Comparison of surface and tropospheric temperature trends estimated from a 63-station radiosonde network, 1958-1998

Comparisons of surface and tropospheric (850-300 mb) temperature trends for climate zones, hemispheres and globe are presented for the period 1958-1998, based on seasonal and annual-mean temperatures from a 63-station radiosonde network. Globally, the surface warmed by 0.14+/- 0.13K/decade during the 41-year period, the 850-300 mb layer by 0.10+/-0.09K/decade. This small difference in global trend results from the surface warming by 0.12K/decade relative to the 850-300 mb layer in the northern hemisphere, but the 850-300 mb layer warming by 0.04K/decade relative to the surface in the southern hemisphere. In north polar and temperate zones the warming of the surface relative to the 850-300 mb layer is greatest in winter-spring and there is little difference in trend in summer. There is a tendency for a similar seasonal variation in trend difference in south extratropics, warming of the surface relative to the 850-300 mb layer occurring only in winter in the south polar zone, and cooling of the surface relative to the 850-300 mb layer greatest in summer in the south temperate zone. Globally, the warming of the surface relative to the 850-300 mb layer is 0.11K/decade during 1979-1998, compared to 0.04K/decade during 1958-1998, but with the 95% confidence intervals approximately twice as great for the 20-year period as for the 41-year period.