A Comparison of Tropospheric Temperature Changes over China Revealed By Multiple Datasets

Abstract:

Based on four radiosonde datasets and three reanalysis datasets, analyzed the long-term tropospheric temperature changes over China for the period 1958-2001 and the uncertainties. The results from all datasets except for HadAT2 and 20th Century Reanalysis data (20CR) show a significant warming trend in the lower-troposphere temperature averaged over China during 1958-2001, but this trend decreases with height and is replaced by a cooling tendency at 500hPa, reaching maximum cooling at 300hPa. The year-by-year changes of temperature over China are largely in agreement among the radiosonde and the reanalysis datasets. The uncertainties of upper-troposphere temperature changes are larger compared with those of the lower troposphere. The uncertainty was relatively small during 1970-1990 and large during 1958-1970 and from 1990 to the present. The trend uncertainty is large in the Northwest for the lower troposphere and in South China for the upper troposphere, with the largest trend uncertainty over Northwest China at 850hPa and east to 100ºE at 300hPa. For the average temperature trend over China, the largest uncertainty peaks at 300hPa for 1958-2001. The tropospheric temperature of China at 300hPa, derived from HadAT2, warms up; this differs greatly from the other datasets. The warming trend is produced mainly by the stations over South China and is due to the choice of neighbor stations during construction. The temperature trend at 300hPa in NCEP-NCAR is cooler than the other datasets due to its abrupt cooling around the early 1990s. 20CR can partly capture the cooling tendency at 300hPa over North China but with weaker magnitude.