ISSN:0035-9009    

DOI:10.1002/qj.49709941902

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe general circulation model whose formulation is described in Corbyet al.(1972) was integrated for 60 days from real data with January radiation and sea surface temperatures. The deficiencies of the model as a representation of the atmosphere were revealed by the extent and rate of the systematic changes as an equilibrium state was approached. For the first ten days, the model lost eddy kinetic energy, then gradually recovered and from about day 30 its tropospheric simulations both synoptically and in its time‐mean cross‐sections at various longitudes, had many realistic features; it failed, however, to maintain a substantial Siberian winter anticyclone. A major weakness, resulting from the use of a single level to represent the 0–200 mb layer, was the progressive deterioration of the model stratos

ISSN:0035-9009    

DOI:10.1002/qj.49709941903

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractWave and aerodynamic properties of the sea surface at Lough Neagh, Northern Ireland, are described with mean wind speedu(at a height of 10 m) varying from 4 to 8 m s−1and fetchFvarying from 8 to 22 km.The sea surface at Lough Neagh is characterized by wind induced waves of dominant period 2 to 4 s and a wave spectrum depending uponuandF, with a steep low frequency face (at frequency nf), sharp peak (at no) and high frequency region with ‘energy’ proportional to frequency to a variable power β in the range —4 to —5. The ‘constant’ of proportionality αg2in the relation ϕ(n) = αg2n−βappropriate to the equilibrium range is variable between 6 and 12 (where unless stated to the contrary n in numerical expressions is in cycles s−1)‐ mean of 7·9 ‐with a mean β of —4·5, which compares to Phillips' overall mean value of αg2of 7·2 with a mean β close to —5.Our data, and those from other sources, suggest the following relations, valid over a range of the dimensionless fetchgF/u2from 102to 105,\documentclass{article}\pagestyle{empty}\begin{document}$$ \sigma \eta {\rm /F = 2}{\rm .0 X }\mathop {{\rm 10}}\nolimits^{{\rm - 4}} {\rm (gF/}\mathop {\rm u}\nolimits^{\rm 2} {\rm)}^{{\rm - 0}{\rm .40}} $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ n_o {\rm u/g = 2}{\rm .6(gF/}\mathop {\rm u}\nolimits^{\rm 2} {\rm )}^{{\rm - 0}{\rm .30}} $$\end{document}And\documentclass{article}\pagestyle{empty}\begin{document}$$ nf^{\rm 2} {\rm F/g = f(g/nfu) or F/}\lambda _{\rm f} = \,{\rm f(cf/u)}{\rm .} $$\end{document}The first two are found to imply σh= 1·4 n−2o.The third relation is interpreted through identification ofnfwith the transition frequency separating a linear from an exponential wave growth.Our data are consistent with the idea of Kitaigorodskii thatzo(u*) depends also upon the degree of wave development σ =gσh/u*2. At Lough Neagh σ* ∼ 10–40, implyingzois closely related tou* as is found to be the case using logarithmic wind profiles.There is evidence that\documentclass{article}\pagestyle{empty}\begin{document}$$ z_o \, \approx \,0.1\,\sigma \eta \,\exp (- \kappa C_o /u_*) $$\end{document}Suggested by earlier Russian work for similar values of σ*.There is no evidence that wave power impresses itself upon the turbulence spectra of the air for value

ISSN:0035-9009    

DOI:10.1002/qj.49709941904

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe variance spectra of daily zonal and meridional winds in the troposphere and lower stratosphere over Gan (00°41′S, 73°09′E) were investigated. The total zonal variance considerably exceeded the total meridional variance at all the levels studied except the surface. In the upper troposphere the total zonal variance had a marked peak caused almost entirely by effects with periodicities greater than 10 days. The variance due to 4‐ to 5‐day meridional effects usually had a maximum slightly below the tropopause. However, at all the levels investigated this variance fluctuated considerably with time although without showing any long‐term regularities. Some specific 4‐day meridional motions at 150 mb over the equatorial regions between Gan and East Africa appeared to progress westward with a zonal wavelength of between 10,000 and 12,000 km.The vertical coherence of daily tropospheric winds over Gan was found to be weak on a scale of several km. Correlation coefficients between daily tropospheric winds over Gan and corresponding winds over Port Victoria (04°37′S, 55°27′E) were found to be small except for part of th

ISSN:0035-9009    

DOI:10.1002/qj.49709941905

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractA classification scheme for satellite observed cloud vortices is used to assess some general features of the behaviour of Southern Hemisphere depressions. From coincident conventional observations the mean variation of surface pressure and upper level geopotential anomaly near the centre of, and in west‐east cross‐section through an extratropical vortex is determined in relation to its age. Data are obtained on the geographical variation of occurrence of vortex type, duration, and frequency of change between development stages. The percentage of vortices developing without a pre‐existing cloud band is found to be greater at higher latitudes but, in general, over 50 per cent of developments occur in this way.Persistent maxima of early vortex development are found in the western South Atlantic and in the central South Pacific, both regions extending into lower latitudes than elsewhere in the hemisphere. Two less prominent maxima are located in the central Indian Ocean, and south of Australia. Generalized vortex track and speed data are obtained, and several areas of high frequency of termination of depression track are observed at high latitudes near the Antarctic coast.In total, the observations tend to point to a circulation pattern having a high frequency of major long wave troughs east of the Andes, and in the central Pacific, with a further frequent trough more variable in space and time being located between the central Indian Ocean and the longitude of the Great Australian

ISSN:0035-9009    

DOI:10.1002/qj.49709941906

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractMeteorological rocket observations of zonal winds at thirteen sites (or pairs of sites) have been analysed for amplitudes and phases of their quasi‐biennial oscillation. The period of the oscillation was taken to be 32 months because from 1962–69 the period was relatively constant, not varying by more than ±3 months. Amplitudes and phases of the oscillation over a wide range of latitude are presented and discussed. The low‐latitude part of the oscillation is well‐defined with maximum amplitudes at 25 to 30 km altitude, which reach about 25 ms−1at the Equator and decrease to a few ms−1at 20° latitude. At other latitudes, amplitudes are less than 5 ms−1except above 50 km at two sites between 50° and 60° latitude, where another main part of the oscillation is indicated. More observations and sites are needed at mid and high latitudes. Observations at the highest latitude site (77°) show no evidence of a diminished amplitude. Phases also depend on height and latitude and may reach gradients of 1 month km−1with height and 2 months deg−1with

ISSN:0035-9009    

DOI:10.1002/qj.49709941907

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe results are given of the analysis of temperature and humidity fluctuations observed from an aircraft in 61 runs at heights of 30–550 m above the open sea in conditions of active convection in the south‐east Trades. The dimensionless temperature fluctuations varied with ( −z/L)−1/3for scale heights from about 0·2 to 2 but thereafter showed little change with height. The spectra obeyed the −5/3 power law for dimensionless frequencies in excess of about 0·3. The variance of virtual potential temperature showed a maximum at a lower dimensionless frequency than the variance of vertical air velocity observed during the same series of o

ISSN:0035-9009    

DOI:10.1002/qj.49709941908

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractRefractive index, temperature and wind profiles, to a height of 2,100 m, obtained from a tethered balloon flight are analysed in terms of static and dynamic stability on a day of an elevated temperature inversion associated with stable layering in humidity and strong intermittent temperature fluctuations. It is shown that large humidity gradients in stratified layers contribute significantly to the total density gradient and must be taken into account in the evaluation of Richardson number. Fluctuations in temperature and humidity occurred both in regions of strong positive and negative static stability. No evidence was found to suggest that the occurrence of fluctuations is associated with a critical gradient Richardson number. Cross‐correlation between humidity and temperature was found to be strongly negative across the boundaries of stratified layers and positive in strong intermittent bursts of temperature observed at the top of the temperature inversion. Spectral slopes of refractive index, temperature and humidity in the region of strong density gradients were found to be, in general, greater than the ‐5/3 slope predicted by inertial subrange the

ISSN:0035-9009    

DOI:10.1002/qj.49709941909

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractA technique is described for stereo photogrammetry of clouds. Movie cameras are set up on a ground baseline 5·6 km long. Time‐lapse films are made with a frame interval of 3 s. The analysis involves the super‐imposition of stereo pair images of the cloud, with advantages over methods previously used.Measurements are presented of an Alberta hailstorm, and estimates are made of horizontal divergence near the cloud tops, and mass flux. Measurements and calculations imply that the ring vortex model of the circulation in small cumulus tops is applicable to some large hail‐bearing storms, and that little or no net mass transfer occurs through the caps of rising cloud

ISSN:0035-9009    

DOI:10.1002/qj.49709941910

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractA marked oscillation with a periodicity slightly greater than a month occurred in the zonal wind at 100 mb over Gan (00°41′S, 73°09′E) through the months January to May 1966. Corresponding oscillations took place during this period over other equatorial stations round the globe, but on the whole the oscillations became weaker with increasing latitude. The meridional wind was not directly involved in the oscillations, which were manifestations of a wave which generally progressed eastward relative both to the earth and to the mean flow with, however, a somewhat irregular rate of progression. The wave had zonal global wave number 1. Although it also advanced southward over the eastern hemisphere, it was not far from being symmetrical (as opposed to antisymmetrical) about the Equator. It was largely confined to the region between 150 mb and 70 mb, but it generally propagated downwards, Over the eastern hemisphere the 100 mb temperature tended to lead the 100 mb zonal wind by about 1/4 cycle. At least over Gan the 100 mb height and the 100 mb zonal wind tended to be in phase. The effect as a whole was sufficiently like an equatorial Kelvin wave to be considered as such. especially over the eastern hemisphere.The wave was linked very indirectly to concurrent events at 100 mb at 40°N. Less marked equatorial Kelvin waves occurred at 100 mb in 1960, 1967 and 1969. The incidence of equatorial Kelvin waves at 100 mb did not appear to be closely related to the phase at 50 mb of the tropical quasi‐biennial zonal wind osc

ISSN:0035-9009    

DOI:10.1002/qj.49709941911

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY