摘要
基于2013-2019年4-9月欧洲中期天气预报中心(ECMWF)集合预报的极端天气指数(EFI)资料和新疆95个气象观测站点的实况降水数据,研究了新疆夏半年(4-9月)极端降水阈值及分布情况,运用TS评分,综合分析降水EFI产品在新疆夏半年极端降水预报中的应用效果。结果表明:(1)夏半年极端降水阈值、极端降水量和极端降水频次的空间分布呈山区高、盆地低的特点,且南疆低于北疆;观测站点平均夏半年极端降水量、极端降水频次总体呈上升趋势,在20世纪90年代前后发生突变。(2)降水EFI预报值与夏半年极端降水量呈正相关,随预报时效延长,降水EFI预报能力在逐渐降低,夏半年极端降水预报的TS评分在降水EFI阈值处于0.50~0.80达到峰值,综合TS评分和预报偏差,新疆夏半年极端降水预报的最优降水EFI阈值集中在0.65~0.75。(3)降水EFI预报对降水落区有一定的指示意义,当降水EFI预报值>0.60时,要考虑出现极端降水的可能性,降水EFI预报值在0.70及以上的范围可作为极端降水的预报落区。
The Extreme Forecast Index(EFI)data from the European Center for Medium-Range Weather Forecasts(ECMWF)ensemble forecast and the precipitation observation data from 95meteorological observation stations in Xinjiang from 2013 to 2019(April to September).The thresholds and distribution of extreme precipitation during the flood season(April to September)in Xinjiang were studied.The performance of precipitation EFI product in extreme precipitation forecast during flood season in Xinjiang was comprehensively analyzed by TS score.The results show that:(1)The extreme precipitation,its threshold and frequency in Xinjiang were higher in mountainous areas and lower in the basin,higher in northern Xinjiang and lower in southern Xinjiang.The area average extreme precipitation and its frequency showed an increasing trend,the abrupt change observed in the1990s.(2)There was a positive correlation between precipitation EFI forecast and extreme precipitation.The forecast ability of precipitation EFI decreased with the increase of the forecast validity.The TS score of extreme precipitation forecast in Xinjiang reached the peak when EFI threshold ranged from 0.50 to 0.80.Based on TS score and forecast bias,the optimal threshold for extreme precipitation forecast during summer half year in Xinjiang was concentrated between 0.65 and0.75.(3)Precipitation EFI gave indication of the rain area.When the precipitation EFI was higher than0.60,the extreme precipitation should be considered.Where the precipitation EFI value beyond 0.70can be defined as the forecast area of extreme precipitation.
作者
周雅蔓
马超
陈鹤
刘成武
ZHOU Yaman;MA Chao;CHEN He;LIU Chengwu(Xinjiang Meteorological Observatory,Urumqi 830002,China;Institute of Desert Meteorology,China Meteorological Administration,Urumqi 830002,China;Center for Central Asian Atmospheric Science Research,Urumqi 830002,China;Hunan Meteorological Observatory,Changsha 410118,China)
出处
《沙漠与绿洲气象》
2022年第2期106-115,共10页
Desert and Oasis Meteorology
基金
第二次青藏高原综合科学考察研究项目(2019QZKK0120)
中国气象局创新发展专项(CXFZ2021Z034-21-104)。
关键词
极端天气指数
极端降水
TS评分
阈值
新疆
extreme forecast index
extreme precipitation
TS score
threshold value
Xinjiang
