Development and Applications of Far Infrared Radiometry in Cold Atmospheres

我的研究和这项提议的总体目的是调查以气溶胶和前体气体形式的人为排放对高纬度大气水循环的间接影响。这项研究的中心是观测光学薄冰云(TIC)和轻降水(钻石尘埃)，它们占北极年降水量的近50%。然而，许多TIC的发生被错误地报告为晴朗的天空，因为地面观测者在极地之夜看到星星。尽管如此，频繁的小雨仍被报告为“痕迹”，没有进行定量评估。因此，TIC过程在大气模式中的表现仍然很差，导致预测误差。现在人们认识到，人造气溶胶可以改变云层和降水。我的研究的原创性是使用一种极具创新性的远红外(FIR)方法来填补高纬度云和轻降水观测方面的现有空白。这些云通过冰核对气溶胶敏感，可以显著调节从地球逃逸的FIR(8-50微米)辐射量，并影响对流层中上层和表面的温度。由于云的FIR特征对它们的性质(晶体大小和形状)和光学厚度非常敏感，这些量也可以从地面和卫星观测中反演。在这个发现计划中，理论计算和测量被用来展示大气远红外将如何为天气预报、数据同化和气候模拟提供关于其水汽含量、冰云和普通光降水的微物理特征的有价值的信息。在这方面，我正在领导“远红外实验中的薄冰云”(TICFIRE)，作为即将在加拿大航天局(CSA)执行的一项卫星任务。在世界气象组织极地预测年计划(Yopp，2017-22)的支持下，我与加拿大航天局(CSA)和加拿大环境局(ECCC)以及其他大学和行业(INO、LR Tech、Honeywell)合作，在中远红外波段领导新的测量，以增进我们对TIC极地云的了解。今年秋天(2018年)，我们部署了基于加拿大创新技术的新型远红外辐射计(FIRR-2)。FIRR是未来TICFIRE卫星和旨在改善极地地区监测和天气预报的新地面仪器的原型。在YOPP计划下，我正在进行创新的实验和扩展的数据分析，导致FIRR的业务应用，并研究TIC微物理和辐射相互作用。这些测量的核心是准确评估冰晶大小的能力，在这里，我最近的结果表明，对于寒冷的极地云和卷云，FIRR可以超越并补充其他技术。

The general aim of my research and for this proposal is to investigate the indirect effects of anthropogenic emission in the form of aerosols and precursor gases on the atmospheric water cycle at high latitudes. Central to this study is the observation of optically Thin Ice Clouds (TIC) and light precipitation (diamond dust), accounting for nearly 50% of the annual precipitation in the Arctic. Yet many of the occurrence of TIC are misreported as clear sky, since a ground observer sees stars during the polar night. Still, frequent light precipitations are reported as "trace", without a quantitative evaluation. As a result, TIC processes are still poorly represented in atmospheric models, leading to forecasting errors. It is now recognized that man-made aerosols can alter cloud and precipitation. The originality of my research is to fill an existing gap in cloud and light precipitation observation at high latitudes using a highly innovative method in the far infrared (FIR). These clouds, sensitive to aerosols via ice nucleation, can significantly modulate the amount of FIR (8-50µm) radiation escaping the Earth and affecting temperatures in the upper to mid troposphere and at the surface. Since FIR signature of clouds is very sensitive to their properties (crystals size and shape) and optical depth, these quantities can also be retrieved from ground-based and satellite observations. In this discovery program, theoretical calculations and measurements are used to show how the atmospheric far IR will provide valuable information for weather forecasting, data assimilation and climate simulations, about its water vapour content, the microphysical characteristics of ice clouds and common light precipitation. In this context, I am leading the "Thin Ice Clouds in the Far InfraRed Experiment" (TICFIRE) as a forthcoming satellite mission at the Canadian Space Agency (CSA). Endorsed by the Year of Polar Prediction program (YOPP, 2017-22), a World Meteorological Organisation initiative, in collaboration with the Canadian Space Agency (CSA) and Environment Canada (ECCC), with other universities and the industry (INO, LR Tech, Honeywell), I am leading new measurements in the mid and far IR range to advance our knowledge of TIC Polar clouds. This fall (2018), we have deployed the new Far IR Radiometer (FIRR-2), base on an innovative Canadian technology. The FIRR is a prototype for the future TICFIRE satellite and for a new ground-based instrument aimed to improve monitoring and weather prediction in Polar Regions. Under YOPP program, I am conducting innovative experiments and extended data analysis leading to operational applications of the FIRR and to study TIC microphysics and radiation interaction. Central to these measurements is the ability to evaluate accurately the size of ice crystals, here, my recent results have shown that for cold polar clouds and cirrus, the FIRR can outperform and complement other technologies.