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1998年京津冀夏季风的低频振荡与降水的特征
FEATURES OF SUMMER MONSOON LFO AND LFR OVER BEIJING-TIANJING-HEBEI AREA IN 1998
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摘要: 使用美国NCAR 1998年再分析资料, 研究了京、津、冀夏季风的低频振荡和低频降水的特征。结果表明, 京、津、冀1998年夏季风存在15~35天的低频振荡, 5~6月低频降水较弱, 7~8月低频降水较强, 低频降水的传播路径倾向于与其上空200 hPa低频辐散带的传播路径相一致, 京、津、冀地区水汽主要来自南部边界和西部边界, 南风低频水汽输送变化对低频多雨期发生发展具有指示意义。Abstract: In the context of NCEP/NCAR reanalysis daily data in 1998, the features of summer monsoon LFO (Low-Frequency Oscillation) and LFR (Low-Frequency Rainfall) over the Beijing-Tianjing-Hebie area in 1998 are studied. Results show that there is a 15-35 d oscillation cycle in summer monsoon in the target region. The LFR is weaker in May and June than in July and August. The migration direction of LFR is more likely the same as the low frequency (LF) divergence at the 200 hPa level. Vapor over the target region mainly comes from the south and west sides of the research area. The variation of LF vapor transportation from south wind can be useful for forecasting the occurence and development of LFR.
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Key words:
- LFO;
- LFR;
- LF divergence;
- Migration;
- Vapor
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图 8 京津冀 (36.5°~42°N, 113°~118°E) 各边界水汽输送值 (正值表示流入, 负值表示流出)
(a) 南边界 (b) 北边界 (c) 西边界 (d) 东边界
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