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.
Lawson, Paul. 2005. Cloud-radiation feedback: boundary layer cloud microphysical properties and processes. Boulder, Colorado USA: National Center for Atmospheric Research, Earth Observing Laboratory. Digital media.
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NCAR/EOL
Codiac Support
E-mail: codiac@ucar.edu
Homepage: http://data.eol.ucar.edu/
| Category | Description |
|---|---|
| Data format | Data are in space-delimited ASCII text format. Portable network graphic (PNG) files of all of the CPI data and plots of the data files are also available. Investigators have provided supplemental readme files in Microsoft Word format and documentation in PDF format. |
| Spatial coverage and resolution | Data were collected over the Beaufort Sea. Southernmost Latitude: 75.4442° N Northernmost Latitude: 78.6105° N Westernmost Longitude: 167.2124° W Easternmost Longitude: 160.6095° W |
| Temporal coverage and resolution | Data were collected during the summer of 1998, May through July. Probe data were collected at a rate of one sample per second, 1 Hz. Different principles were used to divide all flight periods into smaller periods. The smallest time periods ranged from approximately 5 to 15 seconds. |
| Tools for accessing data | Data can be viewed with a text editor and images can be viewed with any image viewer capable of opening PNG files. Files in DOC format can be viewed with Microsoft Word software. |
| File naming convention | See the File and Directory Structure section. |
| File size | File sizes range from 2 KB to 12.5 MB. The volume of the entire data set is 600 MB. |
| Parameter(s) | This data set includes cloud microphysical properties including combined CPI and 2D probe particle size distributions, bulk microphysical and radiation parameters, and images of cloud particles. |
| Procedures for obtaining data | The data were originally distributed on a CD-ROM. The data are now available as a single tar.gz file that contains the contents of the CD-ROM. |
1. Contacts and Acknowledgments
2. Detailed Data Description
3. Data Access and Tools
4. Data Acquisition and Processing
5. References and Related Publications
6. Document Information
Paul Lawson
SPEC Incorporated
3022 Sterling Circle Suite 200
Boulder, CO, USA 80301
NCAR/EOL
Codiac Support
E-mail: codiac@ucar.edu
Homepage: http://data.eol.ucar.edu/
This research was supported by the National Science Foundation (NSF) Office of Polar Programs (OPP) Arctic System Sciences (ARCSS) grant OPP-0084314.
Data are in space-delimited ASCII text format. Portable network graphic (PNG) files of all of the Cloud Particle Imager (CPI) data and plots of the data files are also available. Investigators have provided supplemental readme files in Microsoft Word format and documentation in PDF format.
"Documentation/" - contains documentation provided by investigators
"Data Archive Format/"
- "SPEC Microphysical Data Archive Format.pdf" - provides a format explanation for the reprocessed data submitted to the SHEBA archives
"Final Report/"
- "Final_Report.pdf" - provides a final report and analyses of the data's reprocessing
"Data Archive/" - contains the data from each of the five case studies
"archive_mm.dd.yyyy/" - where mm is the month, dd is the day, and yyyy is the year in which the data were collected for the five case studies
"CPI_images/" - contains all the CPI files, formatted as PNG images, that were collected during the research time periods
- "mmdd_hhnnss_ttt.png" - where mm is the month, dd is the day, hh is the hour, nn is the minute, ss is the second, and ttt is the hundredths of a second time stamp of the last image contained in that file
"graphics_and_ascii_files/" - contains individual time-period folders, each of which contains a handful of graphs formatted as PNG images, and an ASCII text data file
"hhnnss-hhnnss/" - contains data for a specific time period of interest, where hh is the hour; nn is the minute; and ss the second for the start and end of the time period
- "_#_yyyy-m-dd_hh-nn-ss--hh-nn-ss_FFF.ascii" - contains the data in ASCII text format for a specific time period of interest, where yyyy is the year; m is the month; dd is the day; nn is the minute; and ss is the second for the start and end of the time period
- "_#_yyyy-m-dd_hh-nn-ss--hh-nn-ss_FFF.png" - contains graphical representations of the data in PNG format, where yyyy is the year; m is the month; dd is the day; nn is the minute; and ss is the second for the start and end of the time period
- "hhnnss-hhnnss/" - contains data for an even smaller time period than the directory that is one level higher, where hh is the hour; nn is the minute; and ss the second for the start and end of the time period
File sizes range from 2 KB to 12.5 MB. The volume of the entire data set is 600 MB.
Data were collected over the Beaufort Sea.
Southernmost Latitude: 75.4442° N
Northernmost Latitude: 78.6105° N
Westernmost Longitude: 167.2124° W
Easternmost Longitude: 160.6095° W
There are some time periods when there were instrument problems. This information is available in the "SPEC Microphysical Data Archive Format.pdf", which can be found in the "Documentation" subdirectory.
Data were collected during the summer of 1998, May through July. Probe data were collected at a rate of one sample per second, 1 Hz. Different principles were used to divide all flight periods into smaller periods. The smallest time periods ranged from approximately 5 to 15 seconds.
This data set includes cloud microphysical properties including combined CPI and 2D probe particle size distributions, bulk microphysical and radiation parameters, and images of cloud particles.
Please see the detailed documentation provided by the investigators in the files "Final_Report.pdf" and "SPEC Microphysical Data Archive Format.pdf."
Data are distributed as a single tar.gz file containing all of the data.
The entire data set is 600 MB.
Please see the detailed "Final_Report.pdf" document provided by investigators that is distributed with the data.
Lawson, R. P., B. A. Baker, C. G. Schmitt and T. L. Jensen. 2001. An overview of microphysical properties of Arctic clouds observed in May and July during FIRE.ACE. Journal of Geophysical Research 106, 14, 989-15,014.
The following acronyms are used in this document:
ACE: Arctic Cloud Experiment
ARCSS: Arctic System Science
CD-ROM: Compact Disc Read Only Memory
CSIRO: Commonwealth Scientific and Industrial Research Organization
CPI: Cloud Particle Imager
FIRE: First ISCCP Regional Experiment
FSSP: Forward-Scattering Spectrometer Probe
ISCCP: International Satellite Cloud Climatology Project
IWC: Ice Water Content
LWC: Liquid Water Content
NCAR: National Center for Atmospheric Research
OPP: Office of Polar Programs
PMS: Particle Measuring Systems
PNG: Portable Network Graphic
PSD: Particle Size Distribution
SHEBA: Surface Heat Budget of the Arctic
URL: Uniform Resource Locator
UTC: Coordinated Universal Time
March 2009