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基于2005—2007年涡度相关系统实测值和小气候观测资料,利用Priestley-Taylor (简称P-T) 模型对三江平原雨养大豆田5—10月的蒸散量进行模拟和分析。结果表明:P-T模型参数α采用常规值1.26时,大豆出苗前和生长期模拟值明显大于实测值,大豆收割后模拟值明显小于实测值,模型不能用于模拟大豆田蒸散量。大豆生长期内参数α与叶面积指数呈对数正相关关系;当饱和水汽压差较小时,参数α与其呈幂函数正相关关系,当饱和水汽压差较大时,参数α与其呈幂函数负相关关系。大豆出苗前参数α与太阳辐射呈正相关关系,与饱和水汽压差呈负相关关系;大豆收割后参数α与风速呈显著正相关关系。依据回归方程修正参数α后,多个用于检验模型模拟效果的统计量均表明:P-T模型对不同时期大豆田蒸散量的模拟精度明显提高,能够较好地估算大豆田蒸散量。总而言之,P-T模型必须修正参数α方可用于估算三江平原雨养大豆田蒸散量。 相似文献
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一次冰雹云形成发展与闪电演变过程分析 总被引：1，自引：9，他引：1
2004年4月23日,江西中部和南部出现了大范围的冰雹强对流天气过程。通过分析这次强对流天气过程发生前的天气形势和云图特征,并应用闪电定位系统、卫星和多普勒天气雷达观测资料,对这次过程的闪电特征进行了研究。结果表明,在雹云的形成发展和减弱阶段,每10min闪电频数<60次,正闪电频数明显低于负闪电。在雹云成熟阶段,闪电频数每10min平均值>60次,负闪电频数大于正闪电。在降雹前10min,闪电频数有跃变现象,其正闪增加速率和降雹呈正相关关系,降雹的起始时刻与总闪电和正闪电每10min频数出现较大值的时刻有明显的一致性。 相似文献
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Based on the lightning observation data from the Fengyun-4A (FY-4A) Lightning Mapping Imager (FY-4A/LMI) and the Lightning Imaging Sensor (LIS) on the International Space Station (ISS), we extract the “event” type data asthe lightning detection results. These observations are then compared with the cloud-to-ground (CG) lightning observationdata from the China Meteorological Administration. This study focuses on the characteristics of lightning activity inSoutheast China, primarily in Jiangxi Province and its adjacent areas, from April to September, 2017–2022. In addition,with the fifth-generation European Centre for Medium-Range Weather Forecasts reanalysis data, we further delved into thepotential factors influencing the distribution and variations in lightning activity and their primary related factors. Ourfindings indicate that the lightning frequency and density of the FY-4A/LMI, ISS-LIS and CG data are higher in southernand central Jiangxi, central Fujian Province, and western and central Guangdong Province, while they tend to be lower ineastern Hunan Province. In general, the high-value areas of lightning density for the FY-4A/LMI are located in inlandmountainous areas. The lower the latitude is, the higher the CG lightning density is. High-value areas of the CG lightningdensity are more likely to be located in eastern Fujian and southeastern Zhejiang Province. However, the high-value areasof lightning density for the ISS-LIS are more dispersed, with a scattered distribution in inland mountainous areas and alongthe coast of eastern Fujian. Thus, the mountainous terrain is closely related to the high-value areas of the lightning density.The locations of the high-value areas of the lightning density for the FY-4A/LMI correspond well with those for the CGobservations, and the seasonal variations are also consistent. In contrast, the distribution of the high-value areas of thelightning density for the ISS-LIS is more dispersed. The positions of the peak frequency of the FY-4A/LMI lightning andCG lightning contrast with local altitudes, primarily located at lower altitudes or near mountainsides. K-index andconvective available potential energy (CAPE) can better reflect the local boundary layer conditions, where the lightningdensity is higher and lightning seasonal variations are apparent. There are strong correlations in the annual variationsbetween the dew-point temperature (Td) and CG lightning frequency, and the monthly variations of the dew-point tem perature and CAPE are also strongly correlated with monthly variations of CG lightning, while they are weakly correlatedwith the lightning frequency for the FY-4A/LMI and ISS-LIS. This result reflects that the CAPE shows a remarkable effecton the CG lightning frequency during seasonal transitions. 相似文献
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2007年6-7月江西雷电灾害综合分析 总被引：1，自引：1，他引：1
针对2007年6—7月江西雷电灾害特别严重的事实,从闪电定位资料、天气形势背景、对流不稳定指数,以及多普勒雷达回波特征等方面进行了相关对比分析。结果表明,异常频繁的闪电和较高的闪电密度,是造成江西2007年雷击人员伤亡重于往年、重于其他省份的重要因素。雷击死亡人数与闪电次数和闪电密度相关性较好,当闪电密度≥2.0次/km2时,发生雷击伤亡的可能性明显增加。副高位置不稳定、短波槽移动频繁以及不稳定指数偏强,是江西雷电频繁发生的天气背景条件。当雷达组合反射率强度>54 dBz、回波顶高>12 km、垂直积分液态含水量>40 kg/m2时,江西易产生强雷电。 相似文献
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