Site testing on the Greenland Ice Cap

We present a site testing program initiated at the SUMMIT station on the Greenland Ice Cap. A DIMM was mounted in the SWISS tower, 39 m above the ice level, during a period of 3 weeks in the late Arctic summer 2008. Tracking Polaris, the DIMM obtained continuous seeing measurements. The campaign was hampered by poor weather and the measured seeing was fluctuating, suggesting that the boundary layer was very unstable. However, during short periods, the un-calibrated seeing went below 0".5, indicating that the free atmosphere seeing above Greenland is not significantly different from what is found above the Antarctic plateau.