Darielle Dexheimer’s research while affiliated with Sandia National Laboratories and other places

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Publications (28)


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Enhancing Marine Wildlife Observations: The Application of Tethered Balloon Systems and Advanced Imaging Sensors for Sustainable Marine Energy Development
  • Preprint
  • File available

October 2024

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39 Reads

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Darielle Dexheimer

This study investigates the capabilities of a tethered balloon system (TBS) for detecting and monitoring marine wildlife, primarily focusing on gray whales ( Eschrichtius robustus ) and various avian species. Over 55.7 h of aerial and surface footage were collected, yielding significant findings regarding the detection rates of marine mammals and seabirds. A total of 59 gray whale, 100 avian, and 6 indistinguishable marine mammal targets were identified by the airborne TBS, while surface-based observations recorded 1,409 gray whales, 1,342 avian targets, and several other marine mammals. When the airborne and surface cameras were operating simultaneously, 21% of airborne whale and 34% of airborne avian detections were captured with the airborne TBS camera and undetected with the surface-based camera. The TBS was most effective at altitudes between 50 to 200 m above ground, with variable-pitch scanning patterns providing superior detection of whale blows compared to fixed-pitch and loitering methods. Notably, instances of airborne detections not corroborated by surface observations underscore the benefits of combining aerial monitoring with traditional survey techniques. Additionally, the integration of machine-learning (ML) algorithms into video analysis enhances our capacity for processing large datasets, paving the way for real-time wildlife monitoring. Of the total number of blows detected by an ML algorithm, the percentage of blows identified by a human analyst was greater than that uniquely detected by the algorithm. Notably, more unique detections by the ML algorithm occurred during daylight, suggesting that sun artifacts may hinder human detection performance, thereby highlighting the added value of ML under these conditions. This research lays the groundwork for future studies in marine biodiversity monitoring, emphasizing the importance of innovative aerial surveillance technologies and advanced imaging methodologies in understanding species behavior and informing conservation strategies for sustainable marine energy, offshore wind development, and other marine resource management efforts.

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Figure 1. A side view of the TBS VOC sampler with the top and side access panels open (a) and a schematic of the modular sampler, including sample flow, electrical, and data communication paths (b). Additional photos of the finalized designs for both the TBS and UAV samplers are in the supplemental material (Fig. S1 and S2).
Figure 2. Time series of measured parameters from TBS flights on 4 August 2022. (a) TBS flight altitude, ambient temperature, pressure, and relative humidity (RH) observations. (b) VOC flight times (20 min samples, scaled to size) and chemical composition, TBS altitude, ozone measurements, and aerosol measurements on all three flights.
Figure 3. Time series of measured parameters from UAV flights on 13 September 2022. (a) UAV flight altitude, ambient temperature, pressure, and relative humidity (RH) observations. (b) VOC flight times (10 min samples, scaled to size) and chemical composition, UAV altitude, and ozone measurements on two flights.
A modular approach to volatile organic compound samplers for tethered balloon and drone platforms

June 2024

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48 Reads

Situated at a land-sea interface, Houston, Texas, is a national hub for the petrochemical industry and has the second fastest-growing metropolitan population in the United States. Addressing air quality in this region is uniquely challenging, due in part to its wide range of meteorological conditions (e.g., convection systems and temperature inversions) and continuum of volatile organic compound (VOC) and aerosol sources (e.g., anthropogenic and biogenic). As a result, Houston was chosen as the location for the Department of Energy’s Atmospheric Radiation Measurement (ARM) program-led Tracking Aerosol Convection ExpeRiment (TRACER), which investigated cloud and aerosol interactions in the deep convection over the area. Deployed as a key asset, ARM’s tethered balloon system (TBS) was used to investigate questions related to the vertical distributions of aerosols and their formation, including their precursor species volatile organic compounds. Platforms like TBSs and uncrewed aerial vehicles (UAVs) can bridge the vertical gap between ground-based and crewed airplane measurement platforms to focus on near-surface characterization. However, there has been limited effort to modularize and integrate VOC samplers into instrument payloads on both aerial systems. In this study, lightweight and robust VOC samplers were designed and deployed on the TBS and a UAV to collect VOCs in flight. The modular design allowed for scalable adjustments to meet the unique platform requirements and enabled multiple flights per sampling day. Each sampler can autonomously collect VOCs on up to four sorbent tubes for subsequent thermal desorption-gas chromatography-mass spectrometry analysis. The low sampler mass (2.2 kg and 800 g, TBS and UAV, respectively) enables the combination of these VOC samplers with trace gas, aerosol, and meteorological sensors on aerial platforms. These profiles allow us to assess temporal changes in VOC magnitude and composition at multiple locations. Observations from TBS and UAV flights during TRACER are presented and future considerations for sampler design and deployments are discussed.



Capturing plume behavior in complex terrain: an overview of the Nevada National Security Site Meteorological Experiment (METEX21)

November 2023

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102 Reads

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2 Citations

METEX21 was an atmospheric tracer release experiment executed at the Department of Energy’s Nevada National Security Site (NNSS) in the southwestern U.S to study terrain-induced wind and thermodynamic conditions that influence local-scale (<5-km) plume transport under varying atmospheric forcing conditions. Meteorological observations were collected using 10-m tall meteorological towers, 2-m tall tripods with 3-d sonic anemometers, a 3-m tall eddy covariance flux tower, Doppler profiling lidars, Doppler scanning lidars, weather-balloon launched radiosondes, and a tethered balloon equipped with wind, temperature, and aerosol sensors at heights up to 800 m. A smoke tracer was released along three transects in the horizontal and vertical directions and observed with video cameras, aerosol sensors and lidars (via aerosol backscatter). The observations showed evidence of large-scale/synoptic transience as well as local-scale upslope and downslope flows, along-axis valley flows, recirculation eddies on leeward slopes, and periods of strong shear and veer aloft. The release days were classified as either synoptically-driven or locally-driven, and a single case day is presented in detail for each. Synoptically-forced days show relatively narrow smoke plumes traveling down the valley from north to south (with the predominant wind direction), with little deviation in transport direction regardless of the elevation or ground locations of the smoke releases, except near the presence of leeside recirculation eddies. Locally-forced days exhibit a wider range of plume behavior due to the combination of thermally-induced valley and slope flows, which are often flowing in different cardinal directions, and wind shear found aloft at higher altitudes and elevations. We saw evidence of smoke lofting on top of the mesas due to strong upslope flows on these days. A major finding of this experiment was the effectiveness of scanning lidars to measure 2-dimensional plume transport out to a 2–3 km distance; much farther than could be visibly observed. METEX21 was the first of three planned tracer experiments at NNSS, and future experiments will incorporate multiple tracers to improve individual plume identification so that finer resolution flow details can be attained from these measurements, as well as deploy a larger suite of meteorological instrumentation, including more temperature profiling data.


Assessing turbulence and mixing parameterizations in the gray-zone of multiscale simulations over mountainous terrain during the METEX21 field experiment

November 2023

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80 Reads

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2 Citations

Multiscale numerical weather prediction models transition from mesoscale, where turbulence is fully parameterized, to microscale, where the majority of highly energetic scales of turbulence are resolved. The turbulence gray-zone is situated between these two regimes and multiscale models must downscale through these resolutions. Here, we compare three multiscale simulations which vary by the parameterization used for turbulence and mixing within the gray-zone. The three parameterizations analyzed are the Mellor-Yamada Nakanishi and Niino (MYNN) Level 2.5 planetary boundary layer scheme, the TKE-1.5 large eddy simulation (LES) closure scheme, and a recently developed three-dimensional planetary boundary layer scheme based on the Mellor-Yamada model. The simulation domain includes complex (i.e., mountainous) terrain in Nevada that was instrumented with meteorological towers, profiling and scanning lidars, a tethered balloon, and a surface flux tower. Simulations are compared to each other and to observations, with assessment of model skill at predicting wind speed, wind direction and TKE, and qualitative evaluations of transport and dispersion of smoke from controlled releases. This analysis demonstrates that microscale predictions of transport and dispersion can be significantly influenced by the choice of turbulence and mixing parameterization in the terra incognita, particularly over regions of complex terrain and with strong local forcing. This influence may not be apparent in the analysis of model skill, and motivates future field campaigns involving controlled tracer releases and corresponding modeling studies of the turbulence gray-zone.


Validating a Tethered Balloon System and Optical Technologies for Marine Wildlife Detection and Tracking

September 2023

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83 Reads

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1 Citation

The interactions between marine wildlife and marine energy devices are not well understood, leading to regulatory delays for device deployments and testing. Technologies that enable marine wildlife observations can help to fill data gaps and reduce uncertainties about animal–device interactions. A validation test conducted in Galveston Bay near La Porte, Texas, in December 2022 used a technology package consisting of a tethered balloon system and three independent sensor systems, including three-band visible, eight-band multispectral, and single-band thermal to detect three marine-mammal-shaped surrogates. The field campaign aimed to provide an initial step to evaluating the use of the TBS and the effectiveness of the sensor suite for marine wildlife observations and detection. From 2 December to 7 December 2022, 6 flights were conducted under varying altitudes and environmental conditions resulting in the collection of 5454 images. A subset of the images was classified and analyzed with two collection criteria including Beaufort wind force scale and TBS altitude to assess a range of observations of a surrogate from near-shore to offshore based on pixel count. The results of this validation test demonstrate the potential for using TBSs and imaging sensors for marine wildlife observations and offer valuable information for further development and application of this technology for marine energy and other blue economy sectors.


Vertical Gradient of Size-Resolved Aerosol Compositions over the Arctic Reveals Cloud Processed Aerosol in-Cloud and above Cloud

March 2023

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33 Reads

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7 Citations

Environmental Science and Technology

Arctic aerosols play a significant role in aerosol-radiation and aerosol-cloud interactions, but ground-based measurements are insufficient to explain the interaction of aerosols and clouds in a vertically stratified Arctic atmosphere. This study shows the vertical variability of a size resolved aerosol composition via a tethered balloon system at Oliktok Point, Alaska, at different cloud layers for two representative case studies (background aerosol and polluted conditions). Multimodal microspectroscopy analysis during the background case reveals a broadening of chemically specific size distribution above the cloud top with a high abundance of sulfate particles and core-shell morphology, suggesting possible cloud processing of aerosols. The polluted case also indicates broadening of aerosol size distribution at the upper layer within the clouds with the dominance of carbonaceous particles, which suggests that the carbonaceous particles play a potential role in modulating Arctic cloud properties.


An Automated Size and Time-resolved Aerosol Collector Platform Integrated with Environmental Sensors to Study Vertical Profile of Aerosol

September 2022

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54 Reads

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2 Citations

Atmospheric particles affect human health, climate, and ecosystem but assessing their impacts is still challenging. Part of that is because of the limited understanding of the size-dependence of particle properties...


Citations (17)


... Researchers can derive key parameters from the mass spectrometer data, including O:C ratios, carbon oxidation states, aromaticity indices, and organic aerosol volatility distributions. (Roach et al., 2010;Vandergrift et al., 2024;Vandergrift et al., 2022). 130 ...

Reference:

Measurement Report: Vertically resolved Atmospheric Properties Observed over the Southern Great Plains with Uncrewed Aerial System – ArcticShark
Tethered balloon system and High-Resolution Mass Spectrometry Reveal Increased Organonitrates Aloft Compared to the Ground Level

Environmental Science and Technology

... The simulations, referred in this work as ground truth, were originally designed to replicate similar conditions of the REACT (RElease ACTivity) experiment, conducted in October 2022 at the Nevada National Security Site (NNSS), where realtime xenon sensors monitored radiotracer releases [12], [13] (Fig. 9). Xenon is a reliable indicator of nuclear explosions, particularly underground nuclear tests. ...

Capturing plume behavior in complex terrain: an overview of the Nevada National Security Site Meteorological Experiment (METEX21)

... These include a day dominated by synoptic forcing and consistent northerly winds (March 21) and a day with local (e.g., diurnal surface heating) forcing and strong wind veer found between the valley flow and flow aloft (March 22). For readers interested in the atmospheric modeling of these days, those results and discussion are found in Wiersema et al. (2023). elevation, broader Yucca Flat in the south. ...

Assessing turbulence and mixing parameterizations in the gray-zone of multiscale simulations over mountainous terrain during the METEX21 field experiment

... While these technologies are more easily adapted for terrestrial wildlife, they also apply to observations of marine wildlife interactions with ME systems (Bicknell et al. 2016;Danovaro et al. 2016;Wang et al. 2019). However, gaps remain regarding the e cacy of aerial monitoring methods, particularly in varied marine and coastal conditions (Amerson et al. 2023). These gaps include scanning patterns, ight longevity, wind conditions, altitude variations, and comparisons between human observations and machine-learning (ML) detection. ...

Validating a Tethered Balloon System and Optical Technologies for Marine Wildlife Detection and Tracking

... Colocated particle samples for micro-spectroscopy analysis were collected via a sioutas cascade impactor (sioutasSKC) at 9 L/ min (Model B1B-090 V12AN-00, Parker Hannifin), similar to previously reported implementations. 54 Particles were collected on four different stages: A, B, C, and D. All the microspectroscopy analyses were performed on stage D particles, which has a 50% cut-off particle diameter 0.15 μm. Stage D is chosen for its good sample loading in comparison to stages A, B, and C. Microspectroscopy samples were stored at room temperature. ...

Vertical Gradient of Size-Resolved Aerosol Compositions over the Arctic Reveals Cloud Processed Aerosol in-Cloud and above Cloud
  • Citing Article
  • March 2023

Environmental Science and Technology

... 8,9 However, the direct measurement and capture of vertically resolved atmospheric particle samples is not trivial. Numerous techniques have emerged to address the challenges associated with measuring aloft aerosol, including towers, 10−12 tethered balloons, 6,13,14 unmanned aerial vehicles, 15,16 aircraft, 17−21 and remote sensing measurements such as lidars (indirect measurement). 22−26 Remote sensing approaches such as satellite-based observations have also facilitated understanding the relative positions of aerosol and cloud layers and the resulting radiative effects. ...

An Automated Size and Time-resolved Aerosol Collector Platform Integrated with Environmental Sensors to Study Vertical Profile of Aerosol

... POPS (Handix Scientific, USA) is a lightweight (550 g) optical particle counter measuring particle size distributions in the size range of 120 nm to 3 µm at a 1 s time resolution. POPS has become a standard instrument for in situ aerosol measurements on many balloon systems (e.g., Yu et al., 2017;Kloss 150 et al., 2020;de Boer et al., 2018;Pilz et al., 2022;Miller et al., 2024a) and UAVs (e.g., Telg et al., 2017;Liu et al., 2021;Mei et al., 2022;Miller et al., 2024a). Here, the setup was the same as described in Miller et al. (2024a): POPS was contained in a water-tight plastic housing unit attached to the platform of the TBS. ...

Observational data from uncrewed systems over Southern Great Plains

... Generally, atmospheric OSCs are mainly formed via the secondary reactions of volatile organic compounds (VOCs) with inorganic sulfur (Bruggemann et al., 2020;Gao & Zhu, 2021). Various formation mechanisms of small molecular weight and biogenic VOCs-derived organosulfates have been extensively investigated, as they usually showed higher concentrations in atmosphere particularly in Europe (Brüggemann et al., 2017;Luk´acs et al., 2009;Surratt et al., 2008) and North America Hughes et al., 2021;Vandergrift et al., 2022). However, in China, anthropogenic emissions remain at high levels (Fan et al., 2022), and a high fraction of aromatic OSCs (∼50% of total) was observed (Jiang, Li, Tang, Cui, et al., 2022). ...

Molecular Characterization of Organosulfate-Dominated Aerosols over Agricultural Fields from the Southern Great Plains by High-Resolution Mass Spectrometry
  • Citing Article
  • May 2022

ACS Earth and Space Chemistry

... Over the past decade, uncrewed atmospheric measurement platforms (UxS), such as uncrewed aerial systems (UAS) and tethered balloon systems (TBS), have been increasingly used for air quality monitoring (Lambey and Prasad, 2021;Villa et al., 2016) to help fill the gaps left between ground-based and traditional piloted aircraft measurements of atmospheric species (Mei et al., 2022). UAS can be deployed where it would otherwise be too dangerous to fly a piloted aircraft, such as under a forest canopy (Kobziar et al., 2019), or in particularly remote and challenging locations like Artic areas near newly forming 55 sea ice . ...

Observational data from uncrewed systems over Southern Great Plains

... [64] This influence of anthropogenic emissions was inferred to be greater than the influence of marine, terrestrial, and other coastal emissions combined for particle growth events. The growth events lead to particles large enough to act as CCN that are transported upwards [65] and influence cloud radiative properties. [4] It was found that enhanced CCN number concentrations from Prudhoe Bay emissions reduced cloud droplet effective radii by up to 1 µm thereby increasing cloud albedo and inducing cooling at the surface. ...

Assessing the vertical structure of Arctic aerosols using balloon-borne measurements