Full Name: Three-View Cloud Particle Imager
Short Name or Acronym: 3V-CPI
Model if applicable:
Measurements Provided: Images of hydrometeors, sizes, shapes, and concentrations of hydrometeors with sizes from about 10 um to a few mm. Images of a subset of the hydrometeors are recorded in more than one of the three systems, two orthogonal-viewing 2D probes (2D-S) and a high-resolution triggered-laser imager (CPI); when the 2D probes detect a hydrometeor in the sensitive volume of the CPI, they trigger the CPI to also record the image of the particle.
Manufacturer or Builder of the Instrument: SPEC, Inc., Boulder CO
When Acquired: 2010
Operational Status:
requestable, but has problems, needs work before deployment
General Description:
Calibration Methods: Size calibration is checked with a spinning disk (a disk with images on it that is rotated rapidly through the sensing volume). Optical alignment is also needed but is a specialized process best done only occasionally.
History of Significant Changes to the Instrument:
Description of Software, Data Handling, and Data Flow:
Software Components (data acquisition, display, processing, and analysis): An IDL-based program, 3VCPIView, has been provided by SPEC for data processing and analysis of both 2D-S and CPI data. In addition, 2D-S data must undergo a preprocessing step using the data acquisition program in "playback" mode. Processing requires considerable time, typically overnight for data from a full flight. The software permits setting various processing options and is quite flexible, but is not suited to routine processing. RAF, with assistance from SPEC, is in the process of developing a translator that will convert the 2D data from their format to the standard RAF format so that 2D data can be processed with RAF routines. This is a project funded by another sponsor, who has worked with Jorgen Jensen to specify contract requirements that will serve both groups. Considerable progress has been made toward this development, and our plan is to rely on that for routine processing.
Data Processing Chain (from flight to archival): No processing chain is yet in place to handle the data, except that provided by SPEC. Data must be collected from various directories on the acquisition computer and transferred to another device for removal from the aircraft, and the data sizes are large. SPEC makes their programs available to users, so we can provide them to anyone wanting to see the data. A different processing chain will be developed once the translator mentioned above is developed.
QA Procedures and Needs: It is possible to view the operation of the probe on the ground or during flight and determine if reasonable images are being acquired. Only the 3V-CPI data system computer can display the images, so QC procedures in flight are limited. Some parameters are broadcast to the aircraft data system as well. After the flight, the SPEC programs can be used to check the acquired data, but the process is laborious and not well suited to routine checks, so at present we rely mostly on in-flight checks.
Safety Issues:
Examples of Measurements:
CPI images:
Lead Contact: Jorgen Jensen
Operating Manual (preliminary), Data Processing Instructions (using SPEC software), File Transfer Instructions (SPEC).
Internal users: See http://wiki.eol.ucar.edu/rafscience/3VCPI (last edited 2012-12-10)