L波段秒级探空资料在GRAPES同化系统中的应用研究

我国探空站的探空系统升级为L波段探空系统后,可以获取全国120个站点连续自动测定的高空温、压、湿、风等高垂直分辨率秒级和分钟级探空廓线数据。为了分析高垂直分辨率探空秒级资料水平和垂直结构特征,并将其应用于区域GRAPES-3DVAR变分同化预报系统中,文章比较秒/分钟级探空与传统探空资料使用对资料同化预报带来的影响。试验中使用2011年6—7月资料进行分析,结果发现:秒级探空资料具有水平分布均匀,垂直结构非常密集的特点;在850、500 hPa等层次上高度分析比传统探空分析更接近NCEP分析,显示出对分析场的改进效果;同时风场在200 hPa以上的高层分析中改进显著,表现出高分辨率资料使用在高层分析中对系统模拟更加准确的特征。由于模式预报初值的改进,降水预报评分有所提高,预报偏差明显变小。因此高垂直分辨率秒级探空资料的使用对数值模式分析初值及预报的改进有着积极的意义,这为进一步开发利用秒级探空资料打下基础。

Study of L Band Second Level Radiosonde Data Applied in GRAPES Assimilation System

After the radiosonde system of radiosonde station in China was upgraded to the L band sounding system, the high resolution vertical second level or minute level sounding data including temperature, pressure, humidity, wind profiles at 120 national stations can be continuously and automatically obtained. In this study, the high resolution vertical second level sounding profiling data are used to analyze the characteristics of their horizontal and vertical structures and to apply to GRAPES 3DVAR Regional Variational Assimilation Prediction System so as to compare the difference between the high resolution vertical second/minute level sounding profiling data and the traditional ones applied on the assimilation and prediction. The experiments using the data of June and July in the year of 2011 show encouraging results. The second level sounding profiling data can lead to a uniform horizontal distribution with highly dense vertical structure. The analyses of height field at 850 hPa and 500 hPa layers are closer to NCEP analyses than those with the traditional sounding data, which shows the improved effect for the analysis fields. Meanwhile, there is a significant improvement on the wind analysis fields for 200 hPa and higher layers, which shows the application of high resolution data on the high layer analysis can lead to more accurate system simulation. Furthmore, due to the improvement of the initial fields for the model prediction, the performance score for precipitation forecast increased and the forecast deviation obviously becomes smaller. Conclusively, the use of high resolution vertical radiosonde data has a positive impact on the initial analysis and forecast improvements of numerical model, which can provide the necessary foundation for the further development and utilization of second level radiosonde data.