Looking inside a glacier

For the fieldwork of the Junior Re­search Group “De­LIGHT Framework” this spring, we went to Hintereisferner in the Aus­trian Alps. We drove to Rofental on Tues­day and met up with col­leagues from the Uni­versi­tät Inns­bruck (UIBK). To­geth­er, we went to the small re­search sta­tion situ­ated at 3,050 m a.s.l., which offers an excel­lent view of the im­pres­sive glaci­er. The hut was our home for the next three days and is equipped with a small gas stove, a ta­ble, eight beds, plenty of gum­boots, a gui­tar, and an old porta­ble gram­ophone. Upon arrival at the hut, we set­tled in, re­viewed our cre­vasse-rescue tech­niques, and made the final prepa­ra­tions to go onto the glaci­er.

Over the fol­low­ing two days, our goal was to inves­tigate the glaci­er and its sub­glacial water re­gime. We used a ground-pene­trat­ing radar (GPR) an­tenna pro­vided by the Land­slides work­ing group at TUM. The GPR an­tenna sends out radar pulses and re­ceives ech­oes from layers where the densi­ty changes. This makes GPR an ideal tool for de­tecting the bed­rock be­neath the ice, as well as ob­jects or water within or be­neath the ice. 

After test­ing the an­tenna, we began our meas­ure­ments on the lower part of the glaci­er. We skied across the glaci­er in a zigzag pat­tern while drag­ging the an­tenna be­hind us to obtain radar pro­files per­pen­dicu­lar to the flow direc­tion. We used a 50 MHz centre fre­quency for suffi­cient pene­tra­tion depth in the ice and 100 MHz for high reso­lution of small fea­tures. 

We were lucky with the weather on the sec­ond day and en­joyed some sun­shine, which made the scen­ery mag­nifi­cent. We could com­plete our meas­ure­ments and ended up with a dense meas­ure­ment grid of the lower part of the glaci­er. After finish­ing the data acqui­sition, we were able to relax and enjoy the cosy hut and its view on our third even­ing.

On Fri­day, we re­turned to civili­sa­tion, bring­ing with us a new da­taset. With the col­lected data, we now have a record of the engla­cial water con­tent in spring. Lat­er this year - dur­ing the melt sea­son - the meas­ure­ments will be re­peat­ed, and the water con­tent and dis­charge re­gime will be com­pared to the spring data. We are al­ready look­ing for­ward to the next cam­paign.

Acknowl­edgements: We thank Felix Pflu­ger for his sup­port in the field and for providing the GPR an­ten­nas. We also thank Léa Ro­dari for her assis­tance in the field. Our thanks fur­ther go to Rain­er Prinz for the coor­dina­tion, as well as to Marie Schroeder and Leo Schlagbau­er for their hospi­tality at the re­search sta­tion.

Text: Céline Walker, Junior Research Group DeLIGHT Framework