Extended Edited Synoptic Cloud Reports from Ships and Land Stations Over the Globe, 1952-1996 (with Ship data updated through 2008) - NDP-026C

Data Files    NDP-026C Documentation

Date of Publication

Original date of publication: August 1999.
Updated March, 2002: This page and the global cloudiness data set updated to reflect the addition of 12 monthly files of ship reports for 1997.
Updated April, 2009: This page and the global cloudiness data set and documentation updated with an additional 11 years (through 2008) of ship reports. Added a new data directory (ship_199801_200812) containing the reports. Please see the new APPENDIX U in ndp026c.pdf for important details regarding record format differences of these new data files.

Investigators

C. J. Hahn
Dept. of Atmospheric Sciences,
University of Arizona

S. G. Warren
Dept. of Atmospheric Sciences,
University of Washington

DOI

10.3334/CDIAC/cli.ndp026c

Discussion

This database contains surface synoptic weather reports for the entire globe, gathered from various available data sets. The reports were processed, edited, and rewritten to provide a single dataset of individual observations of clouds, spanning the 57 years 1952-2008 for ship data and the 26 years 1971-1996 for land station data. In addition to the cloud portion of the synoptic report, each edited report also includes the associated pressure, present weather, wind, air temperature, and dew point (and sea surface temperature over oceans). This data set is called the "Extended Edited Cloud Report Archive" (EECRA).

Reports from the source data sets that did not meet certain quality control standards were rejected for the EECRA. Minor correctable inconsistencies within reports were edited for consistency. Cases of "sky obscured" were interpreted by reference to the present-weather code as to whether they indicated fog, rain, snow, or thunderstorm. Special coding was added to indicate probable nimbostratus clouds which are not specifically coded for in the standard synoptic code. Any changes made to an original report are also noted in the archived edited report so that the original report can be reconstructed if desired. This "extended edited cloud report" also includes the amounts, either inferred or directly reported, of low, middle, and high clouds, both overlapped and non-overlapped amounts. The relative lunar illuminance and the solar zenith angle associated with each report are also given, as well as an indicator that tells whether our recommended illuminance criterion was satisfied so that the "night-detection bias" for clouds can be minimized.

The EECRA contains about 81 million cloud observations from ships and 311 million from land stations. Each report is 80 characters in length for data through 1997; ocean data reports from 1998 through 2008 have a somewhat different format and are 98 characters in length (see Appendix U of ndp026c.pdf for an explanation). The archive consists of 997 files of edited synoptic reports, one file for each month of data for land and ocean separately, and 4 ancillary files which provide important information about reporting characteristics of the land stations. The 997 synoptic report files have been compressed using unix. Unix/linux users can "uncompress" or "gunzip" the files after downloading.

This data set will be useful for applications such as: (1) development of user-defined cloud climatologies for particular subtypes of clouds, or for different temporal and spatial resolution than we have chosen for our atlases, (2) in comparison of satellite cloud retrievals with surface observations, to help diagnose difficulties in cloud identification from satellite, and (3) to relate formation of individual types of clouds to their meteorological environments.

If you're interested in the NDP-026C database, then you'll also want to read about its follow-up data products, NDP-026D and NDP-026E.

Last updated 04/2009