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24 pages, 4029 KiB

Open AccessArticle

Design and Evaluation of Sensor Housing for Boundary Layer Profiling Using Multirotors

by Ashraful Islam, Adam L. Houston, Ajay Shankar and Carrick Detweiler

Sensors 2019, 19(11), 2481; https://doi.org/10.3390/s19112481 - 30 May 2019

Cited by 21 | Viewed by 5548

Abstract

Traditional configurations for mounting Temperature–Humidity (TH) sensors on multirotor Unmanned Aerial Systems (UASs) often suffer from insufficient radiation shielding, exposure to mixed and turbulent air from propellers, and inconsistent aspiration while situated in the wake of the UAS. Descent profiles using traditional methods [...] Read more.

Traditional configurations for mounting Temperature–Humidity (TH) sensors on multirotor Unmanned Aerial Systems (UASs) often suffer from insufficient radiation shielding, exposure to mixed and turbulent air from propellers, and inconsistent aspiration while situated in the wake of the UAS. Descent profiles using traditional methods are unreliable (when compared to an ascent profile) due to the turbulent mixing of air by the UAS while descending into that flow field. Consequently, atmospheric boundary layer profiles that rely on such configurations are bias-prone and unreliable in certain flight patterns (such as descent). This article describes and evaluates a novel sensor housing designed to shield airborne sensors from artificial heat sources and artificial wet-bulbing while pulling air from outside the rotor wash influence. The housing is mounted above the propellers to exploit the rotor-induced pressure deficits that passively induce a high-speed laminar airflow to aspirate the sensor consistently. Our design is modular, accommodates a variety of other sensors, and would be compatible with a wide range of commercially available multirotors. Extensive flight tests conducted at altitudes up to 500 m Above Ground Level (AGL) show that the housing facilitates reliable measurements of the boundary layer phenomena and is invariant in orientation to the ambient wind, even at high vertical/horizontal speeds (up to 5 m/s) for the UAS. A low standard deviation of errors shows a good agreement between the ascent and descent profiles and proves our unique design is reliable for various UAS missions. Full article

(This article belongs to the Special Issue Application of Unmanned Aircraft Systems for Atmospheric Science)

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32 pages, 12686 KiB

Open AccessArticle

The Multi-Purpose Airborne Sensor Carrier MASC-3 for Wind and Turbulence Measurements in the Atmospheric Boundary Layer

by Alexander Rautenberg, Martin Schön, Kjell zum Berge, Moritz Mauz, Patrick Manz, Andreas Platis, Bram van Kesteren, Irene Suomi, Stephan T. Kral and Jens Bange

Sensors 2019, 19(10), 2292; https://doi.org/10.3390/s19102292 - 17 May 2019

Cited by 42 | Viewed by 6588

Abstract

For atmospheric boundary-layer (ABL) studies, unmanned aircraft systems (UAS) can provide new information in addition to traditional in-situ measurements, or by ground- or satellite-based remote sensing techniques. The ability of fixed-wing UAS to transect the ABL in short time supplement ground-based measurements and [...] Read more.

For atmospheric boundary-layer (ABL) studies, unmanned aircraft systems (UAS) can provide new information in addition to traditional in-situ measurements, or by ground- or satellite-based remote sensing techniques. The ability of fixed-wing UAS to transect the ABL in short time supplement ground-based measurements and the ability to extent the data horizontally and vertically allows manifold investigations. Thus, the measurements can provide many new possibilities for investigating the ABL. This study presents the new mark of the Multi-Purpose Airborne Sensor Carrier (MASC-3) for wind and turbulence measurements and describes the subsystems designed to improve the wind measurement, to gain endurance and to allow operations under an enlarged range of environmental conditions. The airframe, the capabilities of the autopilot Pixhawk 2.1, the sensor system and the data acquisition software, as well as the post-processing software, provide the basis for flight experiments and are described in detail. Two flights in a stable boundary-layer and a close comparison to a measurement tower and a Sodar system depict the accuracy of the wind speed and direction measurements, as well as the turbulence measurements. Mean values, variances, covariance, turbulent kinetic energy and the integral length scale agree well with measurements from a meteorological measurement tower. MASC-3 performs valuable measurements of stable boundary layers with high temporal resolution and supplements the measurements of meteorological towers and sodar systems. Full article

(This article belongs to the Special Issue Application of Unmanned Aircraft Systems for Atmospheric Science)

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32 pages, 56252 KiB

Open AccessArticle

Intercomparison of Small Unmanned Aircraft System (sUAS) Measurements for Atmospheric Science during the LAPSE-RATE Campaign

by Lindsay Barbieri, Stephan T. Kral, Sean C. C. Bailey, Amy E. Frazier, Jamey D. Jacob, Joachim Reuder, David Brus, Phillip B. Chilson, Christopher Crick, Carrick Detweiler, Abhiram Doddi, Jack Elston, Hosein Foroutan, Javier González-Rocha, Brian R. Greene, Marcelo I. Guzman, Adam L. Houston, Ashraful Islam, Osku Kemppinen, Dale Lawrence, Elizabeth A. Pillar-Little, Shane D. Ross, Michael P. Sama, David G. Schmale, Travis J. Schuyler, Ajay Shankar, Suzanne W. Smith, Sean Waugh, Cory Dixon, Steve Borenstein and Gijs de Boer Show full author list Hide full author list

Sensors 2019, 19(9), 2179; https://doi.org/10.3390/s19092179 - 10 May 2019

Cited by 99 | Viewed by 13974

Abstract

Small unmanned aircraft systems (sUAS) are rapidly transforming atmospheric research. With the advancement of the development and application of these systems, improving knowledge of best practices for accurate measurement is critical for achieving scientific goals. We present results from an intercomparison of atmospheric [...] Read more.

Small unmanned aircraft systems (sUAS) are rapidly transforming atmospheric research. With the advancement of the development and application of these systems, improving knowledge of best practices for accurate measurement is critical for achieving scientific goals. We present results from an intercomparison of atmospheric measurement data from the Lower Atmospheric Process Studies at Elevation—a Remotely piloted Aircraft Team Experiment (LAPSE-RATE) field campaign. We evaluate a total of 38 individual sUAS with 23 unique sensor and platform configurations using a meteorological tower for reference measurements. We assess precision, bias, and time response of sUAS measurements of temperature, humidity, pressure, wind speed, and wind direction. Most sUAS measurements show broad agreement with the reference, particularly temperature and wind speed, with mean value differences of 1.6

\pm 2.6^{\circ}

C and 0.22

\pm 0.59

m/s for all sUAS, respectively. sUAS platform and sensor configurations were found to contribute significantly to measurement accuracy. Sensor configurations, which included proper aspiration and radiation shielding of sensors, were found to provide the most accurate thermodynamic measurements (temperature and relative humidity), whereas sonic anemometers on multirotor platforms provided the most accurate wind measurements (horizontal speed and direction). We contribute both a characterization and assessment of sUAS for measuring atmospheric parameters, and identify important challenges and opportunities for improving scientific measurements with sUAS. Full article

(This article belongs to the Special Issue Application of Unmanned Aircraft Systems for Atmospheric Science)

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16 pages, 50849 KiB

Open AccessArticle

Development and Deployment of Air-Launched Drifters from Small UAS

by Sara Swenson, Brian Argrow, Eric Frew, Steve Borenstein and Jason Keeler

Sensors 2019, 19(9), 2149; https://doi.org/10.3390/s19092149 - 9 May 2019

Cited by 7 | Viewed by 4262

Abstract

Supercell thunderstorms can form extremely dangerous and destructive tornadoes. While high fidelity supercell simulations have increased the understanding of supercell mechanics to help determine how and when tornadoes form, there is a lack of targeted, in situ measurements taken aboveground in supercells to [...] Read more.

Supercell thunderstorms can form extremely dangerous and destructive tornadoes. While high fidelity supercell simulations have increased the understanding of supercell mechanics to help determine how and when tornadoes form, there is a lack of targeted, in situ measurements taken aboveground in supercells to validate these simulations. Pseudo-Lagrangian drifters (PLDs) are atmospheric probes that can be used to attain thermodynamic measurements in areas that are difficult or dangerous to access, such as from within supercells. Of particular interest in understanding tornadogenesis is the rear-flank downdraft (RFD). However, strong outflow winds behind the rear-flank gust front (RFGF) make the RFD particularly difficult to access with balloon-borne sensors launched from the ground. A specific type of PLD, an air-launched drifter (ALD) that is released from unmanned aircraft systems (UAS), can be used to access RFD inflows, present at higher altitudes. Results from initial tests of ALDs are shown, along with results from a ground-released PLD test during a supercell intercept in the Oklahoma Panhandle on 12 June 2018. In characterization tests performed at the 2018 International Society for Atmospheric Research using Remotely piloted Aircraft (ISARRA) flight week, it was found that the ALD sensor system performs reasonably well against industry standards. However, improvements will be made to increase the aspiration of the sensor. Full article

(This article belongs to the Special Issue Application of Unmanned Aircraft Systems for Atmospheric Science)

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14 pages, 3985 KiB

Open AccessArticle

Using a Balloon-Launched Unmanned Glider to Validate Real-Time WRF Modeling

by Travis J. Schuyler, S. M. Iman Gohari, Gary Pundsack, Donald Berchoff and Marcelo I. Guzman

Sensors 2019, 19(8), 1914; https://doi.org/10.3390/s19081914 - 23 Apr 2019

Cited by 22 | Viewed by 8911

Abstract

The use of small unmanned aerial systems (sUAS) for meteorological measurements has expanded significantly in recent years. SUAS are efficient platforms for collecting data with high resolution in both space and time, providing opportunities for enhanced atmospheric sampling. Furthermore, advances in mesoscale weather [...] Read more.

The use of small unmanned aerial systems (sUAS) for meteorological measurements has expanded significantly in recent years. SUAS are efficient platforms for collecting data with high resolution in both space and time, providing opportunities for enhanced atmospheric sampling. Furthermore, advances in mesoscale weather research and forecasting (WRF) modeling and graphical processing unit (GPU) computing have enabled high resolution weather modeling. In this manuscript, a balloon-launched unmanned glider, complete with a suite of sensors to measure atmospheric temperature, pressure, and relative humidity, is deployed for validation of real-time weather models. This work demonstrates the usefulness of sUAS for validating and improving mesoscale, real-time weather models for advancements toward reliable weather forecasts to enable safe and predictable sUAS missions beyond visual line of sight (BVLOS). Full article

(This article belongs to the Special Issue Application of Unmanned Aircraft Systems for Atmospheric Science)

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21 pages, 970 KiB

Open AccessArticle

A Method for Detecting Atmospheric Lagrangian Coherent Structures Using a Single Fixed-Wing Unmanned Aircraft System

by Peter J. Nolan, Hunter G. McClelland, Craig A. Woolsey and Shane D. Ross

Sensors 2019, 19(7), 1607; https://doi.org/10.3390/s19071607 - 3 Apr 2019

Cited by 12 | Viewed by 4535

Abstract

The transport of material through the atmosphere is an issue with wide ranging implications for fields as diverse as agriculture, aviation, and human health. Due to the unsteady nature of the atmosphere, predicting how material will be transported via the Earth’s wind field [...] Read more.

The transport of material through the atmosphere is an issue with wide ranging implications for fields as diverse as agriculture, aviation, and human health. Due to the unsteady nature of the atmosphere, predicting how material will be transported via the Earth’s wind field is challenging. Lagrangian diagnostics, such as Lagrangian coherent structures (LCSs), have been used to discover the most significant regions of material collection or dispersion. However, Lagrangian diagnostics can be time-consuming to calculate and often rely on weather forecasts that may not be completely accurate. Recently, Eulerian diagnostics have been developed which can provide indications of LCS and have computational advantages over their Lagrangian counterparts. In this paper, a methodology is developed for estimating local Eulerian diagnostics from wind velocity data measured by a single fixed-wing unmanned aircraft system (UAS) flying in a circular arc. Using a simulation environment, driven by realistic atmospheric velocity data from the North American Mesoscale (NAM) model, it is shown that the Eulerian diagnostic estimates from UAS measurements approximate the true local Eulerian diagnostics and also predict the passage of LCSs. This methodology requires only a single flying UAS, making it easier and more affordable to implement in the field than existing alternatives, such as multiple UASs and Dopler LiDAR measurements. Our method is general enough to be applied to calculate the gradient of any scalar field. Full article

(This article belongs to the Special Issue Application of Unmanned Aircraft Systems for Atmospheric Science)

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17 pages, 1641 KiB

Open AccessArticle

Environmental and Sensor Integration Influences on Temperature Measurements by Rotary-Wing Unmanned Aircraft Systems

by Brian R. Greene, Antonio R. Segales, Tyler M. Bell, Elizabeth A. Pillar-Little and Phillip B. Chilson

Sensors 2019, 19(6), 1470; https://doi.org/10.3390/s19061470 - 26 Mar 2019

Cited by 47 | Viewed by 6568

Abstract

Obtaining thermodynamic measurements using rotary-wing unmanned aircraft systems (rwUAS) requires several considerations for mitigating biases from the aircraft and its environment. In this study, we focus on how the method of temperature sensor integration can impact the quality of its measurements. To minimize [...] Read more.

Obtaining thermodynamic measurements using rotary-wing unmanned aircraft systems (rwUAS) requires several considerations for mitigating biases from the aircraft and its environment. In this study, we focus on how the method of temperature sensor integration can impact the quality of its measurements. To minimize non-environmental heat sources and prevent any contamination coming from the rwUAS body, two configurations with different sensor placements are proposed for comparison. The first configuration consists of a custom quadcopter with temperature and humidity sensors placed below the propellers for aspiration. The second configuration incorporates the same quadcopter design with sensors instead shielded inside of an L-duct and aspirated by a ducted fan. Additionally, an autopilot algorithm was developed for these platforms to face them into the wind during flight for kinematic wind estimations. This study will utilize in situ rwUAS observations validated against tower-mounted reference instruments to examine how measurements are influenced both by the different configurations as well as the ambient environment. Results indicate that both methods of integration are valid but the below-propeller configuration is more susceptible to errors from solar radiation and heat from the body of the rwUAS. Full article

(This article belongs to the Special Issue Application of Unmanned Aircraft Systems for Atmospheric Science)

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21 pages, 7466 KiB

Open AccessArticle

OVLI-TA: An Unmanned Aerial System for Measuring Profiles and Turbulence in the Atmospheric Boundary Layer

by Sara Alaoui-Sosse, Pierre Durand, Patrice Medina, Philippe Pastor, Marie Lothon and Iuri Cernov

Sensors 2019, 19(3), 581; https://doi.org/10.3390/s19030581 - 30 Jan 2019

Cited by 23 | Viewed by 5617

Abstract

In recent years, we developed a small, unmanned aerial system (UAS) called OVLI-TA (Objet Volant Leger Instrumenté–Turbulence Atmosphérique) dedicated to atmospheric boundary layer research, in Toulouse (France). The device has a wingspan of 2.60 m and weighed 3.5 kg, including payload. It was [...] Read more.

In recent years, we developed a small, unmanned aerial system (UAS) called OVLI-TA (Objet Volant Leger Instrumenté–Turbulence Atmosphérique) dedicated to atmospheric boundary layer research, in Toulouse (France). The device has a wingspan of 2.60 m and weighed 3.5 kg, including payload. It was essentially developed to investigate turbulence in a way complementary to other existing measurement systems, such as instrumented towers/masts. OVLI-TA’s instrumental package includes a 5-hole probe on the nose of the airplane to measure attack and sideslip angles, a Pitot probe to measure static pressure, a fast inertial measurement unit, a GPS receiver, as well as temperature and moisture sensors in specific housings. In addition, the Pixhawk autopilot is used for autonomous flights. OVLI-TA is capable of profiling wind speed, wind direction, temperature, and humidity up to 1 km altitude, in addition to measuring turbulence. After wind tunnel calibrations, flight tests were conducted in March 2016 in Lannemezan (France), where there is a 60-m tower equipped with turbulence sensors. In July 2016, OVLI-TA participated in the international project DACCIWA (Dynamics-Aerosol-Chemistry-Clouds Interactions in West Africa), in Benin. Comparisons of the OVLI-TA observations with both the 60 m tower measurements and the radiosonde profiles showed good agreement for the mean values of wind, temperature, humidity, and turbulence parameters. Moreover, it validated the capacity of the drone to sample wind fluctuations up to a frequency of around 10 Hz, which corresponds to a spatial resolution of the order of 1 m. Full article

(This article belongs to the Special Issue Application of Unmanned Aircraft Systems for Atmospheric Science)

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24 pages, 8609 KiB

Open AccessArticle

On the Use of Rotary-Wing Aircraft to Sample Near-Surface Thermodynamic Fields: Results from Recent Field Campaigns

by Temple R. Lee, Michael Buban, Edward Dumas and C. Bruce Baker

Sensors 2019, 19(1), 10; https://doi.org/10.3390/s19010010 - 20 Dec 2018

Cited by 40 | Viewed by 4686 | Correction

Abstract

Rotary-wing small unmanned aircraft systems (sUAS) are increasingly being used for sampling thermodynamic and chemical properties of the Earth’s atmospheric boundary layer (ABL) because of their ability to measure at high spatial and temporal resolutions. Therefore, they have the potential to be used [...] Read more.

Rotary-wing small unmanned aircraft systems (sUAS) are increasingly being used for sampling thermodynamic and chemical properties of the Earth’s atmospheric boundary layer (ABL) because of their ability to measure at high spatial and temporal resolutions. Therefore, they have the potential to be used for long-term quasi-continuous monitoring of the ABL, which is critical for improving ABL parameterizations and improving numerical weather prediction (NWP) models through data assimilation. Before rotary-wing aircraft can be used for these purposes, however, their performance and the sensors used therein must be adequately characterized. In the present study, we describe recent calibration and validation procedures for thermodynamic sensors used on two rotary-wing aircraft: A DJI S-1000 and MD4-1000. These evaluations indicated a high level of confidence in the on-board measurements. We then used these measurements to characterize the spatiotemporal variability of near-surface (up to 300-m AGL) temperature and moisture fields as a component of two recent field campaigns: The Verification of the Origins of Rotation in Tornadoes Experiment in the Southeast U.S. (VORTEX-SE) in Alabama, and the Land Atmosphere Feedback Experiment (LAFE) in northern Oklahoma. Full article

(This article belongs to the Special Issue Application of Unmanned Aircraft Systems for Atmospheric Science)

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20 pages, 37541 KiB

Open AccessArticle

Coordinated Unmanned Aircraft System (UAS) and Ground-Based Weather Measurements to Predict Lagrangian Coherent Structures (LCSs)

by Peter J. Nolan, James Pinto, Javier González-Rocha, Anders Jensen, Christina N. Vezzi, Sean C. C. Bailey, Gijs De Boer, Constantin Diehl, Roger Laurence III, Craig W. Powers, Hosein Foroutan, Shane D. Ross and David G. Schmale III

Sensors 2018, 18(12), 4448; https://doi.org/10.3390/s18124448 - 15 Dec 2018

Cited by 50 | Viewed by 7505

Abstract

Concentrations of airborne chemical and biological agents from a hazardous release are not spread uniformly. Instead, there are regions of higher concentration, in part due to local atmospheric flow conditions which can attract agents. We equipped a ground station and two rotary-wing unmanned [...] Read more.

Concentrations of airborne chemical and biological agents from a hazardous release are not spread uniformly. Instead, there are regions of higher concentration, in part due to local atmospheric flow conditions which can attract agents. We equipped a ground station and two rotary-wing unmanned aircraft systems (UASs) with ultrasonic anemometers. Flights reported here were conducted 10 to 15 m above ground level (AGL) at the Leach Airfield in the San Luis Valley, Colorado as part of the Lower Atmospheric Process Studies at Elevation—a Remotely-Piloted Aircraft Team Experiment (LAPSE-RATE) campaign in 2018. The ultrasonic anemometers were used to collect simultaneous measurements of wind speed, wind direction, and temperature in a fixed triangle pattern; each sensor was located at one apex of a triangle with ∼100 to 200 m on each side, depending on the experiment. A WRF-LES model was used to determine the wind field across the sampling domain. Data from the ground-based sensors and the two UASs were used to detect attracting regions (also known as Lagrangian Coherent Structures, or LCSs), which have the potential to transport high concentrations of agents. This unique framework for detection of high concentration regions is based on estimates of the horizontal wind gradient tensor. To our knowledge, our work represents the first direct measurement of an LCS indicator in the atmosphere using a team of sensors. Our ultimate goal is to use environmental data from swarms of sensors to drive transport models of hazardous agents that can lead to real-time proper decisions regarding rapid emergency responses. The integration of real-time data from unmanned assets, advanced mathematical techniques for transport analysis, and predictive models can help assist in emergency response decisions in the future. Full article

(This article belongs to the Special Issue Application of Unmanned Aircraft Systems for Atmospheric Science)

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Review

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23 pages, 40137 KiB

Open AccessReview

Moving towards a Network of Autonomous UAS Atmospheric Profiling Stations for Observations in the Earth’s Lower Atmosphere: The 3D Mesonet Concept

by Phillip B. Chilson, Tyler M. Bell, Keith A. Brewster, Gustavo Britto Hupsel de Azevedo, Frederick H. Carr, Kenneth Carson, William Doyle, Christopher A. Fiebrich, Brian R. Greene, James L. Grimsley, Sai Teja Kanneganti, Joshua Martin, Andrew Moore, Robert D. Palmer, Elizabeth A. Pillar-Little, Jorge L. Salazar-Cerreno, Antonio R. Segales, Mark E. Weber, Mark Yeary and Kelvin K. Droegemeier

Sensors 2019, 19(12), 2720; https://doi.org/10.3390/s19122720 - 17 Jun 2019

Cited by 54 | Viewed by 11585

Abstract

The deployment of small unmanned aircraft systems (UAS) to collect routine in situ vertical profiles of the thermodynamic and kinematic state of the atmosphere in conjunction with other weather observations could significantly improve weather forecasting skill and resolution. High-resolution vertical measurements of pressure, [...] Read more.

The deployment of small unmanned aircraft systems (UAS) to collect routine in situ vertical profiles of the thermodynamic and kinematic state of the atmosphere in conjunction with other weather observations could significantly improve weather forecasting skill and resolution. High-resolution vertical measurements of pressure, temperature, humidity, wind speed and wind direction are critical to the understanding of atmospheric boundary layer processes integral to air–surface (land, ocean and sea ice) exchanges of energy, momentum, and moisture; how these are affected by climate variability; and how they impact weather forecasts and air quality simulations. We explore the potential value of collecting coordinated atmospheric profiles at fixed surface observing sites at designated times using instrumented UAS. We refer to such a network of autonomous weather UAS designed for atmospheric profiling and capable of operating in most weather conditions as a 3D Mesonet. We outline some of the fundamental and high-impact science questions and sampling needs driving the development of the 3D Mesonet and offer an overview of the general concept of operations. Preliminary measurements from profiling UAS are presented and we discuss how measurements from an operational network could be realized to better characterize the atmospheric boundary layer, improve weather forecasts, and help to identify threats of severe weather. Full article

(This article belongs to the Special Issue Application of Unmanned Aircraft Systems for Atmospheric Science)

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