The first evaluation of a 6-months automatic Meteodrone campaign
Authors: Hervo Maxime , Romanens Gonzague , Hammerschmidt Lukas , Weusthoff Tanja , Martucci Giovanni , Fengler Martin , Haefele Alexander 
Published: March 2022

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&lt;p&gt;&lt;em&gt;&lt;span&gt;The&amp;#160;&lt;/span&gt;&lt;/em&gt;&lt;span&gt;Swis&lt;/span&gt;&lt;span&gt;s federal office of meteorology and climatology&lt;/span&gt;&lt;em&gt;&lt;span&gt;, MeteoSwiss,&amp;#160;&lt;/span&gt;&lt;/em&gt;&lt;span&gt;mandated the company&amp;#160;&lt;/span&gt;&lt;em&gt;&lt;span&gt;Meteomatics&amp;#160;&lt;/span&gt;&lt;/em&gt;&lt;span&gt;for a 6-months campaign to measure vertical profiles of temperature, humidity and wind at Payerne, Switzerland. The aim is to measure 8 profiles per night, up to 1.5km above the ground. The measurements are performed with a hexa-copter&amp;#160;&lt;/span&gt;&lt;em&gt;&lt;span&gt;Meteodrone&amp;#160;&lt;/span&gt;&lt;/em&gt;&lt;span&gt;MM-670 upon remote supervision. The drone was flying automatically beyond the line of sight and was recharged autonomously using the&amp;#160;&lt;/span&gt;&lt;em&gt;&lt;span&gt;Meteobase&lt;/span&gt;&lt;/em&gt;&lt;span&gt;.&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;/p&gt;
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&lt;p&gt;&lt;span&gt;The presentation will focus on the availability and the quality of the measurements. The measurement will be compared to co-localized radio-sounding and remote-sensing measurements like a wind lidar&amp;#160;Windcube&amp;#160;200S, a radar wind profiler PCL1300, the Raman lidar RALMO and a microwave radiometer HATPRO G5. At the end of the campaign, more than 1000 flights should be available, providing a unique data set to compare the performances of these systems.&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;/p&gt;
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&lt;p&gt;&lt;span&gt;On the first month of the campaign, December 2021, 188 flights were performed for an availability of more than 90%. 85% of these flights reached the nominal altitude of 1.5km, the other flights were stopped due to the weather conditions. The measurements were transmitted in real time and compared to simultaneous radio-soundings. Using the WMO/OSCAR requirements and a&amp;#160;preliminary&amp;#160;analysis, the temperature measurements can be classified as a &amp;#8220;breakthrough&amp;#8221; with a temperature uncertainty of 0.82K. The wind data was close to the breakthrough limit (2.85m/s). To obtain useful humidity measurements we had to exclude three nights where the drone was not able to measure correctly a dry layer above the stratus. After this filtering, we obtained an uncertainty of 8.9% on the specific humidity, below the &amp;#8220;threshold&amp;#8221; value of 10%.&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;/p&gt;
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&lt;p&gt;&lt;span&gt;The statistics over the entire period of 6 months will allow to assess the maturity of such systems and inform how they complement the existing observing system.&amp;#160;To our knowledge, it is the first time that such a long-term evaluation is performed, opening the opportunities for automatic drone measurements in the boundary layer.&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;/p&gt;
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