卢冰,孙继松,仲跻芹,王在文,范水勇. 2017. 区域数值预报系统在北京地区的降水日变化预报偏差特征及成因分析[J]. 气象学报, ():-, doi:10.11676/qxxb2017.021
区域数值预报系统在北京地区的降水日变化预报偏差特征及成因分析
Diurnal Variation Deviation Characteristic of Regional Numerical Forecast Precipitation and its Cause Analysis in Beijing Area
投稿时间:2016-11-14  最后修改时间:2016-11-30
DOI:10.11676/qxxb2017.021
中文关键词:  降水日变化  局地环流  温度梯度  地形辐合线  土壤湿度
英文关键词:Diurnal variation of precipitation  Local circulation  Temperature gradient  Topographic convergence  Soil moisture
基金项目:公益性行业(气象)科研专项经费项目(GYHY201406012)
作者单位E-mail
卢冰 中国气象局北京城市气象研究所 blu@ium.cn 
孙继松 北京市气象台 sunjs_0314@sina.com 
仲跻芹 中国气象局北京城市气象研究所 jqzhong@ium.cn 
王在文 中国气象局北京城市气象研究所 zwwang@ium.cn 
范水勇 中国气象局北京城市气象研究所 syfan@ium.cn 
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中文摘要:
      为了研究北京快速更新循环同化预报系统(BJ-RUCv2.0)在北京地区降水日变化的预报偏差特征及其成因,本文利用2012-2015年夏季BJ-RUCv2.0系统第二重区域(3km分辨率)预报结果和北京地区122个自动气象站逐小时观测数据以及观象台 探空观测资料,分析模式对北京地区降水日变化预报偏差的区域性特征和传播特征,研究模式局地环流预报偏差特征及其对降水预报偏差的可能反馈机制。研究结果表明:BJ-RUCv2.0系统多个更新循环的预报在北京平原地区都存在夜间降水漏报问题,降水预报偏差表现为:模式预报降水在西部山区降水偏多,预报降水雨带难以在平原地区增强发展,造成了模式降水在傍晚山区偏多而夜间平原地区降水明显偏少。通过分析模式局地环流预报偏差及其响应机制发现,由于白天平原地区近地层偏暖偏干,山区底层偏冷中层偏湿,造成了山区-平原地区间的温度梯度强度偏强且强温差出现时间提前,西部山区午后降水偏多;由于平原地区地面温度预报持续偏高,入夜后偏北风难以到达平原地区,造成了山区-平原间的地形辐合线位置偏北,影响山区降水雨带向平原地区移动,同时平原地区近地层内水汽持续偏干,抑制降水雨带在东移过程中的发展,造成模式在平原地区夜间降水预报容易出现漏报。模式冷启动所用的GFS资料土壤湿度在北京平原地区明显小于实际观测,是模式预报偏暖偏干的可能原因之一。
英文摘要:
      In order to investigate the diurnal variation precipitation forecast bias characteristic of Rapid Update Cycle Forecast System(BJ-RUCv2.0)and its cause analysis in Beijing area, Auto-weather station and radiosonde are used to evaluate the 3km- resolution forecast of BJ-RUCv2.0 over Beijing region in June to August during 2012 and 2015. The regional difference characteristic and propagation characteristic of diurnal variation precipitation forecast bias are studied, and the response mechanism of local circulation forecast bias is to be revealed. Research results show: most cycle of precipitation forecast of BJ-RUCv2.0 are missing in plain area of Beijing at night, specifically following three respect: the rainfall of model early start in western mountainous area are too muchand accompany by more precipitation; the development of forecasting precipitation is difficult in the plain area; so forecasting precipitation of model is too much in mountain area in the evening while low rainfall is in plain area at midnight. The local circulation forecast bias and its response mechanism illustrate that due to daytime warm and dry forecast bias near surface layer in plain area and moist bias in middle level in mountain area, intense temperature gradient between mountain and plain area come in advance which cause more precipitation in the western mountainous area; the warm bias strengthen after sunset and northerly winds could not prevail in plain area, which result in topographic convergence between mountain and plain area are locating partial north, and affect the move of rain belt from mountain to plain area. There is a continuous dry bias in plain area, which restrain the development of rainfall in plain area and cause the missing forecast of precipitation. Soil moisture of GFS which is background for cold start of BJ-RUCv2.0 is noticeably drier than observation, may contribute to the warm and dry bias near surface layer.forecast of precipitation. Soil moisture of GFS which is background for cold start of BJ-RUCv2.0 is noticeably drier than observation, may contribute to the warm and dry bias near surface layer.
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