A study of objective determination method for the Kunming quasi-stationary frontline

According to synoptic characteristics of Kunming Quasi-Stationary Front (KQSF), an objective method to determine its frontal position is proposed, implemented and verified based on daily ground observations over the Yunnan-Guizhou Plateau and the surrounding area for the period of 1961-2010 and ERA-Interim reanalysis data (0.125°×0.125°).The objective determination method incorporates multiple frontal synoptic characteristics, including vertical and horizontal distributions of thermal fields, wind shears in the direction of latitude and the scale of KQSF over the Yunnan-Guizhou Plateau. Verification of typical weather processes and statistical analysis of relevant climate data indicate that the objective method proposed in the present study is reasonable. Identification of the frontline and its position is basically consistent with subjective results of experienced forecasters. Based on the method, all cases of KQSF are identified for the period of 1961-2010.Some climatic characteristics of KQSF such as its average direction and position, its long-term and annual variations and others spatiotemporal variability characteristics are updated or first revealed by the new statistics work. The objective judgment method can avoid inconsistency in KQSF analyses from different forecasters, and ensure the consistency of long sequence sample identification. This method provides the possibility for quantitative study and numerical prediction of KQSF.