Evidence of a mean meridional circulation in the atmosphere from surface wind observations

Abstract

Since, unless I have made an error, the equations of motion are not invariant to reflections through the midpoint there is no compelling a priori reson for expecting the solutions to have the symmetry Dr. Scorer suggests. Admitting the qualitative differences of symmetry, I can see reasons both for regarding the experiment as responsive to friction at the bottom (and lacking symmetry for that reason) and for seeing more symmetry of this type in the atmosphere than might a t first glance appear. With respect to the first, some related experiments in a large hemisphere have shown that one can have at very low Rossby numbers a similar interior distribution with positive thermal wind and at times waves either with westerlies (maximum at top) or with easterlies (maximum at bottom) almost everwhere. The difference was due to absence or presence of air torque at the top (the rotation was rather high at 10 r.p.m. or more). This certainly suggests that presence of the bottom can determine such things as the overall mean zonal current. Although the measured mean zonal components at the bottom in the present experiment are all easterly, the variations with radius are such as to look quite like a surface wind profile displaced toward easterlies except in the extreme strength of the polar easterlies. I conclude that in this respect the experimental base is behaving more like the ground than at first appears. With respect to the second matter of heating effects, I think one has to regard the interior in the experiment as corresponding, for any fairly detailed comparisons, to a middle latitude strip where advection effects tend to dominate and short time-changes are quasi-adiabatic. The deep tropics then serve the wall function of transferring heat to considerable heights and the motion north of the sub-tropical ridge is, like the experiment, quasi-adiabatic and to a considerable extent independent of the source arrangement at the ground below.Mr. Sawyer's question concerns a more subtle possibility of frictional influence. In some cases experimental jets give a good deal of the impression of separated boundary layers. I am inclined, however, to think that the jet is not essentially connected with friction although that possibility cannot be ruled out at present. A variety of types of experiment exhibit jets in such a way as to suggest that it is an inviscid phenomenon but all involve boundaries, different though they be, that might be a required part of the mechanism. I think it will be very much worth while to run some tests with as much variation in this boundary condition as possible (especially with as nearly a free boundary at the bottom as is feasible and with lids in contact at the top) in order to see what variations occur in the jet. It might then be possible to draw a more definite conclusion.In answer to Mr. Gordon's question I may say that it is feasible to obtain at least some direct variation of the Coriolis parameter by using a container figured to the equilibrium paraboloid for some rather high rotation, say 60...

On the Annual Variation of the Monthly Mean Meridional Circulation

“…I n the upper troposphere, the data showed a three-wave structure superimposed on the northward mean meridional flow. Tucker (1957) extended the work of Riehl and Yeh (1950) by evaluating the surface mean meridional flow over the combined land and ocean areas of the Northern Hemisphere. The inclusion of land areas in the averaging reduced the magnitude of the mean meridional flow at high latitudes.…”

“…Their primary data source was the collection of Upper Wind Statistic Charts of the Northern Hemisphere by Crutcher (1959). These charts provided better upper air statistics than had previously been available but were deficient in that they contained no data below the 850mb level and were based on only a small amount of data south of 15' N. To compensate for this deficiency, the authors used Tucker's (1957) values of surface wind and '(characteristic vertical wind profiles" from the surface to 850 mb. A somewhat crude interpolation technique was used to obtain values between the Equator and 10' N.…”

On the mean meridional circulation in the planetary boundary laye during the winter season in the Northern Hemisphere

“…In the recent times the number of data is increasing, what, of course, contributes to a better understanding of this problem. Tucker [ 13] has analysed surface wind observations in the Northern Hemisphere. Because of this it is necessary to find out a new method for indirect calculation of the flow.…”

“…Because of this it is necessary to find out a new method for indirect calculation of the flow. Their primary data sources were the upper wind statistic charts of the Northern Hemisphere completed by Tucker's [13] surface data. Riehl and Yeh [12] showed the existance of asymmetry of the mean meridional velocity for latitudes below 40~ from a network of ocean surface observations.…”

Analyzing Atmospheric Circulation Patterns Using Mass Fluxes Calculated from Weather Balloon Measurements: North Atlantic Region as a Case Study

“…These views were disputed by multiple researchers (including Tucker) who argued that the three cells-in particular, the Hadley cell-were dominant features of the general circulation of the atmosphere [15,[27][28][29][30][31][32][33][34][35][36]. Some argued that the three-cell model offered the best theoretical explanation for the observed surface winds [27,28,31].…”