GRAPES紫外线（UV）数值预报

应用GRAPES（Global/Regional Assi milation PrEdiction System）模式中的Goddard短波辐射方案,创建了紫外线数值预报系统（GRAPES-UV）。介绍了Goddard短波辐射方案,给出了GRAPES-UV系统的运行和个例分析。研究结果表明,紫外线指数（UVI）除了与纬度、地形和日变化有关外,还与云的分布以及天气形势密切相关,GRAPES模式中云的微物理方案对UV预报有较大的影响,UVI在晴空和对流云降水地区的强烈反差是UVI的重要特征。在个例试验中应用了臭氧总量预报模式,通过T213模式为化学输送模式提供气象背景,利用卫星资料同化技术建立臭氧的初始场,预报大气臭氧总量。应用国际上通常采用的临界成功指数（CSI）对2007年夏季北京和上海UV预报进行统计检验。北京和上海24 h紫外线强度等级为强和很强的CSI分别为0.625和0.780,接近同样方法的美国检验结果0.677。该系统从2006年3月起在中国气象局大气成分观测与服务中心的业务系统中正常运行,并在大气成分中心网站上发布UVI和紫外线强度等级预报,并提醒公众采取合适的方法保护自身免受UV的过度辐射。

GRAPES Numerical Ultraviolet Prediction

The system for numerical ultraviolet （UV） prediction （GRAPES-UV） using Goddard short-wave radiative scheme with GRAPES （Global/Regional Assimilation PrEdiction System） is established. The Goddard short-wave radiative parameterization scheme and the executing of the GRAPES UV system are described, and case studies are conducted. It is shown that the effect of cloud microphysical processes in GRAPES on UV forecasts is important; the improvement of the cloud microphysical scheme make UV forecasts based on weather possibly; ultraviolet index （UVI） correlates to cloud distribution and weather situation; the strong contrast of UVI between clear sky and convective cloudy areas is an important feature of UVI. An application experiment of total ozone prediction was conducted using T213 to provide the meteorological background for the chemical transport model and using the satellite data assimilation technology to establish the initial fields. The UVI forecasts for Beijing and Shanghai in the summer of 2007 are verified statistically using the Critical Success Index （CSI） in common use internationally. The CSIs corresponding to the high and very high exposures of UV grades in 24 hours for Beijing and Shanghai are 0. 625 and 0. 780 respectively, approaching to the results of verification for United States with the same method. The GRAPES-UV system has been running on the operational IBM computer system at the Center for Atmosphere Watch and Services （CAWAS）, the Chinese Meteorological Administration （CMA）, since March 2006, and has issued forecasts for UVI and UV exposure grades to remind the public of overexposure to UV radiation at the CMA/CAWAS website.