Related Research Areas
Atmospheric Composition

The ice crystal size distribution in cirrus has to be accurately measured to understand mid-latitude cirrus cloud physics, to validate remote retrievals and to improve parameterization of numerical models. Large ice crystals that shatter on probe inlets create copious small fragments that are artificially counted as real particles. Measurements using the older-technology CAPS probe and the newer 2D-S imaging probe, which reliably images particles with 10-mm pixel resolution and rejects shattered artifacts, show that the large contribution of small particles in tropical anvil cirrus seen by the CAPS probe is an artifact due to ice crystal shattering. Results based on 2D-S measurements from TC4 now strongly suggest that artifacts from ice crystal shattering produced the small ice crystals that were previously thought to dominate radiative properties in cirrus and anvils. This finding is contrary to previous results from CAPS data collected in 2002 CRYSTAL-FACE project, which showed that extinction was dominated by particles < 50 mm. This proposal is to equip the WB-57F with two instruments that were previously installed on the WB-57F, the 2D-S and cloud particle imager (CPI) and also for installation of two additional probes: A Fast Forward Scattering Spectrometer Probe (FSSP) that records individual particle arrival times to remove the effects of shattering, and a third-generation high volume precipitation spectrometer (HVPS) that uses 2D-S electronics and provides full-view images of particles from 150 mm to 19.2 mm. The combination of these instruments will provide overlapping measurements that define the cirrus cloud particle size distribution from 1 mm to nearly 2 cm. Data analysis will include generation of a composite size distribution and analysis of radiative heating profiles using radiative transfer code.

Project PI: Paul Lawson/SPEC Incorporated

3022 Sterling Circle, Suite 200 Boulder, CO 80301. USA



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Started: Sep 27, 2010

Last Activity: Jan 04, 2011


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