Difference in radiosonde temperature trend for the period 1979–1998 of MSU data and the period 1959–1998 twice as long



The difference in temperature trend for the 20-year period 1979–1998 and 40-year period 1959–1998 is estimated from a 63-station global radiosonde network. The variability of radiosonde-station temperature trends, as measured by their standard deviation, is about twice as great for 1979–1998 as 1959–1998. The cooling trend in the 100–50 mb layer of the low stratosphere is similar in polar, temperate and tropical zones, and about twice as great during 1979–1998 as 1959–1998. The cooling trend in the 300–100 mb layer of extratropics is also greater during 1979–1998 than 1959–1998, but the slight tropical warming is almost the same for the 2 periods. The warming trend in the tropospheric 850–300 mb layer is similar during 1959–1998 and 1979–1998, except in the south temperate zone where there is indicated to be cooling during 1979–1998. At the surface of the north polar zone the warming trend during 1979–1998 is nearly 3 times the warming during 1959–1998. In the global average the surface and 850–300 mb warmings are the same during 1959–1998, but the surface warms relative to the 850–300 mb layer during 1979–1998.