资源环境科技发展态势分析平台

During the Mid-Latitude CIRRUS campaign small (<50 mu m) ice crystals were characterized for their mesoscopic complexity using the Small Ice Detector Mk. 3. It was found that the majority (76%) of all measured small ice crystals were complex. Although some differences were found between the distributions of the complexity parameters between different cloud systems, no real correlation between the mesoscopic complexity and cloud formation mechanisms (liquid origin or in situ) was found. Some decrease in mesoscopic complexity was detected during those missions affected by Saharan dust outbreaks. The link between the crystal growth conditions and the observed mesoscopic complexity was investigated in a case study of an in situ cirrus with the help of trajectory analysis. A relatively weak correlation of r = 0.33 was found between the mesoscopic complexity and the maximum supersaturation with respect to ice along the ice particle trajectory.

Plain LanguageSummary Micrometer-scale features in atmospheric ice particles can significantly change the way these particles interact with sunlight. However, due to the small size of such features, they are difficult to be detected using traditional methods. Using light diffraction, it is possible to detect features in the order of wavelength. Here an instrument measuring diffraction patterns of individual atmospheric ice crystals was used to measure mesoscopic features in midlatitude cirrus clouds and to categorize the measured ice particles as complex or pristine. It was found that the measured ice clouds-independent of their formation mechanism-were mainly composed of complex ice crystals. The presented results support previous remote sensing observations.