Abstract:
The NCDC home page address on the WWW is
http://www.ncdc.noaa.gov/. To obtain the data via direct
internet-FTP: open ftp.ncdc.noaa.gov OR open hurricane.ncdc.noaa.gov;
login: anonymous; password: your email address; cd
/pub/data/globalsod; readme.txt file complete with explanation of
dataset along with GIF image of station locations.
Users may also
... link to the data at:
ftp://ftp.ncdc.noaa.gov/pub/data/globalsod/
The Global Surface Summary of Day (GLOBALSOD) database was built
monthly by the National Climatic Data Center (NCDC), Asheville, NC.
The hourly data used in building these daily summaries are obtained
from the Air Weather Service (AWS) Global Climatology Division,
located in the Federal Climate Complex with NCDC. The latest month of
the daily summary data is placed on line by NCDC for easy access and
download by outside users, and is normally available about 1 month
after the end of the data month. Over 8000 stations' data are
typically included each month. Other periods of GLOBALSOD (up to 20
years or more) can be obtained off-line from NCDC. The daily elements
include mean temperature, mean dew point, mean sea level pressure,
mean station pressure, mean visibility, mean wind speed, maximum
sustained wind speed, maximum wind gust, maximum temperature, minimum
temperature, precipitation amount, snow depth, and indicator for
occurrence of fog, rain, snow, hail, thunder, tornado/funnel cloud.
The GLOBALSOD data for 18 surface meteorological elements are derived
from the synoptic/hourly observations contained in TD-9950 (AWS
DATSAV2 Surface data). The TD-9950 data are normally available about 4
weeks after the end of the data month. Historical data are generally
available for 1973 to the present, with some stations having data back
to about 1930. Generally, data from 1982 (beginning of current
synoptic code) to the present are the most complete. For some
periods, one or more countries' data may not be available due to data
restrictions or communications problems. In deriving the summary of
day data, a minimum of 4 observations for the day must be present
(allows for stations which report 4 synoptic observations/day).
Although the synoptic/hourly data are stored in the hourly database in
metric units, they are converted to English units for this summary of
day data.
The mean daily values are based on the hours of operation for the
station. For some stations/countries, the visibility will sometimes
'cluster' around a value (such as 10 miles) due to the practice of not
reporting visibilities greater than certain distances. The daily
extremes and totals (such as precipitation) will only appear if the
station reports the data sufficiently--such as the daily maximum and
minimum temperatures, or one or more precipitation totals. Therefore,
values for peak wind gust, maximum/minimum temperature, precipitation,
and snow depth will appear less frequently than other values. Also,
these 5 values are derived from the stations' reports during the day,
and may comprise a 24-hour period which includes a portion of the
previous day. The data are reported/summarized based on Greenwich
Mean Time (GMT) since the original synoptic/hourly data are reported
and based on GMT. Further additions and enhancements to these data
will be made in the future.
The record length is 132, with a block length of 7920 for data
provided on magnetic tape. The data can also be provided on diskette
or paper copy. The data are strictly ASCII, with a mixture of
character data, real values, and integer values. 
