Convection and Tropospheric Trace Gases

水在大气中的循环对空气中一些微量化学成分的分布和浓度有很大影响。在大气中形成液态水(即云和降水)的情况下尤其如此。云形成的动力可以将痕量物质从大气的一个区域移动到另一个区域。此外，可以将物种从一种化学形式转变为另一种化学形式的液相反应的重要性，直到现在才得到大气化学研究科学家的认识和记录。虽然实验室和模拟实验表明了云和降水形成过程对大气化学的重要性，但很少有直接的现场测量来验证和量化这类过程的重要性。直接观察这些影响是一项困难的工作，因为需要专门和极其灵敏的测量设备和方法。这个项目的目标是通过继续由美国国家科学基金资助ATM-8305843发起的研究：(1)测量对流云和雷暴引起的化学物质从对流层低层向高层输送的程度；(2)测量云光反射和吸收对光化学过程的影响；(3)测量化合物夹带到云中的程度；以及(4)在对流层上层检验某些光化学理论。这项研究将通过为国家大气研究中心Saberliner飞机配备先进的化学测量仪器来进行，该仪器适用于探测云和风暴系统中选定的物种。化学研究将与风暴形成的气象研究相协调。该项目预计将提供有关对大气科学具有重要意义的物理和化学过程的重要信息。

The cycle of water through the atmosphere greatly influences the airborne distribution and concentration of a number of trace chemical components. This is especially true in cases where liquid water (i.e. clouds and precipitation) is formed in the atmosphere. The dynamics of cloud formation can move trace species from one region of the atmosphere to another. Additionally, the importance of liquid phase reactions which can change species from one chemical form to another is only now being recognized and documented by atmospheric chemical research scientists. While the importance of cloud and precipitation formation processes on atmospheric chemistry has been suggested as the result of laboratory and modeling experiments, there have been very few direct field measurements to verify and quantify the significance of such processes. The direct observation of these effects is a difficult undertaking since specialized and extremely sensitive measurement equipment and methods are required. The objectives of this project are through the continuation of research initiated under NSF grant ATM-8305843 to: (1) measure the extent of convective cloud and thunderstorm induced transport of chemical species from the lower to upper troposphere; (2) measure the influence of cloud light reflection and absorption on photochemical processes; (3) measure the degree of entrainment of chemical compounds into clouds; and (4) test certain theories of photo-chemistry in the upper troposphere. This research will be carried out by equipping the National Center for Atmospheric Research Saberliner aircraft with sophisticated chemical measurement instrumentation suitable for detecting selected species in cloud and storm systems. The chemical studies will be coordinated with meteorological studies of storm formation. This project is expected to provide important information regarding physical and chemical processes which are of significance to the atmospheric sciences.