Tropospheric temperature inversion over central China

A four-tiered pattern of temperature inversion over central China is revealed using radiosonde data at seven stations in China during 1990–2010. The statistical features of climatic distribution, typical temperature structure and seasonal variation of each temperature inversion are obtained. The formation mechanism of this four-tiered pattern is then explored. The results show that there is one temperature inversion layer in the lower troposphere, one in the middle troposphere, and two inversion layers in the upper troposphere. The inversion in the lower troposphere occurs frequently in spring and autumn, and is likely caused by radiation cooling. The inversion in the middle troposphere is a representative of temperature characteristic over central China; it appears in winter and disappears in summer. The inversion in the middle troposphere depends on geographical location and synoptic cold-front system. It is the result of cold advection from northern China at a lower level and warm advections from both western and southern China at a higher level. The two inversions in the upper troposphere are associated with extratropical tropopause and tropical tropopause, respectively. The extratropical tropopause generally occurs in higher latitude and rarely occurs in lower latitude over China, with higher frequencies in winter and spring and a lower frequency in summer. The tropical tropopause varies little with season or latitude, neither does the associated inversion. Only ~ 35% of the extratropical tropopause samples are accompanied by temperature inversion, while nearly 100% of the tropical tropopause samples are accompanied by inversion. The tropical-tropopause inversion is a temperature inflection from troposphere to stratosphere. The mechanism of the extratropical-tropopause inversion needs further study.

► A four-tiered pattern of temperature inversion over central China is discovered.
► Low-troposphere inversion is caused by radiation cooling.
► Mid-troposphere inversion is the co-result of cold advection and warm advections.
► Upper-troposphere inversions are caused by extratropical and tropical tropopause.