Laboratory experiments were conducted to simulate oil weathering process, a medium to long term weathering process for 210-d, using samples collected from five different oil resources. Based on relative deviation and ...Laboratory experiments were conducted to simulate oil weathering process, a medium to long term weathering process for 210-d, using samples collected from five different oil resources. Based on relative deviation and repeatability limit analysis about indexes of these samples, the results show there had been significant changes in diagnostic ratios among the initial and weathered samples of different oils during this process. Changes of selected n-alkane diagnostic ratios of all oil samples displayed more obviously than diagnostic ratios of terpanes,steranes and PAHs in this process. Almost all selected diagnostic ratios of terpanes, steranes and PAHs can be efficiently used in tracking sources of hydrocarbon pollution, differentiating from the n-alkane diagnostic ratios.In these efficient diagnostic ratios, only four ratios maintained good stability in the weathering processes and are more suitable because their relative deviation（RSD） are lower than 5%.展开更多
By employing the T42L9 spectral model introduced flom ECMWF and utilizing the FGGE-III_b data covering the period from 14 June to 19 June 1979,the effects of the Qinghai-Xizang Plateau on the medium- range weather pro...By employing the T42L9 spectral model introduced flom ECMWF and utilizing the FGGE-III_b data covering the period from 14 June to 19 June 1979,the effects of the Qinghai-Xizang Plateau on the medium- range weather processes of the rain during the onset period of the summer monsoon in Eastern Asia in 1979 were studied numerically.According to the initial field of 12GMT 14 June 1979,five-day numerical experiments with or without the orographic effects were carried out respectively.The results show that the Plateau can influence the precipitation significantly during the summer monsoon season.Although the summer monsoon is the result of the seasonal variations of the global circulation and the heating difference between land and sea,it is influenced evidently by the Plateau in medium-range processes.There are very complex interactions between the mountain and diabatic heating effects so that both of them should be considered correctly in the general circulation models in order to describe the nature of the atmosphere reliably.展开更多
In this paper,features for the evolution of the East Asia/Pacific(EAP) events and their association with high-and mid-latitude Rossby waves during the Meiyu period are analyzed on the medium-range time scale.It is sho...In this paper,features for the evolution of the East Asia/Pacific(EAP) events and their association with high-and mid-latitude Rossby waves during the Meiyu period are analyzed on the medium-range time scale.It is shown that life cycles of the positive and negative EAP events cannot be simply regarded as "mirror" each other.In the upper troposphere,downward propagations of Rossby wave packets both over high-and mid-latitude regions of Eurasian continent and over the Asian jet region are responsible for generating basic patterns of high-and mid-latitude anomaly centers of the events.In this layer,Rossby wave packets also propagate from the mid-latitude anomaly center to the high-latitude one.In the middle and lower troposphere,the formation of the subtropical anomaly center of the event is mainly attributed to the anomalous convective activity in the tropical Pacific warm pool.The northward Rossby wave energy dispersion from this center is favorable to the enhancement and maintenance of the mid-latitude anomaly center in the same layer.Finally,it might be hypothesized that typical features of the positive and negative EAP events in their mature phase result from the interaction between(or phase-locking of) respective anomalous circulations induced both by quasi-zonal Rossby wave packets embedded in upper troposphere westerly and by quasi-meridional Rossby wave packets in the background flow of the East Asian summer monsoon in the middle and lower troposphere.展开更多
土壤湿度是控制陆—气界面潜热和感热通量分配的关键要素之一,而且由于其具有一定的记忆特性,可以对多种时空尺度的天气气候过程产生重要影响。在数值模式中,土壤水力参数的不确定性是导致土壤湿度模拟结果不确定性的主要原因之一。本...土壤湿度是控制陆—气界面潜热和感热通量分配的关键要素之一,而且由于其具有一定的记忆特性,可以对多种时空尺度的天气气候过程产生重要影响。在数值模式中,土壤水力参数的不确定性是导致土壤湿度模拟结果不确定性的主要原因之一。本文基于银河全球大气谱模式YHGSM(Yin He Global Spectral Model)的陆面模块,引入了VG(van Genuchten)土壤水分特征曲线模型,并探讨了模型水力参数的两种不同取值方案对土壤湿度离线模拟以及全球中期数值天气预报的影响。其中,土壤水力参数所需要的土壤类型数据来源于全球土壤数据集GSDE(Global Soil Dataset for Earth System Models)。离线试验结果表明,除了冻土和有机土壤的模拟偏差较大外,YHGSM的陆面模块对全球大部分地区土壤湿度的模拟能力较好,模拟精度与ERA5土壤湿度再分析产品的精度近似;土壤水力参数的不同取值方案对土壤湿度模拟有一定影响,其影响程度与土壤类型和局地气候条件密切相关,粗质地和中等质地土壤对模型参数的敏感性更强。从全球中期数值预报结果来看,土壤水力参数通过改变土壤湿度模拟,不仅对近地层温、湿度的短期预报结果产生重要影响,而且可能会导致预报系统积分6天后的大尺度环流场发生显著变化。因此,对于全球中期数值预报系统而言,优化土壤水力参数,提高土壤湿度模拟能力是非常重要的。此外,对于数值预报系统而言,正确模拟土壤湿度随时间的变化特征可能要比土壤湿度模拟值大小的准确与否更加重要。展开更多
It is not only meteorological problems for the medium-range numerical weather prediction (NWP) research to be in operation,but also engineering and technological problems.Here we gener- ally described the results of r...It is not only meteorological problems for the medium-range numerical weather prediction (NWP) research to be in operation,but also engineering and technological problems.Here we gener- ally described the results of research,engineering construction,operation information and testing,in the course of set-up of medium-range NWP operation system in the China National Meteorological Center.展开更多
基于福建省冬半年沿海和港湾岛屿自动站的逐时极大风观测资料和WRF（Weather Research and Forecast）、EC（European Centre for Medium-Range Weather Forecasts）细网格以及T639（TL639L60）三种模式预报的10 m风场资料，将模式预报...基于福建省冬半年沿海和港湾岛屿自动站的逐时极大风观测资料和WRF（Weather Research and Forecast）、EC（European Centre for Medium-Range Weather Forecasts）细网格以及T639（TL639L60）三种模式预报的10 m风场资料，将模式预报的风向风速与观测资料进行对比检验，结果表明：福建省沿海冬半年大风的盛行风向以东北风为主，大风的时空分布极为不均，沿海风力的脉动性、跳跃性、局地性突出。从三种模式对风速风向的模拟效果来看， WRF和EC细网格的预报效果较好，有可参考性， T639可参考性不高。对于风速，模式预报结果相比实况极大风速偏小，港湾岛屿代表站风速的平均绝对误差均小于沿海代表站，预报平均误差由沿海向内陆逐渐减小，由中部向南北逐渐减小。风向相比风速的预报效果要差， WRF和EC细网格的风向预报误差在45°-50°，有一定的参考意义；港湾岛屿代表站风向的平均绝对误差大于沿海代表站，以浮标站的误差最大。当观测风速出现7级及以上风速时，若对大风进行分级检验，则较低风速的预报平均绝对误差小于较高风速；风向预报的平均绝对误差也大大降低，且误差都在45°以内，具有良好的参考性。展开更多
基金The National Natural Science Foundation of China under contract No.41206089Project of on-site sediment microbial remediation of public area of central Bohai Sea,North China Sea Branch of State Oceanic Administration under contract No.QDZC20150420-002Program of Science and Technology Service Network Initiative,Chinese Academy of Sciences under contract No.KFJ-EW-STS-127
文摘Laboratory experiments were conducted to simulate oil weathering process, a medium to long term weathering process for 210-d, using samples collected from five different oil resources. Based on relative deviation and repeatability limit analysis about indexes of these samples, the results show there had been significant changes in diagnostic ratios among the initial and weathered samples of different oils during this process. Changes of selected n-alkane diagnostic ratios of all oil samples displayed more obviously than diagnostic ratios of terpanes,steranes and PAHs in this process. Almost all selected diagnostic ratios of terpanes, steranes and PAHs can be efficiently used in tracking sources of hydrocarbon pollution, differentiating from the n-alkane diagnostic ratios.In these efficient diagnostic ratios, only four ratios maintained good stability in the weathering processes and are more suitable because their relative deviation（RSD） are lower than 5%.
文摘By employing the T42L9 spectral model introduced flom ECMWF and utilizing the FGGE-III_b data covering the period from 14 June to 19 June 1979,the effects of the Qinghai-Xizang Plateau on the medium- range weather processes of the rain during the onset period of the summer monsoon in Eastern Asia in 1979 were studied numerically.According to the initial field of 12GMT 14 June 1979,five-day numerical experiments with or without the orographic effects were carried out respectively.The results show that the Plateau can influence the precipitation significantly during the summer monsoon season.Although the summer monsoon is the result of the seasonal variations of the global circulation and the heating difference between land and sea,it is influenced evidently by the Plateau in medium-range processes.There are very complex interactions between the mountain and diabatic heating effects so that both of them should be considered correctly in the general circulation models in order to describe the nature of the atmosphere reliably.
基金Supported jointly by the 973 Project (Grant No. 2006CB403601)the National Natural Science Foundation of China (Grant Nos. 40523001 and 40575024)
文摘In this paper,features for the evolution of the East Asia/Pacific(EAP) events and their association with high-and mid-latitude Rossby waves during the Meiyu period are analyzed on the medium-range time scale.It is shown that life cycles of the positive and negative EAP events cannot be simply regarded as "mirror" each other.In the upper troposphere,downward propagations of Rossby wave packets both over high-and mid-latitude regions of Eurasian continent and over the Asian jet region are responsible for generating basic patterns of high-and mid-latitude anomaly centers of the events.In this layer,Rossby wave packets also propagate from the mid-latitude anomaly center to the high-latitude one.In the middle and lower troposphere,the formation of the subtropical anomaly center of the event is mainly attributed to the anomalous convective activity in the tropical Pacific warm pool.The northward Rossby wave energy dispersion from this center is favorable to the enhancement and maintenance of the mid-latitude anomaly center in the same layer.Finally,it might be hypothesized that typical features of the positive and negative EAP events in their mature phase result from the interaction between(or phase-locking of) respective anomalous circulations induced both by quasi-zonal Rossby wave packets embedded in upper troposphere westerly and by quasi-meridional Rossby wave packets in the background flow of the East Asian summer monsoon in the middle and lower troposphere.
文摘土壤湿度是控制陆—气界面潜热和感热通量分配的关键要素之一,而且由于其具有一定的记忆特性,可以对多种时空尺度的天气气候过程产生重要影响。在数值模式中,土壤水力参数的不确定性是导致土壤湿度模拟结果不确定性的主要原因之一。本文基于银河全球大气谱模式YHGSM(Yin He Global Spectral Model)的陆面模块,引入了VG(van Genuchten)土壤水分特征曲线模型,并探讨了模型水力参数的两种不同取值方案对土壤湿度离线模拟以及全球中期数值天气预报的影响。其中,土壤水力参数所需要的土壤类型数据来源于全球土壤数据集GSDE(Global Soil Dataset for Earth System Models)。离线试验结果表明,除了冻土和有机土壤的模拟偏差较大外,YHGSM的陆面模块对全球大部分地区土壤湿度的模拟能力较好,模拟精度与ERA5土壤湿度再分析产品的精度近似;土壤水力参数的不同取值方案对土壤湿度模拟有一定影响,其影响程度与土壤类型和局地气候条件密切相关,粗质地和中等质地土壤对模型参数的敏感性更强。从全球中期数值预报结果来看,土壤水力参数通过改变土壤湿度模拟,不仅对近地层温、湿度的短期预报结果产生重要影响,而且可能会导致预报系统积分6天后的大尺度环流场发生显著变化。因此,对于全球中期数值预报系统而言,优化土壤水力参数,提高土壤湿度模拟能力是非常重要的。此外,对于数值预报系统而言,正确模拟土壤湿度随时间的变化特征可能要比土壤湿度模拟值大小的准确与否更加重要。
文摘It is not only meteorological problems for the medium-range numerical weather prediction (NWP) research to be in operation,but also engineering and technological problems.Here we gener- ally described the results of research,engineering construction,operation information and testing,in the course of set-up of medium-range NWP operation system in the China National Meteorological Center.
文摘基于福建省冬半年沿海和港湾岛屿自动站的逐时极大风观测资料和WRF（Weather Research and Forecast）、EC（European Centre for Medium-Range Weather Forecasts）细网格以及T639（TL639L60）三种模式预报的10 m风场资料，将模式预报的风向风速与观测资料进行对比检验，结果表明：福建省沿海冬半年大风的盛行风向以东北风为主，大风的时空分布极为不均，沿海风力的脉动性、跳跃性、局地性突出。从三种模式对风速风向的模拟效果来看， WRF和EC细网格的预报效果较好，有可参考性， T639可参考性不高。对于风速，模式预报结果相比实况极大风速偏小，港湾岛屿代表站风速的平均绝对误差均小于沿海代表站，预报平均误差由沿海向内陆逐渐减小，由中部向南北逐渐减小。风向相比风速的预报效果要差， WRF和EC细网格的风向预报误差在45°-50°，有一定的参考意义；港湾岛屿代表站风向的平均绝对误差大于沿海代表站，以浮标站的误差最大。当观测风速出现7级及以上风速时，若对大风进行分级检验，则较低风速的预报平均绝对误差小于较高风速；风向预报的平均绝对误差也大大降低，且误差都在45°以内，具有良好的参考性。
