Numerical simulations of 18 precipitation days from June to September in 1996with the 3D convective cloud model of CAMS (Chinese Academy of Meteorological Sciences, Version2000) were conducted. In these simulations, t...Numerical simulations of 18 precipitation days from June to September in 1996with the 3D convective cloud model of CAMS (Chinese Academy of Meteorological Sciences, Version2000) were conducted. In these simulations, the concentration of IN (ice nuclei) was assumed toincrease by 5 times. The results show that when IN concentrations increase, the amounts ofprecipitation decrease, cloud tops heighten and the areas of cloud tops increase in 80 percentsimulated clouds. Moreover, in 95 percent simulated clouds, the sizes of ice crystals in cloudsdecrease and quantities increase. These results mean that the physical properties of clouds willchange when IN concentration increases. The radiant properties of clouds and climate may also changedirectly and indirectly.展开更多
非感应起电是指云中冰相粒子间通过相互碰撞而发生的电荷转移现象,尤其以冰晶与霰粒子的碰撞过程为主,被证实是云中电荷产生的主要方式之一。沙尘作为大气冰核的重要组成成分,为了研究沙尘冰核对云中非感应起电过程的影响,本文将两种不...非感应起电是指云中冰相粒子间通过相互碰撞而发生的电荷转移现象,尤其以冰晶与霰粒子的碰撞过程为主,被证实是云中电荷产生的主要方式之一。沙尘作为大气冰核的重要组成成分,为了研究沙尘冰核对云中非感应起电过程的影响,本文将两种不同的非感应起电参数化方案(Takahashi方案,以下简称TAK方案;Saunders and Peck 1998方案,以下简称SP98方案)耦合至一维半云和气溶胶分档云模式中。该模式能够显性地追踪每个水成物粒子中云凝结核和冰核的质量大小,模拟每个冰核的核化过程,以及每个冰粒子的碰撞过程,从而确定霰粒子的数浓度和每个冰相粒子的电荷密度。对不同初始沙尘浓度的非感应起电过程进行了敏感性试验,模式模拟结果表明:随着沙尘粒子数浓度的增多,云中冰晶粒子与霰粒子的数浓度都分别增加,初始起电现象发生的时间提前,空间电荷密度大小增加;SP98方案和TAK方案都能模拟出1981年7月19日的一次积云观测个例的偶极型垂直分布,但SP98方案更接近实况。展开更多
Ice nucleating particle(INP) measurements were made at two high-altitude stations in India. Aerosols collected on filter paper at Girawali Observatory, Inter University Center for Astronomy & Astrophysics(IGO), an...Ice nucleating particle(INP) measurements were made at two high-altitude stations in India. Aerosols collected on filter paper at Girawali Observatory, Inter University Center for Astronomy & Astrophysics(IGO), and at the Radio Astronomy Center, Ooty(RAC), were activated in deposition mode using a thermal gradient diffusion chamber to determine the INP concentrations. The measurement campaigns at IGO were conducted during 2011, 2013 and 2014, and at RAC during 2013 and 2014. When the aerosol samples were exposed to an ice supersaturation of between 5% and 23% in the temperature range-17.6?C to-22?C, the maximum INP number concentration at IGO and RAC was 1.0 L-1and 1.6 L-1, respectively.A maximum correlation coefficient of 0.76 was observed between the INP number concentration and ice supersaturation. The airmass trajectories analyzed for the measurement campaigns showed that the Arabian Desert and arid regions were the main INP contributors. Elemental analysis of particles showed the presence of Na, Cl, Si, Al, Fe, Cu, Co, Cd, S, Mn and K, as well as some rare-Earth elements like Mo, Ru, La, Ce, V and Zr. When aerosols in the size range 0.5–20 μm were considered, the fraction that acted as INPs was 1 : 104to 1 : 106at IGO, and 1 : 103to 1 : 104at RAC. The higher ratio of INPs to aerosols at RAC than IGO may be attributable to the presence of rare-Earth elements observed in the aerosol samples at RAC, which were absent at IGO.展开更多
The Eyjafjallaj?kull 2010 eruption was an extraordinary event in that it led to widespread and unprecedented disruption to air travel over Europe – a region generally considered to be free from the hazards associated...The Eyjafjallaj?kull 2010 eruption was an extraordinary event in that it led to widespread and unprecedented disruption to air travel over Europe – a region generally considered to be free from the hazards associated with volcanic eruptions, excluding the extreme south influenced by Mt. Etna. In situ measurements were performed at the research centre of the National Research Council (CNR) area of Bologna (44?31′ N;11?20′ E), an urban background site, in order to contribute to knowledge concerning the impact of the volcanic emission.Aerosol size distributions measured with a Differential Mobility Particle Sizer (DMPS) and an Optical Particle Counter (OPC) show an increase in concentration of the accumulation and coarse fraction during the transit of the ash cloud, with respect to the subsequent period of the event, while particles smaller than 0.3 μm seem not to be affected by volcanic ash. Ice nuclei measured in the sampled air during and after the ash cloud transit, show an higher concentration during the ash cloud transit, with a ratio of about 1:110 with respect to the aerosol number concentration measured with the OPC.The elemental composition of aerosol particles, performed with SEM-EDX, gives about 30% of the inorganic coarse particles (geometric diameter larger than 1 μm) of volcanic origin on the 20 April. Si and Al concentrations result prevalently much higher than Ca and Fe ones. A large number of particles contained sulphur, indicating secondary processes of sulphate/sulphuric acid formation due to sulphur dioxide oxidation during transport in the volcanic plume.展开更多
基金This work is supported by the project of National Meteorological Center "Improvement and Development of Global Medium-Range Numerical Forecast system".
文摘Numerical simulations of 18 precipitation days from June to September in 1996with the 3D convective cloud model of CAMS (Chinese Academy of Meteorological Sciences, Version2000) were conducted. In these simulations, the concentration of IN (ice nuclei) was assumed toincrease by 5 times. The results show that when IN concentrations increase, the amounts ofprecipitation decrease, cloud tops heighten and the areas of cloud tops increase in 80 percentsimulated clouds. Moreover, in 95 percent simulated clouds, the sizes of ice crystals in cloudsdecrease and quantities increase. These results mean that the physical properties of clouds willchange when IN concentration increases. The radiant properties of clouds and climate may also changedirectly and indirectly.
文摘非感应起电是指云中冰相粒子间通过相互碰撞而发生的电荷转移现象,尤其以冰晶与霰粒子的碰撞过程为主,被证实是云中电荷产生的主要方式之一。沙尘作为大气冰核的重要组成成分,为了研究沙尘冰核对云中非感应起电过程的影响,本文将两种不同的非感应起电参数化方案(Takahashi方案,以下简称TAK方案;Saunders and Peck 1998方案,以下简称SP98方案)耦合至一维半云和气溶胶分档云模式中。该模式能够显性地追踪每个水成物粒子中云凝结核和冰核的质量大小,模拟每个冰核的核化过程,以及每个冰粒子的碰撞过程,从而确定霰粒子的数浓度和每个冰相粒子的电荷密度。对不同初始沙尘浓度的非感应起电过程进行了敏感性试验,模式模拟结果表明:随着沙尘粒子数浓度的增多,云中冰晶粒子与霰粒子的数浓度都分别增加,初始起电现象发生的时间提前,空间电荷密度大小增加;SP98方案和TAK方案都能模拟出1981年7月19日的一次积云观测个例的偶极型垂直分布,但SP98方案更接近实况。
文摘Ice nucleating particle(INP) measurements were made at two high-altitude stations in India. Aerosols collected on filter paper at Girawali Observatory, Inter University Center for Astronomy & Astrophysics(IGO), and at the Radio Astronomy Center, Ooty(RAC), were activated in deposition mode using a thermal gradient diffusion chamber to determine the INP concentrations. The measurement campaigns at IGO were conducted during 2011, 2013 and 2014, and at RAC during 2013 and 2014. When the aerosol samples were exposed to an ice supersaturation of between 5% and 23% in the temperature range-17.6?C to-22?C, the maximum INP number concentration at IGO and RAC was 1.0 L-1and 1.6 L-1, respectively.A maximum correlation coefficient of 0.76 was observed between the INP number concentration and ice supersaturation. The airmass trajectories analyzed for the measurement campaigns showed that the Arabian Desert and arid regions were the main INP contributors. Elemental analysis of particles showed the presence of Na, Cl, Si, Al, Fe, Cu, Co, Cd, S, Mn and K, as well as some rare-Earth elements like Mo, Ru, La, Ce, V and Zr. When aerosols in the size range 0.5–20 μm were considered, the fraction that acted as INPs was 1 : 104to 1 : 106at IGO, and 1 : 103to 1 : 104at RAC. The higher ratio of INPs to aerosols at RAC than IGO may be attributable to the presence of rare-Earth elements observed in the aerosol samples at RAC, which were absent at IGO.
文摘The Eyjafjallaj?kull 2010 eruption was an extraordinary event in that it led to widespread and unprecedented disruption to air travel over Europe – a region generally considered to be free from the hazards associated with volcanic eruptions, excluding the extreme south influenced by Mt. Etna. In situ measurements were performed at the research centre of the National Research Council (CNR) area of Bologna (44?31′ N;11?20′ E), an urban background site, in order to contribute to knowledge concerning the impact of the volcanic emission.Aerosol size distributions measured with a Differential Mobility Particle Sizer (DMPS) and an Optical Particle Counter (OPC) show an increase in concentration of the accumulation and coarse fraction during the transit of the ash cloud, with respect to the subsequent period of the event, while particles smaller than 0.3 μm seem not to be affected by volcanic ash. Ice nuclei measured in the sampled air during and after the ash cloud transit, show an higher concentration during the ash cloud transit, with a ratio of about 1:110 with respect to the aerosol number concentration measured with the OPC.The elemental composition of aerosol particles, performed with SEM-EDX, gives about 30% of the inorganic coarse particles (geometric diameter larger than 1 μm) of volcanic origin on the 20 April. Si and Al concentrations result prevalently much higher than Ca and Fe ones. A large number of particles contained sulphur, indicating secondary processes of sulphate/sulphuric acid formation due to sulphur dioxide oxidation during transport in the volcanic plume.
