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Glacier Mass Balance and Regime: Data of Measurements and Analysis Mark Dyurgerov Editors: Mark Meier (INSTAAR), Richard Armstrong (NSIDC) sea-level change, mm/yr sea-level rise, mm 2.5 14 2 12 10 1.5 8 1 6 0.5 4 sea-level rise, mm sea-level change, mm/yr 0 2 -0.5 0 1960 1965 1970 1975 1980 1985 1990 1995 2000 Contribution of mountain and subpolar glaciers to sea level Occasional Paper No. 55 2002 Institute of Arctic and Alpine Research, University of Colorado Glacier Mass Balance and Regime: Data of Measurements and Analysis Mark Dyurgerov Editors: Mark Meier (INSTAAR), Richard Armstrong (NSIDC) Institute of Arctic and Alpine Research University of Colorado, Boulder, Colorado 80309 2002 University of Colorado Institute of Arctic and Alpine Research Occasional Paper 55 INSTAAR/OP-55 ISSN 0069-6145 2 CONTENTS List of Tables…………………………………………………………………………..5 List of Figures………………………………………………………………………… 5 Abstract ……………………………………………………………………………….7 Preface…………………………………………………………………………………8 Acknowledgements …………………………………………………………………….9 Introduction………………………………………………………………………….…10 CHAPTER 1. AREA OF SUBPOLAR AND MOUNTAIN GLACIERS………….15 CHAPTER 2. DATA ON GLACIER REGIME…………………………………….21 2.1. DATA ON GLACIER CHARACTERISTICS AND VARIABLES OF GLACIER REGIME………..21 2.1.2. Definition of seasonal mass-balance components………………………………….22 2.1.3. Definition of annual, and/or net mass balance……………………………………..25 2.1.4. Definition of equilibrium-line altitude (ELA)……………………………………….26 2.1.5. Definition of accumulation-area ratio (AAR)………………………………………27 2.2. THE GLACIOLOGICAL METHOD……………………………………………………...27 2.2.1. Mass balance of an entire glacier…………………………………………….……30 2.2.2. Errors……………………………………………………………………… …. 31 2.2.3. Estimate of accuracy and variability in glacier mass balance……………………….32 2.3. LARGER ERRORS……………………………………………………………….….35 2.4. ERRORS IN DATA TRANSMISSION AND PUBLICATION………………………………38 2.5. HOW PRECISE CAN MASS-BALANCE DATA BE? …………………………………….38 2.6. SEARCHING, DIGITIZING AND CHECKING DATA QUALITY …………………………...39 2.6.1 Checking data quality……………………………………………………………..40 CHAPTER 3. RESULTS AND ANALYSIS…………………………………………48 3.1. RESULTS …………………………………………………………………………..48 3 3.1.1. Number of records and surface area of glaciers…………………………………...48 3.1.2. Glacier mass balance……………………………………………………………...50 3.1.3. Specific components………………………………………………………………52 3.2. SELECTED APPLICATIONS OF THE RESULTS…………………………………………61 3.2.1. Study of sea-level change…………………………………………………………61 3.2.2. Melt water production…………………………………………………………….63 3.2.3. Regional and global precipitation at high altitudes………………………………….64 3.2.4. Regional and global monitoring……………………………………………………65 3.2.5. Application to climate studies……………………………………………………..66 3.2.6. Application to study of paleo-environments……………………………………….66 3.2.7. Application of mass-balance variation with elevation………………………………67 CONCLUSIONS AND RECOMMENDATION……………………………………69 REFERENCES CITED……………………………………………………………………………………………...72 APPENDICES 4 TABLES 1.1. Surface area of glaciers outside the major ice sheets 2.1. Comparison of published and recalculated variables 2.2. Comparisons of annual mass balances measured by the glaciological method and by topographical method 2.3. Comparisons of mass balance and surface area calculations for three glaciers FIGURES Fig. I.1. Histogram showing the numbers of glaciers with mass balance records, annually since the beginning of continuous mass-balance observations. Fig. I.2. Map showing locations of glaciers with mass-balance records. Fig. 2.1. Shumskiy Glacier (Djungariya Mtn.) mass-balance components Fig. 2.2. Shumskiy Glacier mass-balance components. Fig.2.3. Storglaciären (Sweden), seasonal mass balance components. Fig. 2.4. Correlation between all mass-balance records and records 20-years and longer (1), 30-years and longer (2). Fig. 3.1. Aggregate surface area of mountain and subpolar glaciers where mass balance measurements were carried out. Fig.3.2. Area of glaciers where mass-balance measurements were carried out showing all records including those with large annual variability, and calculated for the 44 glaciers having long-term mass- balance records. Fig. 3.3. (a) Arithmetic mean of glacier mass-balance measurements, calculated annually since the beginning of measurements, together with the number of these glaciers. Mean mass balances calculated for all glaciers are also presented in Appendices 1 and 3. (b) Glacier mass-balance calculated for glaciers with mass-balance records 20 years and longer, and square-root error. (c) Glacier mass balances calculated for glaciers with mass-balance records 30 years and longer, and square-root error. (d) Extreme mass-balance values for glaciers with mass-balance records 20 years and longer. (e) Cumulative mass-balance sums given for all measurements, and for those with records 20 years and longer. Fig. 3.4. (a) Winter mass balance and number of measurements (glaciers). (b) Summer mass balance and number of measurements (glaciers). (c) Extremes (minimum, maximum) and standard-deviation values 5 of winter mass balance. (d) Extremes (minimum, maximum) and standard-deviation values of summer mass balance. (e) Winter mass balances and standard-deviation values calculated for all glaciers (number of glaciers annually is given in Fig. 1) with one small snow patch Hamagury Yuki and without. (f) Summer mass balances and standard-deviation values calculated for all glaciers (number of glaciers annually is given in Fig. 1) with one small snow patch Hamagury Yuki and without (a more detailed explanation is given in the text). Fig. 3.5. (a) Equilibrium-line altitude calculated as annual arithmetic means for all measurements together with number of observations. (b) Standard deviations, and square-root errors. Fig. 3.6. (a) Accumulation-area ratio for all measurements and for long-term (l-t) records. (b) Standard deviation and square-root errors for all glaciers, and standard deviation for long-term measurements (square-root errors are the same as for all measurements). Fig. 3.7. Mass balance versus altitude. Data from FoG volumes (1967, 1973, 1977, 1985, 1988, 1993, 1998) and INSTAAR data base. Curves of mass-balance change for 81 glaciers versus altitude relate to different time periods. Fig. 3.8. Vertical gradients of mass balance of 21 glaciers, averaged over 15-year periods (1971-75, 1986-95). Fig. 3.9. Distribution of aggregate area given for 21 glaciers listed in Fig.3.8 versus altitude (columns). Values above columns are numbers of glaciers in that particular altitude range. Fig. 3.10. Specific mass balance versus altitude, averaged for the 21 glaciers (same as in Fig. 3.8) for two years: 1972, the coldest, and 1990, one of the warmest years during the period of consideration. Fig. 3.11. Specific mass balance vs altitude averaged for 21 glaciers for relatively cold (1971-75) and warm (1991-1995) years. Fig. 3.12. Global glacier mass balance calculated as an arithmetic mean for all measurements since 1961 and expressed in sea-level change equivalent. Fig. 3.13. Annual melt-water production by mountain and subpolar glaciers. 6 ABSTRACT This is the most complete data set of parameters of glacier regime have ever been compiled and published before. Data presented in appendixes include annual mass balances and related variables of mountain and subpolar glaciers outside the two major ice sheets. All available sources of information, such as publications, archived data, personal communications have been collected and include time- series of about 280 glaciers. Only observational data have been used over the period since the beginning of measurements started in 1945/46 and until 1998. Data have been digitized, quality checked, all errors found were eliminated. These all enhanced our knowledge on the modern glacier states, particularly: 1. The rate of annual melt-water production (ablation) by glaciers has been increasing, and comprised of about 1.7 m/yr in water equivalent for the period. 2. The annual accumulation (winter balance) rate has also been increasing with the average value of about 1.5 m/yr in water equivalent. 3. Annual volume change has been 90 km3/yr adding about 15-20% (0.25±0.11 mm/yr) to sea-level rise over the period. 4. The equilibrium-line altitude has risen by 200 m (square root error is about 100 m). 5. Accumulation area ratio decreased from about 60 % in 1968 to 50% in 1998 (square root error is about 5%). 6. The mass balance sensitivity with respect to air temperature has changed at the end of 1980’s and reached – 700 mm per degree °C. The existing trend in glacier volume change shows that wastage of glaciers will accelerate in continental regions, North America South America, Central Asia. Subpolar glaciers, outside the two major ice sheets, will contribute more to sea-level rise. 7 PREFACE The study of glacier fluctuations is relevant to an understanding of climate and climate change over temporal scales from years to centuries, and at spatial scales from regions to the global domain. It is internationally recognized that mountain and subpolar glaciers are substantional contributors to water cycle. The IPCC-1995 and IPCC-2000 have shown that glaciers contribute up to 20% to sea level rise over the previous century. Still glaciological data are not been widely used in hydrology and for climate monitoring. One important obstacle is that observational data are not generally accessible to the scientific community in a form convenient for modeling and analysis. The raw data come from many sources and publications, available to
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