Evolution of boundary‐layer aerosol particles due to in‐cloud chemical reactions during the 2nd Lagrangian experiment of ACE‐2     

Anthony J. Dore  Douglas W. Johnson  Simon R. Osborne  Thomas W. Choularton  Keith N. Bower  Meinrat O. Andreae  Brian J. Bandy 《Tellus. Series B, Chemical and physical meteorology》2000,52(2):452-462

The second Aerosol Characterisation Experiment (ACE‐2) was aimed at investigating the physical, chemical and radiative properties of aerosol and their evolution in the North Atlantic region. In the 2nd "Lagrangian" experiment, an air mass was tracked over a 30‐h period during conditions of extensive stratocumulus cover. Boundary‐layer measurements of the aerosol size distribution obtained with a passive cavity aerosol spectrometer probe (PCASP) during the experiment show a gradual growth in size of particles in the 0.1–0.2 μm diameter mode. Simultaneously, SO₂ concentrations were found to decrease sharply from 800 to 20 ppt. The fraction of sulphate in aerosol ionic mass increased from 0.68±0.07 to 0.82±0.09 for small particles (diameter below 1.7 μm) and from 0.21±0.04 to 0.34±0.03 for large particles (diameter above 1.7 μm). The measurements were compared with a multicyclic parcel model of gas phase diffusion into cloud droplets and aqueous phase chemical reactions. The model was able to broadly reproduce the observed transformation in the aerosol spectra and the timescale for the transformation of SO₂ to sulphate aerosol. The modelled SO₂ concentration in the boundary layer fell to below half its initial value over a 6.5‐h time period due to a combination of the entrainment of cleaner tropospheric air and cloud chemical reactions. NH₃ and HCl gas were also found to play an important rôle in cloud processing in the model.  相似文献   

Gamma ray burst studies with THESEUS     

Ghirlanda  G.  Salvaterra  R.  Toffano  M.  Ronchini  S.  Guidorzi  C.  Oganesyan  G.  Ascenzi  S.  Bernardini  M. G.  Camisasca  A. E.  Mereghetti  S.  Nava  L.  Ravasio  M. E.  Branchesi  M.  Castro-Tirado  A.  Amati  L.  Blain  A.  Bozzo  E.  O’Brien  P.  Götz  D.  Le Floch  E.  Osborne  J. P.  Rosati  P.  Stratta  G.  Tanvir  N.  Bogomazov  A. I.  D’Avanzo  P.  Hafizi  M.  Mandhai  S.  Melandri  A.  Peer  A.  Topinka  M.  Vergani  S. D.  Zane  S. 《Experimental Astronomy》2021,52(3):277-308

Gamma-ray Bursts (GRBs) are the most powerful transients in the Universe, over–shining for a few seconds all other γ-ray sky sources. Their emission is produced within narrowly collimated relativistic jets launched after the core–collapse of massive stars or the merger of compact binaries. THESEUS will open a new window for the use of GRBs as cosmological tools by securing a statistically significant sample of high-z GRBs, as well as by providing a large number of GRBs at low–intermediate redshifts extending the current samples to low luminosities. The wide energy band and unprecedented sensitivity of the Soft X-ray Imager (SXI) and X-Gamma rays Imaging Spectrometer (XGIS) instruments provide us a new route to unveil the nature of the prompt emission. For the first time, a full characterisation of the prompt emission spectrum from 0.3 keV to 10 MeV with unprecedented large count statistics will be possible revealing the signatures of synchrotron emission. SXI spectra, extending down to 0.3 keV, will constrain the local metal absorption and, for the brightest events, the progenitors’ ejecta composition. Investigation of the nature of the internal energy dissipation mechanisms will be obtained through the systematic study with XGIS of the sub-second variability unexplored so far over such a wide energy range. THESEUS will follow the spectral evolution of the prompt emission down to the soft X–ray band during the early steep decay and through the plateau phase with the unique ability of extending above 10 keV the spectral study of these early afterglow emission phases.

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Evolution of Stratocumulus Over Land: Comparison of Ground and Aircraft Observations with Numerical Weather Prediction Simulations     

Simon R. Osborne  Steven J. Abel  Ian A. Boutle  Franco Marenco 《Boundary-Layer Meteorology》2014,153(2):165-193

Forecasting of low cloud continues to challenge numerical weather prediction. With this in mind, surface and airborne observations were made over East Anglia, UK, during March 2011 to investigate stratus and stratocumulus advecting from the sea over land. Four surface sites were deployed at various distances inland aligned approximately along the flow. In situ data include cloud-droplet measurements from an aircraft operating off the coast and a tethered balloon 100 km inland. Comparisons of thermodynamic and cloud properties are made with Met Office operational model simulations at horizontal resolutions of 4 and 1.5 km. The clouds contained droplet concentrations up to 600 cm \(^{-3}\) within polluted outflow off Europe. These measurements were compared to three different model schemes for predicting droplet concentration: two of them perform well at low to moderate concentrations but asymptote to 375 cm \(^{-3}\) . Microwave radiometers at the ground sites retrieved liquid water paths that reduced with distance inland and were generally below 200 g m \(^{-2}\) . The modelled water path performs well upstream but more erratically far inland. Comparisons of thermodynamic profiles are made within both Lagrangian and Eulerian frameworks and show the model predicted changes in equivalent potential temperature generally within 1 K, with occasional errors of 2 K or more. The modelled cloud-top temperatures were in good agreement with the observations down to \(-\) 7  \(^{\circ }\) C, but the magnitude of the temperature inversion, although good at times, was too small by on average 1.6 K. The different simulations produced different cloud-top water contents due to a combination of resolution and scientific upgrades to the model, but they generally underestimate the amount of cloud water. Major changes, such as the mesoscale temporary cloud breaks on 2 March 2011 and the complete clearance on 4 March, were seemingly predicted by the model for the correct reasons.  相似文献   

A fast hybrid algorithm for exoplanetary transit searches     

A. Collier Cameron  D. Pollacco  R. A. Street  T. A. Lister  R. G. West  D. M. Wilson  F. Pont  D. J. Christian  W. I. Clarkson  B. Enoch  A. Evans  A. Fitzsimmons  C. A. Haswell  C. Hellier  S. T. Hodgkin  K. Horne  J. Irwin  S. R. Kane  F. P. Keenan  A. J. Norton  N. R. Parley  J. Osborne  R. Ryans  I. Skillen  P. J. Wheatley 《Monthly notices of the Royal Astronomical Society》2006,373(2):799-810

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The THESEUS space mission: science goals,requirements and mission concept     

Amati  L.  O’Brien  P.T.  Götz  D.  Bozzo  E.  Santangelo  A.  Tanvir  N.  Frontera  F.  Mereghetti  S.  Osborne  J. P.  Blain  A.  Basa  S.  Branchesi  M.  Burderi  L.  Caballero-García  M.  Castro-Tirado  A. J.  Christensen  L.  Ciolfi  R.  De Rosa  A.  Doroshenko  V.  Ferrara  A.  Ghirlanda  G.  Hanlon  L.  Heddermann  P.  Hutchinson  I.  Labanti  C.  Le Floch  E.  Lerman  H.  Paltani  S.  Reglero  V.  Rezzolla  L.  Rosati  P.  Salvaterra  R.  Stratta  G.  Tenzer  C. 《Experimental Astronomy》2021,52(3):183-218

Experimental Astronomy - THESEUS, one of the two space mission concepts being studied by ESA as candidates for next M5 mission within its Comsic Vision programme, aims at fully exploiting Gamma-Ray...  相似文献   

Time‐scale analysis of marine boundary layer aerosol evolution: Lagrangian case studies under clean and polluted cloudy conditions     

Claudia Hoell  Colin O'Dowd  Simon Osborne  Doug Johnson 《Tellus. Series B, Chemical and physical meteorology》2000,52(2):423-438

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Boundary layer and aerosol evolution during the 3rd Lagrangian experiment of ACE‐2     

Robert Wood  Doug Johnson  Simon Osborne  Meinrat O. Andreae  Brain Bandy  Timothy S. Bates  Colin O'Dowd  Paul Glantz  Kevin Noone  Patricia K. Quinn  Jochen Rudolph  Karsten Suhre 《Tellus. Series B, Chemical and physical meteorology》2000,52(2):401-422

Aircraft measurements are presented of the Lagrangian evolution of a marine boundary layer over a 30‐h period during the ACE‐2 field campaign. At the start of the observational period, a 500‐m deep polluted marine internal boundary layer (MIBL) was overlain by the remnants of a polluted continental boundary layer extending to around 2 km below a clean, dry free troposphere. The MIBL grew rapidly to a thickness of 900–1000 m in response to increasing sea surface temperatures. No significant aerosol spectral evolution was observed in the boundary layer. Low concentrations of SO₂ were observed in the MIBL suggesting that the air mass contained relatively aged aerosol. Aerosol spectra show a broad mode with a modal diameter of around 0.1μm. The polluted layer between the MIBL and the unpolluted free troposphere was only weakly and intermittently turbulent which prevented significant entrainment of clean air into the polluted layer from aloft. The polluted layer depth was thus controlled mainly by subsidence which as a result becomes shallower, decreasing from over 2000 m to around 1200 m during the observational period. The aerosol characteristics of the polluted layer were similar to those in the MIBL and so although the MIBL entrained considerable amounts of air from above the MIBL the aerosol characteristics underwent no significant change. This has important implications for the rate at which a polluted continental air mass is converted to a clean marine one. The dataset should prove useful in the validation of the modelling of continental pollution outbreaks.  相似文献   

Discovery of high-amplitude X-ray variability in the Seyfert–LINER transition galaxy NGC 7589     

W. Yuan  St. Komossa  D. Xu  J. P. Osborne  M. G. Watson  R. G. McMahon 《Monthly notices of the Royal Astronomical Society》2004,353(3):L29-L33

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The AVOID programme’s new simulations of the global benefits of stringent climate change mitigation     

R. Warren  J. A. Lowe  N. W. Arnell  C. Hope  P. Berry  S. Brown  A. Gambhir  S. N. Gosling  R. J. Nicholls  J. O’Hanley  T. J. Osborn  T. Osborne  J. Price  S. C. B. Raper  G. Rose  J. Vanderwal 《Climatic change》2013,120(1-2):55-70

Quantitative simulations of the global-scale benefits of climate change mitigation are presented, using a harmonised, self-consistent approach based on a single set of climate change scenarios. The approach draws on a synthesis of output from both physically-based and economics-based models, and incorporates uncertainty analyses. Previous studies have projected global and regional climate change and its impacts over the 21st century but have generally focused on analysis of business-as-usual scenarios, with no explicit mitigation policy included. This study finds that both the economics-based and physically-based models indicate that early, stringent mitigation would avoid a large proportion of the impacts of climate change projected for the 2080s. However, it also shows that not all the impacts can now be avoided, so that adaptation would also therefore be needed to avoid some of the potential damage. Delay in mitigation substantially reduces the percentage of impacts that can be avoided, providing strong new quantitative evidence for the need for stringent and prompt global mitigation action on greenhouse gas emissions, combined with effective adaptation, if large, widespread climate change impacts are to be avoided. Energy technology models suggest that such stringent and prompt mitigation action is technologically feasible, although the estimated costs vary depending on the specific modelling approach and assumptions.  相似文献   

Neoliberalism,Mineral Development and Indigenous People: a framework for analysis     

Cathy Howlett  Monica Seini  Diana McCallum  Natalie Osborne 《The Australian geographer》2011,42(3):309-323

There have been suggestions in recent literature that neoliberalism and globalisation present positive opportunities for Indigenous communities engaging in resource development projects on their traditional lands. This paper will present evidence from preliminary research on the neoliberal restructuring that has endured for those Indigenous communities of Queensland who have engaged with mineral development opportunities. Initial findings indicate that the State has devolved some of its responsibilities to the mining company in relation to Indigenous development and service provision. This paper develops a theoretical and analytical framework to enable an examination of the implications of this voluntary devolution of responsibility for Indigenous development and service provision and questions whether this represents a positive opportunity for Indigenous people in the region.  相似文献