Characteristics of number of high temperature days and heat wave from 1961 to 2010 in Liaoning province

Using daily maximum temperature data at 52 weather stations in Liaoning province from 1961 to 2010, characteristics of number of high tempetaure days and heat wave as well as their trends were analyzed. The results show that the number of annual mean high temperature day is 7.72 days per year in Liaoning province. For spatial distribution, it is higher in the west than in the east. High temperature days are seldom in the coast regions, and never appear in some regions. High temperatue days occur mainly in Chaoyang with 26.84 days per year. The number of annual high temperature days is in a gradually increasing trend since 1960s. The highest number of temperature days occurs in 2000 according to historical record of meteorologcal observation. Spatial distribution of heat wave is similar to that of high temperature, namely more in the west and less in the east. The significant heat wave occurs in Chaoyang, and its frequency is 2.90 per year. Light heat wave with 3-5 days duration is the main type in Liaoning province, accounting for 86.27 %, and then middle heat wave is 12.58%, while severe heat wave with more than 10 days duration is 1.14% and it only appears in Kazuo, Beipiao and Yangshan stations.