Energy balance calculations from five years' meteorological records at Vernagtferner, Oetztal Alps

During the months May to September, global radiation, longwave radiation, air temperature, relative humidity, precipitation, wind speed and direction are continuously recorded at the Pegelstation Vernagtbach (2640 m a. s. 1.). Based on this material, monthly means of global radiation, air temperature and monthly sums of precipitation for the years 1978 to 1982 are discussed with respect to their influence on shortwave radiation balance and sensible heat flux of Vernagtferner. As the Albedo, which is derived from daily photographs of the glacier increases while global radiation decreases during summer, shortwave radiation balance usually rises from May to August; the lowest value was observed in June 1982 with 48 Wm-2, the highest one in August 1980 with 96 W/m2. The Variation of sensible heat flux follows the change of air temperatures, as wind speed does not vary much during summer. Meltwater production as calculated from the energy balance, lies between 5 % and 30 % below the total measured runoff

Two decades of runoff measurements (1974 to 1993) at the pegelstation Vernagtbach/Oetztal Alps

This report summarizes the runoff data collected at the "Pegelstation Vernagtbach" in the Oetztal Alps, Tyrol. The drainage basin controlled by the Station Covers 11.44 km2, of which 81 % is glacierized by Vernagtferner and hasan altitudinal ränge from 2635 m a.s.l. to 3635 m a.s.l., with 3115 m a.s.l. as the mean altitude. Runoff records, which start in 1974, are given as monthly, daily and hourly mean values. In addition, the mean diurnal Variation is presented for each month. The records show the typical features of the glacier runoff regime, with high discharge during fair weather periods in summer, and low discharge during bad weather and throughout the winter and spring; thus, on average, about 90 % of annual runoff is recorded between June and September. The climatic pattern of the two decades and the resulting mass balances of Vernagtferner tend towards increasing runoff amounts, in particular since the middle of the 1980s. 1991 was the year with highest runoff (0.806 nr/s yearly average), August 1992 delivered the highest monthly mean (4.048 m/s), on July 19,1987 an average daily runoff of 6.123 m3/s was recorded, and 10.68 m3/s was the highest hourly average on August 22, 1993. The rise in absolute amounts was accompanied by increasing diurnal variations, which, on average, were less than 1 m3/s in August 1974, but almost 5 m / s in the same month of 1992

The compensating effect of glaciers: Characterizing the relation between interannual streamflow variability and glacier cover

Meltwater from glaciers is not only a stable source of water but also affects downstream streamflow dynamics. One of these dynamics is the interannual variability of streamflow. Glaciers can moderate streamflow variability because the runoff in the glacierized part, driven by temperature, correlates negatively with the runoff in the non-glacierized part of a catchment, driven by precipitation, thereby counterbalancing each other. This is also called the glacier compensation effect (GCE), and the effect is assumed to depend on relative glacier cover. Previous studies found a convex relationship between streamflow variability and glacier cover of different glacierized catchments, with lowest streamflow variability at a certain optimum glacier cover. In this study, we aim to revisit these previously found curves to find out if a universal relationship between interannual streamflow variability and glacier cover exists, which could potentially be used in a space-for-time substitution analysis. Moreover, we test the hypothesis that the dominant climate drivers (here precipitation and temperature) switch around the suggested optimum of the curve. First, a set of virtual nested catchments, with the same absolute glacier area but varying non-glacierized area, were modelled to isolate the effect of glacier cover on streamflow variability. The modelled relationship was then compared with a multicatchment data set of gauged glacierized catchments in the European Alps. In the third step, changes of the GCE curve over time were analysed. Model results showed a convex relationship and the optimum in the simulated curve aligned with a switch in the dominant climate driver. However, the multicatchment data and the time change analyses did not suggest the existence of a universal convex relationship. Overall, we conclude that GCE is complex due to entangled controls and changes over time in glacierized catchments. Therefore, care should be taken to use a GCE curve for estimating and/or predicting interannual streamflow variability in glacierized catchments

A glacier discharge model based on results from field studies of energy balance, water storage and flow ( Vernagtferner, Oetztal Alps, Austria).

In this paper, a discharge model is described which calculates the runoff of the glacier Vernagtferner (9.3km2, Oetztal Alps, Austria), using the meltwater production on its surface as input data. For the ablation period of 1979, the hourly mean values of the model output are in good agreement with the recorded runoff

Abfluss in und von Gletschern T. 1.2. Abschlussbericht ueber das Teilprojekt A1. Foerderungszeitraum: 1974-1986

Contains a mapTIB: FR 357 (1)+(2) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman