徐枝芳,吴洋,龚建东,蔡怡. 2021. GRAPES 3DVar系统2m相对湿度资料同化研究[J]. 气象学报, (0):-, doi:10.11676/qxxb2021.060
GRAPES 3DVar系统2m相对湿度资料同化研究
Assimilation study of 2m relative humidity observation in GRAPES 3Dvar system
投稿时间:2021-02-24  修订日期:2021-06-02
DOI:10.11676/qxxb2021.060
中文关键词:  2m相对湿度 GRAPES 3DVar 同化 理查森数
英文关键词:2 meters relative humidity,GRAPES 3DVar,assimilation, Richardson number
基金项目:
作者单位邮编
徐枝芳 国家气象中心 100081
吴洋 Tianjin Jinnan District Meteorological Bureau 300350
龚建东 National Meteorological Centre 100081
蔡怡 National Meteorological Centre 100081
摘要点击次数: 52
全文下载次数: 34
中文摘要:
      为了提高GRAPES(Global and Regional Assimilation PrEdiction System) 区域3km同化系统中2m相对湿度资料的应用效果,改善模式中相对湿度的分析和降水预报,本文通过分析2015年6-8月T639(T639L60全球中期数值预报系统,0.28125°×0.28125°)分析场低层相对湿度和2m相对湿度之差与表征稳定度理查森数(Richardson数)的关系,发现二者有很好的相关性,当大气不稳定(Ri<0)时,模式低层相对湿度与2m相对湿度的差异较小,基本在同化观测误差范围内。依据该统计结果,本文对GRAPES区域同化系统中2m相对湿度同化方案进行了优化,当大气不稳定(Ri<0)时,将观测站地形低于模式地形下的2m相对湿度观测由观测站高度改为模式最底层高度进行同化,从形成新的2m相对湿度同化方案,意在解决2m相对湿度资料同化时模式地形与观测站地形差异的影响。个例和连续试验结果显示:新的2m相对湿度同化方案同化分析资料量明显增加,08时(北京时)增加的资料量高于20时,这与T639分析场分析结果基本一致(08时大气不稳定测站数高于20时),新增观测点信息向量差(背景减观测B-O)与周围原有观测信息向量差保持基本一致,分析增量偏差和均方根误差减小,降水预报效果明显改善。
英文摘要:
      In order to improve the relative humidity analysis and forecast of GRAPES (Global and Regional Assimilation PrEdiction System) 3DVar (Dimensional Variational ) data assimilation system with 3km resolution, a new observation operator for 2m relative humidity observation, the tangent linear and its adjoint have been coded, tested, and then introduced in the GRAPES 3DVar operation assimilation system. The T639( T639L60 Global Medium Range Forecast System, 0.28125°×0.28125°) analysis of three months (1 June to 31 August, 2015) shows that the difference between relative humidity at lowest model level and at two meters as a function of the Richardson number. So 2m relative humidity can be directly compared to relative humidity at the lowest model level. The observation operator assumes that relative humidity is constant in the unstable surface layer. The results show that more 2m relative humidity observation is used in 3DVAR assimilation system with this scheme, and the relative humidity analysis is more close to observation. The EST (Equitable Threat Score) value of summer (1-31 July, 2018) experiments is higher when 2m relative humidity observations are assimilated with this scheme. The assimilation of surface relative humidity observations seems to be beneficial.
查看全文   查看/发表评论  下载PDF阅读器
分享按钮