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Adam Kochanski

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Adam Kochanski

Abstract

Mean meridional cross-sections were constructed from the equator to the North Pole along 80°W, for January, April, July and October. The profiles of the zonal flow extend to 25-millibar heights (circa 26 kilometers). The temperature profiles reach 10 mb (circa 31 km). The westerly component of the mean geostrophic flow and the laws governing the distribution of the mean temperature in the stratosphere are discussed. A comparison with earlier cross-sections for various meridians suggests that certain gross features of the general circulation in the 16- to 30-km layer along 8O°W may be common to most longitudes of both northern and southern hemispheres.

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Adam Kochanski

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This paper examines apparent ageostrophic deviations at 300 and 200 mb over the United States, their relationship to upper-air synoptic patterns, and the extent to which ageostrophic deviations affect wind forecasts made from geostrophic maps. For spot winds, ageostrophic RMS vector deviations are 19 kn at 300 mb and 20 kn at 200 mb. For the same set of data, geostrophic wind forecasts (36-hr) result in a 34-kn RMS vector error if verified by the geostrophic winds, and 38-kn RMS error if verified by the rawins. Prognostic errors of route winds decrease as the route length increases: for a route length 1900 n mi, the 36-hr geostrophic wind forecast gives RMS vector error 17 kn if verified by geostrophic wind and 19 kn if verified by the rawins. Instrumental uncertainties inherent in the present upper-wind reports prevent the use of the rawins as an absolute standard for verification. In all, it appears that a medium-period forecast of spot and route winds can be made with tolerable approximation from the geostrophic prognostic charts.

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Adam Kochanski

Abstract

Interlevel correlations of the wind are shown to be quite stable over large areas of the Northern Hemisphere. Based on this fact, vertical correlation coefficients for 70 stations were categorized into three types, each type occupying certain areas of the hemisphere. The analysis was extended over Asia, but within that area it must be considered, at best, an educated guess. The RMS errors resulting from the use of model-values are probably acceptable for most purposes. The law governing the decay of correlation coefficients with increasing separation was also studied. The rate of decay shows large variations, but it can be approximated, at least in the majority of cases, by a simple exponential function.

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Adam Kochanski

Horizontal temperature gradients as large as 7C° per distance of one degree latitude are observed occasionally on 200-mb maps and (with a generally opposite direction) on 500-mb maps. These values are derived from gradient measurements in the vicinity of stations with temperature observations. Aircraft reports yield still higher horizontal gradients: 9C° to 11C° per 1 deg lat. An extreme temperature difference of 13C° over a distance of % deg lat appears feasible, based on extrapolation of differences found over greater distances. The last value is equivalent geostrophically to a vertical wind shear (allegedly observed by aircraft) of 60 kts/1000 ft.

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Adam Kochanski

Models of daily thickness patterns were developed for the layers 500–300 mb, 300–200 mb and 200–100 mb. Isotherm models are also given for the 300-, 200-, and 100-mb levels. The models apply to an idealized wave-pattern and show the substantial difference between conditions over contour troughs and those over contour ridges. Tropospheric-type patterns (cold troughs, warm ridges) are predominant in the 500–300-mb layer while stratospheric patterns (warm troughs, cold ridges) prevail in the 200–100-mb layer. The 300–200-mb layer shows a mixed tropospheric and stratospheric type. The presented models are only tentative as limited data were available for their construction. The use of models in analysis and forecasting is discussed.

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ADAM KOCHANSKI

Abstract

Atmospheric motions from 54 sodium cloud firings are examined in the 80–200-km. height region. To gain an insight into various types of motion that are presumably present in the total observed wind, an oscillatory component assigned to internal gravity waves, and the residual motion containing tides and prevailing wind, are studied. Data from apparent movements of ionospheric irregularities seem, in many respects, consistent with sodium drift measurements and are utilized to estimate the prevailing wind and the 24-hr. and 12-hr. periodic variations. Only inferential results can be obtained from many parts of this analysis, but there is a strong suggestion that a slowly varying prevailing wind has a substantial role in these motions; the magnitude of this wind appears to be 45 m./sec. in the 100–115-km. layer and 65 m./sec. near 160 km. At three stations located within the 30°–40° N. latitudes, both the observed and the derived motions are very similar, as if a well organized circulation existed at all heights from 80 to 180 km. Fort Churchill data indicate that farther north this circulation may be considerably stronger.

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ADAM KOCHANSKI

Abstract

In the 80- to 105-km height region, zonal winds and their vertical shears, as well as ionospheric drifts, show a semiannual variation that is in phase with a similar oscillation in temperature and density at satellite heights (190–1130 km). At higher latitudes, the effect is purely semiannual, but at 35° latitude a 12-mo term seems to be superimposed. Similar variations must exist in the latitudinal temperature gradient that is associated with vertical shears. Temperature data were not available for this study, requiring a chain of assumptions in order to draw some inferences regarding this parameter. Under these assumptions, the mean temperature of the 80- to 105-km layer could possess temporal variations nearly parallel to changes observed in shears. This would suggest, for midlatitudes, a temperature variation composed of a 12-mo and a 6-mo term of roughly equal magnitudes. Such variations in temperature and in the latitudinal temperature gradient could be explained by systematic changes in the vertical thermal structure of the 80- to 105-km layer.

At least in the parameters of motion, a latitudinal effect appears to be present up to a height of 160 km, whereas seasonal changes attenuate rapidly above 100 km. It is thus possible that the semiannual variation in motion parameters is exposed, as a primary factor, at heights not far removed from 120 km. Whether an analogous situation exists in temperature is at present a matter of conjecture.

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Adam Kochanski
and
Peter E. Wasko

Several daily series of 100-, 50-, and 25-mb maps over North America were analyzed. The wind flow at these levels and the thermal structure in the 100- to 25-mb region of the atmosphere are discussed and certain conclusions drawn.

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Adam Kochanski
and
Peter E. Wasko

Mean 200-, 100-, 50-, and 25-mb contour maps with isotherms were constructed covering North America and the adjacent sections of the oceans for the four mid-seasonal months. The wind flow and temperature patterns at these levels are discussed and certain conclusions drawn.

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