Behaviour of the winter North Atlantic eddy-driven jet stream in the CMIP3 integrations   总被引：1，自引：1，他引：0  

Abdel Hannachi  Elizabeth A. Barnes  Tim Woollings 《Climate Dynamics》2013,41(3-4):995-1007

A systematic analysis of the winter North Atlantic eddy-driven jet stream latitude and wind speed from 52 model integrations, taken from the coupled model intercomparison project phase 3, is carried out and compared to results obtained from the ERA-40 reanalyses. We consider here a control simulation, twentieth century simulation, and two time periods (2046–2065 and 2081–2100) from a twenty-first century, high-emission A2 forced simulation. The jet wind speed seasonality is found to be similar between the twentieth century simulations and the ERA-40 reanalyses and also between the control and forced simulations although nearly half of the models overestimate the amplitude of the seasonal cycle. A systematic equatorward bias of the models jet latitude seasonality, by up to 7°, is observed, and models additionally overestimate the seasonal cycle of jet latitude about the mean, with the majority of the models showing equatorward and poleward biases during the cold and warm seasons respectively. A main finding of this work is that no GCM under any forcing scenario considered here is able to simulate the trimodal behaviour of the observed jet latitude distribution. The models suffer from serious problems in the structure of jet variability, rather than just quantitiative errors in the statistical moments.  相似文献   

The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: Overview and Performance     

J. Todd Hoeksema  Yang Liu  Keiji Hayashi  Xudong Sun  Jesper Schou  Sebastien Couvidat  Aimee Norton  Monica Bobra  Rebecca Centeno  K. D. Leka  Graham Barnes  Michael Turmon 《Solar physics》2014,289(9):3483-3530

The Helioseismic and Magnetic Imager (HMI) began near-continuous full-disk solar measurements on 1 May 2010 from the Solar Dynamics Observatory (SDO). An automated processing pipeline keeps pace with observations to produce observable quantities, including the photospheric vector magnetic field, from sequences of filtergrams. The basic vector-field frame list cadence is 135 seconds, but to reduce noise the filtergrams are combined to derive data products every 720 seconds. The primary 720 s observables were released in mid-2010, including Stokes polarization parameters measured at six wavelengths, as well as intensity, Doppler velocity, and the line-of-sight magnetic field. More advanced products, including the full vector magnetic field, are now available. Automatically identified HMI Active Region Patches (HARPs) track the location and shape of magnetic regions throughout their lifetime. The vector field is computed using the Very Fast Inversion of the Stokes Vector (VFISV) code optimized for the HMI pipeline; the remaining 180^° azimuth ambiguity is resolved with the Minimum Energy (ME0) code. The Milne–Eddington inversion is performed on all full-disk HMI observations. The disambiguation, until recently run only on HARP regions, is now implemented for the full disk. Vector and scalar quantities in the patches are used to derive active region indices potentially useful for forecasting; the data maps and indices are collected in the SHARP data series, hmi.sharp_720s. Definitive SHARP processing is completed only after the region rotates off the visible disk; quick-look products are produced in near real time. Patches are provided in both CCD and heliographic coordinates. HMI provides continuous coverage of the vector field, but has modest spatial, spectral, and temporal resolution. Coupled with limitations of the analysis and interpretation techniques, effects of the orbital velocity, and instrument performance, the resulting measurements have a certain dynamic range and sensitivity and are subject to systematic errors and uncertainties that are characterized in this report.  相似文献   

A CH₃CN and HCO⁺ survey towards southern methanol masers associated with star formation     

C. R. Purcell  R. Balasubramanyam  M. G. Burton  A. J. Walsh  V. Minier  M. R. Hunt-Cunningham  L. L. Kedziora-Chudczer  S. N. Longmore  T. Hill  I. Bains  P. J. Barnes  A. L. Busfield  P. Calisse  N. H. M. Crighton  S. J. Curran  T. M. Davis  J. T. Dempsey  G. Derragopian  B. Fulton  M. G. Hidas  M. G. Hoare  J.-K. Lee  E. F. Ladd  S. L. Lumsden  T. J. T. Moore  M. T. Murphy  R. D. Oudmaijer  M. B. Pracy  J. Rathborne  S. Robertson  A. S. B. Schultz  J. Shobbrook  P. A. Sparks  J. Storey  T. Travouillion 《Monthly notices of the Royal Astronomical Society》2006,367(2):553-576

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A wide-field H i study of the NGC 1566 group     

Virginia A. Kilborn  Bärbel S. Koribalski  Duncan A. Forbes  David G. Barnes  Ruth C. Musgrave 《Monthly notices of the Royal Astronomical Society》2005,356(1):77-88

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Probing the IRC+10 ° 216 circumstellar envelope using spectroscopic observations of background stars     

Tim Kendall  Nicolas Mauron  June McCombie  Peter Sarre 《Astrophysics and Space Science》2004,289(3-4):203-206

A unique and novel set of observations has been undertaken to study the circumstellar envelope (CSE) of the nearby (130 pc) carbon star IRC +10° 216 using optical absorption spectroscopy towards twobackground stars lying beyond the envelope.The primary aim of the observations is to search for diffuse band (DIB)carriers in the CSE. The circumstellar H+2H₂column density expected along the line of sight towards the targets islarge compared to that derived from the small interstellar reddening inthis region, E _B-V< 0.03 mag. We summarise our mainfindings, already reported in Kendall et al. (2002): The 6284Å DIB is detected in the VLT/UVES spectrum of one target, but clearly arises inthe foreground ISM. No other DIB is seen. Hence the DIB carriers, if present in the CSE, have a low abundance relative to H in the C-rich envelope of IRC +10°216, in comparison with this ratio in theISM. An important new result, previously unreported, concerns the detectionof circumstellar C₂ via absorption of the Phillips bandnear 8760Å.  相似文献   

Limits on the 2.2-μm contrast ratio of the close-orbiting planet HD 189733b     

J. R. Barnes  Travis S. Barman  L. Prato  D. Segransan  H. R. A. Jones  C. J. Leigh  A. Collier Cameron  D. J. Pinfield 《Monthly notices of the Royal Astronomical Society》2007,382(1):473-480

We obtained 238 spectra of the close-orbiting extrasolar giant planet HD 189733b with resolution   R ∼ 15 000  during one night of observations with the Near-Infrared High-Resolution Spectrograph (NIRSPEC), at the Keck II Telescope. We have searched for planetary absorption signatures in the  2.0–2.4 μm  region where H₂O and CO are expected to be the dominant atmospheric opacities. We employ a phase-dependent orbital model and tomographic techniques to search for the planetary absorption signatures in the combined stellar and planetary spectra. Because potential absorption signatures are hidden in the noise of each single exposure, we use a model list of lines to apply a spectral deconvolution. The resulting mean profile possesses a signal-to-noise ratio (S/N) that is 20 times greater than that found in individual lines. Our spectral time series thus yields spectral signatures with a mean S/N = 2720. We are unable to detect a planetary signature at a contrast ratio of  log₁₀( F _p/ F _*) =−3.40  , with 63.8 per cent confidence. Our findings are not consistent with model predictions which nevertheless give a good fit to mid-infrared observations of HD 189733b. The 1σ result is a factor of 1.7 times less than the predicted 2.185-μm planet/star flux ratio of  log₁₀( F _p/ F _*) ∼−3.16  .  相似文献   

Plumpton-Ferraro Oscillations of a Slowly Rotating Liquid Sphere     

P. C. Kendall  J. A. Lawrie 《Geophysical Journal International》1975,41(3):441-446

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Induction in arbitrarily shaped oceans – V. The circulation of Sq-induced currents around land masses     

D. Beamish  R. C. Hewson-Browne  P. C. Kendall  S. R. C. Malin  D. A. Quinney 《Geophysical Journal International》1980,61(3):479-488

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Estuaries and nutrients: Bruce J. Neilson and L. Eugene Cronin (Editors), Humana Press,Clifton, NJ,U.S.A., 1981 (distr. by John Wiley,Chichester). x + 643 pp. US $ 64.50 (U.S.A.)/US $ 74.50 (outside U.S.A.) (£43.50). Hardback     

M. Barnes 《Marine Chemistry》1983,13(4):358

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Diagnostic monitoring of a changing environment: an alternative UK perspective     

Hardman-Mountford NJ  Allen JI  Frost MT  Hawkins SJ  Kendall MA  Mieszkowska N  Richardson KA  Somerfield PJ 《Marine pollution bulletin》2005,50(12):1463-1471

Adaptive management of the marine environment requires an understanding of the complex interactions within it. Establishing levels of natural variability within and between marine ecosystems is a necessary prerequisite to this process and requires a monitoring programme which takes account of the issues of time, space and scale. In this paper, we argue that an ecosystem approach to managing the marine environment should take direct account of climate change indicators at a regional level if it is to cope with the unprecedented change expected as a result of human impacts on the earth climate system. We discuss the purpose of environmental monitoring and the importance of maintaining long-term time series. Recommendations are made on the use of these data in conjunction with modern extrapolation and integration tools (e.g. ecosystem models, remote sensing) to provide a diagnostic approach to the management of marine ecosystems, based on adaptive indicators and dynamic baselines.  相似文献