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J. K. Angell and Korshover

Abstract

The global variation in temperature, during the period 1958–75 is investigated using a sample of 63 radiosonde stations. The surface temperature as well as the mean temperature in 850–300 mb and 300–100 mb layers is examined, the latter based on thickness analysis. Between 1958 and 1965 there was a significant cooling averaging about 0.3°C over much of the globe, but since 1965 the temperature variations have been small. During the past few years there has been a slight warming in most latitudes. The meridional temperature gradient between the tropics and temperate latitudes has continuously increased, but since 1965 the temperature gradient between temperate and polar latitudes has decreased, with an especially large surface warming indicated for Antarctica. In the tropical troposphere, a temperature oscillation of about 3-year period and 0.3°C amplitude has been dominant since 1965. The eruption of Mt. Agung in 1963 may have decreased the surface temperature by as much as 0.2°C in the tropics, 0.4°C in the south extratropics and 0.6°C in the north extratropics. In the south extmtropics there was also a 0.7°C warming and cooling in the 300–100 mb and 850–300 mb layers, respectively, in the year of the eruption. Also shown is the variation with longitude of the temperature changes and the tendency for increased spatial variability of temperature.

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J. K. Angell and J. Korshover

Abstract

Based on a network of 42 radiosonde stations distributed around the world, the (smoothed) global temperature within the 100–30 mb layer was indicated to be colder in the spring of 1977 than at any time since initiation of the record in 1958, a result mainly of very cold temperatures in the tropics (east wind phase of the quasi-biennial oscillation). This cold followed by about six months the record-cold global temperature observed for the surface–100 mb layer. The highest global temperature of record in the 100–30 mb layer was observed after the eruption of Mt. Agung in 1963, the phase of the quasi-biennial oscillation in the tropics being such as to augment any stratospheric warming induced by Agung. Since the Agung eruption, there is indicated to have been slightly greater global cooling in the 100–30 mb layer than in the surface–100 mb layer. However, this result derives solely from uncertain Southern Hemisphere data and cannot be cited as evidence of a carbon dioxide influence on atmospheric temperature because in the Northern Hemisphere, if anything, an opposite tendency has been observed.

The quasi-biennial oscillation of temperature in the low tropical stratosphere extends, with much reduced amplitude, into the north-temperate-latitude stratosphere with a lag time of about two months. There is evidence of tropospheric temperature variations in north extratropics which follow the three-year oscillations in the tropics by about six months (of obvious importance for seasonal foreshadowing in northern latitudes), as well as evidence that temperature variations in the low tropical stratosphere follow the variations in the tropical troposphere by about nine months. However, a longer data record is required to clarify the relation between El Nin˜o occurrences, or the Southern Oscillation, and the quasi-biennial oscillation of the tropical stratosphere.

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J. Korshover and J. K. Angell

Abstract

The number and location of stagnation days within the eastern United States, as estimated mainly from a surface geostrophic-wind criterion, is presented by month and for the year 1985. The number of “grid-point days” of stagnation was exactly the same in 1985 as in 1984, a year with relatively little stagnation. However, the stagnation in 1985 occurred mainly over the mid-Atlantic states whereas in 1984 it occurred mainly over the Southeast.

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J. K. Angell and J. Korshover

Abstract

No abstract available.

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J. K. Angell and J. Korshover

Abstract

The average latitude, longitude and central pressure of the four centers of action (Icelandic low, Aleutian low, Azores high, Pacific high) have been estimated for each of the 80 years of the Northern Hemisphere Historical Weather Map Series (1899–1978), and compared with year-average values of Northern Hemisphere surface temperature (NHST) and sea surface temperature (SST) in the region 0–10°S, 180–90°W of the equatorial eastern Pacific. Inasmuch as NHST and SST have been positively correlated during the 80-year period, their relations with the centers of action have been estimated using partial correlation coefficients.

While there has been a tendency for northward displacement of all four centers of action at time of hemispheric warming, none of the partial correlations is significant at the 95% level, taking into account the serial correlation of the data. However, the correlation (r) of 0.31 in the case of the Aleutian low is on the verge of significance, and the correlation of 0.33 in the case of the Pacific high is appreciable. Hemispheric warming has, however, been associated with a significant lowering of pressure in the Icelandic low (r = −0.31) and Aleutian low (r = −0.45), the latter correlation being significant at the 99% level. A warm equatorial sea surface temperature has been associated with a significant southward displacement (r = −0.31) and higher pressure (r = −0.35) of the Icelandic low, as well as a significantly lower pressure of the Azores high (r = −0.36) and the Pacific high (r = −0.45), the latter correlation being significant at the 99% level.

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J. K. ANGELL and J. KORSHOVER

Abstract

No Abstract Available.

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J. K. ANGELL and J. KORSHOVER

Abstract

Based upon 78 months of mean-monthly zonal-wind and temperature data, the phase angle and amplitude of the third (26-month) harmonic is determined as a function of latitude and height for stations within or bordering the North Pacific Ocean. In tropical latitudes the 26-month zonal-wind oscillation can always be traced down to the 200-mb. surface and frequently much lower. However, the 26-month temperature oscillation is usually not detectable below the 100-mb. level. In temperate latitudes, particularly at high levels, a mean-monthly zonal-wind oscillation of about 26-month period occurs which, with considerable justification, can be associated with the 26-month oscillation in the Tropics. Analysis of the 26-month temperature oscillation shows that this oscillation is even more easily traced into the temperate latitudes at high levels, but with a rather pronounced phase shift, so that north of the Tropic of Cancer the minimum temperature in the 26-month oscillation occurs at approximately the same time as the maximum temperature occurs south of this latitude. The thermal wind resulting from this temperature change with latitude is consistent with the observed 26-month zonal-wind oscillation.

A search for the cause of the heating and cooling with which the biennial wind oscillation apparently is associated is complicated by the fact that in tropical latitudes the downward progression of the warming with time appears most likely associated with small-scale eddy heat fluxes, while in polar and temperate latitudes the heating and cooling take place nearly instantaneously at all levels, suggesting the influence of vertical motions associated with a reversible meridional cell.

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J. K. Angell and J. Korshover

Abstract

Based on smoothed year-average data for the period 1964–76, there has been considerable similarity among the time trends in equatorial tropopause temperature, water vapor amount in the low stratosphere at Washington, DC, and total ozone in north temperate latitudes, the latter two trends in particularly close agreement with a six-month lag (ozone variation following water vapor variation). The trends in these three parameters have been generally out of phase with the temperature trend in the low stratosphere of north temperate latitudes. The phase lag between radiosonde-derived and rocketsonde-derived temperature variations over the United States suggests that an out-of-phase relation may exist between temperature trends and ozone trends (the latter obtained from Umkehr measurements) in the upper midlatitude stratosphere.

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J. K. Angell and J. Korshover

Abstract

The Brewer-Dobson hypothesis that the stratospheric water vapor amount in temperate latitudes is governed by the water vapor removal capability (temperature) of the tropical tropopause is reexamined using the 11 years of stratospheric water vapor data obtained at Washington, D.C., by Mastenbrook. In the case of the annual variation, the tropopause temperature at equatorial stations Singapore and Gan is a maximum in August, whereas at Washington the water vapor mixing ratio is a maximum in October for the 100–80 mb layer and in March for the 70–50 mb layer. The 5-month difference in lag time implies a rather slow vertical mixing in the low stratosphere. These lag times correspond to mean meridional transport velocities of about 0.8 and 0.2 m s−1, respectively. In the case of the quasi-biennial oscillation, the mixing ratio in the 100–80 mb layer at Washington is a maximum 6 months after the tropopause-temperature maximum at Singapore and Gan, with the lag increasing to 12–13 months for the 70–50 mb layer. These lag times correspond to mean transport velocities of 0.3 and 0.1 m s−1, respectively. Over the 11–14 year period of record, the tropopause saturation mixing ratio at Singapore and Gan increased by about 0.5 ppm, whereas the stratospheric mixing ratio at Washington increased by 0.7 ppm, but this similarity in trend is not found at all stations. While these data tend in general to support the Brewer-Dobson concept, the relations are not sufficiently clear-cut as to completely deny other possibilities.

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J. K. Angell and J. Korshover

Abstract

Temperatures at 50, 30, 20 and 10 mb in the western quadrant of the Northern Hemisphere are used to estimate the stratospheric warming resulting from the volcanic eruptions of Agung in 1963 and El Chichon in 1982. After allowing for quasi-biennial temperature variations, a warming of about 4°C is fond at 50 mb in the equatorial zone following Agung, and at 30 mb in the north subtropics following Chichon. In both cases the warming was at a maximum two seasons after the eruption. The Chichon-induced warming in the American sector of the north subtropics is indicated to be slightly greater than in the Pacific sector.

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