scholarly journals The Impact of Sensor Response and Airspeed on the Representation of the Convective Boundary Layer and Airmass Boundaries by Small Unmanned Aircraft Systems

2018 ◽  
Vol 35 (8) ◽  
pp. 1687-1699 ◽  
Author(s):  
Adam L. Houston ◽  
Jason M. Keeler
Keyword(s):  
Boundary Layer ◽  
Convective Boundary Layer ◽  
Sensor Response ◽  
Unmanned Aircraft ◽  
Unmanned Aircraft Systems ◽  
Lapse Rate ◽  
Convective Boundary ◽  
Aircraft Systems ◽  
The Impact ◽  
Rotary Wing

AbstractThe objective of the research presented is to assess the impact of sensor response and aircraft airspeed on the accuracy of in situ observations collected by small unmanned aircraft systems profiling the convective boundary layer or transecting airmass boundaries. Estimates are made using simulated aircraft flown within large-eddy simulations. Both instantaneous errors (differences between observed temperature, which include the effects of sensor response and airspeed, and actual temperature) and errors in representation (differences between serial observations and representative snapshots of the atmospheric state) are considered. Synthetic data are retrieved assuming a well-aspirated first-order sensor mounted on rotary-wing aircraft operated as profilers in a simulated CBL and fixed-wing aircraft operated through transects across a simulated airmass boundary. Instantaneous errors are found to scale directly with sensor response time and airspeed for both CBL and airmass boundary experiments. Maximum errors tend to be larger for airmass boundary transects compared to the CBL profiles. Instantaneous errors for rotary-wing aircraft profiles in the CBL simulated for this work are attributable to the background lapse rate and not to turbulent temperature perturbations. For airmass boundary flights, representation accuracy is found to degrade with decreasing airspeed. This signal is most pronounced for flights that encounter the density current wake. When representation errors also include instantaneous errors resulting from sensor response, instantaneous errors are found to be dominant for flights that remain below the turbulent wake. However, for flights that encounter the wake, sensor response times generally need to exceed ~5 s before instantaneous errors become larger than errors in representation.

scholarly journals Characterization of a boreal convective boundary layer and its impact on atmospheric chemistry during HUMPPA-COPEC-2010

2012 ◽  
Vol 12 (19) ◽  
pp. 9335-9353 ◽  
Author(s):  
H. G. Ouwersloot ◽  
J. Vilà-Guerau de Arellano ◽  
A. C. Nölscher ◽  
M. C. Krol ◽  
L. N. Ganzeveld ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Atmospheric Chemistry ◽  
Convective Boundary Layer ◽  
Large Scale ◽  
Spatial Scales ◽  
Potential Temperature ◽  
Chemical Species ◽  
Convective Boundary ◽  
The Impact

Abstract. We studied the atmospheric boundary layer (ABL) dynamics and the impact on atmospheric chemistry during the HUMPPA-COPEC-2010 campaign. We used vertical profiles of potential temperature and specific moisture, obtained from 132 radio soundings, to determine the main boundary layer characteristics during the campaign. We propose a classification according to several main ABL prototypes. Further, we performed a case study of a single day, focusing on the convective boundary layer, to analyse the influence of the dynamics on the chemical evolution of the ABL. We used a mixed layer model, initialized and constrained by observations. In particular, we investigated the role of large scale atmospheric dynamics (subsidence and advection) on the ABL development and the evolution of chemical species concentrations. We find that, if the large scale forcings are taken into account, the ABL dynamics are represented satisfactorily. Subsequently, we studied the impact of mixing with a residual layer aloft during the morning transition on atmospheric chemistry. The time evolution of NOx and O3 concentrations, including morning peaks, can be explained and accurately simulated by incorporating the transition of the ABL dynamics from night to day. We demonstrate the importance of the ABL height evolution for the representation of atmospheric chemistry. Our findings underscore the need to couple the dynamics and chemistry at different spatial scales (from turbulence to mesoscale) in chemistry-transport models and in the interpretation of observational data.

Evaluating the Impact of Deploying Unrestricted Unmanned Aircraft Systems in the National Airspace

2012 ◽  
Author(s):  
Abhinav Saxena ◽  
Indranil Roychoudhury ◽  
Christian Neukom ◽  
Greg Pisanich ◽  
Alex Huang ◽  
...  
Keyword(s):  
Unmanned Aircraft ◽  
Unmanned Aircraft Systems ◽  
Aircraft Systems ◽  
The Impact

scholarly journals Data Generated During the 2018 LAPSE-RATE Campaign: An Introduction and Overview

2020 ◽  
Author(s):  
Gijs de Boer ◽  
Adam Houston ◽  
Jamey Jacob ◽  
Phillip B. Chilson ◽  
Suzanne W. Smith ◽  
...  
Keyword(s):  
Unmanned Aircraft ◽  
Unmanned Aircraft Systems ◽  
Lapse Rate ◽  
Special Issue ◽  
Atmospheric Research ◽  
Aircraft Systems ◽  
San Luis ◽  
Remotely Piloted Aircraft ◽  
Innovative Capabilities ◽  
Set Up

Abstract. Unmanned aircraft systems (UAS) offer innovative capabilities for providing new perspectives on the atmosphere, and therefore atmospheric scientists are rapidly expanding their use, particularly for studying the planetary boundary layer. In support of this expansion, from 14–20 July 2018 the International Society for Atmospheric Research using Remotely-piloted Aircraft (ISARRA) hosted a community flight week, dubbed the Lower Atmospheric Profiling Studies at Elevation – a Remotely-piloted Aircraft Team Experiment (LAPSE-RATE, de Boer et al., 2020a). This field campaign spanned a one-week deployment to Colorado’s San Luis Valley, involving over 100 students, scientists, engineers, pilots, and outreach coordinators. These groups conducted intensive field operations using unmanned aircraft and ground-based assets to develop comprehensive datasets spanning a variety of scientific objectives, including a total of nearly 1300 research flights totaling over 250 flight hours. This article introduces this campaign and lays the groundwork for a special issue on the LAPSE-RATE project. The remainder of the special issue provides detailed overviews of the datasets collected and the platforms used to collect them. All of the datasets covered by this special issue have been uploaded to a LAPSE-RATE community set up at the Zenodo data archive (https://zenodo.org/communities/lapse-rate/).

An agent-based modeling approach for simulating the impact of small unmanned aircraft systems on future battlefields

2020 ◽  
pp. 154851292096390
Author(s):  
Carsten Christensen ◽  
John Salmon
Keyword(s):  
Paradigm Shift ◽  
Implementation Strategies ◽  
Agent Based Modeling ◽  
Unmanned Aircraft ◽  
Unmanned Aircraft Systems ◽  
Military Doctrine ◽  
Small Unit ◽  
Agent Based ◽  
Aircraft Systems ◽  
The Impact

The increasing proliferation of small unmanned aircraft systems (sUASs) is forcing a paradigm shift in military doctrine surrounding counter-sUAS and sUAS deployment tactics. This work describes an agent-based model that incorporates established infantry small unit tactics with the ability to deploy sUASs to aid in surveillance and indirect fire targeting. The model is based on current military doctrine and real warfighter experiences and is presented as a foundation from which additional simulation capabilities and analyses may be created. A series of randomly generated situations sets a defending force with the potential to have sUAS capabilities against a superior attacking force without sUAS capabilities. A control case considers defenders without sUAS capabilities. In six experimental cases, defending forces deploy a single sUAS in one of six patrol patterns as a surveillance and indirect fire targeting tool. Subsequent analysis reveals that sUASs generally increase the odds of defender survival during an engagement and that short-range, concentrated patrol patterns lead to higher odds of defender survival and increased indirect fire opportunities. A battery of analyses showcase the model’s capabilities in terms of exploring novel sUAS implementation strategies and illustrating the impact of those strategies over a range of combat effectiveness metrics.

scholarly journals Integrating canopy and large-scale effects in the convective boundary-layer dynamics during the CHATS experiment

2017 ◽  
Vol 17 (3) ◽  
pp. 1623-1640 ◽  
Author(s):  
Metodija M. Shapkalijevski ◽  
Huug G. Ouwersloot ◽  
Arnold F. Moene ◽  
Jordi Vilà-Guerau de Arrellano
Keyword(s):  
Boundary Layer ◽  
Latent Heat ◽  
Convective Boundary Layer ◽  
Friction Velocity ◽  
Surface Fluxes ◽  
Convective Boundary ◽  
Diurnal Variability ◽  
Drag Coefficients ◽  
Boundary Layer Dynamics ◽  
The Impact

Abstract. By characterizing the dynamics of a convective boundary layer above a relatively sparse and uniform orchard canopy, we investigated the impact of the roughness-sublayer (RSL) representation on the predicted diurnal variability of surface fluxes and state variables. Our approach combined numerical experiments, using an atmospheric mixed-layer model including a land-surface-vegetation representation, and measurements from the Canopy Horizontal Array Turbulence Study (CHATS) field experiment near Dixon, California. The RSL is parameterized using an additional factor in the standard Monin–Obukhov similarity theory flux-profile relationships that takes into account the canopy influence on the atmospheric flow. We selected a representative case characterized by southerly wind conditions to ensure well-developed RSL over the orchard canopy. We then investigated the sensitivity of the diurnal variability of the boundary-layer dynamics to the changes in the RSL key scales, the canopy adjustment length scale, Lc, and the β = u*/|U| ratio at the top of the canopy due to their stability and dependence on canopy structure. We found that the inclusion of the RSL parameterization resulted in improved prediction of the diurnal evolution of the near-surface mean quantities (e.g. up to 50 % for the wind velocity) and transfer (drag) coefficients. We found relatively insignificant effects on the modelled surface fluxes (e.g. up to 5 % for the friction velocity, while 3 % for the sensible and latent heat), which is due to the compensating effect between the mean gradients and the drag coefficients, both of which are largely affected by the RSL parameterization. When varying Lc (from 10 to 20 m) and β (from 0.25 to 0.4 m), based on observational evidence, the predicted friction velocity is found to vary by up to 25 % and the modelled surface-energy fluxes (sensible heat, SH, and latent heat of evaporation, LE) vary up to 2 and 9 %. Consequently, the boundary-layer height varies up to 6 %. Furthermore, our analysis indicated that to interpret the CHATS measurements above the canopy, the contributions of non-local effects such as entrainment, subsidence and the advection of heat and moisture over the CHATS site need to be taken into account.

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

Sensors ◽  
2019 ◽  
Vol 19 (6) ◽  
pp. 1470 ◽  
Author(s):  
Brian Greene ◽  
Antonio Segales ◽  
Tyler Bell ◽  
Elizabeth Pillar-Little ◽  
Phillip Chilson
Keyword(s):  
Unmanned Aircraft ◽  
The Body ◽  
Unmanned Aircraft Systems ◽  
Sensor Integration ◽  
Heat Sources ◽  
Aircraft Systems ◽  
Ducted Fan ◽  
Rotary Wing

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.

scholarly journals Ship plume dispersion rates in convective boundary layers for chemistry models

2008 ◽  
Vol 8 (2) ◽  
pp. 6793-6824
Author(s):  
F. Chosson ◽  
R. Paoli ◽  
B. Cuenot
Keyword(s):  
Boundary Layer ◽  
Dilution Rate ◽  
Convective Boundary Layer ◽  
Time Scale ◽  
High Dispersion ◽  
Minor Effect ◽  
Plume Rise ◽  
Plume Dispersion ◽  
Convective Boundary ◽  
The Impact

Abstract. Detailed ship plume simulations in various convective boundary layer situations have been performed using a Lagrangian Dispersion Model driven by a Large Eddy Simulation Model. The simulations focus on early stage (1–2 h) of plume dispersion regime and take into account the effects of plume rise on dispersion. Results are presented in an attempt to provide to chemical modellers community a realistic description of the impact of characteristic dispersion on exhaust ship plume chemistry. Plume dispersion simulations are used to derive analytical dilution rate functions. Even though results exhibit striking effects of plume rise parameter on dispersion patterns, it is shown that initial buoyancy fluxes at ship stack have minor effect on plume dilution rate. After initial high dispersion regimes a simple characteristic dilution time scale can be used to parameterize the subgrid plume dilution effects in large scale chemistry models. The results show that this parameter is directly related to the typical turn-over time scale of the convective boundary layer.

scholarly journals The Innovative Strategies for Observations in the Arctic Atmospheric Boundary Layer Project (ISOBAR) —Unique fine-scale observations under stable and very stable conditions

2020 ◽  
pp. 1-64
Author(s):  
Stephan T. Kral ◽  
Joachim Reuder ◽  
Timo Vihma ◽  
Irene Suomi ◽  
Kristine Flacké Haualand ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Stable Boundary Layer ◽  
Unmanned Aircraft ◽  
Unmanned Aircraft Systems ◽  
The Arctic ◽  
Fine Scale ◽  
Stable Boundary ◽  
Innovative Strategies ◽  
Aircraft Systems ◽  
Stable Conditions

Capsule summaryCombining ground-based micrometeorological instrumentation with boundary layer remote sensing and unmanned aircraft systems for high-resolution observations on the stable boundary layer over sea ice and corresponding modelling experiments.

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