Mount Washington Observatory

Clemmys guttata (Spotted Turtle) is a widespread species of regional conservation concern throughout the eastern United States and Canada, relying upon mosaics of upland and wetland habitats. Spotted Turtles exhibit late maturity and low annual reproductive potential; as a result, many populations are vulnerable to decline and reduced connectivity due to elevated rates of anthropogenic disturbance and mortality. We assessed 3 Spotted Turtle populations that were initially studied between 1989 and 1995 on patchworks of private and public (watershed and state forest) land using mark–recapture methods and a combination of open- and closed-population models. During the initial studies, the 3 populations were estimated to support 98, 18, and 43 turtles, respectively. Our population models for the same sites during 2018 or 2019 provided estimates of 92.3, 25.8, and 36.6 turtles, respectively, suggesting limited evidence of growth or decline over more than 25 years at all 3 sites, though fluctuations were observed. We attribute the lack of significant change in population size at these sites to their landscape context: all 3 are situated within areas >600 ha with no public road access, allowing turtles to shift habitat in response to vegetation succession, hydrological shifts, or other changes and buffering them against roadkill or other anthropogenic threats. We also documented variation in population parameters across both space and time; for example, annual survival estimates varied from 0.924 to 0.986 at the sites, emphasizing the need for locally specific information and long-term studies to inform conservation decisions at both the site and species level.

Road mortality often presents a serious conservation challenge for freshwater turtles. Population-level effects may be skewed toward either sex depending on habitat context and configuration, species, and season, and may be temporally variable. We opportunistically collected occurrence data for all turtle species encountered on roadways in the context of a 2-year radio-telemetry study. We primarily collected field data between March and August 2016 and 2017. We summarized the demographic and species composition of turtles encountered and conducted a logistic regression analysis to evaluate the influence of landscape variables associated with areas of high-density road crossings by Terrapene carolina major (Gulf Coast Box Turtle). In total, we observed 6 species of freshwater turtle on paved and unpaved roads, with 92% of records representing Gulf Coast Box Turtles. Of the roadway observations used to evaluate landscape variables, 91% of the records were Gulf Coast Box Turtles, 80% of which were females. Road crossings were associated with higher percentage of coniferous plantation and greater distance to floodplain swamp. Additionally, for all paved roads evaluated, the percent of individuals found alive varied from 58% to 89%. Our results were expected based on the radio-telemetry data collected on local populations; male box turtles in this area appeared to rely more heavily on floodplain swamps than confierous plantations. We recommend that researchers opportunistically collect road-occurrence data as feasible and coordinate with local partners to develop robust datasets that can be utilized to develop strategic mitigation measures.

Abstract Precipitation regimes are changing in response to climate change, yet understanding of how forest ecosystems respond to extreme droughts and pluvials remains incomplete. As future precipitation extremes will likely fall outside the range of historical variability, precipitation manipulation experiments (PMEs) are critical to advancing knowledge about potential ecosystem responses. However, fewPMEs have been conducted in forests compared to short‐statured ecosystems, and forestPMEs have unique design requirements and constraints. Moreover, past forestPMEs have lacked coordination, limiting cross‐site comparisons. Here, we review and synthesize approaches, challenges, and opportunities for conductingPMEs in forests, with the goal of guiding design decisions, while maximizing the potential for coordination.We reviewed 63 forestPMEs at 70 sites world‐wide. Workshops, meetings, and communications with experimentalists were used to generate and build consensus around approaches for addressing the key challenges and enhancing coordination.Past forestPMEs employed a variety of study designs related to treatment level, replication, plot and infrastructure characteristics, and measurement approaches. Important considerations for establishing new forestPMEs include: selecting appropriate treatment levels to reach ecological thresholds; balancing cost, logistical complexity, and effectiveness in infrastructure design; and preventing unintended water subsidies. Response variables in forestPMEs were organized into three broad tiers reflecting increasing complexity and resource intensiveness, with the first tier representing a recommended core set of common measurements.Differences in site conditions combined with unique research questions of experimentalists necessitate careful adaptation of guidelines for forestPMEs to balance local objectives with coordination among experiments. We advocate adoption of a common framework for coordinating forestPMEdesign to enhance cross‐site comparability and advance fundamental knowledge about the response and sensitivity of diverse forest ecosystems to precipitation extremes.

Abstract Monitoring the long-term radial velocity (RV) and acceleration of nearby stars has been proven as an effective method for directly detecting binary and substellar companions. Some fraction of nearby RV trend systems are expected to be comprised of compact objects that likewise induce a systemic Doppler signal. In this paper, we report the discovery of a white dwarf (WD) companion found to orbit the nearby (π = 28.297 ± 0.066 mas) G9 V star HD 169889. High-contrast imaging observations using NIRC2 at the W. M. Keck Observatory and LMIRCam at the Large Binocular Telescope (LBT) Observatory uncover the (ΔH = 9.76 ± 0.16, ΔL′ = 9.60 ± 0.03) companion at an angular separation of 0.″8 (28 au). Thirteen years of precise Doppler observations reveal a steep linear acceleration in the RV time series and place a dynamical constraint on the companion mass of M ≥ 0.369 ± 0.010 M ⊙. This “Sirius-like” system adds to the census of WD companions suspected to be missing from surveys of in the solar neighborhood.

ABSTRACT Since its launch in 2008, the Fermi Gamma-ray Burst Monitor (GBM) has triggered and located on average approximately two γ-ray bursts (GRBs) every three days. Here, we present the third of a series of catalogs of GRBs detected by GBM, extending the second catalog by two more years through the middle of 2014 July. The resulting list includes 1405 triggers identified as GRBs. The intention of the GBM GRB catalog is to provide information to the community on the most important observables of the GBM-detected GRBs. For each GRB, the location and main characteristics of the prompt emission, the duration, peak flux, and fluence are derived. The latter two quantities are calculated for the 50–300 keV energy band where the maximum energy release of GRBs in the instrument reference system is observed, and also for a broader energy band from 10 to 1000 keV, exploiting the full energy range of GBM's low-energy [Nai[Tl)] detectors. Using statistical methods to assess clustering, we find that the hardness and duration of GRBs are better fit by a two-component model with short-hard and long-soft bursts than by a model with three components. Furthermore, information is provided on the settings and modifications of the triggering criteria and exceptional operational conditions during years five and six in the mission. This third catalog is an official product of the Fermi GBM science team, and the data files containing the complete results are available from the High-Energy Astrophysics Science Archive Research Center.

Abstract With extreme winds, rapidly changing weather, and myriad weather conditions during any given month, Mount Washington, New Hampshire (1,917 m MSL), is an ideal location to observe and learn about atmospheric sciences. During the summer of 2013, Mount Washington Observatory (MWO) welcomed a select group of interns to experience life at the “Home of the World’s Worst Weather” and develop scientific and meteorological skills. The goals of the internship program are to learn how to observe and forecast mountain weather; develop data analysis and critical thinking skills through individual research projects; and live, work, and collaborate effectively with others at a remote mountain-top observatory. Interns are typically undergraduate students or recent graduates of atmospheric science programs and are selected from a highly competitive field of applicants. The summer 2013 interns worked on a variety of research projects, ranging from developing a forecast tool for the gustiness of wind at the summit to understanding the evolution of atmospheric and environmental conditions that lead to avalanches in nearby Tuckerman Ravine. To accomplish their research projects, the interns learned how hourly weather observations are made, used data analysis software, and practiced critical thinking about their methods and results. Weekly meetings with the interns and the MWO director of research allowed for the sharing of research progress, peer feedback, and practice presenting scientific results. The internships ended with presentations of their scientific research to MWO observers, staff, and observatory members. Post-internship survey responses revealed the program was highly effective at meeting its goals and provided constructive suggestions for future internship programs.

We constrain the distribution of calcium across the surface of the white dwarf star G29-38 by combining time series spectroscopy from Gemini-North with global time series photometry from the Whole Earth Telescope. G29-38 is actively accreting metals from a known debris disk. Since the metals sink significantly faster than they mix across the surface, any inhomogeneity in the accretion process will appear as an inhomogeneity of the metals on the surface of the star. We measure the flux amplitudes and the calcium equivalent width amplitudes for two large pulsations excited on G29-38 in 2008. The ratio of these amplitudes best fits a model for polar accretion of calcium and rules out equatorial accretion.

Abstract. The NERC UK SOLAS-funded Reactive Halogens in the Marine Boundary Layer (RHaMBLe) programme comprised three field experiments. This manuscript presents an overview of the measurements made within the two simultaneous remote experiments conducted in the tropical North Atlantic in May and June 2007. Measurements were made from two mobile and one ground-based platforms. The heavily instrumented cruise D319 on the RRS Discovery from Lisbon, Portugal to São Vicente, Cape Verde and back to Falmouth, UK was used to characterise the spatial distribution of boundary layer components likely to play a role in reactive halogen chemistry. Measurements onboard the ARSF Dornier aircraft were used to allow the observations to be interpreted in the context of their vertical distribution and to confirm the interpretation of atmospheric structure in the vicinity of the Cape Verde islands. Long-term ground-based measurements at the Cape Verde Atmospheric Observatory (CVAO) on São Vicente were supplemented by long-term measurements of reactive halogen species and characterisation of additional trace gas and aerosol species during the intensive experimental period. This paper presents a summary of the measurements made within the RHaMBLe remote experiments and discusses them in their meteorological and chemical context as determined from these three platforms and from additional meteorological analyses. Air always arrived at the CVAO from the North East with a range of air mass origins (European, Atlantic and North American continental). Trace gases were present at stable and fairly low concentrations with the exception of a slight increase in some anthropogenic components in air of North American origin, though NOx mixing ratios during this period remained below 20 pptv (note the non-IUPAC adoption in this manuscript of pptv and ppbv, equivalent to pmol mol−1 and nmol mol−1 to reflect common practice). Consistency with these air mass classifications is observed in the time series of soluble gas and aerosol composition measurements, with additional identification of periods of slightly elevated dust concentrations consistent with the trajectories passing over the African continent. The CVAO is shown to be broadly representative of the wider North Atlantic marine boundary layer; measurements of NO, O3 and black carbon from the ship are consistent with a clean Northern Hemisphere marine background. Aerosol composition measurements do not indicate elevated organic material associated with clean marine air. Closer to the African coast, black carbon and NO levels start to increase, indicating greater anthropogenic influence. Lower ozone in this region is possibly associated with the increased levels of measured halocarbons, associated with the nutrient rich waters of the Mauritanian upwelling. Bromide and chloride deficits in coarse mode aerosol at both the CVAO and on D319 and the continuous abundance of inorganic gaseous halogen species at CVAO indicate significant reactive cycling of halogens. Aircraft measurements of O3 and CO show that surface measurements are representative of the entire boundary layer in the vicinity both in diurnal variability and absolute levels. Above the inversion layer similar diurnal behaviour in O3 and CO is observed at lower mixing ratios in the air that had originated from south of Cape Verde, possibly from within the ITCZ. ECMWF calculations on two days indicate very different boundary layer depths and aircraft flights over the ship replicate this, giving confidence in the calculated boundary layer depth.

Abstract. The NERC UK SOLAS-funded Reactive Halogens in the Marine Boundary Layer (RHaMBLe) programme comprised three field experiments. This manuscript presents an overview of the measurements made within the two simultaneous remote experiments conducted in the tropical North Atlantic in May and June 2007. Measurements were made from two mobile and one ground-based platforms. The heavily instrumented cruise D319 on the RRS Discovery from Lisbon, Portugal to São Vicente, Cape Verde and back to Falmouth, UK was used to characterise the spatial distribution of boundary layer components likely to play a role in reactive halogen chemistry. Measurements onboard the ARSF Dornier aircraft were used to allow the observations to be interpreted in the context of their vertical distribution and to confirm the interpretation of atmospheric structure in the vicinity of the Cape Verde islands. Long-term ground-based measurements at the Cape Verde Atmospheric Observatory (CVAO) on São Vicente were supplemented by long-term measurements of reactive halogen species and characterisation of additional trace gas and aerosol species during the intensive experimental period. This paper presents a summary of the measurements made within the RHaMBLe remote experiments and discusses them in their meteorological and chemical context as determined from these three platforms and from additional meteorological analyses. Air always arrived at the CVAO from the North East with a range of air mass origins (European, Atlantic and North American continental). Trace gases were present at stable and fairly low concentrations with the exception of a slight increase in some anthropogenic components in air of North American origin, though NOx mixing ratios during this period remained below 20 pptv. Consistency with these air mass classifications is observed in the time series of soluble gas and aerosol composition measurements, with additional identification of periods of slightly elevated dust concentrations consistent with the trajectories passing over the African continent. The CVAO is shown to be broadly representative of the wider North Atlantic marine boundary layer; measurements of NO, O3 and black carbon from the ship are consistent with a clean Northern Hemisphere marine background. Aerosol composition measurements do not indicate elevated organic material associated with clean marine air. Closer to the African coast, black carbon and NO levels start to increase, indicating greater anthropogenic influence. Lower ozone in this region is possibly associated with the increased levels of measured halocarbons, associated with the nutrient rich waters of the Mauritanian upwelling. Bromide and chloride deficits in coarse mode aerosol at both the CVAO and on D319 and the continuous abundance of inorganic gaseous halogen species at CVAO indicate significant reactive cycling of halogens. Aircraft measurements of O3 and CO show that surface measurements are representative of the entire boundary layer in the vicinity both in diurnal variability and absolute levels. Above the inversion layer similar diurnal behaviour in O3 and CO is observed at lower mixing ratios in the air that had originated from south of Cape Verde, possibly from within the ITCZ. ECMWF calculations on two days indicate very different boundary layer depths and aircraft flights over the ship replicate this, giving confidence in the calculated boundary layer depth.