Classification of Clouds in Airborne Cloud Radar Observations

Various types of clouds and precipitation systems, and even the same types but at different stages of development, have different physical properties. To investigate these characteristics, it is helpful to classify clouds and precipitation systems into meaningful categories. Many such cloud classifications exist. The most famous of these, as described in the WMO International Cloud Atlas, classifies clouds into the basic genera of cirrus, cumulus, and stratus with their respective subcategories, based on characteristics such as cloud base altitude and horizontal and vertical extent. Other classifications focus on the convective or stratiform nature of the clouds and precipitation systems.

Following the latter approach, we developed a cloud and precipitation classification methodology for the airborne HIAPER Cloud Radar to analyze the properties of clouds observed in field campaigns. In the first step of the method, we identify individual clouds using the reflectivity observations, separating or consolidating echo entities into reasonable units. In a second step, we use the results from the recently developed ECCO algorithm which identifies the convective or stratiform nature of the observations. The clouds identified in step one are classified into twelve categories based on their convective/stratiform characteristics and altitude of occurrence. Statistics of cloud properties for the different categories can then be calculated and provide insights into cloud physical mechanisms. Results of this approach are presented.