing diagenetic ice structures in the annual firnpack have been taken into account. An unusual dearth of such structures within the 1997/98 firnpack provided a unique opportunity to facilitate application of the probing technique over broad areas of the nv. This added to our ground truth and verified accuracy of the test-pit measurements used in these long-term mass balance computations. The glacier's continuing negative mass balance has fueled a terminal retreat of 800 m during the 1953–1998 period. The annual balance trend indicates that despite a higher mean elevation and a higher elevation terminus from thinning and retreat, mean annual balance has been strongly negative since 1977 (?0.78 m/a w.e.). Dramatically increased negative mass balances have occurred in the 1990s, with 1996 and 1997 being the only years on record with no retained accumulation since field observations were initiated in the glacier source areas in 1948.     

On the Mass Balance of Low Latitude Glaciers with Particular Consideration of the Peruvian Cordillera Blanca

Glacier mass balance studies in the low latitudes are rare and glaciological methods and terminology are basically adapted from mid- and high latitude conditions. The low latitudes are considered to be the tropics and, to some extent, the adjoining dry subtropics. The outer tropics are proposed as an intermediate zone with tropical character during the humid season and subtropical character during the dry season. Delimitations as well as respective climate and glacier regimes are discussed in order to distinguish them from each other and from the mid-latitudes. Different sensitivities of the glaciers can be expected and promise, in turn, a complex climatological interpretation of glacier fluctuations. For this, detailed mass balance studies on low latitude glaciers are required. The respective discussion is concentrated on the Peruvian Cordillera Blanca whose topographical setting provides both spatial and temporal subdivisions in humid and dry regimes in one region. However, theoretical considerations and field experience show problems for the determination of mass balance variables in the Cordillera Blanca and the low latitudes in general. The absence of annual temperature variations hinders the development of impermeable layers which can be identified as annual reference layers and which prevent meltwater from percolating into the firn body. Thus, a combination of ablation measurements and the application of the flux divergence method for the determination of accumulation is proposed.     

A Mass Balance Model that Uses Low-altitude Meteorological Observations and the Area–Altitude Distribution of a Glacier

A glacier mass balance model that requires only low-altitude precipitation and temperature observations and the glacier's areaaltitude distribution is presented as an alternative to direct field measurements. Input to the model for South Cascade Glacier are daily weather observations at stations 30–60 km from the glacier and at altitudes 1300 to 1500 m lower than the glacier. The model relies on the internal consistency of mass balance variables that are generated by simulation using the low-altitude weather data. The daily values of such balance variables as snowline altitude, zero balance altitude, glacier balance, balance flux and the accumulation area ratio are correlated throughout the ablation season using two-degree polynomial regressions to obtain the lowest fitting error. When the minimum average error (or maximum R ²) is attained, the generated balances and other variables are considered to be real. A simplex optimization technique is used to determine the optimal coefficient values that are used in algorithms to convert meteorological observations to snow accumulation and snow and ice ablation. The independently produced simulation results for the 1959–1996 period are compared with balances measured at the glacier. The agreement between annual balances for individual years is fair and between long-term volume changes measured by the geodetic method is excellent.     

Mass Balance Reconstruction Since 1963 and Mass Balance Model for East Rathong Glacier,Eastern Himalaya,Using Remote Sensing Methods

In this study mass balance, accumulation, ablation, runoff and temperature lapse rate for the East Rathong glacier are estimated for the time period 1963–2011 using remote sensing methods and climate data. A mass balance model is proposed for the glacier that computes mass balance as difference of volumes of consecutive years. Volume estimates of glacier are based on application of volume–area scaling law to glacier area computed from satellite images. It is observed that the glacier is summer‐accumulation type. Time series analysis is applied to the annual mass balance series. The annual mass balance of the glacier is showing a statistically significant negative trend. It is also showing a statistically significant shift in the year 1985. Change in the mean of mass balance before and after the shift year is 0.19 m w.e. Cumulative mass balance suggests that the glacier has lost ～11 m w.e. or 0.047 km³ during the last 48 years.     

A Small Glacier as an Index of Regional Mass Balance: Baby Glacier, Axel Heiberg Island, 1959–1992

Baby Glacier, Axel Heiberg Island, N.W.T., Canada is a small (0.6 km²), high-latitude (79°N), high-altitude (700–1200 m) glacier with a mass balance record extending from 1959–60 to the present. The record demonstrates shrinkage of the glacier, but a statistically significant trend is not evident. Correlations are strong between the mass balance of Baby Glacier and that of the nearby and much larger White Glacier, and also those of even larger, more distant glaciers. Thus programmes of measurement on small, simple ice bodies such as Baby Glacier can be representative of a large region. However, inter-annual changes are more accentuated for Baby Glacier. Baby Glacier does not meet all of the usual criteria for a representative glacier, but it straddles the regional equilibrium zone, a fact which helps to offset the disadvantages of its small size and limited altitudinal range. The equilibrium zone deserves to be an important focus for studies of high-arctic mass balance, with the aim of facilitating future measurement programmes which will rely on satellite remote sensing.     

水文气象学方法计算喜马拉雅山北坡冰川流域物质平衡

卡鲁雄曲是喜马拉雅that坡唯一具有长期常规水文气象观测资料的冰川流域.根据中国冰川水文和气候的分布特征,可推导出一组以水文、气象观测数据计算流域冰川平均物质平衡的公式.据此恢复了1983-2006年卡鲁雄曲流域冰川平均物质平衡各分量的逐年值序列,并用SPSS软件对计算结果进行r统计分析.结果表明:1983-2006年的24 a里,卡鲁雄曲流域的冰川消融逐步加剧:多年平均值为-136.3 mm/a,前12 a(1983-1994年)多年平均值为-83.61 mm/a,后12 a(1995-2006年)多年平均值为-188.98 mm/a,且1986、1998和2005年出现较大的波动,冰川物质平衡值分别为:149.19mm、-654.36 mm和-316.43 mm.通过对影响冰川物质平衡动态变化的影响因素进行分析,发现冰川物质平衡变化主要由强烈消融期(5-9月)的平均温度决定,二者的相关系数达到-0.786,并具有很好的线性关系:MB=-331.8T_(5-9)+2683.5.     

Measurement and Estimative Models of Glacier Mass Balance in China

Attributed to high altitude and inland location, the glaciers in China are characterized by very low temperature. The non-negligible contribution of up to 25% of superimposed ice to the net balance has been taken into account in the mass budget calculation. So too has the internal the accumulation in the infiltration zone of the accumulation area.
The prevailing monsoon climate delivers most of the annual precipitation over glaciated areas of China in the summer, making the major accumulation on those glaciers coincide with the ablation period. Therefore, the annual mass balance should be calculated neither by giving the place of annual accumulation to winter balance, nor annual ablation to summer balance. Rather, it is better done by net accumulation and net ablation during the year. In order to get the annual accumulation and the annual ablation on a glacier, the summer precipitation should be measured at the same time.
Frequent snowfall in the summer season results in intensive fluctuation of surface albedo. This means that, for lack of data on the extremes of ablation, reconstruction of mass balance is unsatisfactory when based on the relationships of accumulation and ablation to precipitation and temperature. The establishment of models, either on the relationship of multi-year mass balance to the equilibrium line and the mass balance gradient of a glacier in steady-state, or on the maximum entropy principle and the hydrometeorological data, helps to estimate the multi-year mass balance of the glacierized area in a mountain range or drainage basin.     

Melt–water Accumulation on the Surface of the Greenland Ice Sheet: Effect on Albedo and Mass Balance

Satellite–derived albedo maps of the western part of the Greenland ice sheet (between 64.5 and 70.5 ^∘ N) reveal a north–south extending zone with relatively low albedos at some distance from the ice margin. In the literature it has been hypothesized that this "dark zone" is due to a local maximum in melt–water accumulation on the ice–covered surface. A plausible explanation for this maximum in melt–water accumulation is thatrelative to the situation within the "dark zone", melt–water accumulation is reduced at higher elevations by a smaller melt–water production rate whereas runoff occurs more easily at lower elevations where slopes are generally steeper. For the present paper AVHRR images from eight years (1990–1997) were analysed. The following indications confirming the "melt–water accumulation hypothesis" were found: (1) there is a significant correlation between the annual mean albedo lowering within the "dark zone" and the annual amount of melt as inferred from local mass–balance measurements; and (2) within each summer season the albedo lowering within the "dark zone" seems to respond to the melt–water production rate as inferred from local temperature measurements. The effect of melt–water accumulation on the albedo implies a positive feedback between the albedo and the amount of melt. It is estimated that approximately 40% of the interannual mass–balance variations in the "dark zone" are due to this feedback.     

Surface Heat Balance and Spatially Distributed Ablation Modelling at Koryto Glacier, Kamchatka Peninsula, Russia

To investigate the characteristics of ablation at Koryto Glacier, a mountain glacier under maritime climate in Kamchatka Peninsula, Russia, we made field observations from August to early September 2000. At a site near the equilibrium line, the 31‐day average net radiation, sensible heat flux, and latent heat flux were 43, 59 and 31 W^?2, respectively. We developed a new distributed ablation model, which only needs measurements of air temperature and global radiation at one site. Hourly ablation rates at this site obtained by the energy balance method are related to measured air temperature and global radiation by linear multiple regression. A different set of multiple regression coefficients is fitted for snow and ice surfaces. Better estimates of ablation rate can be obtained by this approach than by other temperature index models. These equations are then applied to each grid cell of a digital elevation model to estimate spatially distributed hourly melt. Air temperature is extrapolated using a constant temperature lapse rate and global radiation is distributed considering topographic effects. The model enables us to calculate the hourly spatial distribution of ablation rates within the glacier area and could well provide a realistic simulation of ablation over the whole glacier.     

Potassium alum and aluminum sulfate micro-inclusions in polar ice from Dome Fuji,East Antarctica

Water-soluble trace constituents affect the physicochemical properties of polar ice. Their structural distribution provides important insights into the formation history of ice and inclusions. We report the first finding of KAl(SO₄)₂·12H₂O (potassium alum) and Al₂(SO₄)₃·nH₂O (aluminum sulfate) micro-inclusions in the Dome Fuji ice core, East Antartica, using a micro-Raman technique. Eutectic temperatures of these water-soluble species determined using thermal analysis were −0.4 °C for potassium alum and −8.0 °C for aluminum sulfate. Although the formation process of the aluminum-bearing sulfates remains unclear, the occurrence of these salts largely depends on ice depth.     

Gravity measurements with a portable absolute gravimeter A10 in Syowa Station and Langhovde,East Antarctica

Absolute gravity values were measured with a portable absolute gravimeter A10 in East Antarctica, for the first time by the Japanese Antarctic Research Expedition. This study aims to investigate regional spatiotemporal variations of ice mass distributions and associated crustal deformations around Syowa Station by means of repeated absolute gravity measurements, and we obtained the first absolute gravity value in Southern Langhovde on the Antarctic Continent. The average absolute gravity value at the newly installed benchmark AGS01 in Langhovde (obtained on 3 February 2012) was 982535584.2 ± 0.7 μgal (1 [μgal] = 1 × 10^?8 [m/s²]), which was in agreement with the gravity values obtained by the past relative gravity measurements within 1 mgal. In addition, the average absolute gravity value obtained at AGSaux in Syowa Station was consistent with both previous absolute gravity values and those obtained by simultaneous measurements using an FG5 gravimeter, owing to adequate data corrections associated with tidal effects and time variations in atomic clock frequencies. In order to detect the gravity changes associated with the ice mass changes and other tectonic phenomena, we plan to conduct absolute gravity measurements at AGS01 again and at other campaign sites around Syowa Station as well in the near future, with careful attention paid to the impacts of severe environmental conditions in Antarctica on gravity data collection.     

过去44年乌鲁木齐河源一号冰川物质平衡结果及其过程研究

通过1997—2003年度天山乌鲁木齐河源一号冰川物质平衡的观测结果,分析比较了过去44年间一号冰川物质平衡、累积物质平衡的变化过程,以及反映气候一地形要素和冰川发育条件要素的平衡线高度和冰川积累区比率,认为一号冰川负平衡波动期随时间推移而递增,目前处于其观测历史上物质平衡亏损最为强烈的时期。     

Mass Balance of Vernagtferner, Austria, From 1964/65 to 1996/97: Results for Three Sections and the Entire Glacier

In the centre of the highly glacierized Oetztal valley, mass balance is determined for the three neighbouring glaciers Hintereisferner, Kesselwandferner and Vernagtferner, applying the direct glaciological method, related to the 'fixed date' system. The diverging behaviour of the three glaciers due to slightly varying local climatic conditions as well as to different topoclimatological and physiographic features gave reason to analyse the Vernagtferner mass balance separately for three easily discernible sections, i.e. Schwarzwand, Taschachjoch and Brochkogel, each showing characteristic aspect and elevational distributions of area respectively.
The cumulative mass balance of the Vernagtferner for the period 1968/69, when separate mass balance computations for the three sections were started, until 1996/97 amounted to −8.7 m water equivalent (w.e.). The mass loss of the western Schwarzwand section as the part with the largest share of low elevation area was −13.3 m w.e., in contrast to the central Taschachjoch section which lost only −6.6 m w.e. The remaining eastern Brochkogel section with a loss of −8.5 m w.e. fits best the mass balance of the total Vernagtferner although its physiographic characteristics differ markedly from those of the entire glacier. The equilibrium line altitude (ELA) dependence on specific net mass balance ( b ) is slightly different for the three sections, whereas the dependence of the accumulation area–total area ratio (AAR) on b is characterized by nearly identical sensitivities. Moreover, AAR correlates better with b than ELA, therefore AAR is regarded as a more representative parameter for the Vernagtferner than ELA.     

Spatial variations of Pb,As, and Cu in surface snow along the transect from the Zhongshan Station to Dome A,East Antarctica

The spatial distributions of lead, arsenic, and copper(Pb, As, and Cu, respectively) in surface snow along the transect from the Zhongshan Station to Dome A, East Antarctica, are presented. The mean concentrations of Pb, As, and Cu are1.04±1.56 pg/g, 0.39±0.08 pg/g, and 11.2±14.4 pg/g, respectively. It is estimated that anthropogenic contributions are dominant for Pb, As, and Cu. Spatially, Pb concentrations show an exponentially decreasing trend from the coast inland, while a moderate decreasing trend is observed for Cu concentrations in the coastal area(below 2,000 m above sea level(a.s.l.)).In the intermediate area(2,000–3,000 m a.s.l.), the concentrations and enrichment factors of all these elements show high variability due to the complicated characteristics of climate and environment. On the inland plateau(above 3,000 m a.s.l.),the high concentrations of As and Pb are induced by high deposition efficiency, the existence of polar stratospheric precipitation, and the different fraction deposition to East Antarctica. The extremely high concentrations with maximum values of9.59 pg/g and 69.9 pg/g for Pb and Cu, respectively, are suggested to result mainly from local human activities at the station. Our results suggest that source, transport pathway, and deposition pattern, rather than distance from the coast or altitude, lead to the spatial distributions of Pb, As, and Cu; and it is further confirmed by spatial variations of the three metals deposited over the whole continent of Antarctica.     

Evaluating the Process and Outcomes of Collaborative Conservation: Tools,Techniques, and Strategies

Abstract

Collaborative conservation has been touted as a viable option for addressing contentious natural resource stewardship issues in a way that represents the diverse voices impacted by, and involved in, conservation decisions. Engaging meaningfully in collaborative conservation involves overcoming a unique set of challenges while also realizing opportunities. In this special issue, we use the term collaborative conservation evaluation to encompass research and evaluation related to collaborative governance and collaborative natural resource management projects, programs, or decision-making processes that leverage a participatory approach, involve multiple stakeholders, and incorporate a range of contemporary evaluation approaches. Here, we provide a series of articles and tools intended to highlight different approaches to evaluation that utilize a variety of methodologies adapted for different contexts. We intend for these articles to spark further conversation and inspire future directions in evaluating collaborative conservation for researchers and practitioners.     

Changes in the Geometry and Volume of Rabots glaciär,Sweden, 2003–2011: Recent Accelerated Volume Loss Linked to More Negative Summer Balances

Terminus geometry, ice margins, and surface elevations on Rabots glaciär were measured using differential GPS during summer 2011 and compared with those similarly measured in 2003. Glacier length over the eight years decreased by ～105 m corresponding to 13 m a^?1, a rate consistent with ice recession over the last several decades. Measured changes in surface elevations show that between 2003 and 2011 the glacier's volume decreased by ～27.6 ± 2.6 × 10⁶ m³, or 3.5 ± 0.3 × 10⁶ m³ a^?1. This compares favorably with an estimate of ?28.1 ± 2.6 × 10⁶ m³ based on a mass‐balance approach. The rate of volume loss appears, however, to have significantly increased after 2003, being substantially greater than rates determined for the intervals 1959–80, 1980–89, and 1989–2003. This increase corresponds to a sustained interval of more negative summer balances. Previous work suggests that as of 2003 Rabots glaciär had not yet completed its response to a ～1°C warming that occurred c. 1900, and thus the current marked increase rate of ice loss might reflect the effect of recent, or accelerated regional warming that occurred during the last decade superimposed on its continued response to that earlier warming.     

中国西部大陆性冰川与海洋性冰川物质平衡变化及其对气候响应——以乌源1号冰川和帕隆94号冰川为例

为认识全球变暖背景下中国西部大陆性冰川与海洋性冰川物质平衡变化及其对气候响应,本研究以天山乌鲁木齐河源1号冰川和藏东南帕隆94号冰川为例,结合大西沟与察隅站气象资料,对1980 — 2015年两条冰川的物质平衡变化特征及差异进行了分析。结果表明：36 a来乌源1号冰川与帕隆94号冰川物质平衡总体上均呈下降趋势,累积物质平衡达-17102与-8159 mm w.e.,相当于冰川厚度减薄19与9.01 m,且分别于1996、2004年左右发生突变。同期两条冰川所处区域年均温呈显著上升趋势,而降水量却表现出不同的变化态势;二者年内气温分配相仿,但降水分配差异较大。初步分析认为气温上升是导致乌源1号冰川与帕隆94号冰川物质亏损的主要原因,冰川区气温和降水变化幅度的差异和地性因子（坡度、冰川面积）的不同使得乌源1号冰川对气候变化响应的敏感性高于帕隆94号冰川,由于目前海洋性冰川物质平衡监测时段相对较短,为深入研究中国西部冰川物质平衡变化及过程仍需加强对冰川的持续观测。