Jerzy Pereyma Department of Meteorology and Climatology Institute of Geography Wroclaw University, Poland Wyprawy Geograficzne na Spitsbergen UMCS, Lublin 1992 POLAR GLACIER MASS BALANCE IN THE LIGHT OF SOME CLIMATIC FACTORS INTRODUCTION The relations between behaviour of glaciers and climate have been considered for many years (among others Ahlmann 1953), but at present they have become of significant importance. This is conditioned by global changes of natural environment perceived in the forms of glacier recessions in both polar zones. Generally the fact of ice mass recession is associated with a common tendency of climate warming up. Numerous hypotheses (mainly model ones) associate warming up of climate with the increase of C 0 2 content in the atmosphere (Meier, 1984). Does such a basic factor of glacial changes which is a glacier mass balance correlate with air temperature fluctuations? Does an unquestionable, in the light of.measurement results, (Fluctuations of... 1967, 1977, 1985, 1988) negative tendency of forming and annual balance of polar and subpolar glacier masses find its reflection in a definite climatic trend? Based on the analysis of climatologicmaterials (World..., 1959,1966, Monthly..., 1948-1985), it is hard to give an univocal answer. ANALYSIS OF SOME GLACIAL-CLIMATIC MATERIALS In the area of so called High Canadian Arctic, an annual small negative mass balance is observed on two glaciers: Devon Ice Cap and Meighen Ice Cap studied in 1960-1980 (Fig. 1, 8). Some close to zero or low-negative values occur occasionally and do not show time periodicity. Air temperature and average of a balance year are not characterized by a specific trend at the representative meteorological stations (Resolute, Eureka). Positive or less negative values of annual mass balance occur in the years when the average temperature is lower e.g. in the annual balance season 1963/64, 1971/72, 1982/83. The characterization of mass balance of two Alaska glaciers situated differently is far more differentiated (Fig. 2, 8). The Gulkan Glacier situated inland has largely a negative annual mass balance. However, the Volverine Glacier situated on the western coast of Alaska possesses a very changeable course of many years mass balance which is mostly positive. The seasons with 23
positive values of net mass balance (1969/70, 1977/78, 1979/80) are associated with warmer cumulative seasons and higher average air temperatures of the balance year. Another Glacier Igan situated in the northern Ural Mountains has very few positive values of annual mass balance (Fig. 3,8). They result from a decrease of the balance year average temperature (Salehard station) connected with a lower temperature of the ablation season (1968, 1975, 1978). Some Scandinavian glaciers have various characterizations of mass balance (Fig. 4, 5, 7). Being situated far from the sea coast they are characterized by mostly negative values of net mass balance. Very few positive values are associated with cool ablation seasons (1975, 1981, 1982 the data come from Bodo and Orland stations). A quite different picture of mass annual balance is recorded on the Enga Glacier situated close to the coast. As one of few glaciers in the world it has been characterized by a distinct increase of firm mass for a long time. The Austre Broeger Glacier (Fig. 6, 7) situated on the north-west coast of Spitsbergen has had a negative mass balance for years. It is hard to draw an univocal conclusion besides a short term fluctuation from many years course of air temperature on Spitsbergen. However, there seems to be a coexistence of less negative values of net mass balance and colder ablation seasons (1968, 1975, 1982). CONCLUSION It seems that the climatological material presented here and generally known does not allow for drawing a conclusion about existence of a definite climatic tendency. The conclusions about short term climatic fluctuation as e.g. those observed in the Spitsbergen region are more certain (Midtun 1987, Pereyma et al. 1989). Besides a general statement about better (positive) conditions of forming glacier mass balance in the marine climate of polar and subpolar zones (Fig. 7), the fact of coexistence of increase (or smaller losses) of firn mass and cool ablation seasons is significant. It has been stated (Pereyma 1991) that ablation seasons are characterized by a great dynamics and high sums of ablation water outflow, frequent weathers formed by relatively warmer masses of air coming from the S-E sector. Good thermal and solar conditions of these seasons are observed in frequent local foehn effects. Cool ablation seasons with small outflows and even time course are connected with influx of cool and stable air masses from W-NW. Translated by Maria Charmas 24
REFERENCES Ahlmann H. W., 1953.: Glacier variations and climatic fluctuations. American Geogr. Soc., Bowman Memorial Lectures, 93, New York. Fluctuations of Glaciers, 1967, 1977, 1985, 1988. World Glacier Monitoring Service, IASH- -UNESCO, Zurich. Meier M. F., 1984: Mass balance of the glaciers and small ice caps of the World, Glac. Ice Sheets and Sea Level, Washington. Midtun L., 1987: Climatic fluctuations in the Barents Sea. Symp. on Mar. Sc. of the Arctic and Sub-Arctic Regions, Santander. Monthly Climatic Data 1948-1985, NOAA, Asheville. Pereyma J., Swerpel S., Węslawski J. M., 1989: Year-to-year changes in climatic, hydrographic and biological phenomena in the southern Spitsbergen area, Rapp. P.-v. Reun. Cons. int. Explor. Mer., Kobenhavn. Pereyma J., 1991: Climatic conditions of outflow ablative waters from Werenskiold Glacier in Spitsbergen, 1st Inter. Symp. of Glacier Caves and Karst in Polar Regions, Geominero, Madrid. World Weather Records, 1959, 1966, U.S. Depart, of Comm. Washington. STRESZCZENIE Na podstawie danych klimatologicznych z wybranych, reprezentatywnych stacji meteorologicznych północnej strefy polarnej i subpolarnej, oraz materiałów informacyjnych o bilansie masy lodowców z lego obszaru, przedstawiono charakterystykę współczesnych zależności klimatyczno- -glacjalnych. W wyniku analizy stwierdzono, że pomimo braku wyraźnych tendencji do ocieplenia klimatycznego w dolnej atmosferze północnej strefy polarnej, na lodowcach tego obszaru przeważają, w ostatnich kilkudziesięciu latach, ujemne roczne wielkości bilansu masy. Jedynie na niektórych nielicznych lodowcach, o wyraźnie morskich cechach klimatu, położonych na zachodnim wybrzeżu Alaski i Skandynawii obserwuje się przewagę dodatnich rocznych bilansów masy. Lodowce zachodniego Spitsbergenu nie wykazują od wielu lat dodatniego bilansu masy netto. Jest to na ogół skutek ciepłych i solarnych pogód okresu ablacyjnego, z częstymi lokalnymi efektami fenowymi. 25
Resolute, Devon Ice Cap T ('C) В (mm) 1861 1963 1970 1975 19S0 1963 Y e a r s a CD вы Fig. 1. Annual mass balance on Devon Glacier (B) and the average air temperature of the balance year (A) at Resolute station.,. Anchorage, Volverine Glacier T со В (mm * 1000) 1966 1970 1973 1960 Y e a r s s -f-w -*-A H B S ШШШВУ/ CZJbn Fig. 2. Annual balance (BN), summer (BS), winter (BW) of the mass on Volverine Glacier as well as the average air temperature ог the balance year (A), ablation season (S) and accumulative (W) at Anchorage station.
Saiehard, Igan Glacier - s w -*- а ШШ b s ЕНПШ bw L _ J bn Fig. 3. Mass balance on Igan Glacier and air temperature at Saiehard station (explanation as in Bodo, Stor Glacier s -+ - W -*- А В BS ШШШ 8W c m BN Stor Glocier (Kebnekeise) Fig. 4. Mass balance on Stor Glacier as well as air temperature at Bodo station (explanations as in Fic. 21.
Bodo, Engabreen Glacier т Cc) В (mm 1000) 1971 1975 1980 1985 Y e a r s s w -*- а ШЖ bs ШИЛО bw CD bn Fig. 5. Mass balance on Enga Glacier and air temperature at Bodo station (explanation as in Fig. 2). Spitsbergen, Austre Broegger Glacier T ( c) В (mm) 1000.-4-- w BS В BW cm BN l$f ord Rodlo (1967-1975) Svolbord Lufthavn (1976-1985) Fig. 6. Mass balance on Austre Broegger Glacier and air temperature on Spitsbergen (explanations as in Fig. 2).
VAVIIOV SEVERNAYA ZEMIA 80' 1-е MEIOHEN ICE CAP 1 CANADA NE 80* 1-е DEVON ICE CAP t CANADA Nk VOIVERINE ALASKA W. 0(- 60*. m OUIKANA -I ALASKA С. Г ^ 63* 1-е 75*. t-c QAPIARFIUP. A.BROEOGERBREEN o - ШГОШ/ о SPITSBERGEN NW 1 79*. m 65*. m-l STORGIACIEREN KEBNEKEISE 68* t-m ENGABREEN -5ШП55Г 66* m STORBI JOTUNHEIMEN 62* t-m I ' 1945 -T J r 1950 1955 ' I 1960 I 1 1965 1970 1975 1980 t 1985 Fig. 7. Mass balance of glaciers of northern polar and subpolar zones according to cumulative values (m-marine climate, t-transient climate, c-continental climate). 29