摘要:将NCEP的中期全球预报系统（GFS）整套物理过程包引入GRAPES区域模式，并利用美国ARM计划（Atmospheric Radiation Measurement Program）南部大平原外场1997年夏加强观测资料，对GRAPES模式中原有物理过程和GFS物理过程进行了单柱试验的测试和比较，评估了两组物理过程的模拟性能。单柱试验结果表明GFS试验模拟的位温和水汽混合比演变更为准确；到地短波和长波辐射的误差更小；其模拟的地面向上潜热通量与观测更为接近，而原物理过程试验的感热偏大；GFS试验对2 m气温最高和最低值的模拟也比原有物理过程更接近观测。进一步分析降水的模拟发现，两组物理过程对强降水过程均有很好的预报能力，但对中等强度降水存在漏报或者发生时间偏晚的倾向，此外还存在对小雨的空报。在3个降水事件的模拟中，GFS试验模拟的降水误差小于原物理过程试验。最后还对两组试验中明显的降水过程漏报和降水延迟进行了分析，对GFS物理过程包中对流参数化的对流触发方式的修改，可改进此次降水的模拟，进而通过更准确的反馈过程，改善对大尺度场的模拟。
关键词:GRAPES区域模式/
中期全球预报系统(GFS)/
物理过程包/
单柱试验/
对流参数化
Abstract:The physics package of the NCEP Global Forecast System (GFS) and its single column version have been implemented in the GRAPES-MESO model. Using the data collected at the ARM (Atmospheric Radiation Measurement Program) Southern Great Plain site during the intensive observing period in the summer of 1997, several experiments of single-column model (SCM) are conducted to test the performance of a set of original physical schemes of GRAPES-TCM and the GFS physics package implemented. Temperature, moisture, radiation, surface heat flux, surface air temperature and precipitation are evaluated. It is found that the potential temperature and water vapor mixing ratio simulated by the GFS experiment is more accurate than that simulated by the original physical schemes in GRAPESTCM. Errors of surface downward solar and long-wave radiation fluxes simulated by the GFS experiment are less than that by the original physical schemes and upward latent and sensible heat fluxes also agree better with observations. The maximum and minimum 2-m air temperatures of the GFS experiment are close to observations compared with that simulated with the original physical schemes. Analysis of precipitation simulation shows that both sets of physical schemes can well reproduce heavy rainfall events. The failure and delay of moderate rainfall events and overestimation of drizzle events are commonly found for the two sets of experiments. For the case studies of three rainfall events, the errors of precipitation rate simulated by the GFS experiment are smaller than that simulated by the original physical schemes. This study also analyzes cases in which rainfall events are either missed or delayed in forecasts of both experiments and reveals that the modification of the trigger method in the cumulus parameterization scheme can significantly improve the simulation of precipitation, which subsequently improves the simulation of large scale fields via more accurate feedback.
Key words:GRAPES regional model/
GFS (Global Forecast System for Medium Range) physics package/
Single column model experiment/
Convection parameterization/
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