Cloudsat - Adding a new dimension to a classical view of extratropical cyclones

Research into extratropical cyclones has a long and rich history. Indeed, much of modern meteorology has grown out of the study of these weather systems, aided by the development of conceptual models of cyclone structure and evolution. Early versions of these models derived from a combination of physical understanding and collections of observations, and today, results from numerical models are used to augment this process. Though observations have played a key role in understanding extratropical cyclone evolution, global observations of the internal structure of the clouds that accompany these storms have been lacking. The launch of Cloudsat in 2006 introduced a new tool for observing the details of clouds and precipitation produced by midlatitude weather systems. In this paper, we examine recent measurements of frontal clouds and precipitation from Cloudsat, and reflect back on the early view of these systems as represented in the Norwegian Cyclone Model. In the process, we describe how Cloudsat observations can be used as a novel component in the research process to obtain unique information on the distribution and characteristics of clouds and precipitation in midlatitude low pressure systems. We present three cases in which Cloudsat views the clouds and precipitation associated with a frontal system, and point out the unique features evident in the observed clouds. In the process, we also demonstrate how Cloudsat data can be used to assess the performance of a numerical representation of the atmosphere. We finish with a suggestion of Cloudsat's anticipated role in the long chain of research into extratropical cyclone structure and evolution.