1METEO FRANCE/CNRM, Toulouse, France.2METEO FRANCE/ENM, Toulouse, France.3ENAC, Toulouse, France.

UAS for Meteorological andAtmospheric Studies

G. Roberts1, G. Cayez1,2, F. Lavie1, D. Tzanos1, J.L. Brenguier1, C.Ronfle-Nadaud3,G. Hattenberger3, M. Bronz3

AbstractThe National Center for Meteorological Research(CNRM-GAME, Toulouse, France) conducted UAS flights inSouthern France on two UAS platforms (mini and mid-sizeUAS) to demonstrate their feasibility for meteorological andatmospheric studies. The UAS were equipped withmeteorological and aerosol sensors as well as a dataacquisision system. The meteorological sensors(temperature, relative humidty and pressure) were tested indifferent housings to assess the optimum design andplacement of the sensors. In addition, a standardradiosonde device attached to the aircraft fuselage andballoon launches served as a reference. We found thatconvective and radiative components generated biases inthe meteorological measurements. Aerosol concentrationsand particle size distribution were also measured by opticalcounter and compared for two different inlet designs.

Introduction :(Unmanned Aerial System)

UAS are useful tools to study the atmosphere in placesdangerous for aircrafts : hurricanes, fogs, polar research,...

UAS performance and cost comparisons

COST ES0802I UAS starting integration into studies of climate change

and sustainable development.I COST Action coordinates research on using UAS as a

cost-efficient, trans-boundary method for the monitoring ofthe atmospheric boundary layer.

I UAS close observational gaps between ground-based andsatellite-based measurements.

I In-situ observations ultimately improve numerical weathermodels and climate simulation.

I UAS systems come in different sizes, complexity andequipped with different instrumentation.

I The COST Action promotes the conception and furtherdevelopment of UAS for use in atmospheric researchprograms.

I The networking activities have established a foundation atthe European level for the coordination of scientific,technical and legal aspects related to viable operation ofUAS.

http://bllast.sedoo.fr/

Photo campagne BLLAST:Marie LOTHON

VOLTIGE :(Vecteur d’Observation de La Troposphere pour l’investigation et la Gestion de l’Environnement)

I Cloud microphysics of fog events ;I Structure of lower troposphere (inversion height,

atmospheric stability).

I evolution of boundary layer height ;I radiative fluxes and albedo ;I turbulent kinetic energy ;I Few in-situ measurements of the vertical structure of fog ;I Most fog studies are constrained to ground-based

observations and remote sensing ;I Payload adapted for ultra-light UAS airframe for a specific

measurement.

Liquid Water Content

Pyranometer

Pressure,Temperature,and Relative Humidity

turbulence probe

UAS at CNRMSeveral types of vectors :

UAS FunjetPerformances :

I Total weight : 850 g ;I Endurance : ∼ 20 min, electric ;I Ceiling : Tested to ∼ 2,1 km.

UAS EasystarPerformances :

I Total weight : 1000 g ;I Endurance : ∼ 35 min, electric ;I Ceiling : Tested to ∼ 1,6 km.

UAS Avion JaunePerformances :

I Total weight : 20 kg ;I Endurance : ∼ 8 h, thermic ;I Ceiling : ∼ 4 km.

UAS navigation :

General principle of an autopilotPaparazzi man-machine interface

The UAS for VOLTIGE are ultra-light model airframes equipped with a Paparazzi autonomousnavigation system developped by ENAC.

Meteorological instrumentation : Temperature, Pressure, Relative Humidity

Sensors for VOLTIGE operations Data acquisition system

The goal is to design meteorological sensors which conform to standards mandated by Meteo-France.These sensors are used to derive atmospheric parameters including potential temperature, stability,boundary layer height, and lifting condensation level.

Lannemezan site with two mastfor meteorological insitu mesures

Easystar under rain and snow

←We have tested the dronesunder adverse weatherconditions (rain, snow, wind)and in clouds).

Acknowledgments

I M. Gavart, M. Joanne (Avion Jaune System) ;I G.Hattenberger, M. Bronz, M. Gorraz, A.

Bustico (ENAC).

I F. Lohou et M. Lothon (CRA Lannemezan) ;I S. Defoy (Meteo-France).

Mesurements artefactsHysteresis :

view on the UAV helicaltrajectory

Temperature profile andcumulative aerosol profile

← Problem ofhysteresis wasnoticed on thetemperatureprofile.

Sensor bias :Mini-Temperature probe data show→oscillations. As the drone turns, itmight be caused by :I variation of solar heating on probe ;I variation of Solar heating on drone ;I variation of relative wind.A poorly designed probe exacerbatesthe oscillation phenomenon

Proper probe placement and design is importantto ensure viable atmospheric measurements.Cloud droplets, variations in wind speed, evenbiases by drone’s airframe can bias themeasurements.

Table of probes designed and tested

reverse-flowmetallic probe

helical probe

helical probewith double wall

open probe

← Three kinds of temperatureprobe have been created andtested :I reverse-flow probe ;I helical probe (with or without

double wall) ;I open cylindrical probe.

Drones flew hypodromes trajectoriesaround the Lannemezan masts inorder to make some comparisons

between insitu mast measures andthe drone probes measures

Sensor bias of temperature is seen :0.7 ˚ C for helical probe ;

3.5 ˚ C for reverse flow probe

← Comparison stationary / flightOPC concentrations > 1.5

enhancement during flight usingnon-optimised inlet

inlet flow sub-isokinetic / no shroudand no iso-axial, important to designproper aerosol inlet and match flows

Use of the video in flightTemperature and RH Profiles

← Campaign inLandes inFebrary12th-14th :∼ 20 flights andsensor tests