Arctic Ice Crystal Haze

该项目是对极地大气中冰晶的辐射特性的调查，并评估这些冰晶如何影响辐射通量、局部加热率和能见度。冰晶在极地大气中一般不被认为是重要的，主要是因为人们的注意力集中在人为污染物上，几乎没有观察到与中纬度卷云有关的光学效应。然而，在南极大气中，一直可以观测到晴空冰晶降水，而在内陆站，冰晶降水可以占到年降水量的80%以上。在南极站，由于冰晶而产生的光学效应，包括一些相当罕见的效应，经常被观测到。北极冰晶的气候学就不那么确定了。从地面和卫星上观测北极的冰晶都很困难，特别是在极地之夜。冰晶的出现可能会在现在的天气代码中被注意到，但更有可能根本不会被注意到。卫星对冰晶的观测，特别是在雪或冰面上，或在极地夜晚，仍然是一个悬而未决的问题。然而，最近这个问题变得更加突出，因为越来越多的证据表明，北极雾霾事件中的水平能见度明显低于仅凭雾霾粒子的散射特征而预期的水平能见度，而且似乎表明了显著的冰晶浓度。该项目将根据3月和4月对冰晶、化学和气象条件的观测，开发一个云微物理参数化方案。辐射通量散度和加热率的模式输出将与热力学海冰模式相耦合，该模式将反过来提供平衡的海冰厚度值。这将为冰晶如何与极地大气中的化学、动力和辐射过程相互作用提供一个独特和创新的视角。

This project is an investigation into the radiative properties of ice crystals in the polar atmosphere, and an assessment how these crystals affect radiative fluxes, local heating rates, and visibility. Ice crystals have not generally been considered important in the polar atmosphere, primarily because attention was focussed on anthropogenic pollutants, and few optical effects such as those associated with mid- latitude cirrus clouds have been observed. However in the antarctic atmosphere, clear-sky ice crystal precipitation has consistently been observed, and at interior stations can account for more than 80 percent of the annual precipitation. Optical effects, including some quite rare ones, due to ice crystals are observed frequently at South Pole Station. The climatology of arctic ice crystal is much less certain. Observations of ice crystals in the arctic from both the surface and from satellites is difficult, particularly during the polar night. The occurrence of ice crystals may be noted in the synoptic present weather code, but more likely will not be noted at all. Satellite observation of ice crystals, particularly over a snow or ice surface, or in the polar night, remains an unsolved problem. Recently however this question has become more prominent as evidence is accumulating that the horizontal visibility in arctic haze events is significantly less than would be expected from the scattering characteristics of the haze particles alone, and a significant ice crystal concentrations seem to be indicated. This project will develop a cloud microphysics parameterization scheme, based on observations of ice crystals, chemistry, and meteorological conditions to be made in March and April 1989. The model output of the radiative flux divergences and heating rates will be coupled to a thermodynamic sea ice model which will in turn provide equilibrium sea ice thickness values. This will provide a unique and innovative look at how ice crystals interact with the chemical, dynamical and radiative processes in the polar atmosphere.