S. Jevrejeva, Estonian Meteorological and Hydrological Institute

Rävala pst 8, Tallinn, 10143 Estonia

sveta.jevrejeva@neti.ee

The report presents the results of field study on Storglaciären, Swedish Lapland on 11.09.2000 as a part of the European Union funded glaciological training course at Tarfala Research station.

The main objective of this study was to get an experience with field measurements in firn and ice cores by drilling. Samples obtained in this field study were investigated, including calculation of density profile, crystallography and dielectric profiling.

Investigations were carried out on Storglaciären (in the northern niche, north from Regina’s weather station). Storglaciären is a temperate glacier with an area 3.1 km² (Schneider 1994) situated in the Kebnekaise massif in Northern Sweden (67° 54’N, 18°35’E). More detailed description of study area can be found from Hock &Holmgren (1996), Schneider (1994), Grudd& Schneider(1996).

We used a hand drill "PICO" from the Tarfala Research Station for firn core sampling. Drill was established and work started at 13.30 o’clock 11.09.2000. After every meter the core was lifted up on the surface and the length of samples were measured by scale and weight of samples were measured by spring scale. Results of measurements were fixed in the notebook. Samples were packed into the plastic bags and marked for the future analyse in the station. After field study the samples were transported into the cold room, located in the Tarfala station.

Sometimes we were forced to interrupt our drilling and lifted up the samples due to hard layers occurred in snow. All peaces of samples were visually inspected and remarks about ice layers were made in notebook.

We reached the depth about 6 meters, on that depth the ice layer was found. Field measurements were stopped at 17.10 o’clock

Results of firn corning if given in Table 1.

Table 1. Results from firn core drilling in the northern niche 11.09.2000

Our mistakes and problems

1. Sometime we could not recognise exactly the sample from the snow falling from the drill into the hole and compressed during the drilling. I guess we have some errors in measurements.
2. We started to make density measurements from 2 m. If we started from zero we could make comparison with results from snow pit place 10 meter far from our drilling site.
3. We did not make temperature in borehole. We were mostly busy with drill, but if we could have the temperature profile, we could get more results from the that study.

The density (D) values were calculated by using the mass (m) and the length (l) of each sample, which were measured in the field and the diameter (of the drill which was 9.0 cm). The results obtained taking equation (1) are shown in Figure 1 and Table 2.

D=(4*m)/(p *d2*L)* [g/cm3] (1)

With: D: density [g/cm³]; m: mass [g]; d: diameter of tube [cm] and l: length [cm]

Table 2. Calculated density

The mean density was 0.60±0.01g/cm³. Values of density were from 0.49 to 0.69 g/cm³.

From the density profile (Fig. 1) we can see that even on the layers 2-3 meters from surface the density is quit high 0.49-0.56 g/cm³. According our marks concerning ice layers occurred in the samples, from visual inspection we have seen a thin ice layers for the samples taking even from the subsurface depth. Meltwater produced during the summer can percolate into snow and refreezes, creating ice layers. For the deeper samples the density varied from 0.53 to 0.67 g/cm³. There were also ice layers randomly observed in the samples of firn.

Figure 1. Density profile in the northern niche

This work was carried out over one day during the training course, on the base of obtained results the conclusion is quite limited. We obtained the firn core samples from the borehole 6m and made density measurements and visual inspections of samples. Samples were parked in the plastic bags and marked for the future analysis in the station.

From the results of calculated density profile we can see some changes in firn density. Variations in density can be explain by existence of ice layers and layers with meltwaters produced during the summer.

More detailed analysis can be done with respect to the results obtained from the crystallography and dielectric profiling performed by another group from the course.

During this field experiment we have got experiences in use of hand drill PICO, firn core sampling, density measurements. We also got some experience how to organise the field work, what kind of additionally measurements have to be done (in our case temperature measurement).

The course at Tarfala station was funded by a European Union GlacioEuroLab6 grant and organised by Dr. John Moore. I am grateful to Dr. John Moore and all participants for help and advice obtained during the course.

Paterson, W.S.B. (1994). Physics of glaciers (3^rd ed.) Oxford. Pergamon Press

Schneider, T (1994) Water movement and storage in the firn of Storglasiären, Northern Sweden. Forskningsrapport 99.

Grudd, H. & Schneider, T. (1996): Air temperature at Tarfala Research Station 1946-1995. – Geografiska Annaler 78A (2-3): 115-119

Hock, R. & Holmgren, B. (1996): Some aspects of energy balance and ablation of storglaciären, Northern Sweden. - Geografiska Annaler 78A (2-3): 121-131