Graciosa Research Articles

Aerosol-induced closure of marine cloud cells: enhanced effects in the presence of precipitation

Abstract. The Weather Research Forecasting (WRF) version 4.3 model is configured within a Lagrangian framework to quantify the impact of aerosols on evolving cloud fields. Kilometer-scale simulations utilizing meteorological boundary conditions are based on 10 case study days offering diverse meteorology during the Aerosol and Cloud Experiments in the Eastern North Atlantic (ACE-ENA). Measurements from aircraft, the ground-based Atmosphere Radiation Measurement (ARM) site at Graciosa Island in the Azores, and A-Train and geostationary satellites are utilized for validation, demonstrating good agreement with the WRF-simulated cloud and aerosol properties. Higher aerosol concentration leads to suppressed drizzle and increased cloud water content in all case study days. These changes lead to larger radiative cooling rates at cloud top, enhanced vertical velocity variance, and increased vertical and horizontal wind speed near the base of the lower-tropospheric inversion. As a result, marine cloud cell area expands, narrowing the gap between shallow clouds and increasing cloud optical thickness, liquid water content, and the top-of-atmosphere outgoing shortwave flux. While similar aerosol effects are observed in lightly to non-raining clouds, they tend to be smaller by comparison. These simulations show a relationship between cloud cell area expansion and the radiative adjustments caused by liquid water path and cloud fraction changes. The adjustments are positive and scale as 74 % and 51 %, respectively, relative to the Twomey effect. While higher-resolution large-eddy simulations may provide improved representation of cloud-top mixing processes, these results emphasize the importance of addressing mesoscale cloud-state transitions in the quantification of aerosol radiative forcing that cannot be attained from traditional climate models.

Monitoring hydrothermal fumaroles in the Azores archipelago - Applications and sources of analytical uncertainties

The Azores archipelago is located in the North Atlantic Ocean and is formed by nine volcanic islands. Present-day volcanic activity in the archipelago comprises not only seismic swarms and episodes of ground deformation in some volcanoes, but also hydrothermal gas manifestations. The main fumaroles are associated with central quiescent volcanoes and have been sampled in the past decade through the Giggenbach methodology. Analysis of the fumarolic fluids from four volcanic systems in São Miguel, Terceira, and Graciosa islands are displayed for the period between July 2015 and February 2023. No significant changes have been observed both on the selected gas ratios (CO2/CH4, H2/CH4, He/CH4, He/CO2, and H2/Ar), and on the equilibrium temperatures estimated for the reservoirs feeding the fumaroles using the H2/Ar gas geothermometer, what is in agreement with the dormant state of activity of the studied volcanic systems. Equilibrium temperatures ranging between 223 °C and 262 °C are estimated for Fogo and Furnas fumarolic fields (São Miguel Island), and an average equilibrium temperature of 254 °C is inferred for Terceira fumaroles. This study also suggests a procedure based on established guidelines to evaluate the analytical uncertainties of the methodologies associated with the Giggenbach sampling strategy. Comparison of the analytical uncertainties with the overall data variation (including additional natural variations and sampling uncertainty), shows that the analytical uncertainties are not the limiting factor for the interpretation of the survey results.

The use of a low-cost, small-aperture array as an auxiliary tool to improve infrasound monitoring in the Azores region

AbstractThe 2022’s seismo-volcanic crisis on São Jorge Island of the Azores archipelago has provided an opportunity to deploy a portable infrasound array as a collaborative work between the Research Institute for Volcanology and Risk Assessment (IVAR) of the University of the Azores (UAc) and the University of Florence (UniFI). The four-element array, SJ1, became operational on 2 April 2022. Despite being deployed in a first stage to monitor the activities related to the volcanic unrest on São Jorge Island, SJ1 worked as a supporting tool to the existing IMS infrasound station IS42, located on Graciosa Island at ~ 40 km distance, leading to an enhancement of the infrasonic monitoring network in the region. This work emphasises the importance of low-cost portable infrasound arrays to improve the coverage of infrasound observations for local and regional monitoring purposes in the Azores region. Two events recorded by both arrays are briefly exemplified: a low-magnitude earthquake on São Jorge Island and a fireball which crossed the North Atlantic Ocean. Infrasound data from both arrays are combined to obtain a fast but still accurate source localization of the analysed events.

Checklist of Basidiomycota and New Records from the Azores Archipelago

This paper presents an annotated checklist of the Basidiomycota taxa (including lichenicolous fungi and the subdivision Pucciniomycotina) from the Azores archipelago and reviews the published records to account for their taxonomic status. The number of Basidiomycota species recorded in the Azores has increased considerably during the 20th century and now stands at 544 species. This study provides distribution data and includes changes in the nomenclature of the listed taxa. Sampling campaigns contributed to 116 new records of Basidiomycota for the Azores archipelago. In addition, there were new records for eight islands: 162 species found for the first time on São Miguel Island, 55 species new to Santa Maria Island, 33 species new to Flores Island, 15 species new to Terceira Island, 9 species new to Pico Island, 17 species new to São Jorge Island, 4 species new to Graciosa Island, and 2 species new to Corvo Island. The transformation of vegetation cover in the archipelago has been very drastic, and this is reflected in the presence of many foreign fungal species on the islands. From these data, we conclude that within Macaronesia, the diversity of Basidiomycota in the Azores is more similar to that in Madeira than in the Canary Islands.

Long-range transported continental aerosol in the eastern North Atlantic: three multiday event regimes influence cloud condensation nuclei

Abstract. The eastern North Atlantic (ENA) is a region dominated by pristine marine environment and subtropical marine boundary layer clouds. Under unperturbed atmospheric conditions, the regional aerosol regime in the ENA varies seasonally due to different seasonal surface-ocean biogenic emissions, removal processes, and meteorological regimes. However, during periods when the marine boundary layer aerosol in the ENA is impacted by particles transported from continental sources, aerosol properties within the marine boundary layer change significantly, affecting the concentration of cloud condensation nuclei (CCN). Here, we investigate the impact of long-range transported continental aerosol on the regional aerosol regime in the ENA using data collected at the U.S. Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) user facility on Graciosa Island in 2017 during the Aerosol and Cloud Experiments in the Eastern North Atlantic (ACE-ENA) campaign. We develop an algorithm that integrates number concentrations of particles with optical particle dry diameter (Dp) between 100 and 1000 nm, single scattering albedo, and black carbon concentration to identify multiday events (with duration >24 consecutive hours) of long-range continental aerosol transport in the ENA. In 2017, we detected nine multiday events of long-range transported particles that correspond to ∼ 7.5 % of the year. For each event, we perform HYSPLIT 10 d backward trajectories analysis, and we evaluate CALIPSO aerosol products to assess, respectively, the origins and compositions of aerosol particles arriving at the ENA site. Subsequently, we group the events into three categories, (1) mixture of dust and marine aerosols, (2) mixture of marine and polluted continental aerosols from industrialized areas, and (3) biomass burning aerosol from North America and Canada, and we evaluate their influence on aerosol population and cloud condensation nuclei in terms of potential activation fraction and concentrations at supersaturation of 0.1 % and 0.2 %. The arrival of plumes dominated by the mixture of dust and marine aerosol in the ENA in the winter caused significant increases in baseline Ntot. Simultaneously, the baseline particle size modes and CCN potential activation fraction remained almost unvaried, while cloud condensation nuclei concentrations increased proportionally to Ntot. Events dominated by a mixture of marine and polluted continental aerosols in spring, fall, and winter led to a statistically significant increase in baseline Ntot, a shift towards larger particular sizes, a higher CCN potential activation fractions, and cloud condensation nuclei concentrations of >170 % and up to 240 % higher than during baseline regime. Finally, the transported aerosol plumes characterized by elevated concentration of biomass burning aerosol from continental wildfires detected in the summertime did not statistically contribute to increase baseline aerosol particle concentrations in the ENA. However, particle diameters were larger than under baseline conditions, and CCN potential activation fractions were >75 % higher. Consequentially, cloud concentration nuclei concentrations increased by ∼ 115 % during the period affected by the biomass burning events. Our results suggest that, through the year, multiday events of long-range continental aerosol transport periodically affect the ENA and represent a significant source of CCN in the marine boundary layer. Based on our analysis, in 2017, the multiday aerosol plume transport dominated by a mixture of dust and marine aerosol, a mixture of marine and polluted continental aerosols, and biomass burning aerosols caused increases in the NCCN baseline regime of, respectively, 6.6 %, 8 %, and 7.4 % at SS 0.1 % (and, respectively, 6.5 %, 8.2 %, and 7.3 % at SS 0.2 %) in the ENA.

Evaluation of aerosol–cloud interactions in E3SM using a Lagrangian framework

Abstract. A Lagrangian framework is used to evaluate aerosol–cloud interactions in the U.S. Department of Energy's Energy Exascale Earth System Model (E3SM) version 1 (E3SMv1) for measurements taken at Graciosa Island in the Azores where a U.S. Department of Energy Atmosphere Radiation Measurement (ARM) site is located. This framework uses direct measurements of cloud condensation nuclei (CCN) concentration (instead of relying on satellite retrievals of aerosol optical depth) and incorporates a suite of ground-based ARM measurements, satellite retrievals, and meteorological reanalysis products that when applied to over a 1500 trajectories provides key insights into the evolution of low-level clouds and aerosol radiative forcing that is not feasible from a traditional Eulerian analysis framework. Significantly lower concentrations (40 %) of surface CCN concentration are measured when precipitation rates in 48 h back trajectories average above 1.2 mm d−1 in the Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (IMERG) product. The depletion of CCN concentration when precipitation rates are elevated is nearly twice as large in the ARM observations compared to E3SMv1 simulations. The model CCN concentration bias remains significant despite modifying the autoconversion and accretion rates in warm clouds. As the clouds in trajectories associated with larger surface-based CCN concentration advect away from Graciosa Island, they maintain higher values of droplet number concentrations (Nd) over multiple days in observations and E3SM simulations compared to trajectories that start with lower CCN concentrations. The response remains robust even after controlling for meteorological factors such as lower troposphere stability, the degree of cloud coupling with the surface, and island wake effects. E3SMv1 simulates a multi-day aerosol effect on clouds and a Twomey radiative effect that is within 30 % of the ARM and satellite observations. However, the mean cloud droplet concentration is more than 2–3 times larger than in the observations. While Twomey radiative effects are similar amongst autoconversion and accretion sensitivity experiments, the liquid water path and cloud fraction adjustments are positive when using a regression model as opposed to negative when using the present-day minus pre-industrial aerosol emissions approach. This result suggests that tuning the autoconversion and accretion alone is unlikely to produce the desired aerosol susceptibilities in E3SMv1.

Morphological and genetic characterization of the Graciosa donkey breed

ABSTRACT The Graciosa donkey has been associated with husbandry and social activities in Graciosa Island for decades. Although donkeys played an essential role in the development of the island, their numbers are severely reduced. The Graciosa donkey is characterised by its small stature, strong bony constitution and strong hooves. They are extremely gentle, patient and submissive fully integrated into the island's ecosystem. As so they must be considered as elements of an environmentally sustainable ecosystem. This study aimed to define the morphotype of the Graciosa donkey and to access its genetic diversity using microsatellite markers. Biometric data consisted of 15 morphological traits from 39 individuals. The Graciosa donkey is dolichocephalic, hypermetric according to the dactilothoracic index, hypometric regarding the approximate live weight and far from ground. Twenty-four individuals, which showed no kinship, based on results of 13 markers were considered as founders and were genotyped for two additional markers and further analysed in this study. All microsatellites used were polymorphic, but low levels of genetic diversity were identified. As the Graciosa donkey gains popularity, the information obtained from this study will be very useful for conservation and management purposes by safeguarding its genetic diversity.

Human decimation caused bottleneck effect, genetic drift, and inbreeding in the Canarian houbara bustard

AbstractAn endangered subspecies of the African houbara bustard, the Canarian houbara (Chlamydotis undulata fuertaventurae), is endemic to the Canary Islands off southern Morocco (Lanzarote, Fuerteventura, and La Graciosa islands). This population decreased over the last centuries because of hunting and egg collection, and was close to extinction in Lanzarote around the middle of last century. Later, the species recovered because of hunting bans, but in Fuerteventura a significant decline has again occurred in the last decades and houbaras are on the brink of extirpation on that island. We describe the genetic characteristics and recent evolutionary history of this subspecies to provide essential information for the evaluation of the conservation actions implemented and for the development of new measures to prevent further declines and local extirpations. We amplified microsatellite loci to infer genetic variability, population structure, and gene flow. The subspecies exhibited relatively high genetic variability but reduced heterozygosity. In spite of high gene flow among locations and islands, we identified 2 genetic units: 1 comprising La Graciosa and Fuerteventura islands, and the other restricted to Lanzarote. We detected genetic bottlenecks and subsequent inbreeding in both units, with a reduced effective number of alleles in Lanzarote compared to Fuerteventura‐La Graciosa. This genetic structure may be explained by human‐induced historical population declines and an associated bottleneck effect, particularly in Lanzarote. Conservation measures should aim to recover the houbara population of Fuerteventura, improving survival of adults and juvenile productivity, and to ensure that genetic flow continues among breeding locations and islands to recover the original population structure (an unique genetic unit over the range of the species) and prevent further genetic deterioration, which could lead to extirpation of this endemic subspecies.

Distinct Dynamical and Structural Properties of Marine Stratocumulus and Shallow Cumulus Clouds in the Eastern North Atlantic

AbstractLow‐level clouds in a marine environment are examined using multiple ground‐based instruments. We used Doppler radar and Doppler lidar measurements (a) to examine cloud properties including cloud base and top height and thickness and (b) to investigate vertical velocity (w) statistics throughout the subcloud and in‐cloud layers. Marine stratocumulus (Sc) and shallow cumulus (Cu) clouds have distinct properties in their horizontal and vertical extent. We also find that the two cloud types have different thermodynamic (coupled and decoupled conditions) and dynamical characteristics for the first four moments of the w distributions (mean, variance, skewness, and kurtosis). We identify a strong dependence of subcloud mean w on near‐surface horizontal wind direction, implying that topographic effects exert a substantial impact on boundary layer dynamics and cloud properties at Graciosa Island. Our findings strongly suggest that care must be taken when interpreting island‐based observations as representative of a generic marine dynamical environment. This information also can be useful for guiding and constraining the future global model development using an observational data set.

Wind–wave characterization and modeling in the Azores Archipelago

Wind–wave characterization and modeling around a group of islands can have significant challenges due to strong diffraction, shoaling, and reflection. In this work, the wind–wave climate of the Azores archipelago (North Atlantic Ocean) is characterized based on wave buoy measurements recorded between 2012 and 2021 at five different locations with water depth ranging from 80 to 110 m. Moreover, wave measurements during four storms of extratropical origin and two storms of tropical origin are analyzed in detail. Due to identified island shadow effects, the average significant wave height (Hs) ranged between 1.50 m (S. Miguel island) and 1.86 m (Graciosa island) in the south and north of the archipelago, respectively. Under storm conditions, shadow effects can lead to differences up to approximately 7 m in Hs between the north and south of the archipelago. The ability to simulate the local wave conditions by an unstructured WAVEWATCH III model covering the north Atlantic with high resolution around the Azores Archipelago is analyzed. In addition, the model performance and scalability on two different High Performance Computing environments are analyzed considering different numerical schemes and parallelization algorithms.

Diet of the exotic Madeiran wall lizard: first insights into trophic interactions in an Atlantic seabird sanctuary

The Madeiran wall lizard Teira dugesii is a relatively new species to the Azores Archipelago, where it was accidentally introduced about 150 to 200 years ago. This lacertid quickly became naturalised and now occurs in all the nine main islands of the Azores. At Praia Islet, off Graciosa Island, the Madeiran wall lizard was recently observed preying on chicks of the threatened Monteiro’s storm-petrel Hydrobates monteiroi. To characterise the lizards’ trophic niche, we conducted a study of the diet of the Madeiran wall lizard at Praia using stable isotope analysis and next-generation sequencing. Our results indicate that the Madeiran wall lizard has a varied diet, consisting of at least 23 invertebrate taxa, 17 plant species, and occasionally, birds (two species detected, including storm-petrels). Marine derived food items were present in few samples, and it is vital to monitor the trophic interactions at Praia Islet to ensure the conservation of this threatened storm-petrel.

Marine Boundary Layer Decoupling and the Stable Isotopic Composition of Water Vapor

AbstractDecoupling of the subcloud layer in stratocumulus‐topped marine boundary layers (STMBL) influences low‐cloud cover by limiting the supply of water vapor from the surface. However, the relative importance of mixing between surface fluxes and other reservoirs of water vapor as a function of the degree of decoupling is poorly understood. Water vapor transport within the STMBL and its response to decoupling is explored using surface measurements of water vapor isotopic composition that were obtained from Graciosa Island, Azores, during the summer and fall of 2018. The data show an inverse relationship between the decoupling metric, Δq, and the degree of drying from an isotopically depleted water vapor source. The isotopic data require some degree of drying with an isotopically depleted source for coupled conditions, and likely require a small amount of mixing even for strongly decoupled conditions. The data are consistent with mixing between purely local reservoirs of water vapor, subjected to a small amount of condensation and fractionation, and do not require the invocation of large‐scale transport of water vapor aloft or additional cloud‐formation effects aloft.

Plate Boundary Deformation and Volcano Unrest at the Azores Triple Junction Determined From Continuous GPS Measurements, 2002–2017

AbstractGround deformation in the Azores, at the triple junction between the Eurasian, Nubian, and North American plates, has been mapped with continuous Global Positioning System (GPS) geodetic measurements to improve tectonic motion estimates and for understanding volcanic unrest. We compute daily positions, spanning almost 17 years (2000–2017), from 18 continuous GPS stations. The GPS time‐series are analyzed by searching for discontinuities and periodic functions. Results show that Flores and Graciosa islands have displacements close to predicted North American and Eurasian plate motions, respectively, while São Miguel, Terceira, São Jorge, Faial and Pico islands have displacements in between predicted Eurasian and Nubian plate motions. The Eurasian‐Nubian plate boundary in the Azores behaves as a diffuse ultra‐slow oblique spreading center with focused deformation found in the central group (CG) and São Miguel islands. The velocity field is modeled by approximating segments of the Eurasian‐Nubian plate boundary with vertical dislocations with right‐lateral motion and opening below a locking depth. Best fitting models have deep motion in the range of 2.0–2.3 mm yr−1 directed N (82.3–88.7)°E. Such displacement accounts for almost half of predicted Eurasian‐Nubian relative plate motion. The modeling results suggest that the locking depth in the CG islands is at least 20 km while in São Miguel it is about 2 km. We find transient deformation at Fogo volcano, São Miguel Island, due to unrest activity mainly during 2003–2006 and 2011–2012, and local continuous subsidence in Terceira Island, attributed to a deflation source centered on the island.

Contrasting characteristics of open- and closed-cellular stratocumulus cloud in the eastern North Atlantic

Abstract. Extensive regions of marine boundary layer cloud impact the radiative balance through their significant shortwave albedo while having little impact on outgoing longwave radiation. Despite this importance, these cloud systems remain poorly represented in large-scale models due to difficulty in representing the processes that drive their life cycle and coverage. In particular, the mesoscale organization and cellular structure of marine boundary clouds have important implications for the subsequent cloud feedbacks. In this study, we use long-term (2013–2018) observations from the Atmospheric Radiation Measurement (ARM) Facility's Eastern North Atlantic (ENA) site on Graciosa Island, Azores, Portugal, to identify cloud cases with open- or closed-cellular organization. More than 500 h of each organization type are identified. The ARM observations are combined with reanalysis and satellite products to quantify the cloud, precipitation, aerosol, thermodynamic, and large-scale synoptic characteristics associated with these cloud types. Our analysis shows that both cloud organization populations occur during similar sea surface temperature conditions, but the open-cell cases are distinguished by stronger cold-air advection and large-scale subsidence compared to the closed-cell cases, consistent with their formation during cold-air outbreaks. We also find that the open-cell cases were associated with deeper boundary layers, stronger low-level winds, and higher rain rates compared to their closed-cell counterparts. Finally, raindrops with diameters larger than 1 mm were routinely recorded at the surface during both populations, with a higher number of large drops during the open-cellular cases. The similarities and differences noted herein provide important insights into the environmental and cloud characteristics during varying marine boundary layer cloud mesoscale organization and will be useful for the evaluation of model simulations for ENA marine clouds.

Human-Derived Environmental Consequences for Three Sedimentary Systems of The Canary Islands (Spain) – a Study of Changes and Impacts: a Synthesis

This paper explores the relationship in three sedimentary systems of the Canary Islands (Spain) between four major land change processes (resource extraction, urbanization, tourism and nature protection) and six main environmental consequences (impacts on aeolian sedimentary dynamics, changes in sand landforms, disappearance of sand landforms and entire systems, changes in vegetation, impacts on the socioeconomic system, and changes in land use patterns). The results show that all the environmental consequences have impacted all three study sites, except in one of them (La Graciosa island) in producing disappearance of sand landforms and entire systems. It should be noted that the environmental consequences described concerns different scales (from entire systems to landforms). All the impacts are described and analyzed separately, and the results are discussed in detail and in relation to the presence of these environmental consequences in other parts of the world.

El español de la isla de La Graciosa desde una perspectiva prosódica

Abstract Manuel Alvar published the only linguistic work known on Spanish from the island of La Graciosa (Canary Islands) in 1965, focused on the town of Caleta del Sebo, to document, in the field of Linguistic geography, the ALEICan (Linguistic and ethnographic atlas of the Canary Islands [1975–1978]). Alvar’s studies used to cover the lexical, grammatical (morphology and syntax) and phonetic levels of the segmental type, but he did not consider prosodic aspects of speech which would later be incorporated into a new generation of atlases, which would go from paper format to multimedia. As the main exponent, the AMPER project (Atlas Multimédia Prosodique de l’Espace Roman) was created in 2001 and, within its framework, we intend to describe the melodic characteristics of a group of sentences emitted by a man and a woman from Caleta del Sebo, completing thus the study started by Alvar fifty-five years ago. In this way, the results will show for the first time if there is a prosodic proximity between the eighth island and the seven main islands, which have been widely described in previous works both in formal and in informal speech.

Aircraft measurements of aerosol and trace gas chemistry in the eastern North Atlantic

Abstract. The Aerosol and Cloud Experiment in the Eastern North Atlantic (ACE-ENA) investigated properties of aerosols and subtropical marine boundary layer (MBL) clouds. Low subtropical marine clouds can have a large effect on Earth's radiative budget, but they are poorly represented in global climate models. In order to understand their radiative effects, it is imperative to understand the composition and sources of the MBL cloud condensation nuclei (CCN). The campaign consisted of two intensive operation periods (IOPs) (June–July 2017 and January–February 2018) during which an instrumented G-1 aircraft was deployed from Lajes Field on Terceira Island in the Azores, Portugal. The G-1 conducted research flights in the vicinity of the Atmospheric Radiation Measurement (ARM) Eastern North Atlantic (ENA) atmospheric observatory on Graciosa Island. An Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and Ionicon proton-transfer-reaction mass spectrometer (PTR-MS) were deployed aboard the aircraft, characterizing chemistry of non-refractory aerosol and trace gases, respectively. The eastern North Atlantic region was found to be very clean, with an average non-refractory submicrometer aerosol mass loading of 0.6 µg m−3 in the summer and 0.1 µg m−3 in the winter, measured by the AMS. Average concentrations of the trace reactive gases methanol and acetone were 1–2 ppb; benzene, toluene and isoprene were even lower, <1 ppb. Mass fractions of sulfate, organics, ammonium and nitrate in the boundary layer were 69 %, 23 %, 7 % and 1 % and remained largely similar between seasons. The aerosol chemical composition was dominated by sulfate and highly processed organics. Particulate methanesulfonic acid (MSA), a well-known secondary biogenic marine species, was detected, with an average boundary layer concentration of 0.021 µg m−3, along with its gas-phase precursor, dimethyl sulfide (DMS). MSA accounted for no more than 3 % of the submicron, non-refractory aerosol in the boundary layer. Examination of vertical profiles of aerosol and gas chemistry during ACE-ENA reveals an interplay of local marine emissions and long-range-transported aged aerosol. A case of transport of biomass burning emissions from North American fires has been identified using back-trajectory analysis. In the summer, the non-refractory portion of the background CCN budget was heavily influenced by aerosol associated with ocean productivity, in particular sulfate formed from DMS oxidation. Episodic transport from the continents, particularly of biomass burning aerosol, periodically increased CCN concentrations in the free troposphere. In the winter, with ocean productivity lower, CCN concentrations were overall much lower and dominated by remote transport. These results show that anthropogenic emissions perturb CCN concentrations in remote regions that are sensitive to changes in CCN number and illustrate that accurate predictions of both transport and regional aerosol formation from the oceans are critical to accurately modeling clouds in these regions.

How rapidly do self-compatible populations evolve selfing? Mating system estimation within recently evolved self-compatible populations of Azorean Tolpis succulenta (Asteraceae).

Genome‐wide genotyping and Bayesian inference method (BORICE) were employed to estimate outcrossing rates and paternity in two small plant populations of Tolpis succulenta (Asteraceae) on Graciosa island in the Azores. These two known extant populations of T. succulenta on Graciosa have recently evolved self‐compatibility. Despite the expectation that selfing would occur at an appreciable rate (self‐incompatible populations of the same species show low but nonzero selfing), high outcrossing was found in progeny arrays from maternal plants in both populations. This is inconsistent with an immediate transition to high selfing following the breakdown of a genetic incompatibility system. This finding is surprising given the small population sizes and the recent colonization of an island from self‐incompatible colonists of T. succulenta from another island in the Azores, and a potential paucity of pollinators, all factors selecting for selfing through reproductive assurance. The self‐compatible lineage(s) likely have high inbreeding depression (ID) that effectively halts the evolution of increased selfing, but this remains to be determined. Like their progeny, all maternal plants in both populations are fully outbred, which is consistent with but not proof of high ID. High multiple paternity was found in both populations, which may be due in part to the abundant pollinators observed during the flowering season.

Exploring the Constraints on Simulated Aerosol Sources and Transport Across the North Atlantic With Island‐Based Sun Photometers

Atmospheric aerosol over the North Atlantic Ocean impacts regional clouds and climate. In this work, we use a set of sun photometer observations of aerosol optical depth (AOD) located on the Graciosa and Cape Verde islands, along with the GEOS‐Chem chemical transport model to investigate the sources of these aerosol and their transport over the North Atlantic Ocean. At both locations, the largest simulated contributor to aerosol extinction is the local source of sea‐salt aerosol. In addition to this large source, we find that signatures consistent with long‐range transport of anthropogenic, biomass burning, and dust emissions are apparent throughout the year at both locations. Model simulations suggest that this signal of long‐range transport in AOD is more apparent at higher elevation locations; the influence of anthropogenic and biomass burning aerosol extinction is particularly pronounced at the height of Pico Mountain, near the Graciosa Island site. Using a machine learning approach, we further show that simulated observations at these three sites (near Graciosa, Pico Mountain, and Cape Verde) can be used to predict the simulated background aerosol imported into cities on the European mainland, particularly during the local winter months, highlighting the utility of background AOD monitoring for understanding downwind air quality.

Integration of Electric Vehicles in Low-Voltage Distribution Networks Considering Voltage Management

The expected growth of the number of electric vehicles can be challenging for planning and operating power systems. In this sense, distribution networks are considered the Achilles’ heel of the process of adapting current power systems for a high presence of electric vehicles. This paper aims at deciding the maximum number of three-phase high-power charging points that can be installed in a low-voltage residential distribution grid. In order to increase the number of installed charging points, a mixed-integer formulation is proposed to model the provision of decentralized voltage support by electric vehicle chargers. This formulation is afterwards integrated into a modified AC optimal power flow formulation to characterize the steady-state operation of the distribution network during a given planning horizon. The performance of the proposed formulations have been tested in a case study based on the distribution network of La Graciosa island in Spain.