Aviation-induced clouds, especially persistent contrails and contrail cirrus, contribute significantly to anthropogenic climate forcing, often surpassing the short-term impact of aviation CO2 emissions. These clouds form in ice-supersaturated regions, where they trap outgoing longwave radiation and warm the climate. On 25 November 2023, widespread ice-supersaturated layers over eastern Canada and the USA led to extensive contrail formation. Persistent contrails, particularly over Lake Ontario, were confirmed by GOES-16 satellite imagery and ground-based photography. Atmospheric conditions were characterized using ceilometer data from Toronto Pearson International Airport and radiosonde soundings from multiple stations.High-resolution numerical simulations were conducted using the Global Environmental Multiscale (GEM) model with the Predicted Particle Properties (P3) microphysics scheme. The Contrail Avoidance Tool (CoAT), incorporating Schmidt-Appleman Criteria (SAC) and a wake vortex model, was employed to simulate persistent contrail formation and properties. Sensitivity tests modulating ice depositional growth rates were performed to evaluate their impact on ice supersaturation representation. Results indicate that the control (CNTL) simulation underestimated relative humidity with respect to ice (RHi), a common limitation in atmospheric models where moisture is depleted too rapidly. Reduced depositional growth rates improved RHi forecasts and the extent of contrail-forming regions. However, GEM-CoAT underestimated contrail depth and ice number concentration in very shallow high-RHi layers. Additionally, CoAT simulations revealed that SAC alone is insufficient for predicting persistent contrails, as wake vortex dynamics can induce adiabatic warming, leading to complete ice particle sublimation.  Further analysis examined the formation of the contrails for two types of aircraft (A321 and B747). The B747 generated deeper wake vortices, enhancing adiabatic heating and reducing contrail ice number concentrations by 27% in sensitivity simulations and 78% in the CNTL simulations, suggesting that heavier aircraft may inhibit contrail formation. Our findings indicate that without modulating the depositional growth rate of ice to better represent ice supersaturation, GEM-CoAT was unable to accurately simulate contrail formation and persistence on the observed day.

Aviation-induced clouds, especially persistent contrails and contrail cirrus, contribute significantly to anthropogenic climate forcing, often surpassing the short-term impact of aviation CO2 emissions. These clouds form in ice-supersaturated regions, where they trap outgoing longwave radiation and warm the climate. On 25 November 2023, widespread ice-supersaturated layers over eastern Canada and the USA led to extensive contrail formation. Persistent contrails, particularly over Lake Ontario, were confirmed by GOES-16 satellite imagery and ground-based photography. Atmospheric conditions were characterized using ceilometer data from Toronto Pearson International Airport and radiosonde soundings from multiple stations.High-resolution numerical simulations were conducted using the Global Environmental Multiscale (GEM) model with the Predicted Particle Properties (P3) microphysics scheme. The Contrail Avoidance Tool (CoAT), incorporating Schmidt-Appleman Criteria (SAC) and a wake vortex model, was employed to simulate persistent contrail formation and properties. Sensitivity tests modulating ice depositional growth rates were performed to evaluate their impact on ice supersaturation representation. Results indicate that the control (CNTL) simulation underestimated relative humidity with respect to ice (RHi), a common limitation in atmospheric models where moisture is depleted too rapidly. Reduced depositional growth rates improved RHi forecasts and the extent of contrail-forming regions. However, GEM-CoAT underestimated contrail depth and ice number concentration in very shallow high-RHi layers. Additionally, CoAT simulations revealed that SAC alone is insufficient for predicting persistent contrails, as wake vortex dynamics can induce adiabatic warming, leading to complete ice particle sublimation.  Further analysis examined the formation of the contrails for two types of aircraft (A321 and B747). The B747 generated deeper wake vortices, enhancing adiabatic heating and reducing contrail ice number concentrations by 27% in sensitivity simulations and 78% in the CNTL simulations, suggesting that heavier aircraft may inhibit contrail formation. Our findings indicate that without modulating the depositional growth rate of ice to better represent ice supersaturation, GEM-CoAT was unable to accurately simulate contrail formation and persistence on the observed day.

AccessDataset can be accessed and downloaded from the 'ADC' directory via: http://arcticdata.io/data/10.18739/A24Q7QS1S ### Overview The Arctic is warming faster than any other place on Earth, with sea ice declining rapidly and sources of sea spray and biogenic aerosol emissions changing by consequence. Utqiagvik is at the forefront of this change, abutting one of the largest areas of sea ice loss. This change will have far-reaching impacts to both the environment and the community. Because this change has happened largely in the last decade, now is an important time to both document that change and to continue a data record that will allow for a characterization of the New Arctic, as climate is already altering the Arctic landscape forever. The longest and most complete record of aerosol properties in the American Arctic is that of Utqiagvik, making this unique location serve as a regional record of changes in atmospheric aerosol properties. This dataset will extend the baseline measurements of this Arctic aerosol record, including and continuing the 15-year record of submicron inorganic components (Quinn et al., 2009; Quinn et al., 2002), re-instituting the 2-year record of organic components collected a decade ago (Frossard et al., 2011; Shaw et al., 2010), enhancing the chemical analysis with sulfur isotopes to improve interpretation of emission sources (Kunasek et al., 2010; Thiemens & Lin, 2019), continuing particle number size distribution measurements (Freud et al., 2017), and re-starting cloud condensation nuclei measurements (Schmale, Henning, et al., 2018).

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Shorebird movement data used in habitat analyses for "The Amazon Basin's rivers and lakes support Nearctic-breeding shorebirds during southward migration." Data were collected between 2016-2022 using Argos Platform Terminal Transmitters or Pinpoint GPS Argos transmitters affixed to six shorebird species: American Golden-Plovers (Pluvialis dominica), Hudsonian Godwits (Limosa haemastica), Lesser Yellowlegs (Tringa flavipes), and Buff-breasted (Calidris subruficollis), Pectoral (C. melanotos), and Upland Sandpipers (Bartramia longicauda). The devices were deployed by various research groups at sites outside the Amazon Basin. Data has been subset to the Amazon Basin and the approximate timeframe of southward migration (July-December) and filtered to relevant individuals. The CSV file contains the following variables:'individual local identifier': a unique alphanumeric identifier for the individual'timestamp': date-time of the location, in YYYY-mm-dd HH:mm:ss format'location.long': longitude'location.lat': latitude'species': shorebird species alpha code'lc': location quality class for Argos PTT (3, 2, 1, 0, A, B, Z) or GPS (G) locations'argos.semi.major': the length of the semi-major axis of the error ellipse for Argos locations, in meters'argos.semi.minor': the length of the semi-minor axis of the error ellipse for Argos locations, in meters'argos.error.radius': one standard deviation (sigma) of the isotropic location error for Argos locations'argos.orientation': the orientation of the semi-major axis of the error ellipse for Argos locations, in degrees clockwise from north'gps.fix.type.raw': the type of GPS fix (2D, 3D)Links to full studies are provided in 'Related Works.' Please consult links for attribution and data use information.

Shorebird movement data used in habitat analyses for "The Amazon Basin's rivers and lakes support Nearctic-breeding shorebirds during southward migration." Data were collected between 2016-2022 using Argos Platform Terminal Transmitters or Pinpoint GPS Argos transmitters affixed to six shorebird species: American Golden-Plovers (Pluvialis dominica), Hudsonian Godwits (Limosa haemastica), Lesser Yellowlegs (Tringa flavipes), and Buff-breasted (Calidris subruficollis), Pectoral (C. melanotos), and Upland Sandpipers (Bartramia longicauda). The devices were deployed by various research groups at sites outside the Amazon Basin. Data has been subset to the Amazon Basin and the approximate timeframe of southward migration (July-December) and filtered to relevant individuals. The CSV file contains the following variables:'individual local identifier': a unique alphanumeric identifier for the individual'timestamp': date-time of the location, in YYYY-mm-dd HH:mm:ss format'location.long': longitude'location.lat': latitude'species': shorebird species alpha code'lc': location quality class for Argos PTT (3, 2, 1, 0, A, B, Z) or GPS (G) locations'argos.semi.major': the length of the semi-major axis of the error ellipse for Argos locations, in meters'argos.semi.minor': the length of the semi-minor axis of the error ellipse for Argos locations, in meters'argos.error.radius': one standard deviation (sigma) of the isotropic location error for Argos locations'argos.orientation': the orientation of the semi-major axis of the error ellipse for Argos locations, in degrees clockwise from north'gps.fix.type.raw': the type of GPS fix (2D, 3D)Links to full studies are provided in 'Related Works.' Please consult links for attribution and data use information.

<b>Abstract</b><br/><p>After regulation of pesticides, determination of their persistence in the environment is an important indicator of effectiveness of these measures. We quantified concentrations of two types of systemic insecticides: neonicotinoids (imidacloprid, acetamiprid, clothianidin, thiacloprid, and thiamethoxam) and butenolides (flupyradifurone), in off-crop non-target media of hummingbird cloacal fluid, honey bee (<em>Apis mellifera</em>) nectar and honey, and wildflowers before and after regulation of imidacloprid on highbush blueberries in Canada in April 2021. We found that mean total pesticide load increased in hummingbird cloacal fluid, nectar, and flower samples following imidacloprid regulation. On average, we did not find evidence of a decrease in imidacloprid concentrations after regulation. However, there were some decreases, some increases and other cases with no changes in imidacloprid levels depending on the specific media, time point of sampling and site type. At the same time, we found an overall increase in flupyradifurone, acetamiprid, thiamethoxam and thiacloprid, but no change in clothianidin concentrations. In particular, flupyradifurone concentrations observed in biota sampled near to agricultural areas increased by 2-fold in honey bee nectar, 7-fold in hummingbird cloacal fluid, and 8-fold in flowers after the 2021 imidacloprid regulation. The highest residue detected in this study was flupyradifurone at 665 ng/mL (PPB) in honey bee nectar. Mean total pesticide loads were highest in honey samples (84 ± 10 PPB) followed by nectar (56 ± 7 PPB), then hummingbird cloacal fluid (1.8 ± 0.5 PPB), and least, flowers (0.51 ± 0.06 PPB). Our results highlight that limited regulation of imidacloprid does not immediately reduce residue concentrations while other systemic insecticides, possibly replacement compounds, concurrently increase in wildlife.</p>

<b>Abstract</b><br/><p>After regulation of pesticides, determination of their persistence in the environment is an important indicator of effectiveness of these measures. We quantified concentrations of two types of systemic insecticides: neonicotinoids (imidacloprid, acetamiprid, clothianidin, thiacloprid, and thiamethoxam) and butenolides (flupyradifurone), in off-crop non-target media of hummingbird cloacal fluid, honey bee (<em>Apis mellifera</em>) nectar and honey, and wildflowers before and after regulation of imidacloprid on highbush blueberries in Canada in April 2021. We found that mean total pesticide load increased in hummingbird cloacal fluid, nectar, and flower samples following imidacloprid regulation. On average, we did not find evidence of a decrease in imidacloprid concentrations after regulation. However, there were some decreases, some increases and other cases with no changes in imidacloprid levels depending on the specific media, time point of sampling and site type. At the same time, we found an overall increase in flupyradifurone, acetamiprid, thiamethoxam and thiacloprid, but no change in clothianidin concentrations. In particular, flupyradifurone concentrations observed in biota sampled near to agricultural areas increased by 2-fold in honey bee nectar, 7-fold in hummingbird cloacal fluid, and 8-fold in flowers after the 2021 imidacloprid regulation. The highest residue detected in this study was flupyradifurone at 665 ng/mL (PPB) in honey bee nectar. Mean total pesticide loads were highest in honey samples (84 ± 10 PPB) followed by nectar (56 ± 7 PPB), then hummingbird cloacal fluid (1.8 ± 0.5 PPB), and least, flowers (0.51 ± 0.06 PPB). Our results highlight that limited regulation of imidacloprid does not immediately reduce residue concentrations while other systemic insecticides, possibly replacement compounds, concurrently increase in wildlife.</p>

<b>Abstract</b><br/><p>When a single species evolves into multiple descendent species, some parts of the genome can play a key role in the evolution of reproductive isolation while other parts flow between the evolving species via interbreeding. Genomic evolution during the speciation process is particularly interesting when major components of the genome—for instance, sex chromosomes vs. autosomes vs. mitochondrial DNA—show widely differing patterns of relationships between three diverging populations. The golden-crowned sparrow (<em>Zonotrichia atricapilla</em>) and the white-crowned sparrow (<em>Zonotrichia leucophrys</em>) are phenotypically differentiated sister species that are largely reproductively isolated despite possessing similar mitochondrial genomes, likely due to recent introgression. We assessed variation in more than 45,000 single nucleotide polymorphisms (SNPs) to determine the structure of nuclear genomic differentiation between these species and between two hybridizing subspecies of <em>Z. leucophrys</em>. The two <em>Z. leucophrys</em> subspecies showed moderate levels of relative differentiation and patterns consistent with a history of recurrent selection in both ancestral and daughter populations, with much of the sex chromosome Z and a large region on the autosome 1A showing increased differentiation compared to the rest of the genome. The two species <em>Z. leucophrys</em> and <em>Z. atricapilla</em> show high relative differentiation and strong heterogeneity in the level of differentiation among various chromosomal regions, with a large portion of the sex chromosome (Z) showing highly divergent haplotypes between these species. Studies of speciation often emphasize mitochondrial DNA differentiation, but speciation between <em>Z. atricapilla</em> and <em>Z. leucophrys</em> appears primarily associated with Z chromosome divergence and more moderately associated with autosomal differentiation, whereas mitochondria appear highly similar due apparently to recent introgression. These results add to the growing body of evidence for highly heterogeneous patterns of genomic differentiation during speciation, with some genomic regions showing lack of gene flow between populations many hundreds of thousands of years before other genomic regions.</p>