Journal of the Meteorological Society of Japan. Ser. II
Online ISSN : 2186-9057
Print ISSN : 0026-1165
ISSN-L : 0026-1165
Volume 29, Issue 9
Displaying 1-6 of 6 articles from this issue
• On the generalized logarithmic formula of wind velocity distribution
K. Takeda
1951 Volume 29 Issue 9 Pages 287-297
Published: 1951
Released on J-STAGE: February 05, 2009
JOURNAL FREE ACCESS
A formula of vertical wind velocity distribution recently presented by Deacon where, u denotes the wind velocity at the height z, z0 is the roughness parameter, and α and β are constants, seems to settle the old problem whether the velocity is represented by an exponential formula of the type u_??_az1/n (2) or by a logarithmic one u_??_alnz+b (3) That is, the velocity can not be represented by simple formulae such as (2) and (3), but by (1) which may be called a generalized exponential formula. But, in this paper, the author shows that the velocity can be represented also by a formula which contains logarithmic terms only and may be called, so to speak, a generalized logarithmic formula.
As can be seen from recent results of wind velocity measurements, such as Deacon's or Pasquill's, the velocity curve shown on the u/U-lgz chart is concave or convex upwards This seems to be an extreme defect of the formula, but what is important in this case is the actual height of (9). If we adopt as the extremities of β which was given by Deacon as β=1.13 (in the unstable case) and β=0.79 (in the stable case), and estimate the heights from (9) substituting E by 1-β, we have z=2210m for unstable leger and z=0.0086m for stable lager. So this becomes trivial in the actual case.
There still remain some uncertainties as to the form of the logarithmic formula in the adiabatic case. For Rossby and Montgomery and also Sverdrup adopted the type u=alnz+z0/z0, while Paeschke and Thornthwaite used u=alnz-d/z0, where, d is a length characteristic to the roughness. But in view of the pure empirical nature of the formula the author considers it sufficient to adopt, as in the 1st report of this paper, u=alnz/z0, and only when experiments (made near the roughness height) show some deviation from this formula we should use u=alnz±d/z0 in agreement with the conclusion obtained by Deacon that in conditions of neutral stability the logarithmic law can represent the profile between heights of 1m and 13m over the grass of various lengths with great accuracy, provided that both z0 and d are chosen independently to give the best fit. (Sutton: Atmospheric Turbulence, p. 57).
• K. Yakame, Y. Fujii, M. Matsumoto, S. Yokota
1951 Volume 29 Issue 9 Pages 298-303
Published: 1951
Released on J-STAGE: February 05, 2009
JOURNAL FREE ACCESS
A Pitot-static-pressure-tube is used for the transmitter of the anemograph. It suits the anemograph, as the pressure difference measured by it varies less with the variation of the wind direction than that measured by Dines' anemograph. The total and static pressures are conducted to the inside and outside of the metal belows of the recorder, respectively. The metal bellows extend the length in proportion to wind velocity instead of pressure difference by the action of curved levers. The scale of the recording chart is graduated linearly proportional to the wind velocity.
The wind direction is indicated by using a voltmeter which works as the wind vane moves a slider over the tops connected to resistances, the consecutive tops corresponding to 5 degress.
• T. Watanabe
1951 Volume 29 Issue 9 Pages 303-310
Published: 1951
Released on J-STAGE: February 05, 2009
JOURNAL FREE ACCESS
By transformation of the equation of dynamic meteorology, we can assume that ζ+λ+∂θ/∂t is an important factor in treating dynamical phenomena of the atmosphere, where ζ is the relative vorticity, λ is Coriolis' parameter and ∂θ/∂t is the local variation of the wind direction θ. This term was called the absolute vorticity of the second by the author.
Some examples of the above unstationary effect were discussed. Firstly, the gradient wind in case of stationary motion is described as fallows: where, P is the total pressure, so that for an unstationary case, the following expressions are assumed tohold: and the result was derived by solving the equation.
Secondly, as the criterion of dynamical stability is given by the sign of absolute vorticity, assumption can be made that in an unstationary case, the criterion is given by the sign of the absolute vorticty of the second kind ζ+λ+∂θ/∂t, and this result was applied to a simple case in which the parcel method is used, revealing itself to be correct.
Fufther, some other phenomena were also discussed.
• Kyôji Itô
1951 Volume 29 Issue 9 Pages 311-313
Published: 1951
Released on J-STAGE: February 05, 2009
JOURNAL FREE ACCESS
Diamond Dusts or Ice Crystals in the Air were studied from historical standpoints. Their definition was formed after many changes.
• Part 1. Typhoon Eye
K. Watanabe
1951 Volume 29 Issue 9 Pages 314-319
Published: 1951
Released on J-STAGE: February 05, 2009
JOURNAL FREE ACCESS
This investigation on the detailed structure of a typhoon is based on the typhoon reconnaissance flight reports furnished by the 2143 d Air Weather Wing.
Part one begins with a study of the eye of typhoon. Changes in the size of the typhoon eye have close connection with the life stages of the storm. The elongated shape of the eye changes according to the tilt of the center axis, and deepening of the storm occurs when the eye is open to west, and filling occurs when open to east.
The intention of this report is to point out some true features of tropical storms by means of many inflight reports of the typhoons which occurred in the Southwest Pacific during the years 1949-1950.
Most of what we know about typhoons is obtained from surface observations or from time sequence data of upper air soundings when the typhoons approached Japan, and, in most cases, for those in mature stage or having changed to extratropical cyclones.
In this study, I have adopted the next four stages of the storm defined by W. F. Macdonald.
1. Formative stage.... From its formation to typhoon intensity. (Energy accumulating.)
2. Immature stage.... From typhoon intensity to maximum intensity. (Energy rapidly accumulates and concentrates at the center.)
3. Mature stage.... From maximum intensity till it meets with a front, draws in a stable air mass or passes over a land area. (No energy accumulation, and energy diverges outward.)
4. Decay stage.... The typhoon rapidly weakens or becomes an extratropical cyclone. (Energy dissipates or is transferred to frontal wave energy.)
These stages are convenient to show the distribution and accumulation of energy. In the following, the sizes and shapes of the eye are not those observed at the earth's surface, but they are from inflight observations in the eye or from images on the radar scope.