A Quality Analysis And Application Of The GAME Reanalysis Data During The Summer Monsoon In 1998

For understanding the dynamic processes of the all scales cloud systems of Mei Yu, and the relationship between Mei Yu system and the summer monsoon of Eastern Asia, the HUBEX has been carried on by the cooperation of China and Japan in summer since 1998.The data observed by HUBEX, the data observed by other monsoon experiments and the general data (GTS data) were merged into the assimilation system of GAME and made into the GAME reanalysis data, so how the GAME reanalysis data? What new significations of Mei Yu and the summer monsoon of Eastern Asia are discovered in the reanalysis data? Therefore this paper consists of two parts, which we compared the GAME reanalysis data with NCEP/NCAR reanalysis data in the first part and have a dynamic analysis about the summer monsoon of Eastern Asia with the GAME reanalysis data in the second part.In the first part of the paper, on the basis of the weather processes of Huai He basin from June to August in 1998 , the difference and reliability of the two reanalysis data GAME and NCEP from the fields of basic element , derivative, precipitation, and surface flux were studied by diagnostical and statistical methods. The results showed that the GAME reanalysis data is more reliable than NCEP/NCAR reanalysis data at the bottom and mid-high levels of troposphere, and at the precipitation andsurface flux fields the case is just the same. In addition, the paper revealed that the GAME reanalysis data can show the evolution of the southwest vortex but the NCEP/NCAR reanalysis data cannot do so. Meanwhile the results also showed that the main cause of which the GAME reanalysis data being better than the NCEP reanalysis data is the GAME reanalysis data including the sonde data of the GAME but not the different assimilation modes of the two reanalysis data. Therefore the paper also indicated that the HUBEX as the Eastern Asia part of the GAME is necessary to continue, and increasing the temporal and spatial resolution of meteorologic elements observed is important to improve our forecasting accuracy of the weather and climate.In the second part of the paper, with employing the GAME reanalysis data and on the basis of the theories of the baroclinic vorticity development, this paper inferred from the dynamic analysis that the horizontal vorticity can represent the baroclinic intensity of the large-scale atmosphere, and the conversion of the horizontal vorticity converting into the vertical vorticity is actually the phenomenon that the horizontal vorticity flux of the summer monsoon owning the striking longitudinal-direction vertical structure and the strong baroclinicity, influence on the horizontal movement of the atmosphere. To the large-scale atmosphere, we separate the terms of the horizontal vorticity converting into the vertical vorticity, which considered as the baroclinic terms, from the terms that notincluding horizontal vorticity by the rules of the P coordinate transforming to the Z coordinate in the traditional vorticity equation, and carry out the scale analysis, and then conclude that the baroclinic terms are able to reach the same magnitude grade as the partial derivative of the vertical vorticity to time when it takes place the large scale precipitation in the summer monsoon period in china .By analyzing the GAME reanalysis data from April to August in 1998 in the region of Chinese continent, we found that the baroclinic terms is important to the large-scale cyclone developing above the 600hPa , and the magnitude changing of the baroclinic terms is nearly in-phase as the monsoon movement , so which imply exactly that the magnitude changing of the baroclinic terms is the one of the natural characters of the summer monsoon evolution and equivalent to the movement rule of the subtropical high of the western pacific.