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J. K. ANGELL

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J. K. ANGELL

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J. K. ANGELL

Abstract

On the basis of wind speeds and accelerations derived from U.S. Navy sponsored 300-mb. constant level balloon or transosonde flights made during 1953, 1955, and 1956, statistics are presented on the magnitude of the ageostrophic wind and its variation with latitude and wind speed. These statistics indicate that at 300 mb. the average angle between wind and geostrophic wind is 11 degrees and the mean magnitude of the vector deviation between wind and geostrophic wind is 12m.see.−1. The data also show that, through the use of the geostrophic and gradient wind approximations, half the time errors greater than 29 percent and 11 percent, respectively, are introduced into the derived results.

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J. K. Angell

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The quasi-biennial variation in zonal-wind period and amplitude is examined for Balboa and Ascension at 50, 30 and 10 mb, and for Singapore at 50 and 30 mb, through July 1985. The increase in zonal-wind period following the Agung eruption in 1963 is shown to be due almost entirely to an increase in west-wind half period at 50 mb but east-wind half period at 10 mb. There have been average correlation coefficients of 0.96 and 0.71 between zonal-wind half periods at 50 mb and the next downcoming half period of opposite phase at 10 mb. There is little indication of a relation between zonal-wind period or amplitude and equatorial sea-surface temperature (El Niño), and the nearly inverse relation between zonal-wind period and sunspot number is not significant at the 5% level taking into account serial correlations. The 30 mb west-wind amplitude was relatively large at Balboa and small at Ascension after Agung, but there is little evidence of an appreciable change in amplitude or period following the EX Chichón eruption in 1982. Consequently, the impact of volcanic eruptions on the quasi-biennial oscillation is uncertain at this time.

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J. K. Angell

Abstract

Based on an average of the total-ozone changes determined by means of linear regression at individual Dobson stations within climatic zones, trends of total ozone for each of the four seasons have been evaluated for five climatic zones, and the world; intervals are 1960–84, 1965–84, 1970–84 and 1975–84. Based on ozonesonde data, trends of ozone by season in 2–8 km, 8–16 km, 16–24 km and 24–32 km layers have been evaluated for the four extratropical climatic zones for intervals 1965–84, 1970–84 and 1975–84. The decrease in September–October–November (SON) total ozone relative to other seasons in the south polar zone (Antarctica) is observed in the last 10–15 years also in south temperate, tropical and north polar zones, and for the world as a whole, but the seasonal differences in trend are significant only in the south polar zone. In the north temperate zone, where the data are most numerous, the total ozone has decreased in December-January-February (DJF) relative to other seasons, although in the last decade the trends in DJF and SON an comparable. The decrease in SON total ozone relative to other seasons is indicated to be due mainly to an ozone decrease in the 16-24 km layer of the south polar zone and the 24-32 km layer of south temperate and north polar zones, but once again the seasonal differences in trend are not significant. There are inconsistencies in the north temperate zone between relative seasonal changes in total ozone and layer-mean ozone, casting doubt on the representativeness of the ozonesonde data. There has been a substantial decrease of SON temperature in the 16–20 km layer of the south polar zone, presumably associated with the ozone decrease in this region in this season. The global surface temperature has also decreased in SON relative to other seasons, perhaps associated with the relative decrease of global total ozone in this season during the last decade.

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J. K. ANGELL

Abstract

A comparatively unbiased set of wind statistics at jet-stream level from Japan eastward to the 180th meridian may be obtained from the United States Navy constant level balloon (transosonde) flights launched from Japan in 1957–59. Wind speeds so derived are presented as a function of time of year and longitude at pressure surfaces of 300 and 250 mb. At these longitudes and heights the average speed is 103 kt. in fall, 123 kt. in winter, and 101 kt. in spring. A comparison with mean meridional cross sections indicates that at these levels in this area of the north-western Pacific the mean wind speed heretofore may have been underestimated by an amount exceeding 25 kt.

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J. K. ANGELL

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J. K. ANGELL

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J. K. ANGELL

Abstract

Routine Navy-sponsored 300-mb. transosonde flights from Japan for the months September 1957–February 1958 are analyzed. Statistics on the wind velocity, acceleration, and power spectra for the flights are indicated. With the aid of radiosonde data, the mean vertical motions and mean horizontal divergences along the flights are evaluated. Comparisons of transosonde velocities with geostrophic velocities obtained from National Weather Analysis Center maps are presented.

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J. K. ANGELL

Abstract

The magnitude of analysis errors over the northeastern Pacific at 300 and 250 mb. is estimated by means of winds and geostrophic winds derived from operational transosonde flights from Japan. The results suggest that the ratio of vector geostrophic wind error and geostrophic wind varies from 0.15 near the west coast of North America to 0.40 in the North-Central Pacific. The influence of these analysis errors upon numerical forecasting, airplane dispatching, and trajectory estimations is indicated. As one of the, alternative methods for increasing the number of upper-air observations over the oceans, the present stalemate with regard to the horizontal sounding system is considered, and suggestions made for breaking this stalematge.

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