The interactions between clouds and aerosols represent one of the largest uncertainties in assessing the Earth's radiation budget, highlighting the importance of research on the transition zone(TZ) within the clou...The interactions between clouds and aerosols represent one of the largest uncertainties in assessing the Earth's radiation budget, highlighting the importance of research on the transition zone(TZ) within the cloud-aerosol continuum.This study assesses the global distribution of TZ conditions, analyzes its optical characteristics, and determines the cloud or aerosol types most commonly associated with them, using the cloud-aerosol discrimination(CAD) score of the CloudAerosol Lidar with Orthogonal Polarization(CALIOP) instrument on the CALIPSO satellite. The CAD score classifies clouds and aerosols by the probability density functions of attenuated backscatter, total color ratio, volume depolarization ratio, altitude, and latitude. After applying several filters to avoid artifacts, the TZ was identified as those atmospheric layers that cannot be clearly classified as clouds or aerosols, layers within the no-confidence range(NCR) of the CAD score, and cirrus fringes. The optical characteristics of NCR layers exhibit two main clusters: Cluster 1, with properties between high-altitude ice clouds and aerosols(e.g., wispy cloud fragments), and Cluster 2, with properties between water clouds and aerosols at lower altitudes(e.g., large hydrated aerosols). Our results highlight the significant ubiquity of TZ conditions, which appear in 9.5% of all profiles and comprise 6.4% of the detected layers. Cluster 1 and cirrus-fringe layers predominate near the ITCZ and in mid-latitudes, whereas Cluster 2 layers are more frequent over the oceans along the central West African and East Asian coasts, where elevated smoke and dusty marine aerosols are common.展开更多
对小云粒子(粒径<50μm)的相态进行检测是云物理飞机测量领域的一个难点,而利用云粒子的偏振信息对云粒子相态进行鉴别是目前云物理研究领域比较认可的一种方法。本文针对偏振云粒子谱仪(cloud aerosol spectrometer with depolariza...对小云粒子(粒径<50μm)的相态进行检测是云物理飞机测量领域的一个难点,而利用云粒子的偏振信息对云粒子相态进行鉴别是目前云物理研究领域比较认可的一种方法。本文针对偏振云粒子谱仪(cloud aerosol spectrometer with depolarization,CAS-DPOL)所测云粒子偏振参量的应用需求展开研究,通过对现有方法的比较分析,整合出一套适合于该仪器的方法和阈值。基于所整合出的方法和阈值以及该仪器在2021年5月23日东北冷涡天气的一次航测结果,探讨了该仪器在人工影响天气和飞机自然结冰探测领域的应用,此次航测发现温度在-1~-8℃的云内过冷云滴数对总云粒子数占比的平均值可达到80.18%,云相以混合相为主,间有纯过冷水云相存在;此次航测以云粒子谱仪所测数浓度大于5 cm^(-3)作为过冷滴存在的下限判定指标是比较可信的;此外,飞机在此次航测中的自然结冰强度为微量结冰,没有探测到符合《运输类飞机适航标准》附录C曲线要求的结冰气象条件。展开更多
基于2024年5月10日和20日在丹江口水库汇水区开展的针对气溶胶和积层混合云的两次飞机观测,利用机载探测资料,分析了水库汇水区气溶胶和云微物理量的垂直分布特征。结果表明,气溶胶数浓度总体随高度的增加呈下降趋势,与白天相比,夜晚近...基于2024年5月10日和20日在丹江口水库汇水区开展的针对气溶胶和积层混合云的两次飞机观测,利用机载探测资料,分析了水库汇水区气溶胶和云微物理量的垂直分布特征。结果表明,气溶胶数浓度总体随高度的增加呈下降趋势,与白天相比,夜晚近地层气溶胶浓度更高,最高达4000 cm^(-3)。中低层气溶胶中值体积直径约为0.2~0.3μm,有效直径约为0.6~0.8μm。气溶胶粒子主要集中在小粒径段,粒子谱为多峰分布,第一峰值直径为0.14μm。云内气溶胶浓度基本都略低于云外,而更强的吸湿增长作用导致气溶胶粒径更大。气团后向轨迹分析结果表明,近地层气溶胶粒子主要来自局地排放,高层粒子主要来自远距离传输,5月10日观测点周围人为排放产生的污染性细颗粒物是造成近地层气溶胶浓度高于5月20日的主要原因。两次观测的积层混合云内的云滴有效直径整体均在25μm以内,云滴数浓度最大值分别为118 cm^(-3)和205 cm^(-3),5月10日和20日云内液水富集层分别在6100 m和5500 m左右,液水含量最大值分别为0.44 g m^(-3)和0.78 g m^(-3)。由于气溶胶粒子竞争水汽的作用,云底附近的较高气溶胶浓度使得云滴浓度出现高值,同时云滴直径减小。小云滴阶段粒子谱为单峰分布,不同高度的峰值粒径略有差异,主要集中在11~25μm,雨滴和冰晶阶段粒子谱转变为多峰分布。展开更多
通过WRF(Weather Research and Forecasting)模式嵌套包含了高云和气溶胶辐射效应的大气边界层模式,结合激光雷达资料,进行数值模拟,定量分析高云和气溶胶辐射效应对城市边界层的影响。模式能很好地模拟出在高云和气溶胶辐射效应下城市...通过WRF(Weather Research and Forecasting)模式嵌套包含了高云和气溶胶辐射效应的大气边界层模式,结合激光雷达资料,进行数值模拟,定量分析高云和气溶胶辐射效应对城市边界层的影响。模式能很好地模拟出在高云和气溶胶辐射效应下城市边界层的特征。夜间,气溶胶在低层起到保温作用,高云使得保温作用得到加强,地表增温达1.5K。中高层,气溶胶降低所在气层温度,高云使得降温幅度减少,降温达0.2～0.7K。白天,高云和气溶胶减少到达地面的太阳短波辐射,导致低层温度降低,地表降温达1.3K。中高层,气溶胶加热所在的气层,高云使得这一增温幅度减少,在500m处增温最大,达0.85K。无论白天还是夜间,气溶胶的辐射效应都会抵消一部分形成山谷风的热力条件,使得中低层的风速减少,这种影响在白天显得尤为明显。高云的存在使得这种抵消得到少量的补偿。展开更多
基金funded through project NUBOLOSYTI (PID2023149972NB-100) of the Spanish Ministry of Science and Innovation (MICINN)supported by an IFUdG 2022 fellowship。
文摘The interactions between clouds and aerosols represent one of the largest uncertainties in assessing the Earth's radiation budget, highlighting the importance of research on the transition zone(TZ) within the cloud-aerosol continuum.This study assesses the global distribution of TZ conditions, analyzes its optical characteristics, and determines the cloud or aerosol types most commonly associated with them, using the cloud-aerosol discrimination(CAD) score of the CloudAerosol Lidar with Orthogonal Polarization(CALIOP) instrument on the CALIPSO satellite. The CAD score classifies clouds and aerosols by the probability density functions of attenuated backscatter, total color ratio, volume depolarization ratio, altitude, and latitude. After applying several filters to avoid artifacts, the TZ was identified as those atmospheric layers that cannot be clearly classified as clouds or aerosols, layers within the no-confidence range(NCR) of the CAD score, and cirrus fringes. The optical characteristics of NCR layers exhibit two main clusters: Cluster 1, with properties between high-altitude ice clouds and aerosols(e.g., wispy cloud fragments), and Cluster 2, with properties between water clouds and aerosols at lower altitudes(e.g., large hydrated aerosols). Our results highlight the significant ubiquity of TZ conditions, which appear in 9.5% of all profiles and comprise 6.4% of the detected layers. Cluster 1 and cirrus-fringe layers predominate near the ITCZ and in mid-latitudes, whereas Cluster 2 layers are more frequent over the oceans along the central West African and East Asian coasts, where elevated smoke and dusty marine aerosols are common.
文摘基于2024年5月10日和20日在丹江口水库汇水区开展的针对气溶胶和积层混合云的两次飞机观测,利用机载探测资料,分析了水库汇水区气溶胶和云微物理量的垂直分布特征。结果表明,气溶胶数浓度总体随高度的增加呈下降趋势,与白天相比,夜晚近地层气溶胶浓度更高,最高达4000 cm^(-3)。中低层气溶胶中值体积直径约为0.2~0.3μm,有效直径约为0.6~0.8μm。气溶胶粒子主要集中在小粒径段,粒子谱为多峰分布,第一峰值直径为0.14μm。云内气溶胶浓度基本都略低于云外,而更强的吸湿增长作用导致气溶胶粒径更大。气团后向轨迹分析结果表明,近地层气溶胶粒子主要来自局地排放,高层粒子主要来自远距离传输,5月10日观测点周围人为排放产生的污染性细颗粒物是造成近地层气溶胶浓度高于5月20日的主要原因。两次观测的积层混合云内的云滴有效直径整体均在25μm以内,云滴数浓度最大值分别为118 cm^(-3)和205 cm^(-3),5月10日和20日云内液水富集层分别在6100 m和5500 m左右,液水含量最大值分别为0.44 g m^(-3)和0.78 g m^(-3)。由于气溶胶粒子竞争水汽的作用,云底附近的较高气溶胶浓度使得云滴浓度出现高值,同时云滴直径减小。小云滴阶段粒子谱为单峰分布,不同高度的峰值粒径略有差异,主要集中在11~25μm,雨滴和冰晶阶段粒子谱转变为多峰分布。
文摘通过WRF(Weather Research and Forecasting)模式嵌套包含了高云和气溶胶辐射效应的大气边界层模式,结合激光雷达资料,进行数值模拟,定量分析高云和气溶胶辐射效应对城市边界层的影响。模式能很好地模拟出在高云和气溶胶辐射效应下城市边界层的特征。夜间,气溶胶在低层起到保温作用,高云使得保温作用得到加强,地表增温达1.5K。中高层,气溶胶降低所在气层温度,高云使得降温幅度减少,降温达0.2～0.7K。白天,高云和气溶胶减少到达地面的太阳短波辐射,导致低层温度降低,地表降温达1.3K。中高层,气溶胶加热所在的气层,高云使得这一增温幅度减少,在500m处增温最大,达0.85K。无论白天还是夜间,气溶胶的辐射效应都会抵消一部分形成山谷风的热力条件,使得中低层的风速减少,这种影响在白天显得尤为明显。高云的存在使得这种抵消得到少量的补偿。
