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Mechanism of the Spring Persistent Rains over southeastern China

Science China Earth Sciences 2007年第1期50卷 130-144页

作者： WAN RiJin1,2.3 & WU GuoXiong1 1 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Mechanicals (LASG), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 10002., China 2.guangdong climate and {2. center, guangzhou 510080, China 3 Shanghai Typhoon Institute of China Meterological administration, Shanghai 2.0030, China 1. State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Mechanicals (LASG) Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China 2. guangdong climate and {2. center Guangzhou 510080 China 3. Shanghai Typhoon Institute of China Meterological administration Shanghai 200030 China

The Spring Persistent Rains (SPR) in the areas to the south of middle and lower reaches of the Yangtze River or over southeastern China (SEC) is a unique synoptic and climatic phenomenon in East Asia. This study reveals a possible mechanism responsible for the climatic cause of SPR formation through climatic mean data analysis and sensitive numerical model experiments. SEC is located at the down-stream of the southwesterly velocity center (SWVC) which lies on the southeastern flank of the Tibetan Plateau (TP). As a result, there are strong southwesterly wind velocity convergence and moisture con-vergence over SEC. This is the immediate climatic cause of SPR formation. In spring, the seasonal evolution of the southwesterly velocity consists with the surface sensible heating over southeastern TP, indicating that the formation of SPR is related to not only the southwesterly wind of mechanical de-flected flow of TP, but also the southwesterly wind of thermal-forced cyclonic low circulation. Sensitive numerical experiments demonstrate that, without TP, both SWVC and the SPR rain belt will disappear. The southwesterly wind velocity increases almost linearly with the amount of the total diabatic heating with TP rising. Therefore, SWVC is the result of the mechanical forcing and thermal forcing of TP. All these strongly suggest that the presence of TP plays a primary role in the climatic formation of SPR.

关键词： SPR climatic cause of formation southwesterly Tibetan Plateau sensitive experiments.

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CO_2.flux evaluation over the evergreen coniferous and broad-leaved mixed forest in Dinghushan, China

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Science China Earth Sciences 2006年第S2期49卷 127-138页

作者： WANG Chunlin, YU Guirui, ZHOU Guoyi, YAN Junhua, ZHANG Leiming, WANG Xu, TANG Xuli & SUN Xiaomin South China Botanical Garden, Chinese Academy of Sciences, guangzhou 510650, China climate and agrometeorology center of guangdong province, China {2. administration, guangzhou 510080, China Institute of Geographic Science and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China Graduate University of Chinese Academy of Sciences, Beijing 100049, China

The Dinghushan flux observation site, as one of the four forest sites of ChinaFLUX, aims to acquire long-term measurements of CO2.flux over a typical southern subtropical evergreen coniferous and broad-leaved mixed forest ecosystem using the open path eddy covariance method. Based on two years of data from 2.03 to 2.04, the characteristics of temporal variation in CO2.flux and its response to environmental factors in the forest ecosystem are analyzed. Provided two-dimensional coordinate rotation, WPL correction and quality control, poor energy-balance and underestimation of ecosystem respiration during nighttime implied that there could be a CO2.leak during the nighttime at the site. Using daytime (PAR > 1.0μmol-1·m-2.s-1) flux data during windy conditions (u* > 0.2.m·s-1), monthly ecosystem respiration (Reco) was derived through the Michaelis-Menten equation modeling the relationship between net ecosystem CO2.exchange (NEE) and photosynthetically active radiation (PAR). Exponential function was employed to describe the relationship between Reco and soil temperature at 5 cm depth (Ts05), then Reco of both daytime and nighttime was calculated respectively by the function. The major results are: (i) Derived from the Michaelis-Menten equation, the apparent quantum yield (α) was 0.002.±0.0011 mgCO2.μmol-1 photons, and the maximum photosynthetic assimilation rate (Amax) was 1.102.0.2.8 mgCO2.m-2.s-1. Indistinctive seasonal variation of o or Amax was consistent with weak seasonal dynamics of leaf area index (LAI) in such a lower subtropical evergreen mixed forest. (ii) Monthly accumulated Reco was estimated as 95.3±2..1 gC·m-2.mon-1, accounting for about 68% of the gross primary product (GPP). Monthly accumulated NEE was estimated as -43.2.2..6 gC·m-2.mon-1. The forest ecosystem acted as carbon sink all year round without any seasonal carbon efflux period. Annual NEE of 2.03 and 2.04 was estimated as -563.0 and -441.2.gC·m-2.a-1 respectively, accounting for about 32. of G

关键词： carbon dioxide flux eddy covariance Dinghushan southern subtropical region evergreen coniferous and broad-leaved mixed forest ChinaFLUX.

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广东省降水的多尺度时空投影预测方法

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应用气象学报 2018年第2期29卷 217-231页

作者：李春晖潘蔚娟王婷中国气象局广州热带海洋气象研究所/广东省区域数值天气预报重点实验室广州510080 广东省广州市气候中心广州510080

采用多尺度时空投影(MSTP)预测思路建立广东月降水和季节降水预测方法。通过EOF分解、小波分析和Lanczos滤波方法进行周期分解,采用MSTP方法进行预测。借鉴年际增量法,对预报结果用最小二乘法进行误差订正,得到降水预测结果。PS预测评... 详细信息

采用多尺度时空投影(MSTP)预测思路建立广东月降水和季节降水预测方法。通过EOF分解、小波分析和Lanczos滤波方法进行周期分解,采用MSTP方法进行预测。借鉴年际增量法,对预报结果用最小二乘法进行误差订正,得到降水预测结果。PS预测评分和均方根误差10年独立样本检验(2.06—2.15年)结果显示:订正后,PS预测评分起伏较小,68.8%的月降水和季节降水PS预测评分明显提高的年份超过6年,且有87.5%的月降水和季节降水PS预测平均分达到70以上;在±0.5个标准差范围内,订正后均方根误差在40%以上的概率分布明显高于订正前,订正后的月和季节降水占81.3%,订正前占31.3%;在±1个标准差范围内,概率分布在70%以上的月季降水订正前后相差不多,订正后占56.3%,订正前占50%。

关键词： MSTP方法广东月降水和季节降水概率分布

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