Prelaunch and postlaunch calibration results for the Meteor 3/TOMS instrument are presented here. The instrument, launched aboard a Russian spacecraft in 1991, is the second in a series of total ozone mapping spectrometer (TOMS) instruments designed to provide daily global mapping of ozone overburden. Ozone amounts are retrieved from measurements of Earth albedo in the 312‐ to 380‐nm range. The accuracy of albedo measurements is primarily tied to knowledge of the reflective properties of diffusers used in the calibrations and to the instrument's wavelength selection. These and other important prelaunch calibrations are presented. Their estimated accuracies are within the bounds necessary to determine column ozone to better than 1%. However, postlaunch validation results indicate some prelaunch calibration uncertainties may be larger than originally estimated. Instrument calibrations have been maintained postlaunch to within a corresponding 1% error in retrieved ozone. Onboard calibrations, including wavelength monitoring and a three‐diffuser solar measurement system, are described and specific results are presented. Other issues, such as the effects of orbital precession on calibration and recent chopper wheel malfunctions, are also discussed.

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Unmanned aerial vehicles (UAVs), or drones, are being utilized by wildlife biologists to monitor populations of birds and mammals. However, the reaction of wildlife to drones varies by species, so a preliminary evaluation must be conducted to determine if the target species can be detected via drone footage and to determine how the target species will react to drone presence. Lek-mating prairie-chickens (Tympanuchus spp.) seem amenable to drone-based surveys because they are relatively large and display in groups on elevated sites with sparse vegetation. The goal of our study was to determine what flight characteristics maximize prairie-chicken detection on drone video footage, to document the birds' reactions to the drones, and to compare how the noise produced by the drones compares to ambient sounds. We tested 3 sizes of rotary-winged drones, flown at 3 heights, with 3 different camera angles by flying over known prairie-chicken leks.We determined that >65% of prairie-chickens present were detected using video footage at a height of 100 m with a 10°c amera angle. Drones of different sizes had similar detectability. However, observers in blinds adjacent to leks routinely detected more birds than were detected on drone footage (detection on drone footage was 39.7 ± 9.6% of birds present).Prairie-chickens flushed in 96% of trials when a drone was flown over display locations. Time to return to the lek following drone disturbance was similar to prairie-chickens' reactions to natural predators. Prairie-chickens flushed when drone sound levels were comparable to ambient noise. Developing guidelines for the ethical use of drones in wildlife research will

Small unmanned aircraft systems (sUAS) offer key benefits over manned aircraft and satellite platforms used for remote sensing research, such as high spatial resolution, portability, simplicity of implementing ground control, affordability, and lack of reliance upon third-party imagery providers. Mountainous areas, which we define as locations that are higher than 2500 m in elevation and that contain slopes greater than 25 , pose a number of challenges to sUAS mapping operations that other environments do not, including reduced aircraft performance, cold temperatures, high winds, and limited accessibility. The purpose of our paper is to identify these challenges and discuss workflows used to mitigate these difficulties to achieve greater logistical and operational efficiency. We used a DJI Inspire 2 multirotor aircraft to conduct mapping missions in remote, mountainous areas to support subalpine forest inventory and assessment in Nevada and southern Utah. We identified several potential obstacles to collecting highquality aerial image data in environments with high topographic variability and landscape heterogeneity. We found that sUAS are very useful and practical when performing mapping missions in these circumstances when operators account for potential environmental limitations (e.g., poor weather, shortened flight times due to atmospheric conditions, line-of-sight challenges, difficulty implementing ground control across steep sites, ensuring applicable aviation regulations are observed) and technological capabilities (terrain following, flight duration, etc.). This work has implications for a wide variety of scientific and management disciplines that involve low-altitude remote sensing research in mountainous areas.