Intensive field experiment is an important approach to obtain microphysical information about clouds and precipitation. From 1 July to 31 August 2014, the third Tibetan Plateau Atmospheric Science Experiment was carri...Intensive field experiment is an important approach to obtain microphysical information about clouds and precipitation. From 1 July to 31 August 2014, the third Tibetan Plateau Atmospheric Science Experiment was carried out and comprehensive measurements of water vapor, clouds, and precipitation were conducted at Naqu. The most advanced radars in China, such as Ka-band millimeter-wave cloud radar, Ku-band micro-rain radar, C-band continuous-wave radar and lidar, and microwave radiometer and disdrometer were deployed to observe high spatial-temporal vertical structures of clouds and precipitation. The C-band dual- linear polarization radar was coordinated with the China new generation weather radar to constitute a dual- Doppler radar system for the measurements of three-dimensional wind fields within convective precipitations and the structure and evolution of hydrometeors related to precipitation process. Based on the radar measurements in this experiment, the diurnal variations of several important cloud properties were analyzed, including cloud top and base, cloud depth, cloud cover, number of cloud layers, and their vertical structures during summertime over Naqu. The features of reflectivity, velocity, and depolarization ratio for different types of clouds observed by cloud radar are discussed. The results indicate that the cloud properties were successfully measured by using various radars in this field experiment. During the summertime over Naqu, most of the clouds were located above 6 km and below 4 km above ground level. Statistical analysis shows that total amounts of clouds, the top of high-level clouds, and cloud depth, all demonstrated a distinct diurnal variation. Few clouds formed at 1000 LST （local standard time）, whereas large amounts of clouds formed at 2000 LST. Newly formed cumulus and stratus clouds were often found at 3-km height, where there existed significant updrafts. Deep convection reached up to 16.5 km （21 km above the mean sea level）, and updrafts and downdrafts coexisted in t展开更多
阐述了相干差分吸收激光雷达(CDIAL)探测大气二氧化碳(CO_(2))的原理,设计了1.57μm波段微脉冲相干探测系统,并对系统的回波信号进行了仿真。通过仿真计算分别探究了温度、压力、波长等因素对差分光学厚度计算及CO_(2)体积分数的反演精...阐述了相干差分吸收激光雷达(CDIAL)探测大气二氧化碳(CO_(2))的原理,设计了1.57μm波段微脉冲相干探测系统,并对系统的回波信号进行了仿真。通过仿真计算分别探究了温度、压力、波长等因素对差分光学厚度计算及CO_(2)体积分数的反演精度的影响。仿真结果显示:当波长漂移为0.5 pm、温度不确定度为1 K、压强不确定度为1 h Pa、水汽体积分数测量不确定度为10%时,这些参数引起的总体误差为0.45%;在大气中CO_(2)的体积分数为4×10^(-4)时,微脉冲相干激光雷达探测CO_(2)体积分数的测量误差约为1.8×10^(-6)。展开更多
基金Supported by the China Meteorological Administration Special Public Welfare Research Fund(GYHY201406001)National Key Basic Research and Development(973)Program of China(2012CB417202)National Natural Science Foundation of China(91337103 and 41175038)
文摘Intensive field experiment is an important approach to obtain microphysical information about clouds and precipitation. From 1 July to 31 August 2014, the third Tibetan Plateau Atmospheric Science Experiment was carried out and comprehensive measurements of water vapor, clouds, and precipitation were conducted at Naqu. The most advanced radars in China, such as Ka-band millimeter-wave cloud radar, Ku-band micro-rain radar, C-band continuous-wave radar and lidar, and microwave radiometer and disdrometer were deployed to observe high spatial-temporal vertical structures of clouds and precipitation. The C-band dual- linear polarization radar was coordinated with the China new generation weather radar to constitute a dual- Doppler radar system for the measurements of three-dimensional wind fields within convective precipitations and the structure and evolution of hydrometeors related to precipitation process. Based on the radar measurements in this experiment, the diurnal variations of several important cloud properties were analyzed, including cloud top and base, cloud depth, cloud cover, number of cloud layers, and their vertical structures during summertime over Naqu. The features of reflectivity, velocity, and depolarization ratio for different types of clouds observed by cloud radar are discussed. The results indicate that the cloud properties were successfully measured by using various radars in this field experiment. During the summertime over Naqu, most of the clouds were located above 6 km and below 4 km above ground level. Statistical analysis shows that total amounts of clouds, the top of high-level clouds, and cloud depth, all demonstrated a distinct diurnal variation. Few clouds formed at 1000 LST （local standard time）, whereas large amounts of clouds formed at 2000 LST. Newly formed cumulus and stratus clouds were often found at 3-km height, where there existed significant updrafts. Deep convection reached up to 16.5 km （21 km above the mean sea level）, and updrafts and downdrafts coexisted in t
文摘阐述了相干差分吸收激光雷达(CDIAL)探测大气二氧化碳(CO_(2))的原理,设计了1.57μm波段微脉冲相干探测系统,并对系统的回波信号进行了仿真。通过仿真计算分别探究了温度、压力、波长等因素对差分光学厚度计算及CO_(2)体积分数的反演精度的影响。仿真结果显示:当波长漂移为0.5 pm、温度不确定度为1 K、压强不确定度为1 h Pa、水汽体积分数测量不确定度为10%时,这些参数引起的总体误差为0.45%;在大气中CO_(2)的体积分数为4×10^(-4)时,微脉冲相干激光雷达探测CO_(2)体积分数的测量误差约为1.8×10^(-6)。
