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International Comprehensive Ocean-Atmosphere Data Set (ICOADS): Release 2.4
Overview of Long Marine Reports Fixed-length (LMRF6) 22 September 2007
=========================================================================<lmrf>
Document Revision Information (previous version: 18 July 2006): Updates
(heading only) for Release 2.4.
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This document provides an overview of the LMRF format, and of the fields
included in LMRF (Table 1). LMRF6 is a fixed-length packed-binary format
(512 bits = 64 bytes per report) designed to satisfy the needs of most users,
without of complexity of the full variable-length Long Marine Report (LMR6)
format. It incorporates the regular portions of LMR6 plus "trimming" and
other selected quality control flags used to generate 2- and 1-degree monthly
statistics. For Releases 1a and 1b, LMRF6 replaces the CMR5 format (cf.,
Release 1, supp. D). Uncertain duplicate reports that are included in LMR6,
plus landlocked and other suspicious reports, are deleted from LMRF. See
<stat_trim> for specific report rejection rules applied to create LMRF for
Releases 1a and 1b.
Table 1. List of LMRF6 fields,* true values (i.e., unpacked floating-point
values) ranges, and units. Notation is as follows: m:n denotes m through
n inclusive; @ is used as a plain text abbreviation for the degree symbol.
"Units" gives the smallest increment of the data that has been encoded; thus
a change of one unit in the integer coded value represents a change in the
true value of one of the units shown. Units of 1 are explained in detail
in <lmr>, or, for the trimming section fields, in <stat_trim>.
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No. Field Description True value Units
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Location section
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1 B10 10-deg box 1:648 1
2 YR year 1770:2024 1
3 MO month 1=Jan, 2=Feb, ..., 12=Dec) 1:12 1
4 DY day 1:31 1
5 HR hour (UTC) 0:23.99 0.01
6 TI time indic. 0:3 1
7 LON longitude (measured east of Greenwich) 0:359.99 0.01 @E
8 LAT latitude (+N, -S) -90.00:90.00 0.01 @N
9 LI lat/lon indic. 0:6 1
10 DCK deck 0:999 1
11 SID source ID 0:254** 1
12 PT platform type 0:15 1
13 QI quality indic. (currently unused) 0:2 1
14 DS dup status 0:13 1
15 DC dup check 0:2 1
16 TC track check (currently unused) 0:1 1
17 PB pressure bias (currently unused) 0:2 1
Regular section
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18 DI wind dir. indic. 0:6 1
19 D wind direction (+codes: 361=calm; 362=var.) 1:362 1 deg
20 WI wind speed indic. 0:8 1
21 W wind speed 0:102.2 0.1 m/s
22 VI vis. indic. 0:2 1
23 VV visibility 90:99 1
24 WW present weather 0:99 1
25 W1 past weather 0:9 1
26 W2 2nd past weather 0:9 1
27 SLP sea level pressure 870.0:1074.6 0.1 hPa
28 T1 temp. indic. 0:9 1
29 AT air temperature -99.9:99.9 0.1 @C
30 WBT wet bulb temp. -99.9:99.9 0.1 @C
31 DPT dew point temp. -99.9:99.9 0.1 @C
32 SST sea surface temp. -99.9:99.9 0.1 @C
33 SI SST method indic. 0:12 1
34 N total cloud amt. (oktas) 0:9 1
35 NH lower cloud amt. (oktas) 0:9 1
36 CL low cloud type 0:10 1
37 HI cloud height indic. 0:1 1
38 H cloud height 0:10 1
39 CM middle cloud type 0:10 1
40 CH high cloud type 0:10 1
41 WD wave direction 0:38 1
42 WP wave period 0:30 1 s
43 WH wave height*** 0:49.5 0.5 m
44 SD swell direction 0:38 1
45 SP swell period 0:30 1 s
46 SH swell height*** 0:49.5 0.5 m
47 C1 country code 0:40 1
48 C2 2nd country code 0:40 1
49 SC ship course 0:9 1
50 SS ship speed 0:9 1
51 A barometric tendency 0:8 1
52 PPP amt. of SLP change 0:51.0 0.1 hPa
53 IS ice accretion 1:5 1
54 ES ice thickness 0:99 1 cm
55 RS ice accretion rate 0:4 1
56 II ID indic. 0:10 1
57-
64 ID(8) ID/call sign (characters)**** 33:95 1
65 OS observation source 0:6 1
66 OP observation plat. 0:9 1
67 T2 2nd temp. indic. 0:6 1
68 IX stn/weather indic. 1:6 1
69 WX wave per. indic. 1:1 1
70 SX swell per. indic. 1:1 1
71 IRD IMM receipt date 1:255 1
72 A6 allowance 6 flag 0:1 1
Control section
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73 CK checksum (checked by access program) n/a n/a
Trimming sec.: Misc. fields
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74 B2 2-degree box 1:16202 1
75 ND night/day report flag 1:2 1
Trimming sec.: Trimming flags
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76 SF SST flag 1:15 1
77 AF AT flag 1:15 1
78 UF U-wind flag 1:15 1
79 VF V-wind flag 1:15 1
80 PF SLP flag 1:15 1
81 RF rel. humidity flag 1:15 1
Trimming sec.: Composite QC flags (NCDC/other)
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82 ZQ report status flag 1:3 1
83 SQ SST flag 1:3 1
84 AQ AT flag 1:3 1
85 WQ wind flag 1:3 1
86 PQ SLP flag 1:3 1
87 RQ WBT/DPT flag 1:3 1
Trimming sec.: Composite QC flags (NCDC-only)
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88 XQ present weather flag 1:3 1
89 CQ cloud flag 1:3 1
90 EQ wind wave flag 1:3 1
Trimming sec.: Landlocked flag
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91 LZ landlocked flag 1:1 1
Trimming sec.: Source exclusion flags
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92 SZ SST flag 1:1 1
93 AZ AT flag 1:1 1
94 WZ wind flag 1:1 1
95 PZ SLP flag 1:1 1
96 RZ rel. humidity flag 1:1 1
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* In addition, initial fields RPTIN and RPTID (not listed) are used by the
Fortran access software, and 10 bits are unused prior to CK in the control
section.
** To accommodate additional SIDs, the true value range was increased to
0:254 (from 0:99 in previous versions of this document), and the read software
{rdlmrf6} modified to print SID in three positions (formerly two) by shifting
fields to the left of SID left by one character (eliminating a blank formerly
designated for carriage control). The field width (8 bits) was unchanged,
thus we did not classify this as a change in format version.
*** The Fortran access program stores WH/SH with the indicated true value range
and units (in array FTRUE), but prints them in two digits as "height in 1/2
meter increments" (i.e., 1=0.5 m, 2=1 m, etc.).
**** A subroutine call in the Fortran access program will return fields 57-64
as an 8-character string, with blank-fill for any missing ID elements.
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