The Interaction Among Mesoscale Dynamics, Microphysical Properties and Radiative Effects of Mid-latitude Cirrus Clouds

University Of Washington, Seattle WA

Investigators

Abstract

Cirrus clouds form under a variety of dynamical and thermodynamical conditions, and have a profound impact on the radiative energy balance of the Earth. The radiative properties and the radiative impact of cirrus clouds are inherently controlled by their microphysical and macrophysical properties. However, the physical and dynamical mechanisms that govern the formation, microphysical evolution, and the life cycle of cirrus clouds and influence their mesoscale variability are not very well understood, which in turn hinders confident quantification of the radiative impact of cirrus under various conditions. The primary goal of this research is to significantly improve our understanding of the linkages between the microphysical and macrophysical properties of mid-latitude cirrus clouds and the dynamical and thermodynamical properties of the air masses in which they form. We seek to provide a detailed and process-based understanding of the links between the large scale and mesoscale dynamical forcing, the microphysical and macrophysical properties of cirrus clouds and their radiative properties. The methodology used in this study combines (1) numerical simulations with a cloud-resolving regional model; with (2) a novel dynamical state classification technique to cluster cirrus cloud events according to large scale and mesoscale dynamical forcing; and (3) comparison of simulated cirrus cloud properties with observations from aircraft and remote sensors. The cloud-resolving regional model simulations allow for a detailed and process-based investigation of the microphysical and macrophysical properties of cirrus clouds, as well as provide deeper insight into the physical and dynamical mechanisms that affect the evolution and life cycle of cirrus and the mesoscale dynamical feedbacks that are caused by the presence of cirrus. The atmospheric state classification technique enables us to statistically link atmospheric dynamical states with the microphysical and macrophysical characteristics of cirrus clouds, allowing us to draw physically and statistically based conclusions regarding how cirrus cloud properties are affected by different large scale and mesoscale dynamical forcings. The results of the classification are crucial for evaluating and improving cirrus microphysical parameterizations in a regime dependent approach. Comparison of model simulations with observations makes use of an unprecedented data set of new microphysical observations in mid-latitude cirrus clouds. Intellectual merit Substantially improved understanding of the microphysical and dynamical controls of cirrus clouds and a better understanding of how these controls affect the macrophysical and radiative properties of mid-latitude cirrus will be obtained. This knowledge will be invaluable for improving microphysical parameterizations and lead to a more physically based representation of cirrus microphysical, macrophysical, and radiative properties in numerical models on various scales. The improved representation of cirrus cloud properties will then help to better quantify the radiative impact of mid-latitude cirrus. Broader impacts Graduate education and training, collaboration with other scientists, improvement of microphysical parameterization and representation of cirrus clouds in cloud-resolving regional models, and participation in international model inter-comparisons are all planned in this work. Newly acquired data sets and results will be archived and shared with the broader research community. Our research results will be documented in peer-reviewed publications and disseminated through our participation in and presentations at national and international workshops and conferences. In addition we will engage underrepresented minority students in our research and use elements of the data analysis in curriculum development for undergraduate and high school students.