Inventories of International Maritime Meteorological (IMM) Ship Logbook Data for 1960-97 (Releases 1a and 1b)

Keyed ship logbook data back to about 1960 have been exchanged internationally in International Maritime Meteorological (IMM) punched card and tape (IMMPC and IMMT) formats under WMO Resolution 35 (1963), and more recently through WMO Global Collecting Centres (GCCs) located in Germany and the UK.

This page contains year-month inventories and plots of the numbers of IMM data available in ICOADS, separately for each recruiting country (the "country code"). Specifically, data from Releases 1b (1950-79) and 1a (1980-97) for the following decks were used to construct figures and a table of numbers of Long Marine Reports Fixed-length (LMRF) per country code.

The available figures and table are as follows:

Figure 1. Annual (1960-97) plot of LMRF per country code (largest 1960-97 contributors; aggregate across decks 128, 926, and 927).

Table 1. Year-month (1960-97) inventory by country code (C1) of LMRF (same deck aggregate as Fig. 1).

Figure 2. As for Figure 1, except for deck 254.
Figure 3. As for Figure 1, except for deck 732.
Figure 4. As for Figure 1, except for deck 928.

Figure characteristics:

a) Countries are ordered, from top to bottom, from smallest to largest contributors during the plotted time period.

b) Some countries with very small contributions are not shown.

Limitations of the current inventories:

a) Recruiting country may not be the same as the vessel nationality (flag).

b) Although ICOADS generally gives a higher priority to logbook data, Global Telecommunications System (GTS) data, which do not presently contain country code, may in some cases be selected over duplicate logbook reports, thus reducing the logbook counts. The US in more recent years (since ~1995), and possibly some other countries, may submit GTS data to the GCCs. Although, we try to avoid counting US GTS data in these inventories, GTS contributions may be included from other countries.

c) Deck 927 contains only US-keyed ship logbook data since 1980, but during 1970-79 contains data from other countries.

d) Decks 254 and 732, consisting of data received outside of the ordinary channels of international exchange, also have been omitted from aggregate totals (see Figs. 2-3).

e) More work is needed to determine whether the relatively small amounts of data in deck 928 (see Figure 8) should be included in aggregate totals, including checks on the legitimacy of the country codes contained in deck 928.

f) Changes made to the IMM format effective January 1998 to implement a new alphabetic country code have not yet been implemented in the LMR/LMRF observational formats. Thus some US and other data in more recent years are counted under C1=99 (missing or illegal country code). Fig. 1 shows increasing numbers of reports with missing country code in 1996-97, which we believe reflect delayed receipts containing the new country code configuration (recoverable from LMR error attachment).

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