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Based on 1961-2000 NCEP/NCAR monthly mean reanalysis datasets, vapor transfer and hydrological budget over the Tibetan Plateau are investigated. The Plateau is a vapor sink all the year round. In summer, vapor is convergent in lower levels (from surface to 500 hPa) and divergent in upper levels (from 400 to 300 hPa), with 450 hPa referred to as level of non-divergence. Two levels have different hydrologic budget signatures: the budget is negative at the upper levels from February to November, i.e., vapor transfers from the upper levels over the plateau; as to the lower, the negative (positive) budget occurs during the winter (summer) half year. Evidence also indicates that Tibetan Plateau is a "vapor transition belt", vapor from the south and the west is transferred from lower to upper levels there in summer, which will affect surrounding regions, including eastern China, especially, the middle and lower reaches of the Yangtze. Vapor transfer exerts significant influence on precipitation in summertime months. Vapor transferred from the upper layers helps humidify eastern China, with coefficient -0.3 of the upper budget to the precipitation over the middle and lower reaches of the Yangtze (MLRY); also, vapor transferred from east side (27.5°-32.5°N) of the upper level has remarkable relationship with precipitation, the coefficient being 0.41. The convergence of the lower level vapor has great effects on the local precipitation over the plateau, with coefficient reaching 0.44, and the vapor passage affects the advance and retreat of the rainbelt. In general, atmospheric hydrologic budget and vapor transfer over the plateau have noticeable effects on precipitation of the target region as well as the ambient areas. 相似文献
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河套地区春季扬沙天气影响因子的初步研究 总被引:6,自引:0,他引:6
通过对河套地区扬沙日数、冷空气活动及固定地段土壤湿度的研究 ,探讨了冷空气活动和土壤湿度对河套地区春季扬沙天气频次的影响。结果表明 ,春季大范围的冷空气活动提供了重要的扰动能量 ;同时 ,强冷空气活动较大的风速 ,为扬沙天气的出现提供了动力条件 ;土壤湿度偏小、土壤干燥疏松也是河套地区扬沙频繁发生的重要原因 相似文献
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应用TOVS资料变分分析技术增加青藏高原地区摸式初始场信息 总被引:12,自引:1,他引:11
首次在测站稀少的高原地区引入经变分技术处理的 TOVS卫星资料 ,通过动力诊断探讨了解决高原地区测站少、数值预报模式初始场信息误差大的技术关键问题 ,提出了采用TOVS反演资料在高原地区增加模式初始场信息的构思 ,并应用变分法处理 TOVS反演资料 ,显著地提高了高原初始场信息的可靠性 ;并从动力诊断分析角度 ,进一步证实了 TOVS反演资料的应用有利于提高高原动力系统特征的描述能力 ,并显著改善水汽输送通道分布及其层结稳定度等有关初始场信息的客观性 相似文献
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从含非绝热项的准地转运动方程组出发,分析了青藏高原大尺度热力作用下非绝热Rossby波的一些性质,从理论上证明当背景西风气流为正压时,冬季高原冷却作用有利于Rossby波的经向传播,夏季高原大尺度热力作用不利于波动的经向传播。非绝热Rossby波的频率方程说明冬季高原的热力作用是中纬季节内振荡的重要激发机制。同时,在背景西风气流为纯斜压条件下,求解了高原热力作用下非绝热Rossby波的频率,并由频率方程说明冬季高原热力作用有利于波动向不稳定方向发展,而夏季高原的大尺度热力作用对波动稳定性的影响存在临界值。 相似文献
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为了准确表达科研成果,在气象科技论文写作中须了解各种差值的内涵和区别。常用差值包括绝对误差、相对误差、均方根误差、标准差、距平和方差等。绝对误差并非误差的绝对值,是与真值的差值,其单位与真值相同;相对误差是相对于真值的差值,应以百分数形式出现;均方根误差也是相对于真值的差值,其单位与真值相同;标准差是相对于平均值的差值,其单位与真值相同。通常情况下,这些统计量不能混用,要注意辨析,以准确传意,保证科技论文写作的科学性和逻辑性。 相似文献
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In this paper,TOVS satellite data are used through variational method on the data-sparseplateau area.Diagnoses are carried out to find a way to solve the large error problem of modelinitial field.It is put forward that TOVS retrieval data can be used to improve the initial field ofnumerical prediction model on Tibetan Plateau area.Through variational method,TOVS data areprocessed and the liability of the initial information on the plateau is improved.Diagnostic resultsconfirm further that the application of TOVS retrieval data can improve our capability to describethe dynamic system features on the plateau and the objectivity of related initial information such asthe distribution of water vapor channel and stratification stability. 相似文献