Characteristics of the Vernagtferner mass balance
for the period from 1964 to 2004

The main characteristics of the Vernagtferner mass balance are sumarized in the table below. The mass balance years from 1964/65 to 2003/2004 are listed. The table includes the total area of the glacier (basis for the calculations), the equilibrium line altitude (ELA), percentage of the accumulation area in relation to the total area (AAR) and the specific net mass balance in mm w.e. (water equivalent).

The specific mass balance data (column: "Balance" ) are marked with colour to enhance the developments which took place during the monitoring period. Negative values (yellow , orange to red) mean a mass loss, in comparison to positive values (blue tones), which indicate mass gain. Green tones represent rather balanced values, which means that the ice mass remained almost constant. Years with extreme mass losses (over 800 mm) are marked in red. It becomes clear that, after a rather minor growth period in the mid 1970´s, the glacier continually lost mass since the beginning of the 1980´s. Besides that, a clear increase of mass balance years with extreme mass losses could be observed in the last decade.

The "glacier-friendly".summer with a well-balanced mass balance in 1999 could only interrupt the series of years with extreme mass losses, but this means no change in the trend. The minor mass loss in 1999 was caused by a winter snow cover above average, which prevented the glacier from becoming snow free over large areas and thus resulted in a lower ice melt. Although real summer conditions in 2000 were mainly restricted to August and produced a snow free area only slightly larger than in 1999, there have been further ice losses. This trend of negative mass balance continued also in the years 2001 and 2002. Nevertheless, the losses are moderate because a smaller part of the glacier became ice free until autumn (appr. 50 %).

The summer 2003 caused a loss of ice in a dimension never seen since the beginning of the scientific investigations. This resulted from a combination of different factors: after only a moderate winter snowcover the glacier became snow free very early. For the first time the ablation area spanned over the entire glacier (blue fields in the mass balance tables!). Only one short snowfall event interrupted the ablation period, which lasted twice as long as in the years of large losses in the 1990´s. The extreme mass loss in 2003 will also influence the mass balance in the following year 2004.

The graphical representation of the elevation distribution of the specific mass balance together with the absolute mass balance can be found individually for each year by choosing one of the mass balance values from the table. These diagrams also include the area-height-distribution of the glacier and the ablation area. A tabular version of the numeric values in dependence of the elevation, provided separately for the accumulation area, the ablation area and the total glacier, can be found in the column "Tables". Here you can also obtain a legend zfor the used abbreviations. The tables include four sub-tables altogether, where the results for three different parts of the glacier and for the total glacier are displayed. The tables are linked to diagrams, where the main values of the mass balance are illustrated. The graphical representation of the different topics is available over the internet in reduced form only. The version with a higher resolution can be found on the CD-Rom 1999-1 (up to the year 1997/98).

Digital map representations of the mass balance analysis exist only since the change to the analysis software WDG98 . The data can be found, as far as available, in the column Analysis ". If you would like to get an impression of the temporal development of the ablation or accumulation processes at Vernagtferner, you can view a Gif-Animation (655kb!) or an AVI-Video (1,1Mb!) of the mass balance diagrams for the period 1968/69 till 1999/2000. n these animations it becomes clear that the ablation area became distinctively larger at the beginning of the 80´s and even more so during the last decade. This was associated with the observed strong mass losses.

Year

Area [km²]

ELA [m N.N.]

AAR [%]

Balance [mm]

Tables

Analysis

1964/65

9,52

2946

92

751

1965/66

9,52

2940

93

632

1966/67

9,52

3015

70

83

1967/68

9,52

2995

86

301

1968/69

9,45

3153

56

-307

1969/70

9,45

3113

61

-224

1970/71

9,45

3155

39

-424

1971/72

9,45

3028

79

137

1972/73

9,30

3185

43

-460

1973/74

9,30

2999

81

230

1974/75

9,30

3025

80

171

1975/76

9,30

3036

75

50

1976/77

9,30

2984

88

352

1977/78

9,55

3004

85

288

1978/79

9,55

3059

73

44

1979/80

9,55

3027

77

140

1980/81

9,55

3101

72

-55

1981/82

9,35

3418

24

-845

1982/83

9,35

3304

25

-537

1983/84

9,34

3063

71

20

1984/85

9,34

3102

61

-112

1985/86

9,34

3291

19

-808

1986/87

9,34

3143

55

-290

1987/88

9,09

3230

39

-497

1988/89

9,09

3170

50

-312

1989/90

9,09

3283

32

-568

1990/91

9,09

>3630

8

-1079

1991/92

9,09

3268

22

-858

1992/93

9,09

3225

37

-472

1993/94

9,09

>3630

22

-1028

1994/95

9,09

3226

39

-398

1995/96

9,09

3225

40

-413

1996/97

9,07*)

3220

41

-487

1997/98

9,07

3280

30

-1003

1998/99

8,68

3097

56

-108

1999/00

8,68

3123

48

-287

2000/01

8,68

3128

47

-224

2001/02

8,68

3122

53

-266

2002/03

8,53

>3600

0

-2133

2003/04

8,36

3205

34

-407