Cloud-Radiation Feedback: Boundary Layer Cloud Microphysical Properties and Processes

Data Contributors

LAWSON, PAUL

Parameters

AEROSOL PARTICLE PROPERTIES
CLOUD LIQUID WATER/ICE
PARTICULATES

Instruments

2DC : 2D CLOUD PROBE
CPI : CLOUD PARTICLE IMAGER
FSSP : FORWORD SCATTERING SPECTROMETER PROBE
PMS 2D-C PROBE : PARTICLE MEASURING SYSTEMS 2D-C PROBE
PMS 2D-P PROBE : PARTICLE MEASURING SYSTEMS 2D-P PROBE

This data set includes Surface Heat Budget of the Arctic (SHEBA) cloud microphysical data collected onboard the National Center for Atmospheric Research (NCAR) C-130 aircraft. This work focused on improving the quality of algorithms used to process in situ measurements collected during First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment, Arctic Cloud Experiment (SHEBA/FIRE, ACE) and applying the results to the analysis of five case studies. Such research was deemed valuable as a result of weaknesses and inconsistencies in the existing C-130 data set that were pointed out in a SHEBA workshop held in 2000. Data has been reprocessed by SPEC, Inc. to improve quality and add value to the measurements. Investigators selected five research days that were considered to be high priority by the SHEBA science team: 4 May, 8 July, 18 July, 28 July, and 29 July of 1998.

New software algorithms and procedures were developed to objectively combine the measurements from the NCAR C-130 forward-scattering spectrometer probe (FSSP), Commonwealth Scientific and Industrial Research Organization (CSIRO)-King probe, 260X probe, 2D-C probe, and 2D-P probe which were made by Particle Measuring Systems, Inc. (PMS) along with a Cloud Particle Imager (CPI) made by SPEC, Inc. Prior to this work, 2D-probe data had not been analyzed quantitatively; the 260X probe data were used instead. It was found that using the 260X data resulted in severe underestimation of ice water content (IWC), radar reflectivity and effective particle size in most mixed-phase regions of cloud.

The software developed for this research performed several functions. CPI data were separated into water drops and ice crystals in mixed-phase clouds. Ice crystals were classified according to crystal type. An improved algorithm was developed to calculate IWC based on digitization and re-analysis of ice crystal and melted-drop images. The new algorithms were applied to the calculation of IWC, extinction coefficient, radar reflectivity, and ice particle effective size.

Data are distributed on CD-ROM.

Data Citation

Cloud-radiation feedback: boundary layer cloud microphysical properties and processes.