Collaborative Research: A Satellite-Based Climatology of Jet Aircraft Contrails for the Contemporary Period (1995-2000)

人类活动造成的当代和未来气候变化的一个潜在因素是喷气飞机的排放。台站气候数据、密集的野外试验和数值模拟揭示了喷射凝结尾迹卷云对地面和大气辐射和能量收支的影响。一些科学家认为，在某些地区（如西欧中部），飞机尾迹对气候的影响可能已经与目前人为的二氧化碳强迫作用一样重要。然而，在试图评估飞机尾迹对气候的影响之前，为了推断预计的21世纪空中交通量持续增加的影响，需要对当代（1995-2000年）的飞机尾迹发生情况进行全面的空间气候学研究。卫星高分辨率图像是发展飞机尾迹气候学的一个接近理想的数据库。当代轨迹气候学的发展是主要的研究目标，并将利用NOAA极地轨道器存档的热红外图像来实现，这些图像可以在线获得。在1995-2000年期间，美国上空的尾迹的时空变化将使用人工技术确定季节中期的月份。该气候学将包括按日、月和年时间段合成的尾迹发生的标准化地图；绘制不同时期的纬向频率图；以及利用地理信息系统（GIS）方法绘制的按区域绘制的时间变化。在大约7个轨迹“爆发”期，包括地理位置、季节中期和天气气象条件，我们将使用GOES图像追踪轨迹扩散形成卷层云的发生率。在这些情况下，卫星轨迹信息将与飞机水平的温度和风观测相结合，以帮助揭示与持续轨迹相关的重要物理过程。为美国开发的当代尾迹气候学将有助于为评估尾迹对气候的影响提供适当的边界条件，为尾迹在未来气候中可能发挥的作用建模，并最终指导决策者。更具体地说，分析将澄清天气气象条件和飞机尾迹之间的联系，并有助于提供对飞机尾迹实时预测有用的规则。这项研究的最终成果将是统计模型，用于量化航迹数据与喷气式飞机活动的其他代理测量（例如，喷气燃料使用）之间的关系。这将使我们能够推断出21世纪上半叶卷云可能增加的幅度和首选位置，这些云是由持续的尾迹造成的，对气候很重要。

A potential contributor to contemporary and future climate changes from human activities is that due to jet aircraft emissions. Station climate data, intensive field experiments, and numerical modeling reveal the impacts of jet condensation trail (contrail) cirrus clouds on the surface and atmospheric radiation and energy budgets. Some scientists suggest that in certain regions (e.g., central Western Europe) contrails already may be as significant for climate as the present anthropogenic CO2 forcing. However, before attempting to evaluate the climatic impacts of contrails, and in order to extrapolate the effects of the predicted continued increase in air traffic into the 21st century, a comprehensive spatial climatology of contrail occurrences for the contemporary period (1995-2000) is required. Satellite high-resolution imagery are a close-to-ideal database for developing a climatology of contrails. The development of a contemporary contrail climatology is the primary research objective, and will be achieved using the archived thermal infrared imagery from the NOAA polar orbiters, available on-line. The spatial and temporal variations of contrails over the U.S. in the period 1995-2000 will be determined for mid-season months using a manual technique. This climatology will comprise normalized maps of contrail occurrences composited by diurnal, monthly, and annual time periods; graphed zonal frequencies for different periods; and temporal variations plotted by region, facilitated using geographic information system (GIS) methodology. For about 7 contrail "outbreak" periods comprising the range of geographical locations, mid-season months, and synoptic meteorological conditions, the incidence of contrail spreading to form cirrostratus clouds will be tracked using GOES imagery. For these cases also, the satellite contrail information will be allied with aircraft-level temperature and wind observations to help disclose the important physical processes associated with persisting contrails.The contemporary contrail climatology developed for the U.S. will help provide appropriate boundary conditions for assessing the climatic impacts of contrails, for modeling the possible role of contrails in future climate, and for ultimately guiding policymakers. More specifically, the analysis will permit clarification of the associations between synoptic meteorological conditions and contrails, and help provide rules useful for the real-time prediction of contrails. The ultimate products of the research will be statistical models that quantify the relationship between the contrail data and other proxy measures of jet aircraft activity (e.g., jet fuel usage). These will permit an extrapolation into the first half of the 21st century of the magnitude and preferred locations of likely increases in the cirrus clouds that result from persisting contrails, and which are important for climate.