Investigation of Ice Cloud Microphysical Properties of DCSs using Aircraft in situ Measurements

 
Poster PDF

Authors

Xiquan Dong — University of Arizona
Jingyu Wang —

Category

Ice Physical and Radiative Properties

Description

Six deep convective systems (DCSs) with a total of 5,589 5-s samples and a range of temperatures from -41 oC to 0 oC during the Midlatitude Continental Convective Clouds Experiment (MC3E) were selected to investigate the ice cloud microphysical properties of DCSs over the DOE Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site. The ice cloud microphysical properties of the DCS cases have been collected by the University of North Dakota Citation II research aircraft and processed through the following processes. First, the super-cooled liquid water in the ice dominated cloud layers of DCSs has been eliminated using a multi-sensor detection, such as a Rosemount icing detector, King and CDP probes, as well as 2DC and CIP images. Then the Nevzorov-measured ice water contents (IWCs) at maximum diameter Dmax < 4,000 μm are used as a ground truthbest estimate to determine a new mass-dimensional relationship. Finally the newly derived mass-dimensional relationship (a=0.00365, b=2.1) has been applied to a full spectrum of particle size distributions (PSDs, 90120-30,000 μm) constructed from both 2DC and HVPS measurements to calculate the best-estimated IWCs of DCSs during MC3E. The averages of the total number concentrations (Nt), median mass diameter (Dm), Dmax, and IWC from six selected cases are 0.035 cm-3, 1,666 μm, 8,841 μm, and 0.45 gm-3, respectively. The gamma-type-size-distributions are then generated using matching the observedoriginal PSDs (120-30,000 μm), and the fitted gamma parameters are compared with observedoriginal PSDs through multi-moment assessments including first moment (Dm), third moment (IWC), and sixth moment (equivalent radar reflectivity, Ze). For application of observed PSDs to remote sensing community, a series of empirical relationships between fitted parameters and Ze values has been derived and the bullet rosette ice crystal backscattering relationship has been suggested for ground-based remote sensing.