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

Cryo-conditioned rocky coast systems: A case study from Wilczekodden, Svalbard

This paper presents the results of an investigation into the processes controlling development of a cryo-conditioned rock coast system in Hornsund, Svalbard. A suite of nested geomorphological and geophysical methods have been applied to characterise the functioning of rock cliffs and shore platforms influenced by lithological control and geomorphic processes driven by polar coast environments. Electrical resistivity tomography (ERT) surveys have been used to investigate permafrost control on rock coast dynamics and reveal the strong interaction with marine processes in High Arctic coastal settings. Schmidt hammer rock tests, demonstrated strong spatial control on the degree of rock weathering (rock strength) along High Arctic rock coasts. Elevation controlled geomorphic zones are identified and linked to distinct processes and mechanisms, transitioning from peak hardness values at the ice foot through the wave and storm dominated scour zones to the lowest values on the cliff tops, where the effects of periglacial weathering dominate. Observations of rock surface change using a traversing micro-erosion meter (TMEM) indicate that significant changes in erosion rates occur at the junction between the shore platform and the cliff toe, where rock erosion is facilitated by frequent wetting and drying and operation of nivation and sea ice processes (formation and melting of snow patches and icefoot complexes). The results are synthesised to propose a new conceptual model of High Arctic rock coast systems, with the aim of contributing towards a unifying concept of cold region landscape evolution and providing direction for future research regarding the state of polar rock coasts

AC Power and Energy Measurements based on Physical Definitions

The article presents the AC power measurements based on physical definitions as introduced by the draft German standard DIN 40110 in 1970 and its practical application as a power signal processor. The power processor is an electronic device allowing separation of the measured power signal (obtained from the multiplier circuit of voltages and currents) in two components: P+ and P- defined as the input power Pv and return power Pr. The separation is obtained by shifting the phase angle between the current and voltage. The value of return power is negative. Such separation is natural because it is based on physical phenomena of delivered, useful energy and harmful return energy flows. Return power is considered harmful because it causes heating of cables and sources of AC power (as transformers). Presented concepts and meters can be useful for accurate billing purposes for delivered electrical energy as well as for dynamic compensation of nonlinear loads to reduce the return power. Experiments realized using the power meter WL-1 synchro (operating according to physical definitions) confirms high percentage of return power for nonlinear loads, as AC powered LED light sources where the amount of return power can reach 70% of delivered power