***This file is a brief documentation of the NDP026C data archive. The full documentation is contained in the file ndp026c.pdf, requiring Adobe Acrobat Reader. Another file, ndp026c.txt, a flat ASCII file, contains all of the text documentation of ndp026c.pdf, without any tables and figures.*** PLEASE NOTE: On March 20, 2000 this page and the global cloudiness data set were updated to reflect the addition of 12 monthly files of ship reports for 1996. Previously, the ship data extended only through 1995. On April 28, 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. ------------------------------------------------------------------------------ Hahn, C.J., and S.G. Warren, 1999: Extended Edited Synoptic Cloud Reports from Ships and Land Stations Over the Globe, 1952-1996. ORNL/CDIAC-123, NDP026C, Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee. doi: 10.3334/CDIAC/cli.ndp026c (Also available from Data Support Section, National Center for Atmospheric Research, Boulder, CO.) Abstract: Surface synoptic weather reports for the entire globe, gathered from various available data sets, were processed, edited, and rewritten to provide a single dataset of individual observations of clouds, spanning the 45 years 1952-1996 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 over 72 million cloud observations from ships and 311 million from land stations. Each report is 80 characters in length. The archive consists of 841 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. 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. _____ It is important that the user obtain the full documentation from: Carbon Dioxide Information Analysis Center Oak Ridge National Laboratory Post Office Box 2008 Oak Ridge, TN 37831-6335, U.S.A. Telephone (423) 574-3645 http://cdiac.esd.ornl.gov/epubs/ndp/ndp026c/ndp026c.html or Data Support Section National Center for Atmospheric Research Boulder, CO 80307, U.S.A. Telephone (303) 497-1215 _____ The full documentation contains important information about: avoiding the clear-sky and sky-obscured biases for cloud types, computation of cloud type frequencies and amount-when-present, amount-when-present of altostratus clouds for regions of China, 1971-79, and illuminance criteria for avoiding the night-detection bias. It also contains valuable information about reporting characteristics of land stations and describes the four ancillary files provided with this data set. This brief documentation consists of Tables 1,2,3,9 from the full documentation: Table 1. Cloud Information Contained in Synoptic Weather Reports Table 2. Cloud and Weather Type Definitions Used Table 3. Change Codes for Edited Cloud Reports Table 9. Contents and Format of the 80-character Extended Edited Cloud Report. *********-*********-*********-*********-*********-*********-*********-*********- Table 1. Cloud Information Contained in Synoptic Weather Reports ________________________________________________________________ Symbol Meaning Codes# ________________________________________________________________ N total cloud cover 0-8 oktas 9= sky obscured Nh lower* cloud amount 0-8 oktas h lower* cloud base height 0-9 CL low cloud type 0-9 CM middle cloud type 0-9 CH high cloud type 0-9 ww present weather 00-99 Ix present weather indicator 1-6 ________________________________________________________________ # Any category for which information is lacking to the observer is coded as "/" (and converted to "-1" in the EECRA). * The "lower" cloud is the middle level if there are no low clouds. *********-*********-*********-*********-*********-*********-*********-*********- Table 2. Cloud and Weather Type Definitions Used ________________________________________________________________________________ Shorthand Extended Level notation Meaning Synoptic codes codes# ________________________________________________________________________________ Tcc total cloud cover N = 0-9 0-8 Clr completely clear sky N = 0 Ppt precipitation ww= 50-75,77,79,80-99 D drizzle 50-59 R rain 60-69 S snow 70-75,77,79 Ts thunderstorm,shower 80-99 Low CL= Fo sky obscured by fog / with N=9 and ww=F* 11 St stratus 6,7 Sc stratocumulus 4,5,8 Cu cumulus 1,2 Cb cumulonimbus 3,9, or N=9 with ww=Ts 10 Mid CM= Ns nimbostratus 2,7, or N=9, with ww=DRS 12,11,10 / with ww=DRS and CL=0,7 10 / with ww= RS and CL=4-8 10 As altostratus 1; 2 if not DRS Ac altocumulus 3,4,5,6,8,9; 7 if not DRS High CH= Cs cirrostratus 5,6,7,8 Cic cirrus, cirrocumulus 1,4,9 Cid dense cirrus 2,3 ________________________________________________________________________________ # Extended codes shown where they differ from synoptic codes. In the extended code the value "-1", rather than "/", is used to signify missing information. * F represents the fog codes ww=10-12,40-49. *********-*********-*********-*********-*********-*********-*********-*********- Table 3. Change Codes for Edited Cloud Reports _________________________________________________________________________ Occurrence (%) Land Ocean IC* Case (brief description**) Changes made# all light all light __ ________________________________ ______________ __________ __________ 0 none## 87.4 87.4 87.2 86.9 1 N=9 with ppt or fog N=8; CL=10,11 1.6 1.6 2.6 2.6 or CM=10 2 Nh=0 with CM>0 and CL=0 Nh=N 0.8 0.8 0.5 0.5 3 Nh=N with CH>0 and CL=CM=0 Nh=0 0.1 0.1 0.2 0.2 4 Nh 0.11, where RI = P sin(A) (R2/r2) {see full documentation}. *********-*********-*********-*********-*********-*********-*********-*********-