The relationship between cirrus ice microphysical properties and meteorological conditions observed during SPARTICUS.

Description

Cirrus have strong impacts on the Earth’s radiation budget. However, they are poorly represented in global climate models due to the variety of mechanisms that contribute to their formation and uncertainties about their microphysical properties. One of these uncertainties is the result of shattering of large crystals on the tips and inlets of probes used to measure them. The Small PARTicles in CirruS (SPARTICUS) experiment was motivated by the need for routine observations of ice microphysical properties in a variety of meteorological conditions. Using state-of-art probes equipped with anti-shattering tips and processed with shatter detection algorithms (Fast Forward Scattering Spectrometer Probe FFSSP, 2D Stereo Probe 2DS and 2D Precipitation Probe), SPARTICUS made routine in-situ observations of mid-latitude cirrus over the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site from January to June 2010 with the Stratton Park Engineering Company Learjet.. Probability distribution functions of observed and derived microphysical properties (e.g., N, number distribution functions, gamma fits to the number distribution function, bulk extinction, ice water content, etc.) were derived for different meteorological categories (i.e., for synoptically, convectively or orographically generated clouds, according to distance from and time after strongest convection, and according to cloud size derived from space- and ground-based radar/lidar), together with their dependence on other environmental parameters (e.g., temperature, vertical velocity, and relative humidity) identified for each category. The derived relationships take into account uncertainties in measured size distributions from both statistical counting and shattering.