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Abstract: PDF documents detailing summary notes of Intensive Operating Period (IOP) operations and events for the BioAerosols and Convective Storms (BACS) campaign. Details documented include an overview of the IOP observations; a morning forecast briefing summary; and detailed timings and notes on convective storm evolution, cold pool passages, and data collection (e.g. radiosondes released, drone flights conducted, and occasionally aerosol instrumentation operation notes). The data set also includes accompanying animated GIF files of Next Generation Weather Radar (NEXRAD) 0.5° reflectivity from Cheyenne, WY (KCYS) with locations and altitudes of all radiosondes released during the IOP overplotted at each relevant time within the animation. 

Abstract: This dataset contains the Wideband Integrated Bioaerosol Sensor (WIBS) measurements collected as part of the BACS (BioAerosol and Convective Storm) campaign. The purpose of the BACS campaign was to characterize the dynamics between convective storms and bioaerosols in a grassland environment. The focus of PI Stone’s group was on characterizing bioaerosol types, concentrations, and sizes during quiescent and convective conditions using offline techniques combined with online instrumentation. These measurements will provide better insight into the impact of convective storms on bioaerosols, allowing for improved modelling and predictions. This archive is for the Wideband Integrated Bioaerosol Sensor– New electronics Option (WIBS-NEO) which was attached to a flux tower with an elevation of ~9 m. The campaigns took place from May 23 – June 17, 2022, and from May 22 – June 23, 2023, and were conducted in northeastern Colorado, with a latitude of 40.815553 N, a longitude of 104.745622 W, and an average altitude of 1654 m. The WIBS data was collected nearly continuously throughout the campaigns. 

Abstract: These Chemical Tracer Measurements are part of the BACS (BioAerosol and Convective Storm) campaign. The purpose of the BACS campaign was to characterize the dynamics between convective storms and bioaerosols in a grassland environment. The focus of PI Stone’s group was on characterizing bioaerosol types, concentrations, and sizes during quiescent and convective conditions using offline techniques combined with online instrumentation. These measurements will provide better insight into the impact of convective storms on bioaerosols, allowing for improved modelling and predictions. This archive is for chemical tracer measurements of samples collected using high flow impactors in a soil plot located northwest of the NEON flux tower. The campaigns took place from May 23 – June 17, 2022, and from May 22 – June 23, 2023, and were conducted in northeastern Colorado, with a latitude of 40.816284 N, a longitude of 104.746390 W, and an average altitude of 1654 m. Samples were collected continuously throughout both campaigns, with sample durations ranging from 6-24 hours. 

Multirotor drones (part of the category of small Uncrewed Aerial Systems [sUAS] or small Uncrewed Aerial Vehicles [sUAV]) are used in atmospheric research to make measurements of the lower atmosphere, and their use is poised to increase in the future. New drone atmospheric sensing opportunities, such as ride-along applications and drone swarms, are emerging. These opportunities, which may not allow room for specialized shielding or aspiration equipment, together with increased drone usage, necessitate the characterization of the performance of unshielded sensors mounted to drones if the accuracy of such observations is to be understood. In this work, we characterize the accuracy of thermodynamic measurements, specifically temperature and water vapor mixing ratio, based on the sensor mounting position onboard multirotor drones. To assess the influence of the drone mechanics on the measurements, ninety-eight individual drone flights with eight distinct thermodynamic sensor positions were performed next to an instrumented flux tower and a tethersonde carrying identical sensors, where the tower and tethersonde measurements are assumed as truth. The flights were at least nine minutes in length, and nine of the flights were conducted at night. At the best position, absolute daytime temperature errors were between -0.83K and +0.61K at the 95% confidence interval, while nighttime temperature errors were smaller, ranging from -0.28 K and +0.48 K. Water vapor mixing ratio errors are within -0.22 g kg-1 and +0.66 g kg-1. We conclude that measurements in field campaigns are more accurate when sensors are placed away from the main body of the drone and are sufficiently aspirated, such as a position near, but not directly under, a spinning propeller. 

Abstract. Multirotor drones (part of the category of small Uncrewed Aerial Systems [sUAS] or small Uncrewed Aerial Vehicles [sUAV]) are used in atmospheric research to make measurements of the lower atmosphere, and their use is poised to increase in the future. New drone atmospheric sensing opportunities, such as ride-along applications and drone swarms, are emerging. These opportunities, which may not allow room for specialized shielding or aspiration equipment, together with increased drone usage, necessitate the characterization of the performance of unshielded sensors mounted to drones if the accuracy of such observations is to be understood. In this work, we characterize the accuracy of thermodynamic measurements, specifically temperature and water vapor mixing ratio, based on the sensor mounting position onboard multirotor drones. To assess the influence of the drone mechanics on the measurements, ninety-eight individual drone flights with eight distinct thermodynamic sensor positions were performed next to an instrumented flux tower and a tethersonde carrying identical sensors, where the tower and tethersonde measurements are assumed as truth. The flights were at least nine minutes in length, and nine of the flights were conducted at night. At the best position, absolute daytime temperature errors were between −0.83 and +0.61 K at the 95 % confidence interval, while nighttime temperature errors were smaller, ranging from −0.28 and +0.48 K. Water vapor mixing ratio errors are within −0.22 and +0.66 g kg−1. We conclude that measurements in field campaigns are more accurate when sensors are placed away from the main body of the drone and are sufficiently aspirated, such as a position near, but not directly under, a spinning propeller. 

Abstract Heterogeneous landscapes can influence the development of convection through the generation of thermally driven mesoscale circulations. To assess the impacts of these circulations and their interaction with sea breezes, we simulated convection in an idealized coastal environment using the Regional Atmospheric Modeling System (RAMS). We compared simulations with striped patterns of surface vegetation to those of uniform vegetation to identify the importance of vegetation heterogeneity in impacting convective development. Under dry soil conditions representative of those during the Tracking Aerosol Convection Interactions Experiment (TRACER) and Experiment of Sea Breeze Convection, Aerosols, Precipitation, and Environment (ESCAPE) campaigns in June 2022, we found that these vegetation-induced circulations, referred to in the literature as “forest breezes,” are more important than the sea breeze in determining the location of convection initiation. Convection and precipitation are also found to be favored over forests and suppressed over pasture and suburban landscapes as a result of greater surface sensible heat flux over the forest. Our findings also indicate that forest breezes are important for initiating convection along the boundaries of the forest, but that cold pools may play a key role in propagating the forest breezes toward the center of the forest stripe. In our simulations, the collisions of these breezes in the center of the forest stripe lead to uplift and strong convection there; however, a different width of the forest stripe would alter when the forest breezes collide or whether they collide at all. The presence of these cold pools may therefore impact the “ideal stripe width,” the width of each vegetation stripe which maximizes domain-wide precipitation. 

Abstract. The rain produced by thunderstorms has been observed to coincide spatially and temporally with enhanced near-surface concentrations of warm-temperature ice nucleating particles (INPs) of biological origin. However, the air in rainy regions is evaporatively cooled and negatively buoyant, and so it is unclear if it is entrained into its parent storms. Despite bioaerosols being highly ice-nucleation active, the microphysical influence that rain-aerosolized bioaerosols exert on storm processes is therefore not well-understood. We use the RAMS cloud-resolving model to simulate high-resolution archetypal representations of three deep convective storm morphologies: isolated deep convection, a squall line, and a supercell. We measure the degree of entrainment of rainy and non-rainy surface air into its parent storm using passive tracers, as well as calculating measures of each storm’s characteristics that influence the timing and degree of this entrainment. We find different degrees of entrainment between storm morphologies and between rainy and non-rainy surface air, with the squall line and supercell entraining significantly more rainy air than the isolated convective storm for all but the lightest rain. These differences owe to variation between the storms in their degrees of entrainment of surface air, their proportions of entrained surface air that originate in rainy regions, and their amount of rain produced per updraft mass. This study finds a specific and previously unrecognized source of air potentially containing highly ice-active aerosols which is entrained to varying degrees in different convective storm morphologies, and which is likely to exert different microphysical impacts on each type of storm. 

Abstract The impacts of topographic slope on daytime haboob propagation speeds and dust lofting are examined along with how these impacts are modulated by surface roughness length. A suite of 20 idealized, large‐eddy simulations are run with varied linear topographic slopes and surface roughness lengths. It is found that on flat ground, greater surface roughness increases drag on haboobs and causes haboobs to dissipate faster, thereby decreasing both haboob propagation speeds and dust lofting. In simulations with sloped topography, upslope anabatic winds form due to solar heating. As topographic slope and surface roughness are increased, the anabatic winds become faster. Greater surface roughness causes more drag on the anabatic wind, but this is counteracted by greater sensible heat fluxes driving a stronger pressure gradient. These anabatic winds act to advect haboobs upslope. Hence, as the topographic slope is increased, downslope haboob propagation speeds are decreased, and upslope haboob propagation speeds remain mostly unchanged. Anabatic winds act to loft dust as well leading to increased dust lofting jointly by the haboob and anabatic winds as topographic slopes are increased. 

ABSTRACT The individual and synergistic impacts of cold pools and land surface heterogeneity on convection initiation are investigated. Idealized large eddy simulations of deep convection over the Amazon rainforest are conducted. Simulations test realistic and homogenized vegetation, along with realistic and suppressed low‐level evaporation which eliminates cold pools. Updrafts are tracked to determine convection initiation locations. The aggregation of initiation locations is quantified with an organization index. Initiation locations are randomly distributed over homogeneous vegetation, with or without cold pools, demonstrating that cold pools have minimal impacts on initiation locations over homogeneous vegetation. With realistic vegetation, convection initiation is more frequent over forested than deforested areas due to favorable thermodynamics. Heterogeneous vegetation effectively aggregates initiation locations and precipitation compared to homogeneous vegetation, whereas cold pools disaggregate initiation locations and precipitation by propagating into deforested regions and initiating convection. Thus, cold pools partially counteract the effects of anthropogenically driven land surface heterogeneity. 

Abstract: Processed measurements of real-time INP concentration measurements at fixed measurement temperature and supersaturation collected by the Colorado State University Continuous Flow Diffusion Chamber (CSU-CFDC) for selected intensive operating periods during the BioAerosols and Convective Storms (BACS)-II field campaign.