摘要:

AbstractIt is argued that detailed consideration of the 24‐hour waveform of ozone in the upper stratosphere provides a means of testing current photochemical kinetic mechanisms, with measurements requiring good relative rather than good absolute accuracy. The implications of the pronounced changes with height of the waveform for remote sounding and monitoring are pointed out. Diurnal, semidiurnal and higher harmonics of ozone and temperature waveforms are obtained by Fourier analysi

ISSN:0035-9009    

DOI:10.1002/qj.49710946002

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractMeasurements of stratospheric water vapour over Australia (Mildura, 34°S 140°E) during the period 1977–1979 indicate a mean mixing ratio between 15 and 21 km of 2°4p.p.m.m. The record since 1973 shows a quasi‐biennial oscillation with a peak to peak amplitude of 2 p.p.m.m. in the 15–21 km height interval. The latter appears well correlated with 50–30 mb equatorial

ISSN:0035-9009    

DOI:10.1002/qj.49710946003

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractStatistics of the minimum saturation humidity mixing ratio are extracted from 2 500 radiosonde ascents in the tropics (10°N to 10°S) and in the region of the Asian summer monsoon. Two periods of approximately 20 days are examined, one in the northern winter and one in the northern summer. The relation of the observations to an hypothesis, proposed by A. W. Brewer in 1949, of mass exchange between troposphere and stratosphere is briefly discusse

ISSN:0035-9009    

DOI:10.1002/qj.49710946004

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractThe climatic‐mean‐value of the total zonal relative angular momentum of the atmosphere in topographically forced inviscid barotropic models on a sphere is examined using the methods of equilibrium statistical mechanics. Models incorporating wave–wave interactions as well as simplified systems in which only wave–zonal‐flow interactions are allowed are considered. It is shown analytically that for a given truncation the equilibrium state of the system does not depend on the presence of wave–wave interactions although the detailed evolution towards it does.We interpret our results in terms of a generalization of the properties of the equilibrium solutions for unforced barotropic flow. For realistic resolution (with truncation wavenumber ° 15) most flows evolve towards an equilibrium with westward angular momentum, and the solutions are strongly dependent on the initial conditions. An important exception is the case when the flow initially has westward angular momentum, when the equilibrium state remains close to the initial state regardless of resolution. An upper bound on the climatic‐mean‐value of the solid‐body rotation component of the flow is derived. In general, highly truncated systems are insensitive to the initial conditions and evolve towards a state in which the angular momentum is eastward and close to the upper bound.Reasonable rescating of the global topography used has little influence on the climatic‐mean angular momentum, but the case of no topography represents a singular limit in which angular m

ISSN:0035-9009    

DOI:10.1002/qj.49710946005

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractAvailability of potential energy in inland convection and in a sea breeze circulation are compared using a formulation of P. C. Manins and J. S. Turner for the convectively mixed atmospheric boundary layer, and a numerical model of a sea breeze. Entrainment processes during the mixed layer growth appear to affect both the convective scale and the mesoscale, decreasing the amount of potential energy available to the convective scale yet increasing the potential energy available at the mesoscale. The kinetic energy content of the sea breeze cell is explained in terms of a constant efficiency for the conversion of available potential energy inside a cell whose horizontal dimension increases in time. Results of numerical experiments indicate that the current value of the temporally integrated buoyancy flux at the ground is the most important parameter for the sea breeze flow. This parameter determines the strength of the flow as well as the inland movement of the sea breeze front.

ISSN:0035-9009    

DOI:10.1002/qj.49710946006

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractThe consequences for the theory of concentration fluctuations of different proposals by L. F. Richardson and G. K. Batchelor about the rate of separation of pairs of marked particles (giving rise to non‐Gaussian and Gaussian particle separation probability density functions respectively) are explored via two Lagrangian Monte Carlo models.The models are applied to an instantaneous one‐dimensional cloud source (which is approximately equivalent to a continuous line source) and in many respects give similar results for concentration fluctuations. The crucial difference is that whereas the non‐Gaussian model predicts, in agreement with observation, that at large time the fluctuations remain the same order of magnitude as the mean field (the ratio depending only on the source size), the Gaussian model incorrectly predicts that fluctuations ultimately vanish compared with the mean field.The reason for the failure of the Gaussian model is explored by partitioning the total fluctuations into contributions due to the variation of the distribution of material within the cloud (i.e. in coordinates relative to the centre‐of‐mass) and due to motions of the cloud as a whole (meandering). It is shown that at large time the Gaussian model accounts only for the meandering contribution to fluctuations, and by smoothing out all internal structure of the doud eliminates relative flu

ISSN:0035-9009    

DOI:10.1002/qj.49710946007

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractA crosswind‐integrated K model with wind profiles and K profiles described by Monin‐Obukhov similarity relations is solved numerically for the case of the release of a passive substance from a point source at ground level. An extensive analysis is undertaken to compare the numerical model results with experimental results from the Prairie Grass dispersion experiments. Simulations of these experiments are carried out with and without deposition. It is shown that the numerical solution of the diffusion equation yields a good approximation to both the vertical concentration profile and the crosswind‐integrated ground‐level concentrations when consideration is given to the effect of deposition of the tracer. Despite considerable scatter, the measurements are seen to support the use of the eddy diffusivity of heat rather than the modified expression of that of momentum. For comparison Dyer's (1974) expressions for the eddy diffusivity of heat and momentum are also used; only minor differences are found in the performance of the two sets of expr

ISSN:0035-9009    

DOI:10.1002/qj.49710946008

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractResults from the 11.6γm channel on the Nimbus 5 selective chopper radiometer are presented that show ambiguity in the temperature deficit obtained for any tropical sea surface temperature (s.s.t.). The analysis indicates that to gain an accurate measurement of s.s.t. in the 10–13γm band further information on the water vapour content of the overlying atmosphere is required. A transmission model is used to show that for two channels a linear relation exists between the two apparent surface temperatures and simple algorithms are derived that give s.s.t.s with an accuracy better than 0.3K for vertically‐viewing satellite radiometers. Algorithms giving s.s.t. are derived for both dual wavelength and dual angle‐of‐view techniques and these are compared with those derived by othe

ISSN:0035-9009    

DOI:10.1002/qj.49710946009

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractLow elevation aerosol spectra, ocean whitecap cover and 10m wind speeds measured during the 1978 JASIN experiment have been inter‐related and compared with previously published observations. The positive dependence of aerosol concentration upon whitecap cover was found to increase with droplet radius reflecting the expected higher correlation of the concentration of larger droplets, which have shorter effective residence time in the marine atmospheric boundary layer, with the immediate whitecap cover, which reflects the instantaneous rate of aerosol generation at the sea surface. The power‐law wind dependence, Uγof the low elevation concentration of droplets larger than 8γm radius was determined to be similar to the wind dependence of whitecap cover, with γ values of 3.23 and 3.31 resulting from the respective application of the robust bi‐weight fitting technique. This observation is consonant with an aerosol generation model in which the instantaneous rate of production is simply proportional to the immediate whitecap cover.The large droplet end of the JASIN low elevation aerosol spectrum is seen to undergo a marked enhancement when the wind speed exceeds 10ms−1. This is a consequence of the onset at that speed of supplementary droplet production via the mechanical disruption of wave crests. The observed growth, with increasing wind speed, in the disparity in amplitude of near‐sea‐surface and near‐cloud‐base aerosol spectra is in part a consequence of the fact that the larger droplets, produced in relative abundance at the higher wind speeds, fall out before they can be mixed effectively through

ISSN:0035-9009    

DOI:10.1002/qj.49710946010

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractThe considerable increase in requirements for sea state forecasts in recent years has led to development of a numerical wave forecasting system in the Meteorological Office. This is based on a wave prediction model which combines the advantages of the parametric technique in predicting a growing wind‐sea with those of a discrete spectral model in the swell regime. This is done using a discrete model by parametrizing the nonlinear interactions term in the energy balance equation in a way that reproduces the behaviour of the parametric model. The main difficulty with the method is in the separation of wind‐sea and swell required to do this. Propagation of wave energy is performed using an accurate form of the Lax‐Wendroff integration scheme. A two‐term representation of wave growth is used whilst dissipation is modelled by an explicit whitecapping mechanism. Shallow water effects are included by representations of shoaling, refraction and bottom friction. The operational numerical atmospheric model at the Meteorological Office provides the wind input. An extensive program of evaluation has shown that the results provide high quality guidance with 24‐hour forecasts of wave height having a r.m.s. error ranging from 0·6 m in the southern North Sea to 1·0 m east of th

ISSN:0035-9009    

DOI:10.1002/qj.49710946011

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY