Release 2.0 Delayed-mode (ICOADS.DM) Archive Overview (1784-1997)

Background

The underlying Release 2.0 data were from three intermediate releases, described on the following webpages:

Release 1a (1980-97)

Release 1b (1950-79)

Release 1c (1784-1949)

Collectively, these were referred to (starting in 2002) as Release 2.0.

Figures 1a through 4d below illustrate the enhancements in coverage gained in Release 2.0, in comparison to the original COADS Release 1 data. These show total numbers of observations per decade for 2° latitude x 2° longitude boxes for the indicated variables:

Fig. 1a | Fig. 1b | Fig. 1c | Fig. 1d: sea surface temperature (SST)

Fig. 2a | Fig. 2b | Fig. 2c | Fig. 2d: wind speed (WSPD)

Fig. 3a | Fig. 3b | Fig. 3c | Fig. 3d: sea level pressure (SLP)

Fig. 4a | Fig. 4b | Fig. 4c | Fig. 4d: relative humidity (RHUM)

Figure letters indicate the decadal coverage:

1800-09,...,1840-49 (a figures)

1850-59,...,1890-99 (b figures)

1900-09,...,1940-49 (c figures)

1950-59,...,1990-97 (d figures)

The Release 1 data (left-hand column on each figure) are from the "trimmed" version, and the Release 2.0 data (right-hand column) are from the "enhanced" version. Decades prior to 1854 and after 1979 are blank for Release 1 because it only covered 1854-1979, whereas statistics for Release 2.0 covered 1800-1997.

A wide range of colors was used to show different levels of detail during earlier and later time periods. Colors were assigned to ranges of total observations per decade, each equivalent to an average maximum number of observations per year or month (note that all observations within a given decade could fall within one month):

Color	Decadal range	Average maximum
blank	0	0
grey	1-10	1 per year
navy	11-120	1 per month
blue	121-600	5 per month
cyan	601-1200	10 per month
green	1201-1800	15 per month
chartreuse	1801-2400	20 per month
yellow	2401-3000	25 per month
orange	3001-3600	30 per month
red	3601 or more	>30 per month

For the abbreviated decades 1854-59 and 1990-97, the decadal ranges were adjusted so that the colors would have the same meaning under the maximum column.

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