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Effects of downwash during unmanned aircraft system‐assisted water sampling on water mass structure directly below the UAS
Author(s) -
Miura Shingo,
Kohzu Ayato
Publication year - 2020
Publication title -
limnology and oceanography: methods
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.898
H-Index - 72
ISSN - 1541-5856
DOI - 10.1002/lom3.10367
Subject(s) - downwash , sampling (signal processing) , environmental science , remote sensing , meteorology , physics , optics , geology , detector , vortex
In recent years, unmanned aircraft system (UAS) have played an increasing role in fields such as topographic mapping using optical cameras and thermal mapping using infrared cameras in aquatic environmental research. UAS‐assisted water sampling has important advantages, such as reducing labor, increasing sampling speed, and enabling sample collection from as‐yet unexplored lakes and marshes. However, downwash effects on water masses have not yet been evaluated. We conducted two experiments to evaluate the impact of UAS downwash on water mass characteristics. In the first experiment, we used temperature sensors and thermal imaging cameras to show that downwash generates bottom‐water upwelling. The results of this experiment are consistent with our hypothesized mechanism for water mass perturbation. In the second experiment, we directly measured downwash speeds and used the data to recommend a maximum downwash speed of 4.0 m s −1 for UAS‐assisted water sampling. However, we caution that even slower downwash speeds may be required for certain field conditions and research questions. Our results showed that the ongoing development of UAS‐assisted water sampling must include efforts to measure and minimize downwash.