ALBERT

Description: Ice nucleating particles (INPs) are required for initial ice crystal formation in clouds at temperatures warmer than about -36 °C and thus play a crucial role in cloud and precipitation formation. Biomass burning has been found to be a source of INPs in previous studies, and is also a major contributor to atmospheric black carbon (BC) concentrations. This study focuses on isolating the BC contribution to the INP population associated with biomass combustion. Emissions of condensation mode INPs from a number of globally relevant biomass fuels were measured at -30 °C and above water saturation as fires progressed from ignition to extinguishment in a laboratory setting. Number emissions of INPs were found to be highest during intense flaming combustion (modified combustion efficiency 〉 0.95). Overall, combustion emissions from 13 of 22 different biomass fuel types produced measurable INP concentrations for at least one replicate experiment. On average, all burns that produced measureable INPs had higher combustion efficiency, which is associated with higher BC emissions, than those that did not produce measureable INPs. Across all burns that produced measureable INPs, concentrations ranged from 0.1 – 10 cm -3 and the median emission factor was about 2 × 10 7 INPs per kilogram of fuel burned. For a subset of the burns, the contribution of refractory black carbon (rBC) to INP concentrations was determined by removing rBC via laser induced incandescence (LII). Reductions in INPs of 0 – 70% were observed, indicating an important contribution of rBC particles to INP concentrations for some burns, especially marsh grasses.

Description: Using field experiments, we investigated the responses of bats to street lights with different emission spectra. Fast‐flying species are attracted to orange, white and green light, while slower‐flying species are deterred. The threatened lesser horseshoe bat Rhinolophus hipposideros is also deterred by red light, challenging a previously held assumption that red light is safe for bats. Using radio tracking, we demonstrate that the impact of lights on R. hipposideros can be mitigated by controlling light spill along preferred commuting routes. We argue it is essential to preserve dark corridors to mitigate the impacts of light pollution on bats. Abstract The rapid global spread of artificial light at night is causing unprecedented disruption to ecosystems. In otherwise dark environments, street lights restrict the use of major flight routes by some bats, including the threatened lesser horseshoe bat Rhinolophus hipposideros, and may disrupt foraging. Using radio tracking, we examined the response of individual female R. hipposideros to experimental street lights placed on hedgerows used as major flight routes. Hedgerows were illuminated on one side over four nights using lights with different emission spectra, while the opposite side of the hedge was not illuminated. Automated bat detectors were used to examine changes in overall bat activity by R. hipposideros and other bat species present. R. hipposideros activity reduced significantly under all light types, including red light, challenging a previously held assumption that red light is safe for bats. Despite this, R. hipposideros rapidly adapted to the presence of lights by switching their flight paths to the dark side of the hedgerow, enabling them to reach foraging sites without restriction. Red light had no effect on the activity of the other species present. Slow‐flying Myotis spp. avoided orange, white and green light, while more agile Pipistrellus spp. were significantly more active at these light types compared to dark controls, most probably in response to accumulations of insect prey. No effect of any light type was found for Nyctalus or Eptesicus spp. Our findings demonstrate that caution must be used when promoting forms of lighting that are thought to be safe for wildlife before they are tested more widely. We argue that it is essential to preserve dark corridors to mitigate the impacts of artificial light at night on bat activity and movements.

Description: ABSTRACT Oceanic island flora is vulnerable to future climate warming, which is likely to promote changes in vegetation composition, and invasion of non‐native species. Sub‐Antarctic islands are predicted to experience rapid warming during the next century; therefore, establishing trajectories of change in vegetation communities is essential for developing conservation strategies to preserve biological diversity. We present a Late‐glacial‐early Holocene (16 500–6450 cal a bp) palaeoecological record from Hooker's Point, Falkland Islands (Islas Malvinas), South Atlantic. This period spans the Pleistocene‐Holocene transition, providing insight into biological responses to abrupt climate change. Pollen and plant macrofossil records appear insensitive to climatic cooling during the Late‐glacial, but undergo rapid turnover in response to regional warming. The absence of trees throughout the Late‐glacial‐early Holocene enables the recognition of far‐travelled pollen from southern South America. The first occurrence of Nothofagus (southern beech) may reflect changes in the strength and/or position of the Southern Westerly Wind Belt during the Late‐glacial period. Peat inception and accumulation at Hooker's Point is likely to be promoted by the recalcitrant litter of wind‐adapted flora. This recalcitrant litter helps to explain widespread peatland development in a comparatively dry environment, and suggests that wind‐adapted peatlands can remain carbon sinks even under low precipitation regimes.

Description: Global increases in the occurrence of large, severe wildfires in forested watersheds threaten drinking water supplies and aquatic ecology. Wildfire effects on water quality, particularly nutrient levels and forms, can be significant. The longevity and downstream propagation of these effects, as well as the geochemical mechanisms regulating them remain largely undocumented at larger river basin scales. Here, phosphorus (P) speciation and sorption behavior of suspended sediment were examined in two river basins impacted by a severe wildfire in southern Alberta, Canada. Fine grained suspended sediments (〈125 μm) were sampled continuously during ice-free conditions over a two year period (2009-2010), 6 and 7 years after the wildfire. Suspended sediment samples were collected from upstream reference (unburned) river reaches, multiple tributaries within the burned areas, and from reaches downstream of the burned areas, in the Crowsnest and Castle River basins. Total particulate phosphorus [TPP], particulate phosphorus [PP] forms (non-apatite inorganic P [NAIP], apatite P [AP], organic P [OP]), and the equilibrium phosphorus concentration (EPC 0 ) of suspended sediment were assessed. Concentrations of TPP and the EPC 0 were significantly higher downstream of wildfire-impacted areas compared to reference (unburned) upstream river reaches. Sediments from the burned tributary inputs contained higher levels of bioavailable particulate P (NAIP)—these effects were also observed downstream at larger river basin scales. The release of bioavailable P from post-fire, P-enriched fine sediment is a key mechanism causing these effects in gravel-bed rivers at larger basin scales. Wildfire-associated increases in NAIP and the EPC 0 persisted 6 and 7 years after wildfire. Accordingly, this work demonstrated that fine sediment in gravel-bed rivers is a significant, long-term source of in-stream bioavailable P that contributes to a legacy of wildfire impacts on downstream water quality, aquatic ecology, and drinking water treatability. This article is protected by copyright. All rights reserved.

Description: Mode Selective Enhanced Surveillance (Mode-S EHS) reports are aircraft-based observations that have value in numerical weather prediction (NWP). These reports contain the aircraft's state vector in terms of its speed, direction, altitude and Mach number. Using the state vector, meteorological observations of temperature and horizontal wind can be derived. However, Mode-S EHS processing reduces the precision of the state vector from 16-bit to 10-bit binary representation. We use full precision data from research grade instruments, on-board the United Kingdom's Facility for Atmospheric Airborne Measurements, to emulate Mode-S EHS reports and to compare with derived observations. We aim to understand the observation errors due to the reduced precision of Mode-S EHS reports. We derive error models to estimate these observation errors. The temperature error increases from 1.25 K to 2.5 K between an altitude of 10 km and the surface due to its dependency on Mach number and also Mode-S EHS precision. For the cases studied, the zonal wind error is around 0.50 ms − 1 and the meridional wind error is 0.25 ms − 1 . The wind is also subject to systematic errors that are directionally dependent. We conclude that Mode-S EHS derived horizontal winds are suitable for data assimilation in high-resolution NWP. Temperature reports may be usable when aggregated from multiple aircraft. While these reduced precision, high frequency data provide useful, albeit noisy, observations; direct reports of the higher precision data would be preferable.

Description: Continuous measurements of atmospheric methane (CH 4 ) mole fractions measured by NOAA's Global Greenhouse Gas Reference Network in Barrow, AK (BRW), show strong enhancements above background values when winds come from the land sector from July through December from 1986-2014, indicating that emissions from arctic tundra continue through autumn and into early winter. Twenty-nine years of measurements show little change in seasonal mean land-sector CH 4 enhancements, despite an increase in annual mean temperatures of 1.2 ± 0.8 °C/decade (2σ). The record does reveal small increases in CH 4 enhancements in November and December after 2010 due to increased late-season emissions. The lack of significant long-term trends suggests more complex biogeochemical processes are counteracting the observed short-term (monthly) temperature sensitivity of 5.0 ± 3.6 ppb CH 4 /°C. Our results suggest that even the observed short-term temperature sensitivity from the Arctic will have little impact on the global atmospheric CH 4 budget in the long-term if future trajectories evolve with the same temperature sensitivity.

Description: Climate change is likely to have major impacts on the distribution of planted and natural forests. Here we demonstrate how a process-based niche model (CLIMEX) can be extended to project globally the potential habitat suitable for Douglas-fir. Within this distribution we use CLIMEX to predict abundance of the pathogen P haeocryptopus gaeumannii and severity of its associated foliage disease, Swiss needle cast. The distribution and severity of the disease, which can strongly reduce growth rate of Douglas-fir, is closely correlated with seasonal temperatures and precipitation. This model is used to project how climate change during the 2080s may alter the area suitable for Douglas-fir plantations within New Zealand. The climate change scenarios used indicate that the land area suitable for Douglas-fir production in the North Island will be reduced markedly from near 100% under current climate to 36 – 64% of the total land area by 2080's. Within areas shown to be suitable for the host in the North Island, four of the six climate change scenarios predict substantial increases in disease severity that will make these regions at best marginal for Douglas-fir by the 2080's. In contrast, most regions in the South Island are projected to sustain relatively low levels of disease, and remain suitable for Douglas-fir under climate change over the course of this century.

Description: The surface radiation budget (SRB) is modulated by smoke aerosols that attenuate solar and emit thermal infrared radiation. Direct radiative impacts of smoke depend on several factors that lead to large uncertainties in assessing how wildfires influence climate. To quantify the impact of smoke on the SRB, evaluations of the longwave (LW) as well as the shortwave (SW) radiative forcing efficiencies (RFElw and RFEsw) are needed. Radiative forcing efficiency (RFE) is defined as the change in net irradiance per unit increase in aerosol optical depth at 500 nm (AOD500). An opportunity to evaluate RFElw and RFEsw of smoke presented itself on 6–7 September 2010, when a wildfire burned west of Boulder, Colorado. Smoke passed over sites where SRB, atmospheric state, and AOD measurements were being made. Values of RFE were derived empirically from coincident SRB and AOD measurements made over a range of Sun angles. RFEsw ranged between −65 and −194 Wm−2AOD500−1 as solar zenith angles decreased from 73° to 34° (at solar noon). RFElw averaged ∼10 (±7) Wm−2AOD500−1 throughout the daylight hours. During the event, the diurnally integrated value of net RFE was −51.5 Wm−2AOD500−1, revealing the dominance of SW cooling over LW warming attributed to the smoke. In response, the surface under the smoke plume cooled by 2°–5°C during the day, depending on the smoke's opacity. No evaluation of nighttime effects were possible, although very slight warming may have occurred owing to thermal emissions from the plume.

Description: The first Nitryl Chloride (ClNO 2 ) measurements in the United Kingdom were made during the summer 2012 ClearfLo campaign with a chemical ionisation mass spectrometer, utilising an I − ionisation scheme. Concentrations of ClNO 2 exceeded detectable limits (11 ppt) every night with a maximum concentration of 724 ppt. A diurnal profile of ClNO 2 peaking between 4 and 5 am, decreasing directly after sunrise was observed. Concentrations of ClNO 2 above the detection limit are generally observed between 8 pm and 11 am. Different ratios of the production of ClNO 2 : N 2 O 5 were observed throughout with both positive and negative correlations between the two species being reported. The photolysis of ClNO 2 and a box model utilising the Master Chemical Mechanism modified to include chlorine chemistry was used to calculate Cl atom concentrations. Simultaneous measurements of hydroxyl radicals (OH) using low pressure laser-induced fluorescence and ozone enabled the relative importance of the oxidation of three groups of measured VOCs (alkanes, alkenes and alkynes) by OH radicals, Cl atoms and O 3 to be compared. For the day with the maximum calculated Cl atom concentration, Cl atoms in the early morning were the dominant oxidant for alkanes, and over the entire day contributed 15%, 3% and 26% towards the oxidation of alkanes, alkenes and alkynes, respectively.