摘要
在对流性天气预报工作中,沙瓦特指数是一个被广泛应用的物理量,准确、快捷计算该指数一直以来都具有重要的实际意义。根据干、湿绝热过程相当位温守恒原理,运用David Bolton给出的系列公式计算凝结温度、相当位温,利用计算机编程实现了应用探空资料自动、准确计算沙瓦特指数。11个实例的计算表明,与其他5种沙瓦特指数计算方案相比,新方案计算简洁、绝对误差的平均值与最大值均有所减小。其可能的原因是,计算中间过程避免了繁琐的数学推导和多次近似处理,且抬升凝结温度、相当位温等重要物理量计算比较准确。利用2010—2011年湖北省汉口站MICAPS格式探空资料,对比了查表法与新计算的沙瓦特指数对有、无雷暴天气的预示作用。结果表明:如果规定该指数小于零时有雷暴,则计算得出的数据可以减少雷暴漏报。
Since Showalter index is widely applied in convective weather analysis and forecast, it is meaningful to calculate it accurately and rapidly all the time. Based on the rule that equivalent potential temperature is unchangea- ble during both dry and moist processes, condensation temperature and equivalent potential temperature were calcu- lated using a series of equations provided by David Bolton. Showalter index was computed automatically and accu- rately by a program in terms of radiosonde data. 11 cases were selected to calculate Showalter index using the new method. Compared with other 5 methods, the new method has characteristics of simple calculation, less average and maximum absolute errors. The possible reasons included two aspects. Many complex derivations and approximation treatments had been avoided. On the other hand, the deduced figures such as the lifting condensation level tempera- ture,the equivalent potential temperature were more accurate than that from other methods. Based on the radio- sonde data with MICAPS format from 2010 to 2011 at Hankou station in Hubei province, the forecast accuracy of two methods, namely, a table method and the new method in this paper, was compared for thunderstorm. The re- suits show that the missed number of thunderstorm is reduced if a negative Showalter index is used as a factor to show the possible presence of thunderstorm. In addition, a limitation of the new method is also discussed.
出处
《气象与环境学报》
2013年第1期12-17,共6页
Journal of Meteorology and Environment
基金
公益性行业(气象)科研专项"华南持续性暴雨中尺度特征诊断分析和预报技术研究"(GYHY201106003)
国家自然科学基金青年科学基金"江淮梅雨锋暴雨降水日变化的分析与模拟研究"(41105073)
国家自然基金(41105072)共同资助
关键词
相当位温守恒
沙瓦特指数
计算流程
绝对误差
Conservation of equivalent potential temperature
Showalter index
Calculation process
Absolute error