603 research outputs found
Captive breeding programmes for nocturnal prosimians
Due to the nocturnal and arboreal nature of nocturnal prosimians field research on these species is limited. Maintaining populations in zoos provides an opportunity to increase our knowledge of these elusive species. This study aimed to update and contribute to the limited research on captive populations of nocturnal prosimians. The study consists of two parts. Part one aimed to identify the current European captive population of six nocturnal prosimian species (aye-aye, fat-tailed dwarf lemur, Goodmanâs mouse lemur, grey mouse lemur, grey slender loris and pygmy slow loris) and determine their demographic self-sustainability. To achieve this aim studbook data was analysed. The difference between birth and death rates, infant mortality rates, age structure and sex composition were investigated. The study concludes populations of aye-aye, fat-tailed dwarf lemur, grey slender loris and pygmy slow loris were not self-sustaining whereas Goodmanâs mouse lemur are self-sustaining and grey mouse lemur were found to have an increasing population trend. Part two focussed on the European captive population of pygmy slow loris and grey slender loris. This section sort to determine if husbandry methods affect breeding success. This involved conducting a survey of the current husbandry methods used in 20 European zoos. Statistical tests were carried out to determine if there was a correlation between institution breeding success and the husbandry methods used. The study concludes that there was a significant correlation between institution breeding success and the interval duration between cleaning the fixed enclosure furniture (P=0.030). Results also strongly suggested pygmy slow lorises housed with another species have a higher breeding success than those housed as
a single-species exhibit
Increasing concentrations of dichloromethane, CH2Cl2, inferred from CARIBIC air samples collected 1998â2012
Atmospheric concentrations of dichloromethane, CH2Cl2, a regulated toxic air pollutant and minor contributor to stratospheric ozone depletion, were reported to have peaked around 1990 and to be declining in the early part of the 21st century. Recent observations suggest this trend has reversed and that CH2Cl2 is once again increasing in the atmosphere. Despite the importance of ongoing monitoring and reporting of atmospheric CH2Cl2, no time series has been discussed in detail since 2006. The CARIBIC project (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) has analysed the halocarbon content of whole-air samples collected at altitudes of between ~10â12 km via a custom-built container installed on commercial passenger aircraft since 1998, providing a long-term record of CH2Cl2 observations. In this paper we present this unique CH2Cl2 time series, discussing key flight routes which have been used at various times over the past 15 years. Between 1998 and 2012 increases were seen in all northern hemispheric regions and at different altitudes, ranging from ~7â10 ppt in background air to ~13â15 ppt in regions with stronger emissions (equating to a 38â69% increase). Of particular interest is the rising importance of India as a source of atmospheric CH2Cl2: based on CARIBIC data we provide regional emission estimates for the Indian subcontinent and show that regional emissions have increased from 3â14 Gg yr^-1 (1998â2000) to 16â25 Gg yr^-1 (2008). Potential causes of the increasing atmospheric burden of CH2Cl2 are discussed. One possible source is the increased use of CH2Cl2 as a feedstock for the production of HFC-32, a chemical used predominantly as a replacement for ozone-depleting substances in a variety of applications including air conditioners and refrigeration
Atmospheric drivers of melt on Larsen C Ice Shelf: Surface energy budget regimes and the impact of foehn
Recent ice shelf retreat on the east coast of the Antarctic Peninsula has been principally attributed to atmospherically driven melt. However, previous studies on the largest of these ice shelvesâLarsen Câhave struggled to reconcile atmospheric forcing with observed melt. This study provides the first comprehensive quantification and explanation of the atmospheric drivers of melt across Larsen C, using 31-months' worth of observations from Cabinet Inlet, a 6-month, high-resolution atmospheric model simulation and a novel approach to ascertain the surface energy budget (SEB) regime. The dominant meteorological controls on melt are shown to be the occurrence, strength, and warmth of mountain winds called foehn. At Cabinet Inlet, foehn occurs 15% of the time and causes 45% of melt. The primary effect of foehn on the SEB is elevated turbulent heat fluxes. Under typical, warm foehn conditions, this means elevated surface heating and melting, the intensity of which increases as foehn wind speed increases. Less commonlyâdue to cooler-than-normal foehn winds and/or radiatively warmed iceâthe relationship between wind speed and net surface heat flux reverses. This explains the seemingly contradictory results of previous studies. In the model, spatial variability in cumulative melt across Larsen C is largely explained by foehn, with melt maxima in inlets reflecting maxima in foehn wind strength. However, most accumulated melt (58%) occurs due to solar radiation in the absence of foehn. A broad north-south gradient in melt is explained by the combined influence of foehn and non-foehn conditions
The Causes of Foehn Warming in the Lee of Mountains
The foehn effect is well known as the warming, drying, and cloud clearance experienced on the lee side of mountain ranges during âflow overâ conditions. Foehn flows were first described more than a century ago when two mechanisms for this warming effect were postulated: an isentropic drawdown mechanism, where potentially warmer air from aloft is brought down adiabatically, and a latent heating and precipitation mechanism, where air cools less on ascentâowing to condensation and latent heat releaseâthan on its dry descent on the lee side. Here, for the first time, the direct quantitative contribution of these and other foehn warming mechanisms is shown. The results suggest a new paradigm is required after it is demonstrated that a third mechanism, mechanical mixing of the foehn flow by turbulence, is significant. In fact, depending on the flow dynamics, any of the three warming mechanisms can dominate. A novel Lagrangian heat budget model, back trajectories, high-resolution numerical model output, and aircraft observations are all employed. The study focuses on a unique natural laboratoryâone that allows unambiguous quantification of the leeside warmingânamely, the Antarctic Peninsula and Larsen C Ice Shelf. The demonstration that three foehn warming mechanisms are important has ramifications for weather forecasting in mountainous areas and associated hazards such as ice shelf melt and wildfires
Tracking electricity losses and their perceived causes using nighttime light and social media
Urban environments are intricate systems where the breakdown of critical
infrastructure can impact both the economic and social well-being of
communities. Electricity systems hold particular significance, as they are
essential for other infrastructure, and disruptions can trigger widespread
consequences. Typically, assessing electricity availability requires
ground-level data, a challenge in conflict zones and regions with limited
access. This study shows how satellite imagery, social media, and information
extraction can monitor blackouts and their perceived causes. Night-time light
data (in March 2019 for Caracas, Venezuela) is used to indicate blackout
regions. Twitter data is used to determine sentiment and topic trends, while
statistical analysis and topic modeling delved into public perceptions
regarding blackout causes. The findings show an inverse relationship between
nighttime light intensity. Tweets mentioning the Venezuelan President displayed
heightened negativity and a greater prevalence of blame-related terms,
suggesting a perception of government accountability for the outages
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Foehn jets over the Larsen C Ice Shelf, Antarctica
Previously unknown foehn jets have been identified to the east of the Antarctic Peninsula (AP) above the Larsen C Ice Shelf. These jets have major implications for the east coast of the AP, a region of rapid climatic warming and where two large sections of ice shelf have collapsed in recent years.
During three foehn events across the AP, leeside warming and drying is seen in new aircraft observations and simulated well by the Met Office Unified Model (MetUM) at âŒ1.5 km grid spacing. In case A, weak southwesterly flow and an elevated upwind inversion characterise a highly nonlinear flow regime with upwind flow blocking. In case C strong northwesterly winds characterise a relatively linear case with little upwind flow blocking. Case B resides somewhere between the two in flow regime linearity.
The foehn jets â apparent in aircraft observations where available and MetUM simulations of all three cases â are mesoscale features (up to 60 km in width) originating from the mouths of leeside inlets. Through back trajectory analysis they are identified as a type of gap flow. In cases A and B the jets are distinct, being strongly accelerated relative to the background flow, and confined to low levels above the Larsen C Ice Shelf. They resemble the âshallow foehnâ of the Alps. Case C resembles a case of âdeep foehnâ, with the jets less distinct. The foehn jets are considerably cooler and moister relative to adjacent regions of calmer foehn air. This is due to a dampened foehn effect in the jet regions: in case A the jets have lower upwind source regions, and in the more linear case C there is less diabatic warming and precipitation along jet trajectories due to the reduced orographic uplift across the mountain passes
Artificially lit surface of Earth at night increasing in radiance and extent
This is the author accepted manuscript. The final version is available from AAAS via the DOI in this record.A central aim of the âlighting revolutionâ (the transition to solid-state lighting technology) is decreased energy consumption. This could be undermined by a rebound effect of increased use in response to lowered cost of light. We use the first-ever calibrated satellite radiometer designed for night lights to show that from 2012 to 2016, Earthâs artificially lit outdoor area grew by 2.2% per year, with a total radiance growth of 1.8% per year. Continuously lit areas brightened at a rate of 2.2% per year. Large differences in national growth rates were observed, with lighting remaining stable or decreasing in only a few countries. These data are not consistent with global scale energy reductions but rather indicate increased light pollution, with corresponding negative consequences for flora, fauna, and human well-being.This article is based upon work from COST Action ES1204 LoNNe, supported by COST (European Cooperation in Science and Technology). The authors acknowledge the funding received by ERA-PLANET
(www.era-planet.eu) funded by the EC as part of H2020 (contract no. 689443). NOAAâs participation
was funded by NASAâs VIIRS science program, contract number NNH15AZ01I. ASMâs
contribution was funded by ORISON project (H2020-INFRASUPP-2015-2) Cities at Night
Investigating African trace gas sources, vertical transport, and oxidation using IAGOS-CARIBIC measurements between Germany and South Africa between 2009 and 2011
Between March 2009 and March 2011 a commercial airliner equipped with a custom built measurement container (IAGOS-CARIBIC observatory) conducted 13 flights between South Africa and Germany at 10â12 km altitude, traversing the African continent north-south. In-situ measurements of trace gases (CO, CH4, H2O) and aerosol particles indicated that strong surface sources (like biomass burning) and rapid vertical transport combine to generate maximum concentrations in the latitudinal range between 10°N and 10°S coincident with the inter-tropical convergence zone (ITCZ). Pressurized air samples collected during these flights were subsequently analyzed for a suite of trace gases including C2-C8 non-methane hydrocarbons (NMHC) and halocarbons. These shorter-lived trace gases, originating from both natural and anthropogenic sources, also showed near equatorial maxima highlighting the effectiveness of convective transport in this region. Two source apportionment methods were used to investigate the specific sources of NMHC: positive matrix factorization (PMF), which is used for the first time for NMHC analysis in the upper troposphere (UT), and enhancement ratios to CO. Using the PMF method three characteristic airmass types were identified based on the different trace gas concentrations they obtained: biomass burning, fossil fuel emissions, and âbackgroundâ air. The first two sources were defined with reference to previously reported surface source characterizations, while the term âbackgroundâ was given to air masses in which the concentration ratios approached that of the lifetime ratios. Comparison of enhancement ratios between NMHC and CO for the subset of air samples that had experienced recent contact with the planetary boundary layer (PBL) to literature values showed that the burning of savanna and tropical forest is likely the main source of NMHC in the African upper troposphere (10â12 km). Photochemical aging patterns for the samples with PBL contact revealed that the air had different degradation histories depending on the hemisphere in which they were emitted. In the southern hemisphere (SH) air masses experienced more dilution by clean background air whereas in the northern hemisphere (NH) air masses are less diluted or mixed with background air still containing longer lived NMHC. Using NMHC photochemical clocks ozone production was seen in the BB outflow above Africa in the NH
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