Impacts Of Surface Heating Anomaly Of The Tibetan Plateau In Winter On Snow And Ice Weather Over South China

Based on NCEP/NCAR, NCEP/DOE reanalysis data and the 743 station data provided by national climate center, this paper analyzed the character of surface heat flux on Tibetan plateau(TP) in winter and defined a TP heat index, based on this index, this paper used composite analysis, correlation analysis and several other methods analyzed the connection between the TP surface heating anomaly and the temperature and precipitation anomaly in south China, as well as the connection between the surface heating anomaly and atmospheric circulation. The main results are shown as following:(1) In winter, surface heat flux on TP have significant inter-annual oscillation, which is mainly influenced by surface sensitive heat flux, because the surface latent heat flux is very stable. In January, the value of surface heat flux is about 10W/m2 bigger than December(the year before), and in February the value is about 10W/m2 bigger than January. The whole trend of December and February are similar, which decreased between 1959 and 1982, and increased between 1982 and 2005. However, there is no significant mutation in January. Comparing the years of surface heat anomaly high with the years freezing rain/snow/ice stroke South China, we may find that they are well accorded in January but in February and December we cannot see this phenomenon.(2) TP surface heat flux is closely connected with surface minimum temperature in South China in January and February, when the TP surface heat flux is abnormally high, the minimum temperature is abnormally low in South China. However, for the December, connection character is just the opposite. For the geopotential height field, the increase of TP surface heat flux is helpful for establishing the Siberian high in December and assist the cold air move downward to China in January, while the Siberia high is more likely to be break in February if the TP surface heat flux is abnormally high. In addition, the TP surface heating is helpful for the northerly strengthen in near surface levels(such as 925 h Pa) and strength the southerly in mid and low levels(such as 700 h Pa).(3) In January 2008, extreme freezing rain struck South China. At the same time, the Tibetan Plateau(TP) was experiencing pronounced surface heating. The character of this extreme weather and its linkage to the TP surface heating anomaly were analyzed and the results show that: 1) Anomalous heating of the TP help to form and sustain the Siberia blocking high, which is important for dry and cold Siberian air flow southward persistently. 2).TP heating helps the moisture flux move more north and strength the southerly wind. 3).There are two Rossby wave trains in the middle and high layers of mid-latitudes(about 20°N–40°N). Correlation analysis reveal TP heating anomaly have great relation with these Rossby wave trains. 4). The Rossby wave propagates downstream from the TP to South China in the mid and high layers of the atmosphere when the TP changes swiftly from a heat sink to a heat source. This implies that anomalous heating on the TP may stimulate the Rossby wave train propagate downward in mid-latitudes.