To further reveal the influence of micro-segregation on the precipitation behavior of MnS in sulfur-bearing steel system, a coupled model of micro-segregation and MnS precipitation was established by the finite-differ...To further reveal the influence of micro-segregation on the precipitation behavior of MnS in sulfur-bearing steel system, a coupled model of micro-segregation and MnS precipitation was established by the finite-difference method based on various calculation domains and the solid diffusion degrees, and a new controlled diffusion equation with more stable convergence was also used. 49MnVS3 and 1215 steels were used to analyze the influence of calculation domain, segregation model and S content on the precipitation behavior of MnS. The calculation results were verified by a high- temperature confocal laser scanning microscope （HT-CLSM）. The results show that the domain has little effect on the precipitation temperature, precipitation solid fraction and precipitation amount of MnS, but affects the precipitation location and segregation of the solutes. For low- and medium-sulfur steels, the temperatures calculated by the diffusion control growth （DCG） model and the Lever model were nearly identical, whereas the temperature calculated by the Scheil model was lower. However, for high-sulfur steels, the precipitation temperatures calculated by three segregation models were nearly same. The precipitation solid fraction is more reasonable to describe the precipitation behavior of MnS. The precipitation behavior of MnS, observed by the HT-CLSM, matches well with that in the DCG model.展开更多
The central and western Tibetan Plateau(CWTP)is characterized by harsh environment and strong interactions among the spheres of earth as well as significant changes in climate and water cycles over the past four decad...The central and western Tibetan Plateau(CWTP)is characterized by harsh environment and strong interactions among the spheres of earth as well as significant changes in climate and water cycles over the past four decades.The lack of precipitation observations is a bottleneck for the study of land surface processes in this region.Over the past six years,we have designed and established two observation transects across the south-north and the west-east in this region to obtain hourly rainfall data during the warm season(May-September).The south-north transect extends from Yadong Valley on the southern slope of the Himalayas to Shuanghu County in the hinterland of the plateau,with a total of 31stations;the west-east transect extends from Shiquanhe in the west to Naqu in the central TP,with a total of 22 stations.The observation dataset has been applied to clarify the spatiotemporal characteristics of precipitation in the CWTP,to evaluate the quality of typical gridded precipitation products,to support the development of regional climate models,and to reveal the processes of summertime lake-air interactions.The observation dataset has been released in the National Tibetan Plateau Data Center.展开更多
基于TIGGE(THORPEX Interactive Grand Global Ensemble)资料,通过对比两类强降水过程,分析了集合变换卡尔曼滤波(Ensemble Transform Kalman Filter,ETKF)适应性观测敏感区识别方法在实际应用中的具体环节。试验中使用两种分辨率和不...基于TIGGE(THORPEX Interactive Grand Global Ensemble)资料,通过对比两类强降水过程,分析了集合变换卡尔曼滤波(Ensemble Transform Kalman Filter,ETKF)适应性观测敏感区识别方法在实际应用中的具体环节。试验中使用两种分辨率和不同范围的集合预报资料得到的信号方差空间分布和极大值区基本一致,而在实施计算中使用适当分辨率和范围的集合预报资料能够大大节省计算时间;使用可获得的最近时刻为初值的集合预报资料得到的敏感区识别结果更加可靠;使用不同中心集合预报资料得到的敏感区识别结果有一定差异,但对于比较典型的夏季主雨带降水过程,各中心资料得到的结果较一致,敏感区识别结果比较可靠;不同类型强降水过程的敏感区对选取的度量函数具有一定依赖性。展开更多
Quantitative precipitation estimation and rainfall monitoring based on meteorological data, potentially provides continuous, high-resolution and large-coverage data, are of high practical use: Think of hydrogeological...Quantitative precipitation estimation and rainfall monitoring based on meteorological data, potentially provides continuous, high-resolution and large-coverage data, are of high practical use: Think of hydrogeological risk management, hydroelectric power, road and tourism. Both conventional long-range radars and rain-gauges suffer from measurement errors and difficulties in precipitation estimation. For efficient monitoring operation of localized rain events of limited extension and of small basins of interest, an unrealistic extremely dense rain gauge network should be needed. Alternatively C-band or S-band meteorological long range radars are able to monitor rain fields over wide areas, however with not enough space and time resolution, and with high purchase and maintenance costs. Short-range X-band radars for rain monitoring can be a valid compromise solution between the two more common rain measurement and observation instruments. Lots of scientific efforts have already focused on radar-gauge adjustment and quantitative precipitation estimation in order to improve the radar measurement techniques. After some considerations about long range radars and gauge network, this paper presents instead some examples of how X-band mini radars can be very useful for the observation of rainfall events and how they can integrate and supplement long range radars and rain gauge networks. Three case studies are presented: A very localized and intense event, a rainfall event with high temporal and spatial variability and the employ of X-band mini radar in a mountainous region with narrow valleys. The adaptability of such radar devoted to monitor rain is demonstrated.展开更多
Ground-based microwave radiometers profilers(MWRPs)have been used in numerical weather prediction(NWP)systems and show different impacts on forecasts.Currently,there are around hundreds of ground-based MWPRs used in w...Ground-based microwave radiometers profilers(MWRPs)have been used in numerical weather prediction(NWP)systems and show different impacts on forecasts.Currently,there are around hundreds of ground-based MWPRs used in weather stations over China;however,the application of MWPRs in NWP systems is rather limited.In this work,two MWRP retrieved profiles were assimilated into the Weather Research and Forecasting(WRF)model for a rainstorm event that occurred in Beijing,China.The quality of temperature and humidity profiles retrieved from the MWRP was evaluated against radiosonde observations and showed the reliability of the two MWRP products.Then,comparisons between the measurements of ground-based rain gauges and the corresponding forecasted precipitation in different periods of the rainstorm were investigated.The results showed that assimilating the two MWRPs affected the distribution and intensity of rainfall,especially in the early stage of the rainstorm.With the development of the rainstorm,adding MWRP data showed only a slight influence on the precipitation during the stable and mature period of the rainstorm,since the two MWRP observations were too limited to affect the large area of heavy rainfall.展开更多
基金Acknowledgements The work is financially sponsored by the National Key Research and Development Program of China （No. 201SYFB0704400）, the State Key Laboratory of Development and Application Technology of Automotive Steels （Bao-steel Group Co. Ltd.）, and the National Natural Science Foundation of China （No. 51671124）.
文摘To further reveal the influence of micro-segregation on the precipitation behavior of MnS in sulfur-bearing steel system, a coupled model of micro-segregation and MnS precipitation was established by the finite-difference method based on various calculation domains and the solid diffusion degrees, and a new controlled diffusion equation with more stable convergence was also used. 49MnVS3 and 1215 steels were used to analyze the influence of calculation domain, segregation model and S content on the precipitation behavior of MnS. The calculation results were verified by a high- temperature confocal laser scanning microscope （HT-CLSM）. The results show that the domain has little effect on the precipitation temperature, precipitation solid fraction and precipitation amount of MnS, but affects the precipitation location and segregation of the solutes. For low- and medium-sulfur steels, the temperatures calculated by the diffusion control growth （DCG） model and the Lever model were nearly identical, whereas the temperature calculated by the Scheil model was lower. However, for high-sulfur steels, the precipitation temperatures calculated by three segregation models were nearly same. The precipitation solid fraction is more reasonable to describe the precipitation behavior of MnS. The precipitation behavior of MnS, observed by the HT-CLSM, matches well with that in the DCG model.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grants No.2019QZKK0206)the National Key Research and Development Project(Grants No.2018YFA0605400)the National Natural Science Foundation of China(Grants No.41975125)。
文摘The central and western Tibetan Plateau(CWTP)is characterized by harsh environment and strong interactions among the spheres of earth as well as significant changes in climate and water cycles over the past four decades.The lack of precipitation observations is a bottleneck for the study of land surface processes in this region.Over the past six years,we have designed and established two observation transects across the south-north and the west-east in this region to obtain hourly rainfall data during the warm season(May-September).The south-north transect extends from Yadong Valley on the southern slope of the Himalayas to Shuanghu County in the hinterland of the plateau,with a total of 31stations;the west-east transect extends from Shiquanhe in the west to Naqu in the central TP,with a total of 22 stations.The observation dataset has been applied to clarify the spatiotemporal characteristics of precipitation in the CWTP,to evaluate the quality of typical gridded precipitation products,to support the development of regional climate models,and to reveal the processes of summertime lake-air interactions.The observation dataset has been released in the National Tibetan Plateau Data Center.
文摘基于TIGGE(THORPEX Interactive Grand Global Ensemble)资料,通过对比两类强降水过程,分析了集合变换卡尔曼滤波(Ensemble Transform Kalman Filter,ETKF)适应性观测敏感区识别方法在实际应用中的具体环节。试验中使用两种分辨率和不同范围的集合预报资料得到的信号方差空间分布和极大值区基本一致,而在实施计算中使用适当分辨率和范围的集合预报资料能够大大节省计算时间;使用可获得的最近时刻为初值的集合预报资料得到的敏感区识别结果更加可靠;使用不同中心集合预报资料得到的敏感区识别结果有一定差异,但对于比较典型的夏季主雨带降水过程,各中心资料得到的结果较一致,敏感区识别结果比较可靠;不同类型强降水过程的敏感区对选取的度量函数具有一定依赖性。
文摘Quantitative precipitation estimation and rainfall monitoring based on meteorological data, potentially provides continuous, high-resolution and large-coverage data, are of high practical use: Think of hydrogeological risk management, hydroelectric power, road and tourism. Both conventional long-range radars and rain-gauges suffer from measurement errors and difficulties in precipitation estimation. For efficient monitoring operation of localized rain events of limited extension and of small basins of interest, an unrealistic extremely dense rain gauge network should be needed. Alternatively C-band or S-band meteorological long range radars are able to monitor rain fields over wide areas, however with not enough space and time resolution, and with high purchase and maintenance costs. Short-range X-band radars for rain monitoring can be a valid compromise solution between the two more common rain measurement and observation instruments. Lots of scientific efforts have already focused on radar-gauge adjustment and quantitative precipitation estimation in order to improve the radar measurement techniques. After some considerations about long range radars and gauge network, this paper presents instead some examples of how X-band mini radars can be very useful for the observation of rainfall events and how they can integrate and supplement long range radars and rain gauge networks. Three case studies are presented: A very localized and intense event, a rainfall event with high temporal and spatial variability and the employ of X-band mini radar in a mountainous region with narrow valleys. The adaptability of such radar devoted to monitor rain is demonstrated.
基金This work was supported by the National Key R&D Program of China[grant number 2017YFC1501700]the National Natural Science Foundation of China[grant number 41575033].
文摘Ground-based microwave radiometers profilers(MWRPs)have been used in numerical weather prediction(NWP)systems and show different impacts on forecasts.Currently,there are around hundreds of ground-based MWPRs used in weather stations over China;however,the application of MWPRs in NWP systems is rather limited.In this work,two MWRP retrieved profiles were assimilated into the Weather Research and Forecasting(WRF)model for a rainstorm event that occurred in Beijing,China.The quality of temperature and humidity profiles retrieved from the MWRP was evaluated against radiosonde observations and showed the reliability of the two MWRP products.Then,comparisons between the measurements of ground-based rain gauges and the corresponding forecasted precipitation in different periods of the rainstorm were investigated.The results showed that assimilating the two MWRPs affected the distribution and intensity of rainfall,especially in the early stage of the rainstorm.With the development of the rainstorm,adding MWRP data showed only a slight influence on the precipitation during the stable and mature period of the rainstorm,since the two MWRP observations were too limited to affect the large area of heavy rainfall.
