TITLE OF DATA SET

Climatological Data For Clouds Over The Globe From Surface Observations


DATA CONTRIBUTORS

Carole J. Hahn
Cooperative Institute for Research in Environmental Sciences
University of Colorado
Boulder, Colorado

Stephen G. Warren
Department of Atmospheric Sciences
University of Washington
Seattle, Washington

Julius London
Department of Astrophysical, Planetary, and Atmospheric Sciences
University of Colorado
Boulder, Colorado

Roy L. Jenne
Robert M. Chervin
National Center for Atmospheric Research
Boulder, Colorado

DOI: 10.3334/CDIAC/cli.ndp026

SOURCE AND SCOPE OF THE DATA

     Climatological data for clouds derived from surface observations are presented in this
subdirectory.  The data files document the numerical results presented on the maps in the atlases
listed below and provide additional information such as cloud amounts for individual years and
individual times of day.  The atlases contain global maps (with typically a 5 degree latitude by
5 degree longitude grid size) of long-term monthly and/or seasonal total cloud cover, cloud type
amounts and frequencies of occurrence, low cloud base heights, harmonic analyses of annual and
diurnal cycles, interannual variations and trends, and cloud type co-occurrences.  Detailed
documentation of the contents and format for each data file are provided below.  This subdirectory
also includes a FORTRAN program RDTAPE, written by Hahn, which can be used to read data
from the tape and generate selected maps.  Further details about the data and data analysis, as well
as sample listings of data files and output, are provided in the documentation that accompanies this
data set.
     Despite the limitations of the data and the fact that many observations could not be used, it is
important to note that a very large number of reports were used in compiling the data for the atlases
and that these atlases presently offer the best available cloud-type information derived from ground-
based observations.  More detailed information concerning possible biases and the analysis procedures
may be found in the atlases or the accompanying documentation.


DATA FORMAT


     Thirteen ASCII files are provided within this subdirectory (NDP026) including this documentation
file (NDP026.TXT); one data file that provides grid box information including latitude, longitude,
land fraction, and number of land stations information (NDP026.F1); two data files that provide
seasonal and monthly averages for total cloud cover over land (NDP026.F2) and ocean (NDP026.F6);
two data files that contain cloud types (i.e., frequency of occurrence and amount-when-present) over
land (NDP026.F3) and oceans (NDP026.F7); two data files that contain the phase and amplitude of
the annual harmonic of total cloud cover for land (NDP026.F4) and oceans (NDP026.F8); two data
files that contain the land (NDP026.F5) and ocean (NDP026.F9) interannual variation and trends;
one data file that contains cloud data for the time covered by the First GARP Global Experiment
(NDP026.F10); one data file that contains cloud type co-occurrences (contingency probabilities)
[NDP026.F11]; and one file that contains a FORTRAN program that enables the user to read
specific files and generate desired maps (NDP026.F12).
     Further details on the format and content of each data file are provided in the documentation
that accompanies this data set.

REFERENCES

Hahn, C.J., S.G. Warren, J. London, R.M. Chervin, and R.L. Jenne. 1982.  Atlas of simultaneous
     occurrence of different cloud types over the ocean. NCAR Technical Note NCAR/TN-201+STR,
     Boulder, Colorado. (NTIS number PB83-152074)

Hahn, C.J., S.G. Warren, J. London, R.M. Chervin, and R.L. Jenne. 1984.  Atlas of simultaneous
     occurrence of different cloud types over land. NCAR Technical Note NCAR/TN-241+STR, Boulder,
     Colorado. (NTIS number PB88-118641/AS)

Warren, S.G., C.J. Hahn, J. London, R.M. Chervin, and R.L. Jenne. 1986.  Global distribution of
     total cloud cover and cloud type amounts over land. NCAR Technical Note NCAR/TN-273+STR
     and DOE Technical Report No. DOE/ER/60085-H1, U.S. Department of Energy, Carbon Dioxide
     Research Division, Washington, D.C. (NTIS number DE87-006903)

Warren, S.G., C.J. Hahn, J. London, R.M. Chervin, and R.L. Jenne. 1988.  Global distribution of
     total cloud cover and cloud type amounts over the ocean. NCAR Technical Notes NCAR/TN-
     317+STR and DOE Technical Report No. DOE/ER-0406, U.S. Department of Energy, Carbon
     Dioxide Research Division, Washington, D.C.

Hahn, C.J., S.G. Warren, J. London, R.M. Chervin, and R.L. Jenne. in preparation.  Atlas of cloud
     distributions during FGGE. NCAR Technical Note, Boulder, Colorado.