This study concerns a Ka-band solid-state transmitter cloud radar, made in China, which can operate in three different work modes, with different pulse widths, and coherent and incoherent integration numbers, to meet ...This study concerns a Ka-band solid-state transmitter cloud radar, made in China, which can operate in three different work modes, with different pulse widths, and coherent and incoherent integration numbers, to meet the requirements for cloud remote sensing over the Tibetan Plateau. Specifically, the design of the three operational modes of the radar（i.e., boundary mode M1, cirrus mode M2, and precipitation mode M3） is introduced. Also, a cloud radar data merging algorithm for the three modes is proposed. Using one month＇s continuous measurements during summertime at Naqu on the Tibetan Plateau,we analyzed the consistency between the cloud radar measurements of the three modes. The number of occurrences of radar detections of hydrometeors and the percentage contributions of the different modes＇ data to the merged data were estimated.The performance of the merging algorithm was evaluated. The results indicated that the minimum detectable reflectivity for each mode was consistent with theoretical results. Merged data provided measurements with a minimum reflectivity of -35 dBZ at the height of 5 km, and obtained information above the height of 0.2 km. Measurements of radial velocity by the three operational modes agreed very well, and systematic errors in measurements of reflectivity were less than 2 dB. However,large discrepancies existed in the measurements of the linear depolarization ratio taken from the different operational modes.The percentage of radar detections of hydrometeors in mid- and high-level clouds increased by 60% through application of pulse compression techniques. In conclusion, the merged data are appropriate for cloud and precipitation studies over the Tibetan Plateau.展开更多
Data from a long term measurement of Micro Rain Radar （MRR） at a mountain site （Daegwallyeong, DG, one year period of 2005） and a coastal site （Haenam, HN, three years 2004-2006） in South Korea were analyzed to ...Data from a long term measurement of Micro Rain Radar （MRR） at a mountain site （Daegwallyeong, DG, one year period of 2005） and a coastal site （Haenam, HN, three years 2004-2006） in South Korea were analyzed to compare the MRR measured bright band characteristics of stratiform precipitation at the two sites. On average, the bright band was somewhat thicker and the sharpness （average gradient of reflectivity above and below the reflectivity peak） was slightly weaker at DG, compared to those values at HN. The peak reflectivity itself was twice as strong and the relative location of the peak reflectivity within the bright band was higher at HN than at DG. Importantly, the variability of these values was much larger at HN than at DG. The key parameter to cause these differences is suggested to be the difference of the snow particle densities at the two sites, which is related to the degree of riming. Therefore, it is speculated that the cloud microphysical processes at HN may have varied significantly from un-rimed snow growth, producing low density snow particles, to the riming of higher density particles, while snow particle growth at DG was more consistently affected by the riming process, and therefore high density snow particles. Forced uplifting of cloudy air over the mountain area around DG might have resulted in an orographic supercooling effect that led to the enhanced riming of supercooled cloud drops.展开更多
In this study, the vertical profiles of radar refractive factor(Z) observed with an X-band Doppler radar in Jurong on July 13, 2012 in different periods of a stratiform cloud precipitation process were simulated using...In this study, the vertical profiles of radar refractive factor(Z) observed with an X-band Doppler radar in Jurong on July 13, 2012 in different periods of a stratiform cloud precipitation process were simulated using the Sim RAD software, and the contributions of each impact resulting in the bright band were analyzed quantitatively. In the simulation, the parameters inputted into Sim RAD were updated until the output Z profile was nearly consistent with the observation. The input parameters were then deemed to reflect real conditions of the cloud and precipitation. The results showed that a wider(narrower) and brighter(darker) bright band corresponded to a larger(smaller) amount, wider(narrower) vertical distribution, and larger(smaller) mean diameter of melting particles in the melting layer. Besides this,radar reflectivity factors under the wider(narrower) melting layer were larger(smaller). This may be contributed to the adequate growth of larger rain drops in the upper melting layer. Sensitivity experiments of the generation of the radar bright band showed that a drastic increasing of the complex refractive index due to melting led to the largest impact,making the radar reflectivity factor increase by about 15 d BZ. Fragmentation of large particles was the second most important influence, making the value decrease by 10 d BZ. The collision-coalescence between melting particles, volumetric shrinking due to melting, and the falling speed of raindrops made the radar reflectivity factor change by about 3-7d BZ. Shape transformation from spheres to oblate ellipsoids resulted in only a slight increase in the radar reflectivity factors(about 0.2 d BZ), which might be due to the fact that there are few large particles in stratiform cloud.展开更多
Using infrared sensors to detect ice clouds in different atmospheric layers is still a challenge.The different scattering and absorption properties of longwave and shortwave infrared channels can be utilized to fulfil...Using infrared sensors to detect ice clouds in different atmospheric layers is still a challenge.The different scattering and absorption properties of longwave and shortwave infrared channels can be utilized to fulfill this purpose.In this study,the release of Suomi-NPP Cross-track Infrared Sounder(Cr IS)full spectrum resolution is used to select and pair channels from longwave(~15μm)and shortwave(~4.3μm)CO2 absorption bands under stricter conditions,so as to better detect ice clouds.Besides,the differences of the weighting function peaks and cloud insensitive level altitudes of the paired channels are both within 50 h Pa so that the variances due to atmospheric conditions can be minimized.The training data of clear sky are determined by Visible Infrared Imaging Radiometer Suite(VIIRS)cloud mask product and used to find the linear relationship between the paired longwave and shortwave CO2 absorption channels.From the linear relationship,the so-called cloud emission and scattering index(CESI)is derived to detect ice clouds.CESI clearly captures the center and the ice cloud features of the Super Typhoon Hato located above 415 h Pa.Moreover,the CESI distributions agree with cloud top pressure from the VIIRS in both daytime and nighttime in different atmospheric layers.展开更多
针对传统消防监控系统存在开发成本高、误警率高、实时监控不便的问题,提出一种基于物联网云平台的智慧消防远程监控系统。采用STM32单片机作为中枢控制芯片,经多传感器采集温度、湿度、烟雾、火焰等环境数据,通过窄带物联网(NB-IoT,Nar...针对传统消防监控系统存在开发成本高、误警率高、实时监控不便的问题,提出一种基于物联网云平台的智慧消防远程监控系统。采用STM32单片机作为中枢控制芯片,经多传感器采集温度、湿度、烟雾、火焰等环境数据,通过窄带物联网(NB-IoT,Narrow Band Internet of Things)上传至OneNET云平台。经数据分析后以可视化方式呈现,对异常数据触发报警实时响应。通过手机APP实现数据实时监测及一键处置。经测试,监控系统报警准确率高于97.2%,数据延迟低于50 ms,表明该系统能够实现消防火警的无线远程监控,并做出快速反应,满足中小微企业和普通家庭用户的消防监控需要。展开更多
卫星观测与辐射传输分析证明,对流云团红外水汽与窗区亮温差(brightness temperature difference,BTD)具有显著特征,利用对流云团BTD红外亮温特征可以识别对流云团。基于对流云团BTD特征建立的全球对流识别系统(global convection diagn...卫星观测与辐射传输分析证明,对流云团红外水汽与窗区亮温差(brightness temperature difference,BTD)具有显著特征,利用对流云团BTD红外亮温特征可以识别对流云团。基于对流云团BTD特征建立的全球对流识别系统(global convection diagnostic,GCD)算法通过设立一个BTD单阈值检测对流云团的有无,但是它不能进一步量化对流云团强度。本文利用FY-2GVISSR红外观测数据与CINRAD CAR(CAPPI of reflectivity)雷达观测数据进行对比研究,结果表明:BTD/CAR具有较好线性正相关关系;BTD不仅可以用于识别对流云团的存在,还可以进一步量化对流云团强度;BTD作为对流云团识别因子优于IRW(infrared window)亮温法。基于BTD/CAR相关关系可以实现基于静止卫星红外水汽和窗区观测的对流云团识别与定强。展开更多
基金funded by the National Sciences Foundation of China(Grant No.91337103)the China Meteorological Administration Special Public Welfare Research Fund(Grant No.GYHY201406001)
文摘This study concerns a Ka-band solid-state transmitter cloud radar, made in China, which can operate in three different work modes, with different pulse widths, and coherent and incoherent integration numbers, to meet the requirements for cloud remote sensing over the Tibetan Plateau. Specifically, the design of the three operational modes of the radar（i.e., boundary mode M1, cirrus mode M2, and precipitation mode M3） is introduced. Also, a cloud radar data merging algorithm for the three modes is proposed. Using one month＇s continuous measurements during summertime at Naqu on the Tibetan Plateau,we analyzed the consistency between the cloud radar measurements of the three modes. The number of occurrences of radar detections of hydrometeors and the percentage contributions of the different modes＇ data to the merged data were estimated.The performance of the merging algorithm was evaluated. The results indicated that the minimum detectable reflectivity for each mode was consistent with theoretical results. Merged data provided measurements with a minimum reflectivity of -35 dBZ at the height of 5 km, and obtained information above the height of 0.2 km. Measurements of radial velocity by the three operational modes agreed very well, and systematic errors in measurements of reflectivity were less than 2 dB. However,large discrepancies existed in the measurements of the linear depolarization ratio taken from the different operational modes.The percentage of radar detections of hydrometeors in mid- and high-level clouds increased by 60% through application of pulse compression techniques. In conclusion, the merged data are appropriate for cloud and precipitation studies over the Tibetan Plateau.
基金funded by the Korean Meteorological Administration Research and Development Program under Grant CATER 2006-2307.
文摘Data from a long term measurement of Micro Rain Radar （MRR） at a mountain site （Daegwallyeong, DG, one year period of 2005） and a coastal site （Haenam, HN, three years 2004-2006） in South Korea were analyzed to compare the MRR measured bright band characteristics of stratiform precipitation at the two sites. On average, the bright band was somewhat thicker and the sharpness （average gradient of reflectivity above and below the reflectivity peak） was slightly weaker at DG, compared to those values at HN. The peak reflectivity itself was twice as strong and the relative location of the peak reflectivity within the bright band was higher at HN than at DG. Importantly, the variability of these values was much larger at HN than at DG. The key parameter to cause these differences is suggested to be the difference of the snow particle densities at the two sites, which is related to the degree of riming. Therefore, it is speculated that the cloud microphysical processes at HN may have varied significantly from un-rimed snow growth, producing low density snow particles, to the riming of higher density particles, while snow particle growth at DG was more consistently affected by the riming process, and therefore high density snow particles. Forced uplifting of cloudy air over the mountain area around DG might have resulted in an orographic supercooling effect that led to the enhanced riming of supercooled cloud drops.
文摘地基云雷达是云的重要探测手段,但随着运行时间的增加,雷达发射机、接收器等参数的变化,会使观测数据产生漂移偏差,从而对云物理特性的反演产生显著影响,因此云雷达数据的校准是一个重要的基础问题。针对KAZR(Ka-Band Zenith Radar,K波段云雷达)云雷达特征,本文在Pavlos等提出的雷达数据校准方法基础上进行改进,优化了对弱云和降水的信号识别,利用CloudSat星载雷达观测的反射率因子,气体衰减校正等数据,对兰州大学半干旱气候环境监测站(Semi-Arid Climate and Environment Observatory of Lanzhou University,SACOL)KAZR云雷达2013年8月至2017年5月反射率因子数据进行了校准,建立了KAZR雷达反射率因子46个月的历史资料校准数据库,并对校准周期的变化进行了对比分析。校准数据库的建立对SACOL站云的长期观测研究具有重要意义,同时为不同波段地基雷达的对比增加了可行性。
基金National Natural Science Foundation of China(41275043)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘In this study, the vertical profiles of radar refractive factor(Z) observed with an X-band Doppler radar in Jurong on July 13, 2012 in different periods of a stratiform cloud precipitation process were simulated using the Sim RAD software, and the contributions of each impact resulting in the bright band were analyzed quantitatively. In the simulation, the parameters inputted into Sim RAD were updated until the output Z profile was nearly consistent with the observation. The input parameters were then deemed to reflect real conditions of the cloud and precipitation. The results showed that a wider(narrower) and brighter(darker) bright band corresponded to a larger(smaller) amount, wider(narrower) vertical distribution, and larger(smaller) mean diameter of melting particles in the melting layer. Besides this,radar reflectivity factors under the wider(narrower) melting layer were larger(smaller). This may be contributed to the adequate growth of larger rain drops in the upper melting layer. Sensitivity experiments of the generation of the radar bright band showed that a drastic increasing of the complex refractive index due to melting led to the largest impact,making the radar reflectivity factor increase by about 15 d BZ. Fragmentation of large particles was the second most important influence, making the value decrease by 10 d BZ. The collision-coalescence between melting particles, volumetric shrinking due to melting, and the falling speed of raindrops made the radar reflectivity factor change by about 3-7d BZ. Shape transformation from spheres to oblate ellipsoids resulted in only a slight increase in the radar reflectivity factors(about 0.2 d BZ), which might be due to the fact that there are few large particles in stratiform cloud.
基金National Key R&D Program(2018YFC1506904)Natural Science Foundation of China(41590873,41705089)。
文摘Using infrared sensors to detect ice clouds in different atmospheric layers is still a challenge.The different scattering and absorption properties of longwave and shortwave infrared channels can be utilized to fulfill this purpose.In this study,the release of Suomi-NPP Cross-track Infrared Sounder(Cr IS)full spectrum resolution is used to select and pair channels from longwave(~15μm)and shortwave(~4.3μm)CO2 absorption bands under stricter conditions,so as to better detect ice clouds.Besides,the differences of the weighting function peaks and cloud insensitive level altitudes of the paired channels are both within 50 h Pa so that the variances due to atmospheric conditions can be minimized.The training data of clear sky are determined by Visible Infrared Imaging Radiometer Suite(VIIRS)cloud mask product and used to find the linear relationship between the paired longwave and shortwave CO2 absorption channels.From the linear relationship,the so-called cloud emission and scattering index(CESI)is derived to detect ice clouds.CESI clearly captures the center and the ice cloud features of the Super Typhoon Hato located above 415 h Pa.Moreover,the CESI distributions agree with cloud top pressure from the VIIRS in both daytime and nighttime in different atmospheric layers.
文摘针对传统消防监控系统存在开发成本高、误警率高、实时监控不便的问题,提出一种基于物联网云平台的智慧消防远程监控系统。采用STM32单片机作为中枢控制芯片,经多传感器采集温度、湿度、烟雾、火焰等环境数据,通过窄带物联网(NB-IoT,Narrow Band Internet of Things)上传至OneNET云平台。经数据分析后以可视化方式呈现,对异常数据触发报警实时响应。通过手机APP实现数据实时监测及一键处置。经测试,监控系统报警准确率高于97.2%,数据延迟低于50 ms,表明该系统能够实现消防火警的无线远程监控,并做出快速反应,满足中小微企业和普通家庭用户的消防监控需要。
文摘卫星观测与辐射传输分析证明,对流云团红外水汽与窗区亮温差(brightness temperature difference,BTD)具有显著特征,利用对流云团BTD红外亮温特征可以识别对流云团。基于对流云团BTD特征建立的全球对流识别系统(global convection diagnostic,GCD)算法通过设立一个BTD单阈值检测对流云团的有无,但是它不能进一步量化对流云团强度。本文利用FY-2GVISSR红外观测数据与CINRAD CAR(CAPPI of reflectivity)雷达观测数据进行对比研究,结果表明:BTD/CAR具有较好线性正相关关系;BTD不仅可以用于识别对流云团的存在,还可以进一步量化对流云团强度;BTD作为对流云团识别因子优于IRW(infrared window)亮温法。基于BTD/CAR相关关系可以实现基于静止卫星红外水汽和窗区观测的对流云团识别与定强。
