Variations and Trends in Tropospheric and Stratospheric Global Temperatures, 1958–87

Abstract

Examined in this paper are the variations and trends in tropospheric and low-stratospheric temperature for seven climatic zones, hemispheres, and world for intervals 1958?87 and 1973?87, based on 63 well-distributed radiosonde stations. For the 30-yr interval 1958?87, these data indicate an increase in year-average global temperature at the surface and in the tropospheric 850?300 mb layer of 0.08°C (10 yr)?1 and 0.09°C (10 yr)?1, respectively, just significant at the 5% level. Nevertheless during this interval there is evidence for a slight decrease in year-average temperature at the surface and in the troposphere of the north polar and north temperate zones. The global 300?100 mb temperature is indicated as having decreased by 0.18°C (10 yr)?1 during this 30-yr interval (significant at the 1% level), with a temperature decrease in all seven climatic zones, though largest in the south polar zone (associated with the Antarctic ?ozone hole? phenomenon). For the 15-yr interval 1973?87, the global temperature in the low-stratospheric 100?50 mb layer is indicated as having decreased by a significant 0.62°C (10 yr)?1, the decrease again largest in the south polar zone 2.04°C (10 yr)?1 but observed in all zones except the north temperate zone. During 1958?87, there is evidence for an increase in the meridional temperature gradient between equatorial zone and north polar zone both at the surface and in the troposphere, but in the Southern Hemisphere then has been a decrease in this gradient at the surface and essentially no change in the troposphere. In the hemispheric and global average, warming has been greater (though not significantly so) in MAM (March?April?May) and JJA than in DJF and SON, both at the surface and in the troposphere, though in both polar zones the surface warming has been greatest in winter. The close relation between sea-surface temperature in the eastern equatorial Pacific and tropospheric temperature in the tropics is discussed in some detail. Finally, temperature variations and trends in the western hemisphere tropics are examined up to heights of 55 km using high-level radiosonde data and rocketsonde data.