The Objective Identification And The Climatic Characteristics Of TPV

Considering the geometry feature and the manual identification criterion of Tibetan Plateau Vortex, and Blender's near searching method, the TPV objective identification method was defined in this paper which has the similar theory with former researchers but with unique technology. First, using the NECP/CFSR high-resolution reanalyzed data in 2001 to 2010, the TPV database, about 10 years length, is built by this objective identification method. Then comparing and analyzing this database with other existed results, this method was perfected and testified. At the last, utilizing this improved method, it is calculated by NCEP/CFSR high-resolution reanalyzed data in 1981 to 2010, which the 30-years-long TPV statistic database. Further, the climatic character of TPV is found based on this database. The results are,(1)The unique objective identification method was defined, and the agreement rate between the result of this method and the subjective method database which based on NCEP/NCAR reanalyzed data, is greater than 60%, and 50% with the TPV Yearbook. The feasibility of using objective identification method on high-resolution reanalyzed data to long-term TPV statistic is primarily proved.(2)In last 30 years, by objective identification method, the annual average number of TPV presents a decreasing trend about 60 per year, and the inclination rate is-0.4 per year. Therefore, there is not a significant mutation of the annual mean frequency of TPV, but is period about 4a and 9a. The frequency of summer TPV shows the decreasing trend too, and the inclination rare is-0.03 per year. The amount of summer TPV is 1144, in this 30 years period, 66 % of total, and the maximum shows in June(3)The distribution of TPV central geopotential height value shows the character of Gaussian distribution, maximum in middle and minimum in sides. The 82.6% of central geopotential height appear at level 571 to 587 dapgm. By the objective identification method, the annual high frequency area of TPV is located at Naqu, Gaize, Shuanghu, the western Ali of Tibet and the Zarenkewu of Qinghai. And for annual, the west TPV about 717(39.4% of total), 632 for central(34.7%) and 468 for east(25.7%). For summer, the type of west TPV about 298(35.05% of total), central type about 301(35.4%) and east type about 251(29.5%). The summer generation area is the upside down delta-shaped region around Gaize, including Naqu, Ali, Shannan and the west of Qinghai. The main declining region of TPV is around Naqu of northeast Tibet, Golmud of Qinghai, Tanggula Mountains, Ulan Moron, Shigatse, and Western Sichuan Plateau. The declining region have a correlation with topography.(4)The amount of eastward moving-out Tibetan Vortices(MPTVs) account for 53.5% in summer, and the max month is July about 1.53 per year. The rate of moving-out TPVs is 15.59%. The annual average amount of eastward MTPVs in the whole year is 6.23, while that in spring and summer is 1.9 and 3.33.There is no significant mutation in the quantity of the MTPVs in the whole year and in spring, and the cycles of the MTPVs in the whole are 3 year and 7 year. There is no significant mutation in the quantity of the MTPVs in summer too, but the cycles of the MTPVs in summer are 2 year and 7 year.(5)In the high-frequency year of TPVs, there is a so strong airflow that draws abundant moisture from the south, and the positive vorticity advection accelerate the development of the TPVs. In the low-frequency year of TPVs, the north flow restrain the development of the TPVs.