武汉上空钠原子层结构短期演化特征

对1996年3月1日～3日钠荧光散射雷达获得的观测数据进行了分析与处理,得到了武汉（30#+[o]32'N,114#+[o]22'E）上空钠原子层结构的短期演化特征分布图,并对它作了初步分析。结果指出,武汉上空钠原子层结构具有显著的时空变化特点,钠原子数密度的变化在1 h之内可达50%。     

Mie 散射激光雷达探测大气气溶胶的进展

简要论述了激光雷达探测大气的优点,以及求解M ie散射激光雷达方程的理论方法,并阐述了国内外近20 a来M ie散射激光雷达探测大气气溶胶的主要成果,及其存在的问题。     

Airborne and lidar measurements of aerosol and cloud particles in the troposphere over Alert Canada in April 1986

As a component of the Canadian Arctic Haze Study, held coincident with the second Arctic Gas and Aerosol Sampling Program (AGASP II), vertical profiles of aerosol size distribution (0.17 m), light scattering parameters and cloud particle concentrations were obtained with an instrumented aircraft and ground-based lidar system during April 1986 at Alert. Northwest Territories. Average aerosol number concentrations range from about 200 cm^–3 over the Arctic ice cap to about 100 cm^–3 at 6 km. The aerosol size spectrum is virtually free of giant or coarse aerosol particles, and does not vary significantly with altitude. Most of the aerosol volume is concentrated in the 0.17–0.50 m size range, and the aerosol number concentration is found to be a good surrogate for the SO₄ ⁼ concentration of the Arctic haze aerosol. Comparison of the aircraft and lidar data show that, when iced crystal scattering is excluded, the aerosol light scattering coefficient and the lidar backscattering coefficient are proportional to the Arctic haze aerosol concentration. Ratios of scattering to backscattering, scattering to aerosol number concentration, and backscattering to aerosol number concentration are 15.3 steradians, 1.1×10^–13 m², and 4.8×10^–15 m² sr^–1, respectively. Aerosol scattering coefficients calculated from the measured size distributions using Mie scattering agree well with measured values. The calculations indicate the aerosol absorption optical depth over 6 km to range between 0.011 and 0.018. The presence of small numbers of ice crystals (10–20 crystals 1^–1 measured) increased light scattering by over a factor of ten.     

A vertical sounding of severe haze process in Guangzhou area

We detected a severe haze process in Guangzhou area with lidar and microwave radiometer, performed an inversion to get boundary layer height by wavelet covariance transform, and analyzed the correlation between meteorological factors of boundary layer and visibility from the perspective of dynamical and thermodynamic structures. Our results indicate that the boundary layer height shows significant daily changes, consistent with ground visibility variation. During the cleaning process, the boundary layer height exceeded 1 km; during severe haze, the height was only 500 m. Temperature gradient of 50–100 m, which was 30 h lag, was remarkably correlated with visibility, with the correlation coefficient of 0.77. High layer visibility(255 m) and low layer stability were significantly anticorrelation, and the maximum anticorrelation coefficient was up to-0.76 in cleaning days and-0.49 in haze days. In the related boundary layer meteorological factors, surface ventilation coefficient was linearly correlated with ground visibility, with the greatest correlation coefficient of 0.88. The correlation coefficients of boundary layer height, ground wind velocity, relative humidity and ground visibility were 0.76, 0.67, and-0.77, respectively. There was a strong correlation between different meteorological factors. The dominant meteorological factor during this haze process was surface ventilation coefficient. In the area without boundary layer height sounding, ground visibility and wind velocity could be used to estimate boundary layer height.     

合成孔径技术在光学领域的应用

介绍了合成孔径技术的发展及其基本原理,对国外合成孔径激光雷达的发展进行了综述,最后对合成孔径激光雷达的优势进行了分析.     

中间层顶重力波耗散引起钠原子输送的激光雷达观测研究

利用中国科学院国家空间科学中心廊坊站（40.0°N,116.3°E）钠荧光多普勒激光雷达2011年至2013年共约82 h的钠原子数密度和垂直风观测数据,分析了廊坊地区中间层顶区域大气重力波耗散引起的钠原子输送特征.分析得到,90~100 km处重力波耗散引起的平均钠原子垂直通量整体为负,钠原子向下输送,在93 km处达到最大负值-1.47×10⁸m^-3 m·s^-1,85~90 km处平均钠原子垂直通量为正,钠原子向上输送,但通量值随高度递减.钠原子垂直通量方向在90 km处发生转变,垂直通量随高度的变化造成钠原子汇聚,汇聚效应引起的平均钠原子产生率最大值在91 km处达到了1.40×10⁸ m^-3/h,该值超过了相同高度上模式计算流星烧蚀注入引起的钠原子产生率峰值,说明重力波耗散对钠层结构的形成具有重要影响.与美国SOR和Maui观测结果相比,平均钠原子产生率峰值大小相近,但出现高度不同,说明大气重力波耗散引起的物质输送具有显著的地域变化特征.研究结果可为大气物质输送理论的完善以及大气金属层物理模式的改进提供观测事实参考.

     

大气中水汽混合比的Raman激光雷达探测

介绍了作者自行研制的L625Raman激光雷达系统的结构和主要技术参数,叙述了Raman激光雷达探测水汽混合比的基本原理和数据处理方法。使用这台激光雷达在合肥地区进行了水汽混合比垂直分布的探测,对获得的水汽混合比垂直廓线进行了初步的分析和研究。最后就L625Raman激光雷达探测水汽混合比的误差进行了分析和讨论。     

激光测风雷达PPI扫描监测风切变的数值模拟

低空风切变严重威胁飞机起降安全,而激光测风雷达在晴空风切变监测方面具有显著优势,但其监测性能受到风场特点和监测算法的影响。由于无法对局地空间风场进行时空同步精细化探测,且风场具有阵性,导致风切变监测会出现虚警率、漏报等现象,只能通过数值模拟仿真的方式,对不同风场的监测性能进行分析评估。本文首先仿真构建了四种具有代表性的风场类型,然后模拟激光测风雷达平面—位置显示（Plane Position Indication,PPI）扫描方式获取不同仿真风场下的径向风速数据,最后利用八邻域系统算法对径向风速数据进行风切变监测,验证不同类型风场下激光测风雷达PPI扫描方式监测风切变算法的有效性。结果表明,激光测风雷达PPI扫描结果能够真实地反映风场情况;八邻域系统算法能够有效识别风切变;在进行风切变检测时,应尽可能地考虑到多个方位上的切变值,避免漏报。     

国家自然科学基金共享航次计划固定调查断面概述

基于科考船的海洋调查是获取海洋变化第一手资料的重要方式,是孕育海洋科学原创成果的基础。2009年以来,国家自然科学基金共享航次计划实施情况表明,研究项目所需的海上调查“船时”和观测数据得以共享,但不同年份之间同一海域的站位设置及其观测方案变化较大,缺乏相对固定的调查断面研究。为进一步提升国家自然科学基金的资助成效,加强海洋过程的长期变化规律研究,自2020年起国家自然科学基金共享航次计划规划设置了34条固定调查断面,其中10余条固定断面调查要求已在随后的年度申请指南中发布。基于顶层设计思想提出的固定调查断面遵循了“突出重点、承前启后;科学引领、绩效为本;统筹兼顾、分步实施”的设置原则。其中,近海固定断面以生物多样性丰富、生产力水平较高、陆海相互作用强烈、受气候变化和人类活动双重干扰、资源环境问题突出的海域为重点,聚焦近海生态系统健康与服务功能维持、陆海相互作用的资源环境效应等关键科学问题;深远海固定断面则以对全球变化响应敏感、与我国海洋环境和气候变化关联紧密、海洋防灾减灾需求强烈的西太平洋和东印度洋海域为重点,聚焦地球系统多圈层相互作用、极端海洋环境与生命过程等关键科学问题。文章详细介...