Effects and observation of migrating birds on a boundary-layer windprofiler in Eastern Germany

Abstract

Boundary-layer windprofilers recently have become more and more a standard technique for measuring lower atmospheric wind profiles operationally. Although the availability of reasonable data is quite high, there are about 2 % of all profiles which show unrealistic large deviations compared with standard rawinsondes. This paper, on the one hand statistically investigates large deviations of measurements made by a 1290 Mhz windprofiler in Eastern Germany and proves on the other hand the association to events of strong bird migration by comparing measurements from a (ATC) tracking radar in Berlin, used by the German military to minimize birdstrikes on aircraft with an occurrence of large deviations in windprofiler-derived mean wind profiles compared to rawinsondes. It is shown that the deviations correspond to events of strong bird migration. Assuming typical bird migration values from literature, the effect of birds on mean wind profiles derived from windprofiler radar is investigated, too, and finally, an easy and immediate method to identify bird migration is given using a SNR threshold value in connection with a non-precipitation criterion.

Keywords

• rawinsondes
• birdstrikes
• bird migration
• windprofile
• standard-rawinsonden
• vogelschlag