What are we doing?
Ice rises are grounded ice bodies (at least partially) surrounded by the floating ice shelf. They provide buttressing to the neighboring ice shelves and play a key role in controlling dynamics and mass balance of the Antarctic Ice Sheet. In turn, evolution of an ice rise is affected by the surrounding coastal environment. We are investigating glaciological settings, recent mass balance, and millennial evolution of Blåskimen Ice Rise, located in Dronning Maud Land. East Antarctica.
What does this figure tells us?
This figure shows a radar profile we took with a shallow sounding (400 MHz) radar across the ice rise (inset), to map the internal structure of the firn column. The radar pulse penetrates into the firn column and reflects back where the dielectric constant of firn changes (mostly by density changes for upper hundreds of meters). In this figure we see several continuous internal layers (some of them are shown with black curves), which are isochronous (deposited at the same time) by nature. To know when these layers were deposited, we drilled a firn core (location shown in the figure) and dated it, to develop a depth age relationship, and then used it to associate ages to different layers (as shown in the figure). Now, if we look at the third layer from top, we see the that it is deeper (15m) on the southern side and becomes shallow (10m) towards north, which implies that there is higher surface mass balance (accumulation + wind deposition - wind scouring) on the southern side from the northern side, in the past 10 years. By using different layers and other such radar profiles, we are able to study the surface mass balace variation over the ice rise both spatially and temporally. This understanding is later used to assess if the ice rise is growing, thinning or in balance.