Are Estimates of Wind Characteristics Based on Measurements with Pitot Tubes and GNSS Receivers Mounted on Consumer-grade Unmanned Aerial Vehicles Applicable in Meteorological Studies?

The objective of this paper is to empirically show that estimates of wind speed and wind direction based on measurements carried out using the Pitot tubes and GNSS receivers, mounted on consumer-grade unmanned aerial vehicles (UAVs), may accurately approximate true wind parameters. The motivation for the study is that a growing number of commercial and scientific UAV operations may soon become a new source of data on wind speed and wind direction, with unprecedented spatial and temporal resolution. The feasibility study was carried out within an isolated mountain meadow of Polana Izerska located in the Izera Mountains (SW Poland) during an experiment which aimed to compare wind characteristics measured by several instruments: three UAVs (swinglet CAM, eBee, Maja) equipped with the Pitot tubes and GNSS receivers, wind speed and direction meters mounted at 2.5 m and 10 m (mast), conventional weather station and vertical sodar. The three UAVs performed seven missions along spiral-like trajectories, most reaching 130 m above take-off location. The estimates of wind speed and wind direction were found to agree between UAVs. The time series of wind speed measured at 10 m were extrapolated to flight altitudes recorded at a given time so that a comparison was made feasible. It was found that the wind speed estimates provided by the UAVs on a basis of the Pitot tube/GNSS data are in agreement with measurements carried out using dedicated meteorological instruments. The discrepancies were recorded in the first and last phases of UAV flights

Trial analysis of high efficiency atmospheric precipitation with respect to atmospheric circulation in selected stations of the Atlantic part of the Arctic in 1981-2010

Opad atmosferyczny o dużej wydajności, szczególnie w odniesieniu do zmian klimatu, jest jednym z ważnych czynników wpływających na funkcjonowanie geoekosystemów środowiska obszarów polarnych. Celem niniejszego opracowania była analiza dobowych sum opadu atmosferycznego na dziewięciu wybranych stacjach synoptycznych atlantyckiego sektora Arktyki w wieloleciu 1981-2010. Dla całego analizowanego obszaru stwierdzono istotny udział opadów o dobowych sumach przekraczających 10 mm w rocznych i miesięcznych sumach opadu. Na części analizowanych stacji (Hornsund, Ny Alesund) odnotowano niewielki wzrost częstości występowania opadów o dużych sumach dobowych, jednak na podstawie przeanalizowanych danych nie można jednoznacznie stwierdzić wzrostu w odniesieniu do wszystkich analizowanych stacji, a tym bardziej do całego atlantyckiego wycinka Arktyki. Występowanie opadów o dużym natężeniu wiązało się z konkretnymi typami cyrkulacji atmosferycznej. Dla większości stacji najbardziej opadonośna była cyrkulacja z sektora południowego.Contemporary climate change mark out intensively in polar regions. Due to some climatologists one of the most important effects of climate change is increase of frequency and intensity of atmospheric precipitation. It has a significant meaning for functioning of polar geoecosystems, especially for glacier ice mass balance, duration and height of snow cover, intensity of hydrological and geomorphological processes as well as the animated environment. The research objective of this study is trial analysis of high efficiency precipitation events in nine chosen synoptic stations in the Atlantic part of the Arctic in period 1981-2010 with particular focus on the first decade of the 21st century as well analyses of these cases in terms of synoptic conditions. Significant contribution of high efficiency precipitation in monthly and yearly precipitation sums have been found in all analysed stations. In some of the analysed stations there was a slight increase of frequency of high efficiency precipitation noticed, however basing on the analysed data it is impossible to explicitly show an increasing trend neither in all analysed stations nor the more in the whole Atlantic Arctic. Correlation between high efficiency precipitation and atmospheric circulation types was very clear. For majority of stations the southern circulation was crucial for high precipitation (humid air masses inflow). In some cases there was clearly visible role of location of the station and influence of orography on the precipitation field. It is important to notice the quality of available databases and considerable difficulties in obtaining reliable, complete and homogenous precipitation data, what makes all analyses of this climatological element in polar areas difficult. The results shown in this study should be regarded as preliminary and basis for further discussion on signalized problems