Search Results

You are looking at 11 - 20 of 22,955 items for :

  • Middle atmosphere x
  • All content x
Clear All
Scott M. Osprey, Lesley J. Gray, Steven C. Hardiman, Neal Butchart, Andrew C. Bushell, and Tim J. Hinton

operational analysis data were obtained from the British Atmospheric Data Centre ( http://badc.nerc.ac.uk ). S. Osprey and L. Gray were supported by the NERC National Centre for Atmospheric Science (NCAS) Climate directorate; N. Butchart and S. C. Hardiman were supported by the Joint DECC and Defra Integrated Climate Programme–DECC/Defra (GA01101). REFERENCES Andrews , D. G. , J. R. Holton , and C. B. Leovy , 1987 : Middle Atmosphere Dynamics . Academic Press, 489 pp . Baldwin , M. P. , and T

Full access
Yoshio Kawatani, Kevin Hamilton, Lesley J. Gray, Scott M. Osprey, Shingo Watanabe, and Yousuke Yamashita

impacts the troposphere as well as the lower stratosphere. This raises the question of how much the inclusion of a well-resolved middle atmosphere changes weather and climate simulations in numerical models. Studies as early as Boville and Cheng (1988) have investigated the effects of the stratosphere on representations of tropospheric phenomena within global circulation models. More recently Sassi et al. (2010) discussed simulations using the “low top” standard Community Atmosphere Model, version

Open access
V. I. Fomichev, A. I. Jonsson, J. de Grandpré, S. R. Beagley, C. McLandress, K. Semeniuk, and T. G. Shepherd

1. Introduction The observed increase in atmospheric CO 2 concentrations represents the single most significant anthropogenic perturbation to the climate system. Most attention naturally focuses on the associated warming effects in the troposphere. In the middle atmosphere, the enhanced infrared emission associated with the CO 2 increase acts instead to cool the region, particularly at the stratopause where the temperature maximizes. Indeed, a cooling of the middle atmosphere in recent

Full access
Kaoru Sato, Takenari Kinoshita, and Kota Okamoto

1. Introduction Material circulation of the middle atmosphere is essentially driven by the momentum deposition of atmospheric waves such as gravity waves and Rossby waves propagating from the troposphere as well as the diabatic heating by radiative processes, while differential latent and sensible heatings are also important for the tropospheric circulation. The circulation in the mesosphere forms one cell with a meridional flow from the high latitudes of the summer hemisphere to the high

Full access
Bodil Karlsson and Maartje Kuilman

1. Introduction Ultraviolet radiation interacts strongly with atoms and molecules in the upper part of the middle atmosphere, making this region particularly sensitive to changes in the solar irradiance. Above about 100 km, in the thermosphere, the direct effect of the solar flux has the dominating influence on the temperature field. In the mesosphere, on the other hand, the breaking of gravity waves (GWs) drives the circulation ( Lindzen 1981 ) in a way that makes adiabatic processes dominate

Open access
William Randel, Petra Udelhofen, Eric Fleming, Marvin Geller, Mel Gelman, Kevin Hamilton, David Karoly, Dave Ortland, Steve Pawson, Richard Swinbank, Fei Wu, Mark Baldwin, Marie-Lise Chanin, Philippe Keckhut, Karin Labitzke, Ellis Remsberg, Adrian Simmons, and Dong Wu

1. Introduction Climatological datasets for the middle atmosphere are useful for empirical studies of climate and variability, and are also necessary for constraining the behavior of numerical models. Current general circulation model (GCM) simulations routinely extend into the middle atmosphere (model tops at 50 km or higher), and require observational datasets for validation (e.g., Pawson et al. 2000 ). A number of middle-atmosphere climatologies have been developed in the research community

Full access
Yoshio Kawatani, Jae N. Lee, and Kevin Hamilton

production in the middle atmosphere. The chemical source in the water vapor mass mixing ratio tendency equation is expressed as , where k is a rate (specified as a function of pressure), Q is a parameter set at 4.25 × 10 −6 (corresponding to 6.8 ppmv), and q is the model H 2 O mass mixing ratio [see ECMWF (2013) for more details and references therein]. Our T106 MIROC AGCM integrations reported in this paper were conducted with annually repeating sea surface temperatures (SSTs) based on present

Full access
Yoshio Kawatani, Kevin Hamilton, Kaoru Sato, Timothy J. Dunkerton, Shingo Watanabe, and Kazuyoshi Kikuchi

, https://doi.org/10.1002/qj.637 . 10.1002/qj.637 Andrews , D. G. , J. R. Holton , and C. B. Leovy , 1987 : Middle Atmosphere Dynamics . Academic Press, 489 pp . Baldwin , M. P. , and Coauthors , 2001 : The quasi-biennial oscillation . Rev. Geophys. , 39 , 179 – 229 , https://doi.org/10.1029/1999RG000073 . 10.1029/1999RG000073 Barton , C. A. , and J. P. McCormack , 2017 : Origin of the 2016 QBO disruption and its relationship to extreme El Niño events . Geophys. Res. Lett

Free access
A. K. Smith, N. M. Pedatella, and Z. K. Mullen

1. Introduction Analysis of observations and output from numerical models has repeatedly shown that the middle atmosphere in the summer hemisphere responds to dynamical variability in the winter stratosphere. Two aspects of this problem have received attention. First, there are responses of the Brewer–Dobson circulation, the ozone concentration, and the temperature in the summer stratosphere to short-term variations, particularly those associated with sudden stratospheric warmings (e

Free access
Kirill Semeniuk and Theodore G. Shepherd

1. Introduction The diabatic circulation plays an important role in the climate of the middle atmosphere as the primary agent of transport of chemically and radiatively active constituents ( Andrews et al. 1987 ). Stratospheric transport is characterized by upwelling in the Tropics with poleward and downward motion in the extratropics. Current understanding of the dynamics of the diabatic circulation holds that it is driven by extratropical wave drag ( Holton et al. 1995 ). However, Dunkerton

Full access