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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. 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

During the pronounced 1982–83 El Niño, the 300 mb north circumpolar vortex was displaced further toward Japan (from its mean seasonal locations) than observed since the beginning of the vortex record in 1963. However, during the strong 1972–73 El Niño, the vortex was displaced toward the 180th meridian, and during the weaker 1965–66 El Niño toward the eastern Pacific, so that vortex displacements are not indicated to have been the same for different El Niño episodes. Based on the full 21-year record, the vortex has tended to be displaced toward 90°W when sea surface temperature (SST) in the region 0°–10°S, 180–80°W was above average, but toward the 180th meridian when the magnitude of SST deviation from average is considered.

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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 1982 as a whole. Unlike the situation in 1981 when there were an above-average number of stagnation days in comparison with the period 1936–75, with unique occurrences of stagnation in a belt extending from Minnesota to Maine, the year 1982 seems quite typical with respect to both number and location of stagnation days.

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J. K. Angell
and
J. Korshover

Abstract

A network of 63 well-distributed radiosonde stations has been used to estimate mean-annual temperature variations at the surface and for 85–30 kPa (850–300 mb), 30–10 kPa, 10–5 kPa, 10–3 kPa, and surface- 10 kPa layers for five climatic zones, both hemispheres, and the world for the interval 1958–81. At the surface and in the 85–30 kPa layer there was global cooling of about 0.5°C between 1958 and about 1970, and global warming since, with 1980 and 1981 values approximately 0.1°C warmer than observed in 1958 and 1959. However, an update using seasonal data indicates appreciable cooling again between the northern springs of 1981 and 1982. In the 30–10 kPa layer there has been slight global cooling during most of the interval 1958–81, resulting in an increase in lapse rate in the 85–30 and 30–10 kPa layers during the last decade. In the middle and high stratosphere (26–55 km), Northern Hemisphere rocketsonde data suggest a 3–5°C cooling between 1970 and 1976, but little temperature change since.

There is evidence for an 0.3°C decrease in Northern Hemisphere surface temperature following the Agung eruption in 1963, as well as at least a 1.0°C temperature increase in the low stratosphere of the tropics, but no convincing evidence that the eruptions of Fuego in 1974 or St. Helens in 1980 affected either tropospheric or stratospheric temperatures. Between 1958 and 1981, the correlation between sea-surface temperature (SST) in the equatorial eastern Pacific, and global temperature for the surface-10 kPa layer, is a significant 0.58 at a lag of two seasons, SST leading. There is some indication that, in the tropics, this lag increases slightly with distance from the equator and height in the troposphere. During the past decade there has been a close (inverse) relation between the area of the 30 kPa (300 mb) north polar vortex and 85–30 kPa temperature. During 1958–81 the departure from the mean of the seasonal 85–30 kPa temperature in north temperate latitudes averaged −0.4°C three seasons after cool SST in the equatorial eastern Pacific when the quasi-biennial oscillation (QBO) at 5 kPa in the tropics was in the eastwind phase, and 0.2°C three seasons after warm SST when the QBO was in the westwind phase. Inasmuch as SST has warmed through 1982, and the QBO east wind maximum at 5 kPa occurred in mid 1982, this relation would imply a relatively warm north-temperate troposphere in 1983.

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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. 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 1984. The number of “grid point days” of stagnation was considerably less in 1984 than in 1981 and 1983, and only Slightly more than in 1982. Thus, 1984 must be considered a year with relatively little stagnation. The stagnation episodes that did occur were almost an in the Southeast.

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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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J. K. Angell
and
J. Korshover

Abstract

Tropospheric temperatures tended to cool after the Agung (8°S) eruption in 1963, but warm after the El Chichón (17°N) eruption in 1982. Thus, over the one-year period following the eruptions, Northern Hemisphere surface temperature is indicated as cooling 0.34°C after Agung, but warming 0.37°C after El Chichón, a difference significant at the 0.5% level according to Student';s t-test. This difference in Northern Hemisphere temperature change is mainly due to differences in north temperate latitudes where, over the one-year period, the surface temperature is indicated as cooling 0.36°C after Agung but warming 1.27°C after El Chichón. It is proposed that the warming after El Chichón is mostly due to the anomalously warm sea surface temperature (SST) in the eastern equatorial Pacific (El Niño) in 1982–83, the relation between SST and tropospheric temperature being an obvious one in the tropics but of a more indirect nature in midlatitudes. The best evidence so far for a tropospheric cooling due to El Chichón is in the north subtropics (10–30°N) where the zonally-averaged air temperature continued to cool after the eruption in the spring of 1982, whereas SST in the region 0–10°S, 180–80°W warmed abruptly, the opposite of the relation usually observed. Since this SST returned nearly to normal at the end of 1983, the cooling effect of El Chichón should be more evident in 1984.

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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, me presented by month and for the year 1983 as a whole. The distribution of stagnation days in 1983 was quite typical of the 40-year mean, with the number of such days failing halfway between the relatively high number observed in 1981 and the relatively low number observed in 1982. A diagram shows the variation of “grid-point days” of stagnation with latitude and longitude for 1981–1983.

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