Variation in global tropospheric temperature after adjustment for the El Nino influence, 1958–89

Abstract

Data from a 63‐station radiosonde network are used to estimate the variation in global tropospheric (850–300 mb) temperature between 1958 and 1989. The annual temperature was a maximum in 1988, 0.42°C above the 1958–88 mean. However, the 1989 value is indicated to be only 0.12°C above this mean. During 1958–88, there has been a correlation of 0.76 (significant at the 0.1% level) between annual values of global tropospheric‐temperature deviation and annual values of sea‐surface temperature (SST) deviation in eastern equatorial Pacific two seasons earlier. The associated linear‐regression line indicates that an annual SST deviation of 1°C in the region 12°S‐2°N, 180°‐90°W has been related on average to an annual global tropospheric‐temperature deviation of 0.36°C. The annual values of global tropospheric temperature have been adjusted based on this regression. With this adjustment, the year‐to‐year variability in global tropospheric temperature is halved, the increase in decadal mean temperature between the 1960's and 1980's is reduced from 0.33°C to 0.24°C, the annual temperature is a maximum in 1989 (0.39°C above the 31‐year mean) rather than in 1988, and there is much more convincing evidence that the eruptions of Agung in 1963 and El Chichon in 1982 decreased global tropospheric temperatures by 0.2–0.3°C for about 3 years.