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Daytime precipitation identification scheme based on multiple cloud parameters retrieved from visible and infrared measurements

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Science China Earth Sciences 2014年第9期57卷 2112-2124页

作者： liu xiantong liu Qi FU YunFei LI Rui Key Laboratory of the Atmospheric Composition and Optical Radiation Chinese Academy Sciences School of Earth and Space SciencesUniversity of Science and Technology of China Institute of Tropical and Marine Meteorology/Guangdong Provincial Key Laboratory of Regional Numerical Weather Prediction China Meteorological Administration

Visible and infrared(VIR) measurements and the retrieved cloud parameters are commonly used in precipitation identification algorithms, since the VIR observations from satellites, especially geostationary satellites, have high spatial and temporal resolutions. Combined measurements from visible/infrared scanner(VIRS) and precipitation radar(PR) aboard the Tropical Rainfall Measuring Mission(TRMM) satellite are analyzed, and three cloud parameters, i.e., cloud optical thickness(COT), effective radius(Re), and brightness temperature of VIRS channel 4(BT4), are particularly considered to characterize the cloud status. By associating the information from VIRS-derived cloud parameters with those from precipitation detected by PR, we propose a new method for discriminating precipitation in daytime called Precipitation Identification Scheme from Cloud Parameters information(PISCP). It is essentially a lookup table(LUT) approach that is deduced from the optimal equitable threat score(ETS) statistics within 3-dimensional space of the chosen cloud parameters. South and East China is selected as a typical area representing land surface, and the East China Sea and Yellow Sea is selected as typical oceanic area to assess the performance of the new scheme. It is proved that PISCP performs well in discriminating precipitation over both land and oceanic areas. Especially, over ocean, precipitating clouds(PCs) and non-precipitating clouds(N-PCs) are well distinguished by PISCP, with the probability of detection(POD) near 0.80, the probability of false detection(POFD) about 0.07, and the ETS higher than 0.43. The overall spatial distribution of PCs fraction estimated by PISCP is consistent with that by PR, implying that the precipitation data produced by PISCP have great potentials in relevant applications where radar data are unavailable.

关键词： precipitation identification cloud parameters Tropical Rainfall Measuring Mission(TRMM)

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Effect of Aerosol Particles on Orographic Clouds:Sensitivity to Autoconversion Schemes

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Advances in Atmospheric Sciences 2020年第2期37卷 229-238页

作者： Hui XIAO Yan YIN Pengguo ZHAO Qilin WAN xiantong liu Guangzhou Institute of Tropical and Marine Meteorology China Meteorological AdministrationGuangzhou 510641China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science and TechnologyNanjing 210044China College of Atmospheric Science Chengdu University of Information&TechnologyChengdu 610225China

Aerosol particles can serve as cloud condensation nuclei(CCN)to influence orographic ***,which describes the initial formation of raindrops from the collision of cloud droplets,is an important process for aerosol-cloud-precipitation *** this study,seven autoconversion schemes are used to investigate the impact of CCN on orographic warm-phase *** the initial cloud droplet concentration is increased from 100 cm^(-3)to 1000 cm^(-3)(to represent an increase in CCN),the cloud water increases and then the rainwater is suppressed due to a decrease in the autoconversion rate,leading to a spatial shift in surface *** of the results from the autoconversion schemes show that the sensitivity of cloud water,rainwater,and surface precipitation to a change in the concentration of CCN is different from scheme to *** particular,the decrease in orographic precipitation due to increasing CCN is found to range from-87%to-10%depending on the autoconversion ***,the surface precipitation distribution also changes significantly by scheme or CCN concentration,and the increase in the spillover(ratio of precipitation on the leeward side to total precipitation)induced by increased CCN ranges from 10%to 55%under different autoconversion *** simulations suggest that autoconversion parameterization schemes should not be ignored in the interaction of aerosol and orographic cloud.

关键词： orographic cloud precipitation autoconversion aerosol particles

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Vertical distribution characteristics of PM in the surface layer of Guangzhou

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Particuology 2015年第3期13卷 3-9页

作者： Xuejiao Deng Fei Li Yuanhong Li Jianyong Li Hongzhi Huang xiantong liu Institute of Tropical and Marine Meteorology/Guangdong Provincial Key Laboratory of Regional Numerical Weather Prediction China Meteorological Administration(CMA) Guangdong Atmosphere Sounds Technology Centre

Measurements of particulate matter （PM）, i.e., PM10, PM2.5, and PM1, have been performed on the Can- ton Tower, a landmark building in Guangzhou, at heights of 121 and 454 m since November 2010, using a GRIMM 180 aerosol particle spectrometer （Germany）. Analyses of data from November 2010 to May 2013 showed that the annual average values of PM10, PM2.5, and PM 1 at the observation height of 121 m above the ground were 44.1, 38,2, and 34.9 μg/m3, respectively, and those at 454m above the ground were 35.7, 30,4, and 27.5 μg/m3, respectively. By considering the values of the secondary concentration limits given in the Ambient Air Quality Standards issued in 2012, it was observed that the annual average values of PM10 at the observation heights of 121 and 454 m, as well as those of PM2.5 at 454 m, reached those standards. Furthermore, the over-standard amplitude of the annual average value of PM2.5 at the observation height of 121 m was 9.1%. During the observation period, the maximum daily average val- ues of PM10, PM2.5, and PMI at the observation height of 121 m were 183.3, 144.8, and 123.8 μg/m3, respectively, and those at 454 m were 102.8, 92.7, and 86.4 μg/m3. The daily average values of PM10 at the observation height of 454 m were not above the standards. The over-standard frequencies of the daily average values of PM10 and PM2.5 at the observation height of 121 m were 0.6% and 10,7% respectively, and the over-standard amplitudes were 9.0% and 24.4%, respectively. The over-standard frequency of the daily average value of PM2.5 at the observation height of 454 m was 2.0%, and the over-standard amplitude was 10.4%. Accordingly, it can be stated that the air at the observation height 454 m above the ground did not reach the secondary limit of the new standards. The pollution was most serious during winter, and the air was relatively cleaner during summer, Overall, the vertical distributions of PM10, PM2.5, and PMI decreased with height. The lapse rates showed the fo

关键词： PM10PM2.5PM10ver-standardVertical distributionSurface layer

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Precipitation Microphysical Characteristics of Typhoon Ewiniar(2018) before and after Its Final Landfall over Southern China

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Advances in Atmospheric Sciences 2023年第6期40卷 1005-1020页

作者： Lu FENG Hui XIAO xiantong liu Sheng HU Huiqi LI liusi XIAO Xiao HAO Guangzhou Institute of Tropical and Marine Meteorology China Meteorological AdministrationGuangzhou 510641China Guangdong Provincial Key Laboratory of Regional Numerical Weather Prediction China Meteorological AdministrationGuangzhou 510641China Guangzhou Meteorological Observatory China Meteorological AdministrationGuangzhou 511430China

In this paper, the evolution of the microphysical characteristics in different regions(eyewall, inner core, and outer rainbands) and different quadrants [downshear left(DL), downshear right(DR), upshear left(UL), and upshear right(UR)]during the final landfall of Typhoon Ewiniar(2018) is analyzed using two-dimensional video disdrometer and S-band polarimetric radar data collected in Guangdong, China. Due to the different types of underlying surfaces, the periods before landfall(mainly dominated by underlying sea surface) and after landfall(mainly dominated by underlying land surface) are also analyzed. Both before landfall and after landfall, the downshear quadrants had the dominate typhoon precipitation. The outer rainbands had more graupel than the inner core, resulting in a larger radar reflectivity, differential reflectivity, specific differential phase shift, and mass-weighted mean diameter below the melting layer. Compared with other regions, the eyewall region had the smallest mean logarithmic normalized intercept parameter before landfall and the smallest mean mass-weighted mean diameter and the largest mean logarithmic normalized intercept parameter after landfall. The hydrometeor size sorting was obvious in the eyewall and inner core(especially in the eyewall) after landfall. A high concentration of large raindrops fell in the DL quadrant, and more small raindrops fell in the UR quadrant. Although the icephase process and warm rain process were both important in the formation of tropical cyclone precipitation, the warm rain process(ice-phase process) contributed more liquid water before landfall(after landfall). This investigation provides a reference for improving the microphysical parameterization scheme in numerical models.

关键词： tropical cyclone precipitation microphysics raindrop size distribution southern China

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Significant impacts of the TRMM satellite orbit boost on climatological records of tropical precipitation

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Chinese Science Bulletin 2012年第9期57卷 4627-4634页

作者： liu xiantong FU YunFei liu Qi Laboratory of Atmospheric Observation and Climatological Environment School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China

With the unprecedented spaceborne precipitation radar(PR),the Tropical Rainfall Measuring Mission(TRMM) satellite has collected high-quality precipitation measurements for over ten *** TRMM/PR data are nowadays extensively exploited in numerous meteorological and hydrological *** an artificial orbit boost of the TRMM satellite in August 2001 modulated the observation parameters,which inevitably affects climatological applications of the PR data and needs to be *** study investigates the orbit boost effects of the TRMM satellite on the PR-derived precipitation *** the potential impacts on precipitation frequency(PF) and precipitation intensity(PI) are carefully *** results show that the total PF decreases by 8.3% and PI increases by 4.0% over the tropics after the orbit *** changes significantly exceed the natural variabilities and imply the strong effects of orbit boost on precipitation *** impacts on stratiform precipitation and convective precipitation are inconsistent,which is attributed to their distinct precipitation *** analysis reveal that the increased PI of stratiform precipitation is mainly due to the decreased frequencies of light precipitation,while the semi-constant PI of convective precipitation is caused by the concurrently decreased frequencies of light and heavy precipitation.A modification is applied to the post-boost PR precipitation data to retrieve the actual trends of tropical precipitation *** is found that the PI of total-precipitation approximately keeps invariable from 1998 to *** total PF has no obvious trend over tropical oceans but decreases considerably over tropical lands.

关键词： TRMM卫星卫星轨道热带降水气候记录热带降雨测量卫星对流性降水层状云降水星载测雨雷达

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Raindrop Size Distribution Parameters Retrieved from Guangzhou S-band Polarimetric Radar Observations

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Journal of Meteorological Research 2018年第4期32卷 571-583页

作者： xiantong liu Qilin WAN Hong WANG Hui XIAO Yu ZHANG Tengfei ZHENG Lu FENG Institute of Tropical and Marine Meteorology of China Meteorological Administration Guangzhou 510640 Guangzhou Meteorological Observatory Guangzhou 511430

According to the statistical shape-slope （μ-A） relationship observed for the first time by several 2D-Video-Distro-meters （2DVD） in southern China, a constrained gamma （C-G） model was proposed for the retrieval of rain drop size distributions （DSDs） from Guangzhou S-band polarimetric radar observations. Two typical precipitation processes were selected to verify the accuracy of the retrieval scheme. The p-A relationship： A = 0.0241μ^2 ＋ 0.867μ ＋ 2.453 was obtained based on the 2DVD observation results from at Huizhou Longmen station, which is a very representat-ive location in the area. Relying on the Guangzhou polarimetric radar measurements of radar reflectivity （ZHH） and differential reflectivity （ZDR）, the gamma （F） size distribution parameters （No, μ, and A） can be retrieved by the C-G model retrieval scheme. The results show that the Guangzhou polarimetric radar retrievals of DSDs were close to the 2DVD observations at Guangzhou Maofengshan station. The rain rate, mass mean diameter, and normalized inter-cept parameter of radar retrievals were in good agreement with the 2DVD observations, and the relative errors were less than 10%. The overall accuracy of the retrieval scheme was high. The retrieval scheme has established the rela-tionship between the polarimetric radar measurements and gamma size distribution parameters. It will be helpful to in-depth research and application of the dual-polarization radar data in microphysical precipitation processes analysis, as well as convection-resolved numerical model data assimilation and prediction effect evaluation.

关键词： Guangzhou S-band polarimetric radar 2D-Video-Disdrometer raindrop size distribution retrieval microphysics

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基于光学厚度和有效半径的白天降水云识别方案

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大气科学 2011年第5期35卷 903-911页

作者：刘显通刘奇傅云飞中国科学技术大学地球和空间科学学院大气探测与气候环境实验室合肥230026

基于卫星资料观测和反演降水是当前监测全球尺度降水的主要方式,而其中一大难题就是如何将降水云与非降水云在像素尺度进行有效分离,这也是准确反演地表降水量的基本前提。为建立一套适用于常见星载可见光/红外探测仪器的降水云识别方法... 详细信息

基于卫星资料观测和反演降水是当前监测全球尺度降水的主要方式,而其中一大难题就是如何将降水云与非降水云在像素尺度进行有效分离,这也是准确反演地表降水量的基本前提。为建立一套适用于常见星载可见光/红外探测仪器的降水云识别方法,本文利用热带测雨卫星(TRMM)可见光/红外辐射计(VIRS)和测雨雷达(PR)的融合观测资料,针对选定的代表性区域,统计分析了较长时间尺度上降水云与非降水云的典型云属性差异。在此基础上,提出了一种基于云光学厚度和云滴有效半径的白天降水云识别方案(IPCτRe)。由于用来获取上述云参数的可见光/红外信号无法透过降水性云层,此方案不受下垫面条件的影响,适用于陆地和海洋区域。为验证IPCτRe方案的降水云识别效果,本文以PR瞬时降水探测结果为真值,采用三种二元预报评价因子对识别结果进行了定量评估,并与Inoue and Aonashi(2000)和Nauss and Kokhanovsky(2006)提出的降水云识别方案进行了比较。研究表明,IPCτRe方案的降水云识别性能均高于其它两种方案。特别是在洋面上,降水云识别比例达到84%,而对非降水云的误判率只有6%,到达了降水卫星监测和预报业务所要求的精度。

关键词：降水云识别光学厚度有效半径热带测雨卫星

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数字通信系统中的位同步技术

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电子技术（上海） 2021年第3期50卷 38-39页

作者：刘贤童厦门市海沧区职业中专学校福建361027

阐述数字通信系统中的位同步技术,最大似然算法、快速位同步捕获、锁相环法、Gardner定时恢复等定时同步算法,分析Gardner定时恢复,定时同步算法的未来发展方向:机器学习。

关键词：通信系统位同步 Gardner算法机器学习

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两种雨滴谱仪观测对比及对雷达降水估测精度影响研究

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气象 2023年第10期49卷 1157-1170页

作者：陈超刘黎平罗聪刘显通张阿思广东省气象台广州510640 中国气象科学研究院灾害天气国家重点实验室北京100081 中国气象局广州热带海洋气象研究所广州510640

利用广东龙门、新丰和佛冈布设的二维视频雨滴谱仪(2D-video-disdrometer,2DVD)和HY-P1000激光雨滴谱仪观测资料,分析了相同地点和相同时间两类雨滴谱仪降水滴谱观测和降水反演精度的差异。根据收集的2018年和2019年的雨滴谱观测数据,... 详细信息

利用广东龙门、新丰和佛冈布设的二维视频雨滴谱仪(2D-video-disdrometer,2DVD)和HY-P1000激光雨滴谱仪观测资料,分析了相同地点和相同时间两类雨滴谱仪降水滴谱观测和降水反演精度的差异。根据收集的2018年和2019年的雨滴谱观测数据,拟合了双偏振雷达定量降水估测基本关系式,并应用于S波段双偏振雷达(CINRAD/SAD)定量降水估测(quantitive precipitation estimation,QPE)优化组合方案中。结果表明:较HY-P1000雨滴谱仪而言,2DVD可观测到更多的1 mm以下的小粒子降水,但观测到的大于3.5 mm的雨滴数明显少于HY-P1000雨滴谱仪;对比由2DVD和HY-P1000观测数据计算得到的双偏振参数与CINRAD-SAD 0.5°仰角观测得到的双偏振参数,发现参数间均存在一定的差别,其中差分反射率因子差别相对较大;此外,利用2DVD观测数据可整体提升双偏振雷达QPE精度,对中雨及以下量级精度提升尤为明显。

关键词：雨滴谱仪双偏振雷达定量降水估测(QPE)

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一种基于TMI观测结果的海表温度反演算法

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气象学报 2011年第1期69卷 149-160页

作者：王雨傅云飞刘奇刘国胜刘显通程静中国科学技术大学地球与空间科学学院卫星遥感和气候环境实验室合肥230026 中国科学院大气物理研究所大气边界层物理和大气化学国家重点实验室北京100029 中国气象科学研究院灾害天气国家重点实验室北京100081 美国佛罗里达州立大学气象系塔拉哈西上海市气象信息传媒中心上海200030

基于星载微波仪器观测结果反演海表温度,能很好地克服云对反演结果的干扰,实现对海表温度全天候的监测。文中利用热带测雨卫星所搭载的微波成像仪的观测结果,建立了一种新的适用于非降水条件下的海表温度反演算法。作为一种半经验统计算... 详细信息

基于星载微波仪器观测结果反演海表温度,能很好地克服云对反演结果的干扰,实现对海表温度全天候的监测。文中利用热带测雨卫星所搭载的微波成像仪的观测结果,建立了一种新的适用于非降水条件下的海表温度反演算法。作为一种半经验统计算法,它以辐射传输方程为基础,通过理论模拟计算,建立海表温度与微波成像仪多通道亮温之间的关系,较好地反演海表温度。该算法最大的特点是选择了合适的5个微波成像仪通道,并通过这5个通道亮温的对数线性组合方式提取海表温度信息,从而有效地避开了其他环境参数对反演结果的影响。海表温度的反演结果与地基浮标观测结果的比较表明,二者间的均值相差0.116K、均方根误差为0.665K。在不同的风速、风向及天空状态(有无云)情况下,二者的相关系数均在0.95以上,均值差异小于0.2K,均方根误差在0.65K左右。在全球尺度上海表温度的反演结果与现有海表温度产品的比较显示,二者的差异一般不超过1K,且差异不随其他环境参数发生明显变化;与多年月平均海表温度产品对比研究结果表明,本算法反演获得的海表温度在全球大部分地区(除高风速高水汽区外)与其他海表温度资料的差异在1K范围以内。上述结果表明,该反演算法不仅适用于实时反演,亦能用于气候尺度研究。

关键词：海表温度反演微波成像仪半经验统计算法

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