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Abstract BackgroundPrescribed fire is an essential tool employed by natural resource managers to serve ecological and fuel treatment objectives of fire management. However, limited operational resources, environmental conditions, and competing goals result in a finite number of burn days, which need to be allocated toward maximizing the overall benefits attainable with fire management. Burn prioritization models must balance multiple management objectives at landscape scales, often providing coarse resolution information. We developed a decision-support framework and a burn prioritization model for wetlands and wildland-urban interfaces using high-resolution mapping in Everglades National Park (Florida, USA). The model included criteria relevant to the conservation of plant communities, the protection of endangered faunal species, the ability to safely contain fires and minimize emissions harmful to the public, the protection of cultural, archeological, and recreational resources, and the control of invasive plant species. A geographic information system was used to integrate the multiple factors affecting fire management into a single spatially and temporally explicit management model, which provided a quantitative computations-alternative to decision making that is usually based on qualitative assessments. ResultsOur model outputs were 50-m resolution grid maps showing burn prioritization scores for each pixel. During the 50 years of simulated burn unit prioritization used for model evaluation, the mean burned surface corresponded to 256 ± 160 km2 y−1, which is 12% of the total area within Everglades National Park eligible for prescribed fires. Mean predicted fire return intervals (FRIs) varied among ecosystem types: marshes (9.9 ± 1.7 years), prairies (7.3 ± 1.9 years), and pine rocklands (4.0 ± 0.7 years). Mean predicted FRIs also varied among the critical habitats for species of special concern:Ammodramus maritimus mirabilis(7.4 ± 1.5 years),Anaea troglodyta floridalisandStrymon acis bartramibutterflies (3.9 ± 0.2 years), andEumops floridanus(6.5 ± 2.9 years). While mean predicted fire return intervals accurately fit conservation objectives, baseline fire return intervals, calculated using the last 20 years of data, did not. Fire intensity and patchiness potential indices were estimated to further support fire management. ConclusionsBy performing finer-scale spatial computations, our burn prioritization model can support diverse fire regimes across large wetland landscape such as Everglades National Park. Our model integrates spatial variability in ecosystem types and habitats of endangered species, while satisfying the need to contain fires and protect cultural heritage and infrastructure. Burn prioritization models can allow the achievement of target fire return intervals for higher-priority conservation objectives, while also considering finer-scale fire characteristics, such as patchiness, seasonality, intensity, and severity. Decision-support frameworks and higher-resolution models are needed for managing landscape-scale complexity of fires given rapid environmental changes. 

Abstract Accurate prediction of tropical cyclone (TC) intensity remains a significant challenge partially due to physics deficiencies in forecast models. Improvement of boundary layer physics in the turbulent “gray zone” requires a better understanding of spatiotemporal variations of turbulent properties in low-level high-wind regions. To fill the gap, this study utilizes Anduril’s Altius 600, a small uncrewed aircraft system (sUAS), that collected data in the eye and eyewall regions of category 5 Hurricane Ian (2022) at altitudes below 1.4 km. The highest observed wind speed (WSPD) exceeded 105 m s⁻¹at 650-m altitude. The Altius measured turbulent kinetic energy (TKE) and momentum fluxes that were in good agreement with previous crewed aircraft observations. This study explores the scale-awareness turbulent structure by quantifying turbulence-scale (100 m–2 km) and mesoscale (2–10 km) contributions to the total flux and TKE. The results show that mesoscale eddies dominate the horizontal wind variances compared to turbulent eddies. The horizontal wind variances contribute 70%–90% of the total TKE, while the vertical wind variances contribute 10%–30% of the total TKE. Spectral and wavelet analyses demonstrate eddy scales from a few hundred meters up to 10 km, with unique distributions depending on where observations were taken (e.g., eye vs eyewall). These findings underscore the complex and multiscale nature of TKE and momentum fluxes in intense hurricanes and highlight the critical need for advanced observational tools within the high-wind hurricane boundary layer environment. Significance StatementIt is crucial to improve the understanding of turbulent processes in the low-level high-wind regions of tropical cyclones (TCs) for accurate intensity forecasts. Traditional data collection methods involving crewed aircraft are too risky to access these critical regions. This study demonstrates the use of a small uncrewed aircraft system (sUAS) to collect data at low levels within an intense Hurricane Ian (2022). The wind speed measured by the sUAS exceeded 105 m s⁻¹. Important turbulence parameters are estimated and presented as a function of wind speed, height, and radial locations. We found that mesoscale (2–10 km) eddies contributed to a significant portion of the total momentum transfer relative to turbulence-scale (100 m–2 km) eddies. This work demonstrates the usefulness of sUASs for improving the basic understanding of key physical processes in the high-wind hurricane boundary layer. 

Abstract In the marine boundary layer, the exchange of momentum, heat, and moisture occurs between the atmosphere and ocean. Since it is too dangerous for a crewed aircraft to fly close to the ocean surface to directly obtain these measurements, a sUAS (small Uncrewed Aircraft System) is one of the only viable options. On 24 March 2023 a Black Swift Technologies S0 sUAS was deployed from the NOAA P‐3 on a calm clear day off the west coast of Florida. For 23 min at the end of the mission, the sUAS flew 8 straight line legs with an average length of 2.15 km, at roughly 10 m above the ocean surface, with wind speeds between 3.0 and 4.5 m s⁻¹. For the first time over the open ocean using a sUAS, the 4‐Hz wind and thermodynamic data was used to calculate surface momentum flux, sensible heat flux, and latent flux using both direct covariance methods and the bulk aerodynamic formulas. Since all the flux quantities can be found using both direct and indirect methods, we are able to calculate the exchange coefficients of momentum flux (C_D), latent heat flux (C_E), and sensible heat flux (C_H) with results that are generally in good agreement with previous studies over the same wind speed range. This study demonstrates the ability of sUAS to measure air‐sea interactions. Future intention is to use sUAS to obtain similar measurements in high wind events such as hurricanes which could better help understand hurricane intensification and improve model physics. 

Abstract This study documents the capabilities of the StreamSonde, a lightweight (24 g) instrument manufactured by Skyfora that measures atmospheric temperature, pressure, humidity, and wind velocity. Unique features of the StreamSonde are its wind speed accuracy enabled by a dual-band Global Navigation Satellite System (GNSS) receiver, the ability to vary the terminal fall velocity, a theoretical maximum communication distance between the instrument and the deployment aircraft of 250 km, and the ability to simultaneously operate up to eight instruments (50 in the future). Skyfora’s GNSS receiver receives signals on two bands from U.S. global positioning system (GPS) (L1/L5), European Galileo (E1/E5a), and Chinese BeiDou (B1I/B2a) satellites to calculate the wind speed. The combination of dual GNSS and lower terminal fall velocity results in more accurate wind retrievals than from single-band GPS potentially allowing us calculate turbulence quantities, especially near the surface. StreamSondes were launched as dropsondes from the NOAA P-3 aircraft in both clear-air low-wind testing environments and in Hurricane Nigel (2023). The pressure, temperature, humidity (in clear air), and derived wind velocity collected by the StreamSonde compare favorably to the widely used RD41 dropsonde that was developed at the National Center for Atmospheric Research (NCAR) and is manufactured by Vaisala. At coreleased drops in Hurricane Nigel, mean absolute differences between RD41 dropsondes and StreamSondes are generally below 1°C for air temperature, 1.5 m s⁻¹for wind speed, and 6° for wind direction. The benefits of using the StreamSonde instrument along with planned improvements to the platform are discussed. Significance StatementThis study presents proof of concept for operational deployment of a new, lightweight atmospheric profiler called the StreamSonde in a tropical cyclone. It uses advanced positioning technology to accurately measure three-dimensional wind velocity, has an adjustable terminal velocity, and can be deployed in “swarms” of sensors that have up to eight (50 in the future) instruments simultaneously active. The versatility of this emerging technology makes it useable for many meteorological applications. 

The evolution of sexual secondary characteristics necessitates regulatory factors that confer sexual identity to differentiating tissues and cells. InColias eurythemebutterflies, males exhibit two specialized wing scale types—ultraviolet-iridescent (UVI) and spatulate scales—which are absent in females and likely integral to male courtship behavior. This study investigates the regulatory mechanisms and single-nucleus transcriptomics underlying these two sexually dimorphic cell types during wing development. We show thatDoublesex(Dsx) expression is itself dimorphic and required to repress the UVI cell state in females, while unexpectedly, UVI activation in males is independent fromDsx. In the melanic marginal band,Dsxis required in each sex to enforce the presence of spatulate scales in males, and their absence in females. Single-nucleus RNAseq reveals that UVI and spatulate scale cell precursors each show distinctive gene expression profiles at 40% of pupal development, with marker genes that include regulators of transcription, cell signaling, cytoskeletal patterning, and chitin secretion. Both male-specific cell types share a low expression of theBric-a-brac(Bab) transcription factor, a key repressor of the UVI fate. Bab ChIP-seq profiling suggests that Bab binds thecis-regulatory regions of gene markers associated to UVI fate, including potential effector genes involved in the regulation of cytoskeletal processes and chitin secretion, and loci showing signatures of recent selective sweeps in a UVI-polymorphic population. These findings open new avenues for exploring wing patterning and scale development, shedding light on the mechanisms driving the specification of sex-specific cell states and the differentiation of specialized cell ultrastructures. 

Context.Most stars form in clusters or associations, but only a small number of these groups are expected to remain bound for longer than a few megayears. Once star formation has ended and the molecular gas around young stellar objects has been expelled via feedback processes, most initially bound young clusters lose the majority of their binding mass and begin to disperse into the Galactic field. Aims.This process can be investigated by analysing the structure and kinematic trends in nearby young clusters, particularly by analyzing the trend of expansion, which is a tell-tale sign that a cluster is no longer gravitationally bound and dispersing into the field. Methods.We combinedGaiaDR3 five-parameter astrometry with calibrated RVs for members of the nearby young clusterλOri (Collinder 69). Results.We characterised the plane-of-sky substructure of the cluster using theQ-parameter and the angular dispersion parameter. We find evidence that the cluster contains a significant substructure but that this is preferentially located away from the central cluster core, which is smooth and likely remains bound. We found strong evidence for expansion inλOri in the plane of sky by using a number of metrics, but we also found that the trends are asymmetric at the 5σsignificance level, with the maximum rate of expansion being directed nearly parallel to the Galactic plane. We subsequently inverted the maximum rate of expansion of 0.144_−0.003^+0.003kms⁻¹pc⁻¹to give an expansion timescale of 6.944_−0.142^+0.148Myr, which is slightly larger than the typical literature age estimates for the cluster. We also found asymmetry in the velocity dispersion as well as signatures of cluster rotation, and we calculated the kinematic ages for individual cluster members by tracing their motion back in time to their closest approach to the cluster centre. 

Abstract The tidal tributaries of the lower Chesapeake Bay experience seasonally recurring harmful algal blooms and the significance of submarine groundwater discharge (SGD) as a nutrient vector is largely unknown. Here, we determined seasonal SGD nutrient loads in two tributaries with contrasting hydrodynamic conditions, river‐fed (York River) vs. tidally dominated (Lafayette River). Radon surveys were performed in each river to quantify SGD at the embayment‐scale during spring and fall 2021. Total SGD was determined from a²²²Rn mass balance and Monte Carlo simulations. Submarine groundwater discharge rates differed by a factor of two during spring (Lafayette = 11 ± 17 cm d⁻¹; York = 6 ± 10 cm d⁻¹) and a factor of six during fall (Lafayette = 19 ± 27 cm d⁻¹; York = 3 ± 7 cm d⁻¹). Groundwater N concentrations and fluxes varied seasonally in the York (4–7 mmol N m⁻²d⁻¹). In the Lafayette River, seasonal N fluxes (22–37 mmol N m⁻²d⁻¹) were driven by seasonal water exchange rates, likely due to recurrent saltwater intrusion. Submarine groundwater discharge–derived nutrient fluxes were orders of magnitude greater than riverine inputs and runoff in each system. Additionally, sediment N removal by denitrification and anaerobic ammonium oxidation would only remove ~ 1–11% of dissolved inorganic nitrogen supplied through SGD. The continued recurrence of harmful algal blooms in the Bay's tidal tributaries may be indicative of an under‐accounting of submarine groundwater‐borne nutrient sources. This study highlights the importance of including SGD in water quality models used to advise restoration efforts in the Chesapeake Bay region and beyond.