This study investigates the influence of airflow transport pathways on seasonal rainfall in the mountainous region of the Liupan Mountains(LM) during the rainy seasons from 2020 to 2022, utilizing observational data f...This study investigates the influence of airflow transport pathways on seasonal rainfall in the mountainous region of the Liupan Mountains(LM) during the rainy seasons from 2020 to 2022, utilizing observational data from seven ground gradient stations located on the eastern slopes, western slopes, and mountaintops combined with backward trajectory cluster analysis. The results indicate 1) that the LM's rainy season, characterized by overcast and rainy days, is mainly influenced by cold and moist airflows(CMAs) from the westerly direction and warm and moist airflows(WMAs) from a slightly southern direction. The precipitation amounts under four airflow transport paths are ranked from largest to smallest as follows: WMAs, CMAs, warm dry airflows(WDAs), and cold dry airflows(CDAs). 2) WMAs contribute significantly more to the intensity of regional precipitation than the other three types of airflows. During localized precipitation events,warm airflows have higher precipitation intensities at night than cold airflows, while the opposite is true during the afternoon. 3) During regional precipitation events, water vapor content is the primary influencing factor. Precipitation characteristics under humid airflows are mainly affected by high water vapor content, whereas during dry airflow precipitation, dynamic and thermodynamic factors have a more pronounced impact. 4) During localized precipitation events, the influence of dynamic and thermodynamic factors is more complex than during regional precipitation, with the precipitation characteristics of the four airflows closely related to their water vapor content, air temperature and humidity attributes, and orographic lifting. 5) Compared to regional precipitation, the influence of topography is more prominent in localized precipitation processes.展开更多
Anomalous characteristics of the atmospheric water cycle structure are highly significant to the mechanisms of seasonal-scale meteorological droughts.They also play an important role in the identification of indicativ...Anomalous characteristics of the atmospheric water cycle structure are highly significant to the mechanisms of seasonal-scale meteorological droughts.They also play an important role in the identification of indicative predictors of droughts.To better understand the causes of seasonal meteorological droughts in the middle and lower reaches of the Yangtze River(MLRYR),characteristics of the atmospheric water cycle structure at different drought stages were determined using standardized anomalies.The results showed that the total column water vapor(TCWV)was anomalously low during drought occurrence periods.In contrast,there were no anomalous signals at the drought persistence and recovery stages in the MLRYR.Moreover,there was no significant temporal correlation between the TCWV anomaly and seasonal-scale drought index(the 3-month standardized precipitation index(SPI_(3))).During drought events,water vapor that mainly originated from the Bay of Bengal was transported southwest of the MLRYR.Meanwhile,the anomalous signal of water vapor transport was negative at the drought appearance stage.At the drought persistence stage,the negative anomalous signal was the most significant.Water vapor flux divergence in the MLRYR showed significant positive anomalous signals during drought events,and the signal intensity shifted from an increasing to a decreasing trend at different drought stages.In addition,a significant positive correlation existed between the anomaly of water vapor flux divergence and regional SPI_(3).Overall,water vapor flux divergence is more predictive of droughts in the MLRYR.展开更多
为深入认识四川盆地持续性暴雨的水汽特征及来源,提高该地区暴雨预报能力,利用四川省4955个国家级及区域级自动气象站资料、全球资料同化系统(Global Data Assimilation System,GDAS)资料、欧洲中期天气预报中心(European Centre for Me...为深入认识四川盆地持续性暴雨的水汽特征及来源,提高该地区暴雨预报能力,利用四川省4955个国家级及区域级自动气象站资料、全球资料同化系统(Global Data Assimilation System,GDAS)资料、欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)第五代大气再分析资料(ERA5),基于拉格朗日方法对四川盆地2020年8月的一次持续性暴雨过程的水汽输送特征进行了分析。结果表明:强降水开始前和强降水过程中,不同起始高度层水汽输送特征有所不同。中高层起始高度(5500~10000 m),强降水开始前气团轨迹源地主要为低纬洋面,而在强降水过程中调整为地中海南岸并为盆地带来中高纬西风带干冷空气;中低层起始高度(1500~5500 m),降水过程中气团轨迹源地由地中海南岸逐渐调整为低纬洋面并为盆地带来低纬洋面暖湿空气;低层起始高度(地面至1500 m),强降水开始前轨迹源地率先调整为低纬洋面并为盆地输送比中低层更为暖湿的气流。统计不同源地水汽贡献率可知,孟加拉湾—泰国湾的水汽占主导(66.6%)、阿拉伯海次之(23.9%)、中国南海最低(9.5%)。展开更多
黄土疏松多孔且黄土区干旱少雨,汽态水可能在剖面水分运移中扮演重要角色。因此,了解非饱和带土壤水汽通量的循环运移规律,对实现干旱区水资源的可持续发展具有重要意义。基于黄土高原旱地苹果园剖面(0~200 cm)高频定位监测试验,采用水-...黄土疏松多孔且黄土区干旱少雨,汽态水可能在剖面水分运移中扮演重要角色。因此,了解非饱和带土壤水汽通量的循环运移规律,对实现干旱区水资源的可持续发展具有重要意义。基于黄土高原旱地苹果园剖面(0~200 cm)高频定位监测试验,采用水-汽-热-气耦合的STEMMUS(Simultaneous Transfer of Energy,Mass and Momentum in Unsaturated Soil)模型,探讨黄土剖面液态水和汽态水通量运移规律。结果表明:STEMMUS模型准确地再现了旱地苹果园剖面土壤水分(d介于0.81~0.98,NRMSE介于5.5%~15%)和土壤温度(d介于0.98~0.99,NRMSE介于1.4%~4.6%)的动态变化,对苹果树蒸发蒸腾量的模拟表现出良好的一致性(d介于0.92~0.96)。降雨对基质势梯度、温度梯度、液态水与汽态水通量均有显著影响,液态水与汽态水运移分别主要由基质势梯度与温度梯度驱动,且二者对土壤水分的最大补给深度在研究期内分别为100 cm和160 cm,表明土壤水通过向下的汽态水能够运移至更深层土壤。研究结果可增进对黄土剖面水分运移规律的认识。展开更多
基金supported by the National Natural Sciences Foundation of China (Grant Nos. 42075073 and 42075077)。
文摘This study investigates the influence of airflow transport pathways on seasonal rainfall in the mountainous region of the Liupan Mountains(LM) during the rainy seasons from 2020 to 2022, utilizing observational data from seven ground gradient stations located on the eastern slopes, western slopes, and mountaintops combined with backward trajectory cluster analysis. The results indicate 1) that the LM's rainy season, characterized by overcast and rainy days, is mainly influenced by cold and moist airflows(CMAs) from the westerly direction and warm and moist airflows(WMAs) from a slightly southern direction. The precipitation amounts under four airflow transport paths are ranked from largest to smallest as follows: WMAs, CMAs, warm dry airflows(WDAs), and cold dry airflows(CDAs). 2) WMAs contribute significantly more to the intensity of regional precipitation than the other three types of airflows. During localized precipitation events,warm airflows have higher precipitation intensities at night than cold airflows, while the opposite is true during the afternoon. 3) During regional precipitation events, water vapor content is the primary influencing factor. Precipitation characteristics under humid airflows are mainly affected by high water vapor content, whereas during dry airflow precipitation, dynamic and thermodynamic factors have a more pronounced impact. 4) During localized precipitation events, the influence of dynamic and thermodynamic factors is more complex than during regional precipitation, with the precipitation characteristics of the four airflows closely related to their water vapor content, air temperature and humidity attributes, and orographic lifting. 5) Compared to regional precipitation, the influence of topography is more prominent in localized precipitation processes.
基金supported by the National Key Research and Development Program of China(Grants No.2019YFC0409000,2017YFC1502403,and 2018YFC0407701)the Fundamental Research Funds for the Central Universities(Grant No.B200204045).
文摘Anomalous characteristics of the atmospheric water cycle structure are highly significant to the mechanisms of seasonal-scale meteorological droughts.They also play an important role in the identification of indicative predictors of droughts.To better understand the causes of seasonal meteorological droughts in the middle and lower reaches of the Yangtze River(MLRYR),characteristics of the atmospheric water cycle structure at different drought stages were determined using standardized anomalies.The results showed that the total column water vapor(TCWV)was anomalously low during drought occurrence periods.In contrast,there were no anomalous signals at the drought persistence and recovery stages in the MLRYR.Moreover,there was no significant temporal correlation between the TCWV anomaly and seasonal-scale drought index(the 3-month standardized precipitation index(SPI_(3))).During drought events,water vapor that mainly originated from the Bay of Bengal was transported southwest of the MLRYR.Meanwhile,the anomalous signal of water vapor transport was negative at the drought appearance stage.At the drought persistence stage,the negative anomalous signal was the most significant.Water vapor flux divergence in the MLRYR showed significant positive anomalous signals during drought events,and the signal intensity shifted from an increasing to a decreasing trend at different drought stages.In addition,a significant positive correlation existed between the anomaly of water vapor flux divergence and regional SPI_(3).Overall,water vapor flux divergence is more predictive of droughts in the MLRYR.
文摘为深入认识四川盆地持续性暴雨的水汽特征及来源,提高该地区暴雨预报能力,利用四川省4955个国家级及区域级自动气象站资料、全球资料同化系统(Global Data Assimilation System,GDAS)资料、欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)第五代大气再分析资料(ERA5),基于拉格朗日方法对四川盆地2020年8月的一次持续性暴雨过程的水汽输送特征进行了分析。结果表明:强降水开始前和强降水过程中,不同起始高度层水汽输送特征有所不同。中高层起始高度(5500~10000 m),强降水开始前气团轨迹源地主要为低纬洋面,而在强降水过程中调整为地中海南岸并为盆地带来中高纬西风带干冷空气;中低层起始高度(1500~5500 m),降水过程中气团轨迹源地由地中海南岸逐渐调整为低纬洋面并为盆地带来低纬洋面暖湿空气;低层起始高度(地面至1500 m),强降水开始前轨迹源地率先调整为低纬洋面并为盆地输送比中低层更为暖湿的气流。统计不同源地水汽贡献率可知,孟加拉湾—泰国湾的水汽占主导(66.6%)、阿拉伯海次之(23.9%)、中国南海最低(9.5%)。
文摘黄土疏松多孔且黄土区干旱少雨,汽态水可能在剖面水分运移中扮演重要角色。因此,了解非饱和带土壤水汽通量的循环运移规律,对实现干旱区水资源的可持续发展具有重要意义。基于黄土高原旱地苹果园剖面(0~200 cm)高频定位监测试验,采用水-汽-热-气耦合的STEMMUS(Simultaneous Transfer of Energy,Mass and Momentum in Unsaturated Soil)模型,探讨黄土剖面液态水和汽态水通量运移规律。结果表明:STEMMUS模型准确地再现了旱地苹果园剖面土壤水分(d介于0.81~0.98,NRMSE介于5.5%~15%)和土壤温度(d介于0.98~0.99,NRMSE介于1.4%~4.6%)的动态变化,对苹果树蒸发蒸腾量的模拟表现出良好的一致性(d介于0.92~0.96)。降雨对基质势梯度、温度梯度、液态水与汽态水通量均有显著影响,液态水与汽态水运移分别主要由基质势梯度与温度梯度驱动,且二者对土壤水分的最大补给深度在研究期内分别为100 cm和160 cm,表明土壤水通过向下的汽态水能够运移至更深层土壤。研究结果可增进对黄土剖面水分运移规律的认识。
