摘要:

AbstractThe sensitivity of a two‐dimensional model to the diabatic heating rates used in the lower stratosphere is discussed. Different radiation schemes are described; in particular a longwave scheme which allows for interaction between surface temperature, ozone amounts and the heating rates in the ozone 9·6 μm band. Near‐infrared heating is also included.A model run including the new radiation schemes is compared with a control run in which radiative equilibrium is assumed in the 150–30 mb region (as in previous versions of this model) and with a run in which fixed heating rates are adopted in the same region. The temperature and ozone distributions of each run are discussed. The ozone structure is very sensitive to the scheme used and the inclusion of the new schemes improves the model's ozone distribution. The importance of the diabatic heating in determining the mean meridional circulation and the transport of trace constituents is stressed.Perturbation experiments of Haigh and Pyle are repeated in the model including the new schemes. The effect on ozone of increasing CO2is found to have a stronger latitudinal and seasonal variation. The effect of including chlorofluorocarbons is a larger ozone depletion at all latitudes. The problems associated with assessing the uncertainties in model predictions are discussed.A simple scheme for representing cloud cover in the longwave scheme is described. The effect of inclusion of clouds on heating in the ozone 9·6 μm band, and thus on the ozone distribution, is discussed. The results of changing the effective albedo in the solar heating scheme are considere

ISSN:0035-9009    

DOI:10.1002/qj.49711046312

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractA zonal Fourier analysis has been made of selected meteorological fields produced in a general circulation model extending up to 100 km. The model was set up for non‐diurnal, fixed January conditions, included land‐sea contrast but omitted mountains. The results largely conform to the predictions of the Charney‐Drazin criterion, at least in that only low wavenumbers in the winter are able to penetrate to the lower thermosphere. Higher wavenumbers are rapidly attenuated above the tropopause, but, very interestingly, they are regenerated with increasing amplitudes from 50 to 100 km. The occurrence of such small‐scale features is consistent with deduced dissipation rates and aeronomical characteristics in the lower thermosphere. The energy source for these small waves appears to be partially attributable to barotropic energy transfer, responding to a wave spectrum excited by baroclinic instability and internal gravity waves. A further unquantifiable energy source is associated with upwards‐propagating gravity waves. The combination of baroclinic and inertial instabilities together with barotropic processes, upwards‐propagating planetary and gravity waves indicates the wealth of dynamical processes occurring in the middle atmosphere and reproduced i

ISSN:0035-9009    

DOI:10.1002/qj.49711046313

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThis paper describes some simple time‐dependent analytical solutions to the problem of a sudden ‘switch‐on’ of heating localized about the equator. The equations used are the shallow water equations on the β plane under the ‘long wave approximation’. It is shown that, with a reasonable amount of dissipation, it can take several days for a steady state response to be established. In the early stages, the circulation differs considerably from that of the steady state. The long time scale for the adjustment process has implications in numerical weather prediction since it implies that if the initial data are not in balance with the model's forcing, it may take several days for a balance to be established, by which time the quasi‐stationary tropical flow may have been irrev

ISSN:0035-9009    

DOI:10.1002/qj.49711046314

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractWe describe a model for stratospheric tracers in which transport consists of advection by the mean diabatic circulation and chemical eddy transport arising from longitudinal variations inin situsources and sinks. The ozone distribution is reproduced well by the model and all species show interesting variations with longitude. The limitations of the model are discussed; we speculate that the most important of these is the neglect of transient contributions.

ISSN:0035-9009    

DOI:10.1002/qj.49711046315

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe predictions of a radiative‐photochemical model are compared with observations of the diurnal variation of mesospheric ozone obtained from rocket‐borne experiments. Temperature observations from the SAMS instrument on the Nimbus‐7 satellite are used to define the basic atmospheric state. Good agreement is found, provided that low water vapour abundances are accepted, together with slow rate coefficients for the recombination of odd hydrogen species. Sensitivity tests performed with the model show that uncertainties in the ozone calculations arise chiefly from uncertainties in water vapour concentrations, solar irradiance, O2absorption cross‐sections and certain rate coefficients, and that the sensitivity of ozone to these parameters may be markedly different at different times of day, especially above 60 km. The model's representation of the ozone variation around dawn is also used to estimate the error caused by the assumption of spherical uniformity when deriving ozone concentrations from solar occultation expe

ISSN:0035-9009    

DOI:10.1002/qj.49711046316

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractWhen a shade‐ring is used to shield a pyranometer from direct solar radiation, a correction to the measured diffuse radiation is necessary to account for diffuse radiation occluded by the ring. The shade‐ring correction depends on the dimensions and positioning of the ring and on the anisotropy of sky radiance. In this analysis these factors are separated using a simple model of sky radiance as the sum of a uniform background and a circumsolar component. The predictions of the model are tested against standard distributions of radiance and measured shade‐ring corrections for clear skies. The model is also used to describe average distributions of radiance for cloudy skies and is in good agreement with the limited measurements available. This analysis enables measurements of solar radiation to be partitioned more exactly into direct and diffuse components and may also be applicable to the estimation of diffuse irradiance on other shaded sur

ISSN:0035-9009    

DOI:10.1002/qj.49711046317

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractEvidence is produced which suggests that sympathetic fluctuations in cloud top height and total cloud water content observed during two case studies of nocturnal anticyclonic stratocumulus at Cardington (52°06′N, 0°24′W) may be due to vertical adiabatic displacements of the cloud layer as a whole, perhaps forced by local topography. Simultaneous observations from more than one site will be needed to test this tentative hypothesis, and these are de

ISSN:0035-9009    

DOI:10.1002/qj.49711046318

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractA cloud can be produced by injecting steam into a large plastic‐walled chamber. The liquid water content and drop size distribution of the cloud are found to depend chiefly on the power input to the steam boiler and the size of the boiler orifice respectivel

ISSN:0035-9009    

DOI:10.1002/qj.49711046319

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

ISSN:0035-9009    

DOI:10.1002/qj.49711046320

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

ISSN:0035-9009    

DOI:10.1002/qj.49711046322

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY