摘要:

AbstractA two‐level quasi‐geostrophic model, developed to probe into certain large‐scale features of the general circulation of the atmosphere, is discussed together with two main results of particular interest. Firstly, on averaging over longitude and over a typical cycle in eddy kinetic energy, the model indicates a functional dependence of meridional flux of zonal momentum on latitude which is approximately in step with the dependence of meridional temperature gradient on latitude. Although it is known that this type of model is not accurate in describing the motion of very long waves, the result gives some interesting theoretical support for one of the basic premises of the long time period average model of the general circulation discussed by Williams and Davies (1965). Secondly, the significance is clearly demonstrated of the particular functional forms chosen for the initial distribution of perturbation stream function values, as used in the past in a great deal of general circulation work. This is achieved by working from several initial distributions and noting that the ensuing differences in large‐scale characteristics are very clearly stamped on the flow for at least the thirty days of time integration considered in this paper. From the standpoint of calculating a ‘theoretical limit of predictability of the atmosphere’ these results can therefore be interpreted to indicate that the functional form assumed for the distribution of the initial perturbations could appreciably influence a calculation of this limit, although such calculations were not carried out in this paper. Several other results concerning the influence on these large‐scale characteristics of the forms adopted to describe vertical transfer of momentum and of total heating function are also discussed, together with the effects of introducing certain alternative comp

ISSN:0035-9009    

DOI:10.1002/qj.49709540310

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractThe predictions of a simplified theory of anemometers are compared with observation.The theoretical response of cup and vane anemometers to steady and varying flows are derived analytically and by using an analogue computer.It is found that the mean indicated windspeed can be overestimated by as much as 20 per cent and that the form of fluctuations is distorted and their amplitude considerably reduced.

ISSN:0035-9009    

DOI:10.1002/qj.49709540311

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractThe effect of atmospheric haze upon Umkehr observations is calculated in two ways. First, observed Umkehr curves are compared with computed Umkehr curves reconstructed from simultaneous direct soundings of the vertical ozone distribution. The difference between the two curves gives the ‘experimental’ haze effect. In the second method, Umkehr curves are computed for model atmospheres with and without haze, the difference giving a ‘theoretical’ haze effect. When the two haze‐effect curves are normalized to zero for a solar zenith angle of 60°, both exhibit the same characteristics, viz., the ‘correction’ to be subtracted from an observed (with haze) curve is negative at all solar zenith angles, the correction reaches a maximum near 81°, and there is a second small reversal near 87–88°. Application of the derived haze corrections in the Umkehr evaluation procedure results in slightly higher ozone content at and just below the main maximum and slightly lower ozone

ISSN:0035-9009    

DOI:10.1002/qj.49709540312

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractA comparison between the changes in wind calculated from Doppler data and from an inertial system shows that variations in Doppler winds of over five knots may be caused by small changes of heading and air speed. The accuracy of average winds over a ten minute period is thought to be better than five or six kt.A 500 mb wind field has been measured across a 50 nm square centred on the Scilly Isles and a value for the divergence out of the square has been calculated from the wind measurements. The accuracy of this measurement is estimated to be ± 3 × 10−5se

ISSN:0035-9009    

DOI:10.1002/qj.49709540313

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractThe space‐time averaged zonal wind equation has been used in a two dimensional model to infer the mean meridional circulation of the Northern Hemisphere upper troposphere and lower stratosphere at the solstices. A three cell system is found with maximum meridional speed of 120 cm sec−1in winter and 40 cm sec−1in summer and vertical speeds of 0.3 cm sec−1in winter and 0.1 cm sec−1in summer. The lower stratosphere circulation shows a continuation of the tropospheric cells with speeds decreasing with height.Using these results together with estimates of the eddy convergence terms and the ‘diabatic’ contributions based on values obtained from the literature the component terms in the zonal momentum and heat budgets are listed. In the former, in agreement with other workers, the main balance is between the convergence of the horizontal eddy flux and the mean meridional flow (Coriolis torque) terms. In the latter the balance is principally between the ‘diabatic’ term, the (subsidence) term due to the mean vertical flow and both the horizontal and vertical eddy heat flux convergence terms.The limitations of the data on which the calculations are based are emphasized and estimations of the consequent uncertainties in the results are obtained by repeating the computations with different input data. In particular no measurements are available of the term due to the convergence of the vertical eddy flux of momentum. Most authors have assumed it to be zero but calculations have also been made here using values based on results given by Smagorinsky, Manabe and Holloway (1965) for their 9‐level general circulatio

ISSN:0035-9009    

DOI:10.1002/qj.49709540314

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

ISSN:0035-9009    

DOI:10.1002/qj.49709540316

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

ISSN:0035-9009    

DOI:10.1002/qj.49709540317

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

ISSN:0035-9009    

DOI:10.1002/qj.49709540319

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

ISSN:0035-9009    

DOI:10.1002/qj.49709540320

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

ISSN:0035-9009    

DOI:10.1002/qj.49709540323

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY