===============================================================================
International Comprehensive Ocean-Atmosphere Data Set (ICOADS):     Release 2.4
Translation Specifications: US Maury Collection               22 September 2002
===============================================================<maury_transpec>


Document Revision Information (previous version: 9 September 2002): Updates
(heading only) for Release 2.4.  Author: S. Woodruff

-------------------------------------------------------------------------------


{1. Introduction}

The US Maury Collection data were extracted from NCDC (1998), and processed
through a series of quality control steps.  The CD-ROM data are split into a
separate file corresponding to each original microfilm reel, keyed into the
format described by <maury_format> [1].  Two parallel files (per reel) were
then used as input to this translation: (1) The pre-processed records in the
digitization format; and (2) abbreviated records in the quality control ("qc")
format, including time elements adjusted to the 24-hour clock, interpolated
positions, and other information.  References to the qc format are by "qc"
with field number appended [2].

The digitization format contains two types of 173-character records: (1)
header, and (2) data.  These two record types were linked together by voyage
number (the concatenation of the 2-digit original microfilm reel number and
4-digit frame number, and a 1-digit voyage sequence number).  The voyage number
in the header record is named cvoyh and that in the data record cvoyd.  These
and other references to fields in the digitization format are by field name,
as defined in <maury_format>.  Each field name uniquely defines a character
position or range of positions in either the header or data record.

Within the digitization file, record type was determined by checking for blank
in column eight, indicating a header record (column eight of the data record
is the first position of year, which we assumed was always extant).

The following consistency checks were made among header and data records, and
the qc records, based on voyage number:
     (a) Each digitization file was required to begin with a header record,
         and each header record to contain a form type of 1 or 2, or the
         program terminated with an error.
     (b) The data records following a header record were required to agree in
         voyage number, or they (and the parallel qc records) were rejected.
     (c) The qc records were required to agree with the sequentially
         corresponding digitization (either header or data) records in voyage
         number, or both the qc and digitization records were rejected.

The US Maury digitization data comprise two general form types: (1) daily, and
(2) reports more than once a day.  The data record format contains fields for
up to three air and sea surface temperatures (each with a field available to
indicate observation hour), one barometric measurement (also with a field
available to indicate observation hour), and wind entries for the first,
middle, and latter parts of the day.  However, the second and third temperature
groups were almost always missing in the keyed data, as was the barometer
observation hour; thus these fields were ignored for purposes of constructing
fields HR, AT, and SST.

Moreover, as expected, an extant hour associated with the first temperature
group was almost always associated with form type 1, and, when extant, was
almost always set to 9am.  Elms (1999) proposed assigning HR = 9am (unless
another time was reported) to the form type 1 reports, and then using wind
data from the latter part of the day, centered about 9am, to complete each
daily report:
     Part of day    Hours
     ------------   -----
     First          12-20
     Middle         20-04
     Latter         04-12
As discussed in Elms (1999), the proposed method assumed that the parts of the
day were uniformly defined in this way in the US Maury Collection, and that the
maritime day generally ended at noon.   This statement from Oliver and Kingston
(1970) may also be applicable: "Daily entries were made in the journal or log-
book for the previous 24 hours."

However, it was later suggested (Mike Chenoweth, personal communication) that
many temperatures may have actually been taken at local noon for observational
convenience, rather than at 9am.  But in this case it is not certain whether 
the temperature observation would normally have been taken at the beginning
or end of each maritime day.  In view of the many uncertainties, we adopted
the following simplified procedure for form type 1 reports:
     --HR was set to missing.
     --Data from the first temperature group were always used for AT and SST
       (since the other groups held negligible amounts of data).
     --Wind data from the first (or only) part of the day were always used
       (since the other groups held smaller amounts of usable data).
For form type 2 reports, the procedure was the same except hour was normally
extant.  We decided to use wind data from the first (or only) part of the
day, rather than the latter, to simplify procedures and maximize the amount
of wind data.  As a result, however, it seems likely that the wind data used
to construct the form type 1 reports are separated in time and space from the
temperature data (perhaps by as much as a day in time and in ship's movement).

An exception was made for a small number of voyages [3] keyed as form type
1, but that actually consisted (partly or entirely) of form type 2 data (as
was verified through microfilm examination).  Extant hours were assigned
in the qc format for these voyages, or portions of the voyages, believed
to be mis-labeled as form type 1.  Otherwise qc hour was always missing for
voyages labeled form type 1.  The qc hour was utilized for setting HR in
these form type 1 voyages, but form type was not changed.


{2. Translation to LMR6 location and regular fields}

In the event of a missing or erroneous year, month, latitude, or longitude,
the report was written out to the reject file.  For other fields that were
assembled from external input, the input data (or a subset as indicated by
"Attm5") were included in the error attachment in the event of data problems
or unusable data (concatenation is indicated by "//").

Fields in the digitization format were missing if all blank.  Representation
of missing data in the qc format is specified in [2].

1) B10  10-degree box
   calculated by {wrlmr6}

2) YR  year
   input = year (qc3)

3) MO  month
   input = month (qc4)

4) DY  day
   input = day (qc5)

5) HR  hour
   input = year, month, day, and hour (qc3-6); longitude (qc8); and form
           type (cft) (Attm5=uhr; 4-character field from step d)
   (a) Hour (qc6) was used for HR, regardless of form type (unless missing,
       it was multiplied by 100 after input, to yield hundredths).  For form
       type 1, qc6 was extant only for a few voyages (or portions of voyages)
       in which form type was incorrectly assigned [3] (thus most form type
       1 data were not subject to UTC adjustment).
   (b) Year, month, day were converted to julian day (via {ixdtnd}), unless:
           (i) julian calculation not attempted (missing year/month).
          (ii) julian calculation failed (missing/illegal day, e.g., 31 June).
               [NOTE: This calculation would also fail in the event of an
               illegal year/month, but the qc format contained no illegal
               values for year, month, hour, or longitude.]
         (iii) hour or longitude was missing (which would otherwise lead
               to a subsequent failure of the UTC calculation).
       In these 3 cases any extant hour was set to missing (since it could
       not be adjusted), and the remaining steps were skipped.
   (c) Hour 2400 was changed to 0000, and one was added to julian day (thus
       incrementing day, and year and/or month, if applicable).
   (d) Hour, longitude, and julian day were input to {rxltut}, which converted
       from local to UTC hour (uhr), and also returned UTC julian day.
   (e) {rxnddt} was called to convert UTC julian day to year, month, and day.
       (thus also incrementing year, month, and/or day, if applicable).
   Externals: {lmrlib.01E:ixdtnd,rxltut,rxnddt}

6) TI  time indicator
   input = no corresponding field
   (a) TI=0 (nearest whole hour).

7) LON  longitude
   input = longitude (qc7)
   (a) Divided by 100 (otherwise already in LMR units).

8) LAT  latitude
   input = latitude (qc8)
   (a) Divided by 100 (otherwise already in LMR units).

9) LI  lat/lon indicator
   input = latitude/longitude indicator (qc9; already in LMR units)

10) DCK  deck
   input = no corresponding field
   (a) Set DCK=701 (US Maury Collection).

11) SID  source ID
   input = no corresponding field
   (a) Set SID=69 (US Maury Collection).

12) PT  platform type
   input = no corresponding field
   (a) Set PT=5 (ship).

13) QI  quality indicator
   input = no corresponding field

14) DS  dup status
   input = no corresponding field

15) DC  dup check
   input = no corresponding field

16) TC  track check
   input = no corresponding field
   (a) Set TC = 1 (track checked).

17) PB  pressure bias
   input = no corresponding field
   (a) If SLP is extant, this field was set as follows depending on whether
       a temperature correction was applied (a gravity correction was always
       applied):
            PB=1: temperature and gravity corrections applied
            PB=2: only gravity correction applied

18) DI  wind direction indicator
   input = no corresponding field
   (a) DI=1 (32-point compass).
   [NOTE:  As discussed in Elms (1999), this was an assumption; individual
   ships may have used, e.g., 16- or 8-point compasses.]

19) D  wind direction
   input = wind direction (cwd1)
   (a) These abbreviations (only if absent any trailing characters) were
       converted to special LMR codes as follows:
            Abbrev.       LMR code
            ------------  --------
            C (calm)           361     
            V (variable)       362     
            B (baffling)       362     
   (b) If the abbreviation formed a recognized 32-point compass abbreviation,
       it was converted to numeric code (1-32) and then to degrees as follows
       (codes and degrees from Release 1, Table F2-1, DI=1 column):
            Abbrev.  code   degrees    Abbrev.  code   degrees
            -------  ----   -------    -------  ----   -------
            NXE         1        11    SXW        17       191
            NNE         2        23    SSW        18       203
            NEXN        3        34    SWXS       19       214
            NE          4        45    SW         20       225
            NEXE        5        56    SWXW       21       236
            ENE         6        68    WSW        22       248
            EXN         7        79    WXS        23       259
            E           8        90    W          24       270
            EXS         9       101    WXN        25       281
            ESE        10       113    WNW        26       293
            SEXE       11       124    NWXW       27       304
            SE         12       135    NW         28       315
            SEXS       13       146    NWXN       29       326
            SSE        14       158    NNW        30       338
            SXE        15       169    NXW        31       349
            S          16       180    N          32       360
   (c) Otherwise, including any abbreviations containing non-blank characters
       after position four, the abbreviation was considered unrecognizable and
       written out to the error attachment.

20) WI  wind speed indicator
   input = no corresponding field
   (a) WI=5 (Beaufort force)

21) W  wind speed
   input = wind force (cwf1)
   (a) The original data were either force 0-12, 2-digit codes 20-33, or 2-
       or 3-digit codes corresponding to additional text terms (as defined in
       <maury_format>).   Some of the 3-digit codes were equivalent in textual
       meaning to codes 20-32.  All the recognized codes were mapped to force
       0-12 as follows (for additional terms, and "--", W was set to missing):
           Beaufort (1805)  2-digit 3-digit  Force
           ---------------  ------- -------  -----
           Calm                  20      --      0
           Light air             21      --      1
           Light breeze          22     501      2
           Gentle breeze         23     601      3 
           Moderate breeze       24     511      4
           Fresh breeze          25     441      5
           Strong breeze         26     571      6
           Moderate gale         27     512      7
           Fresh gale            28     442      8
           Strong gale           29     572      9
           Whole gale            30      --     10
           Storm                 31      --     11
           Hurricane             32      --     12
           Baffling              33      --     --
   (b) Both original and mapped force were converted to meters per second
       using {fxbfms}; i.e., the "old" midpoints from Release 1, Table K5-5.
   (c) All unrecognized data were written out to the error attachment.
   External: {lmrlib.01E:fxbfms}

22) VI  visibility indicator
   input = no corresponding field

23) VV  visibility
   input = no corresponding field

24) WW  present weather
   data not converted = present weather (cx) and indicator (cxi)
   [NOTE:  Fields cx and cxi are available in the supplementary attachment
   (the bulk of the data were reported as Beaufort or "4-choice" weather
   codes, as opposed to WMO Code 4677).  But the data were not used because
   of conversion questions, and data quality concerns including in the coding
   of non-significant versus missing data (Elms, 1999).]

25) W1  past weather
   input = no corresponding field

26) W2  second past weather
   input = no corresponding field

27) SLP  sea level pressure
   input = barometric pressure (cb), 1st attached thermometer (cbt1),
           and temperature indicator (ct1) or temperature corrections
           [4] (Attm5=cb//cbt1 after any corrections)
   (a) Trailing/leading blanks in the 4-digit cb field were converted to zero.
       Then an internal read converted the field to an integer (letting "b"
       represent blank, thus ensuring, e.g., that 28bb, 280b, and 2800 all
       yield 2800.)  Barometer units were inferred, and the integer value
       divided accordingly, based on the first digit of cb:
        (i) If 2 or 3, English inches were assumed (division by 100)
       (ii) If 7     , millimeters were assumed    (division by 10)
   (b) The temperature correction was calculated depending on the (original)
       temperature units (ct1):
        (i) Fahrenheit: using {fwbptf}
       (ii) Celsius:    using {fwbptc}
       and added to the reported pressure reading (PB is set to 1).  However,
       the calculation was contingent on these conditions (otherwise pressure
       was left uncorrected, and PB set to 2):
        (i) The 1st attached thermometer reading was required to fall within
            the range -50:50C (it was tested in a form already converted to
            Celsius, and corrected if applicable; see AT for details about
            the handling of all temperatures).
       (ii) If the original temperature units were Fahrenheit (Celsius),
            barometer units were required to be inches (millimeters).
       The remaining steps were executed regardless of whether the temperature
       correction was made.  
   (c) The gravity correction was calculated by {fwbpgv} using gmode=2, and
       added to the pressure.
   (d) Barometer units were transformed into hPa from:
        (i) inches:      using {fxeimb} 
       (ii) millimeters: using {fxmmmb}
   Externals: {lmrlib.01E:fwbptf,fwbptc,fwbpgv,fxeimb,fxmmmb}
   [NOTE:  Inventories showed that the 2nd and 3rd attached thermometer fields
   (cbt2 and cbt3) and the hour of barometer observation (chb), were almost
   always missing, so these fields were not used.  There was no indication
   in the keyed data to indicate barometer type (e.g., aneroid or mercurial);
   we assumed all were mercurial in this processing.]

28) T1  temperature indicator
   input = temperature indicator (ct1) or temperature corrections [4]
   (a) If the voyage was subject to temperature corrections, ct1 was ignored
       and:                T1=9 (other; refer to metadata).
   (b) Otherwise if ct1=1, T1=7 (degrees Fahren.; mixed/undetermined precision)
       or        if ct1=2, T1=3 (degrees Celsius; mixed/undetermined precision)
   [NOTE: In the keyed data, only ct1=1 or 2 values were present (temperature
   values were not tested for the presence of a blank/numeric tenths digit).]

29) AT  air temperature
   input = air temp. (1st entry; ca1) and indicator (ct1) or temperature
           corrections [4] (Attm5=ca1 after any corrections)
   (a) If the voyage was subject to temperature corrections, units were
       obtained from [4] rather than ct1, and the temperature value was
       shifted if applicable.
   (b) The field was divided into a tenths character (fourth position) and
       higher-order characters (first three positions).  The two segments
       of the field were converted into separate integers, and then the
       real value was created (higher-order + tenths-character/10).  Default
       input on the higher-order positions had the effect of right-justifying
       the data in the event of trailing blanks within those three positions
       (e.g., letting "b" represent blank, "89bb" became 89.0 rather than
       890.0 as it would under a rigorous format interpretation).
   (c) If ct1=2, or if the units were specified as Fahrenheit by [4], {fxtftc}
       was used to convert to Celsius (otherwise data were already in Celsius).
   [NOTE:  1st attached thermometer (cbt1; for SLP) and water temperature at
   surface (cs1; for SST) were handled similarly.  External {fxtrtc} was not
   used because no data were flagged as Reaumur.]
   Externals: {lmrlib.01E:fxtftc,fxtrtc}

30) WBT  wet bulb temperature
   input = no corresponding field

31) DPT  dew point temperature
   input = no corresponding field

32) SST  sea surface temperature
   input = water temp. at surf. (1st entry; cs1), and indicator (ct1) or
           temperature corrections [4] (Attm5=cs1 after any corrections)
   (a) (See AT for details about the handling of all temperatures.)
   Externals: {lmrlib.01E:fxtftc,fxtrtc}

33) SI  sea surface temperature method indicator
   input = no corresponding field

34) N  total cloud amount
   input = proportion of sky clear (csc)
   (a) Proportion of sky clear was converted to oktas of sky covered by
       {ixt0ok}.
   External: {lmrlib.01E:ixt0ok}

35) NH  lower cloud amount
   input = no corresponding field

36) CL  low cloud type
   input = no corresponding field

37) HI  cloud height indicator
   input = no corresponding field

38) H  cloud height
   input = no corresponding field

39) CM  middle cloud type
   input = no corresponding field

40) CH  high cloud type
   input = no corresponding field

41) WD  wave direction
   input = no corresponding field

42) WP  wave period
   input = no corresponding field

43) WH  wave height
   input = no corresponding field

44) SD  swell direction
   input = no corresponding field

45) SP  swell period
   input = no corresponding field

46) SH  swell height
   input = no corresponding field

47) C1  country code
   input = no corresponding field

48) C2 second country code
   input = no corresponding field

49) SC  ship course
   input = no corresponding field

50) SS  ship speed
   input = no corresponding field

51) A  barometric tendency
   input = no corresponding field

52) PPP  amount of SLP change
   input = no corresponding field

53) IS  ice accretion
   input = no corresponding field

54) ES  ice thickness
   input = no corresponding field

55) RS  ice accretion rate
   input = no corresponding field

56) II  ID indicator
   input = no corresponding field
   Tests were made against ID after editing (next field):
   (a) If ID = blank, II=missing
   (b) Otherwise,     II=10 (composite information from early ship data)

57-64) ID(8)  ID/call sign
   input = name of ship (cnship)
   Extensive editing was used to reduce the 24-character cnship field to a
   set of unique identifiers eight or fewer characters in length.  First
   a set of global rules was applied, then abbreviation or truncation of 
   selected names as specified in Table 1, and finally the resulting string
   was truncated at eight characters and stored in the ID array.  Also the
   editing changed some cnship fields to better match others (Table 2).

   Following are the global editing rules:
   (a) Unnecessary (embedded) blanks were removed (trailing blanks were
       ignored).  A blank was removed if:
            (i) Two (or three) blanks occurred together.
           (ii) Blank followed period (". ") (tests showed no occurrences
                of blank preceding period).
          (iii) Blank preceded or followed ampersand (" &" or "& ").
   (b) Remaining embedded blanks were replaced by underline ("_").

   Table 1.  Modification of individual ship names.  Names containing the
   search substring (starting at position 1 within cnship) were transformed
   into the concatenation of: (i) the shorter replacement substring, plus
   (ii) a residual substring formed starting at the indicated position within
   cnship (in some cases this overlaps with part of the search string).  An
   asterisk (*) suffixes the replacement substring, indicating modification
   (there were no asterisks originally in cnship), followed if applicable by
   an ampersand (&) to replace the word "and."  A special rule converting
   cnship strings such as NO_LIST into blank is discussed in the footnote.
   --------------------------------------------------------------------------
   Search substring (from pos. 1)      Replacement    Residual substring from
   ==========================================================================
   ABSTRACT_JOURNALS                   AJ*                       19
   ADELAIDE                            ADELA*                     9
   ALEXANDER                           ALEXA*                    10
   AMAZON                              AMA*                      11
   AMERICA_OF                          AME*                      11
   AMERICAN                            AMERI*                     9
   ASHBURTO                            ASHBUR*                    9
   BENJAMIN                            BENJA*                     9
   CAROLINE                            CAROL*                     9
   CATHERINE                           CATHE*                    10
   CELESTIAL                           CELES*                    10
   CHALLENGE                           CHALLE*                   10
   CHARLES_                            CHAR*                      8
   CHARLOTTE                           CHARL*                    10
   CINCINNAT                           CINCIN*                   10
   CITY_OF                             CITY*                      8
   CORNELIA                            CORNE*                     9
   CRESCENT                            CRESC*                     9
   DEFIANCE                            DEFIA*                    12
   EARL_OF_                            EARL*                      9
   EASTERN_                            EAS*                       9
   ELECTRIC                            ELECT*                     9
   ELIZA-AND                           ELIZ*&                    10
   ELIZABETH                           ELIZAB*                   11
   EMPRESS_OF                          EMPRE*                    11
   FLYING                              FLYI*                      7
   FRANCES_                            FRAN*                      8
   FRANCIS_                            FRAN*                      8
   FRANKLIN                            FRANK*                    12
   FREDERIC                            FRED*                      9
   GENERAL                             GEN*                       8
   GEORGE_AND                          G*&                       11
   GEORGE_                             GEO*                       7
   GOLDEN                              GOL*                       7
   HARRIET                             HARRI*                     8
   HENRY                               HEN*                       6
   ISAAC_HOWLAND                       I_HOW*                    17
   ISABELLA_                           ISABE*                    12
   JEFFERSON                           JEF*                      10
   JUDGE_SHAW                          JUD_S*                    14
   KATE_AND_                           K*&                       10
   KATHLEEN                            KAT*                      12
   MACEDONIAN                          MACEDO*                   10
   MAJESTIC                            MAJ*                      12
   MANCHESTER                          MAN*                      14
   MARGARET                            MAR*                       9
   MARY_ANNA                           MAR_A*                    14
   MARY_FRA                            MAR_FR*                    9
   MAYFLOWER                           MAYF*                     13
   MECHANICS                           MEC*                      10
   MERCATOR_                           MERCA*                    16
   NO_                                 (blank)#                  NA       
   NORTH_AMERICA                       N_AMER*                   14
   NORTHERN_                           N*                         9
   PLYMOUTH                            PL*                        9
   PRINCE_OF                           P*                        10
   PRINCESS                            PR*                        6
   QUEEN_OF_                           Q*                         9
   REINDEER_                           REIND*                    12
   RESOLUTE_                           RES*                      13
   RETRIEVER                           RETRI*                     8
   RICHARD                             RICHA*                     8
   SAMUEL                              SAM*                       7
   SARAH_H.                            SA*                        6
   SIR_ROBERT                          SIR_R*                    12
   SPARKLING                           SPARK*                    10
   SPLENDID                            SPLE*                     12
   STAR_OF_THE                         STAR_T*                   13
   STEPHEN                             STEP*                      9
   SULPHUR,                            SUL*                       9
   THOMAS_                             THOM*                      8
   UNITED_STATES_                      U.S.*                     14
   VIRGINIAN                           VIRGIN*                    9
   WESTERN                             WESTE*                     8
   WILLIAM_                            WILLI*                     8
   YOUNG_EAGLE                         Y_EAG*                    15
   --------------------------------------------------------------------------
   # This special rule converts NO_ followed by LIST, LIST_SHIP, SHIP_LIST, or
   SPIP_LIST to blank, rendering ID missing (see Table 2).
   ----------

   Table 2.  List of modified ship names (cnship) identical in positions 1-8
   (as a result, or in spite, of editing).  The "No." column gives the position
   of the name in a sorted inventory of the 2021 original names, and frequency
   gives the number of voyages containing the original name.
   --------------------------------------------------------------------------
         Modified                   Original                   Frequency
   No.   12345678|9012345678901234  123456789012345678901234
   ====  ========|================  ========================  ========== 
   1337          |                  NO SPIP LIST                       1
   1336          |                  NO SHIP LIST                       1
   1334          |                  NO LIST                            4
   1335          |                  NO LIST SHIP                       1
     52  AFRICAN_|MET.ABSTRACT      AFRICAN MET. ABSTRACT              2
     51  AFRICAN_|MET.ABSTRACT      AFRICAN MET.  ABSTRACT             1
    406  CORAL_OF|_NEW_BEDFORD      CORAL OF NEW BEDFORD               8
    407  CORAL_OF|_NEW_BEDFORD_S    CORAL OF NEW BEDFORD   S           5
    450  D.FERNAN|DO                D.FERNANDO                         1
    449  D.FERNAN|DO                D. FERNANDO                        1
    693  GEN*_JON|ES                GENERAL JONES                      4
    690  GEN*_JON|ES                GENERAL  JONES                     1
   1248  MINERVA_|SMYTH             MINERVA SMYTH                      3
   1247  MINERVA_|SMYTH             MINERVA  SMYTH                     5
   1647  SAM*_ROB|ERTS              SAMUEL ROBERTS                     4
   1648  SAM*_ROB|ERTSON            SAMUEL ROBERTSON                   3
   1844  THOM*B.W|ALES              THOMAS B.WALES                     3
   1843  THOM*B.W|ALES              THOMAS B. WALES                    2
   --------------------------------------------------------------------------


65) OS  observation source
   input = no corresponding field

66) OP  observation platform
   input = no corresponding field

67) T2  second temperature indicator
   input = no corresponding field

68) IX  station/weather indicator
   input = no corresponding field

69) WX  wave period indicator
   input = no corresponding field

70) SX  swell period indicator
   input = no corresponding field

71) IRD  IMM receipt date
   input = no corresponding field

72) A6  allowance 6 flag
   input = no corresponding field


{3. Contents of supplemental attachment (Attm4)}
Data stored in the supplemental attachment consisted of the entire data record
(173 characters); followed by a selection of fields from, or derived from, the
associated header record (through character 241); and selected fields from the
qc file (total 250 characters):
  # Pos.     Total #  Field  Record
    range    of pos.   name    type  Description of field (of derived field)
--- -------  -------  -----  ------  ----------------------------------------
  1 1-7         7     cvoyd    data  voyage number
... ...               ...       ...  ...
 47 172-173     2     cmvq     data  magnetic variation QC indicator
 NA 174-175     2     cts2   header  (fr ship type, ctship, according to [5])
  4 176-177     2     cft    header  form type
  5 178-193    16     comm   header  commander (first 16 positions only) [6]
  6 194-217    24     cfr    header  from city
  7 218-241    24     cto    header  to city
  2 242-246     5     qc2    qc      reel sequence number
  5 247-248     2     qc5    qc      day  (local time) (99 indicates missing)
  6 249-250     2     qc6*   qc      hour (local time) (99 indicates missing)
--- -------  -------  -----  ------  ----------------------------------------
* Whenever qc6 was 24, zero was inadvertently written out to the supplemental
attachment.  This resulted from an error in the conversion program, but can
be fixed by interpretation of hour zero as hour 24 of qc5 + 1 (as noted in [2],
qc6 originally ranged 1-24, with 24 signifying hour 0 of the next day.  As
intended, qc5 was included in the supplementary attachment in original form.
----------


{4. Notes}

[1] Reels keyed in the Collection
Reels 1-2 and 45 were missing from the digital data obtained from the CD-ROM.
This was explained by CD-ROM documentation "about.txt" (excerpted as follows)
except that it erroneously refers to reel44 (references should be to reel45):
     "There were eighty-eight reels of microfilmed records in the collection.
     Reels One, Two, and Forty-four do not appear on the CD-ROM.  Reel One
     is simply an inventory, and we were unable to produce clear paper copies
     from Reel Two.  Reel Forty-four, keyed in a different format, was used
     in the pilot digitization project to help finalize the formats that
     were adopted for the remainder of the collection.  Reel Forty-four will
     later be converted to a common format."
At this writing, NCDC has been unable to locate the details of the "pilot"
format used for reel45.  Moreover, notes indicated that only about half the
data from the reel were keyed, owing to some paper copies being lost enroute
to China.  These data will need to be re-digitized under a future project.


[2] Quality control (qc)    format:  missing:  description:
qc1 voyage number           (a7      n/a       reel+frame+voyage sequence
qc2 reel sequence number    ,1x,a5   n/a       orig. sequence number on reel 
qc3 year                    ,1x,i4   9999      local time
qc4 month                   ,1x,i2   99        local time
qc5 day                     ,1x,i2   99        local time
qc6 hour                    ,1x,i2   99        local time 1-24 (=0 next day)
qc7 latitude                ,1x,i5   9999      per <lmr> LAT
qc8 longitude               ,1x,i5   99999     per <lmr> LON
qc9 lat/lon indicator       ,1x,i1)  9         per <lmr> LI

Four examples of the 41-character record layout (preceded by header lines):
         1         2         3         4 
12345678901234567890123456789012345678901
-----------------------------------------
0300031 12345
0300031 12346 1850 12 31 24 -9000 35999 4
0300031 12347 9999 99 99 99  9999 99999 9 
0300031 12348 1851  1  1  2  9999 99999 9

QC records that were blank following reel sequence number referred to header
records.  The reel sequence number referred to the original CD-ROM files.
The files corresponded one-for-one with the pre-processed digitization files,
in which voyage numbers 1402671, 1402681, 7602921, and 7602941 (with headers
and/or data out of order) were reordered.  Input of these records was handled
as indicated by the format statement, so that fields most conveniently handled
as integers (e.g., for input to {lmrlib} routines for conversion of time to
julian day and UTC) were made available in that form.  However, to detect a
header record, year was read first as a character string to determine if if
was blank, and in that case all the numeric fields (or individual fields that
are missing in the non-header case) were converted to a uniform integer missing
value.


[3] Voyages mis-labeled as form type 1 (partially or totally form type 2)

The following voyages were labeled form type=1 (daily), but also included
extant hours in the quality control file for all or part of the voyage:
         Line range   Approx.*  Voyage  
Reel   start     end  reports   number  Comments
----   -------------  -------  -------  ---------------------------------------
 44     9668   17442     7764  4407351  entire voyage with extant qc6; atypical
                                        (assumed correct) hour pattern in data
 50    10991   11892      902  5003701  92 reports with missing qc6 at start
 58     1524    1755      232  5800651  42 reports with missing qc6 at start
 71     4768    4876       84  7109391  91 reports with missing qc6 at start
 72     6487    8199     1409  7204311  entire voyage with extant qc6
                      -------
                       ~10391
* The count of reports is approximate because the line range may encompass
reports without these characteristics, or with them but rejected for other
reasons.
----------


[4] Temperature units and other corrections

The following 107 voyages (cvoyd) were subject to units or other corrections
of the temperature fields (cbt1, ca1, cs1).  The temperature indicator (T1)
was set to 9 for reports subject to corrections.  If a "C" ("F") appears under
a field, Celsius (Fahrenheit) was used as the units regardless of the setting
of ct1 (thus allowing mixed units within a report).  A prefix of "L-" ("R-")
for a field indicates that data (or most of the data within a given voyage)
appear to have been digitized with an erroneous shift by one character to the
left (right).  To correct this, the data were shifted in the opposite direction
via an "end-around" shift (i.e., characters ordered 1234 were reordered 4123
for "L-", or 2341 for "R-").  However, the shift was not made (data unchanged)
if the end-around character (1 or 4) was not a blank.  Units are always given
for all three fields, but it should be noted that in many voyages (e.g., those
footnoted) only a subset of fields was actually reported.

  cvoyd    cbt1    ca1    cs1            cvoyd    cbt1    ca1    cs1 
-------    ----   ----   ----          -------    ----   ----   ----
1502821       C      C      C          6703351       C      F      F
1502851       C      C      C          6703401       C      F      F
1502891       C      C      C          6900021       C      C      C
1502921       C      C      C          6900251       C      C      C
1502931       C      C      C          6900271       C      C      C
1502941       C      C      C          6900301       C      C      C
1502991       C      C      C          6900341       C      C      C
1503021       C      C      C          6900511       C      C      C
1503041       C      C      C          6900661       C      C      C
2701881       C      C      C          6900701       C      C      C
4605761       C      C      C          6900731       C      C      C
4605861       C      C      C          6900841       C      C      C
4605871       C      C      C          6901501       C      C      C
4605881       C      C      C          6901721       C      C      C
4605901       C      C      C          6901781       C      C      C
4905971       F      F    L-F          6901831       C      C      C
4905981       F      F    L-F          6901981       C      C      C
4906221       F      F    L-F          6902201       C      C      C
4906241       F      F    L-F          6902251       C      C      C
4906321       F      F    L-F          6902271       C      C      C
4906341       F      F    L-F          6902391       C      C      C
4906411       F      F    L-F          6902441       C      C      C
4906461       F      F    L-F          6902501       C      C      C
4906471       F      F    L-F          6902681       C      C      C
4906531       F      F    L-F          6902831       C      C      C
4906651       F      F    L-F          6902851       C      C      C
4906661       F      F    L-F          6902901       C      C      C
4906741       F      F    L-F          6903031       C      C      C
4906771       F      F    L-F          6903051       C      C      C
4906781       F      F    L-F          6903261       C      C      C
4906811       F      F    L-F          6903331       C      C      C
4906851       F      F    L-F          6903501       C      C      C
4907001       F      F    L-F          6903711       C      C      C
4907021       F      F    L-F          6903801       C      C      C
4907031       F      F    L-F          6903931       C      C      C
4907161       F      F    L-F          6904021       C      C      C
4907221       F      F    L-F          6904181       C      C      C
5601261       C      C      C          6904221       C      C      C
5601511       C      C      C          6904401       C      C      C
5601761       C      C      C          6904491       C      C      C
5601901       F      C      C          6904561       C      C      C
5700711       C      F      F          6904711       C      C      C
5700781       C      F      F          6904991*      F    R-F      F
5700871       C      F      F          6905751*      F    R-F      F
5701061       C      C      C          7400041       C      C      C
5701231       C      C      C          7400061       C      C      C
5701881       C      C      C          7400071       C      C      C
6703151       C      F      F          7400101       C      C      C
6703201       C      F      F          7400121       C      C      C
6703221       C      F      F          7400141       C      C      C
6703251       C      F      F          7400161       C      C      C
6703291       C      F      F          7506861*      F    R-F      F
6703331       C      F      F          7702531       C      C      C
                                       8405121       F      C      C
-------    ----   ----   ----          -------    ----   ----   ----
* AT only; for voyage 7502531 there were ~10 apparent overflows of half a
degree from ca1 into the first position of cs1 (no action taken for this).
----------


[5] Mapping of Type of ship field (ctship) into cts2
Inventories of the Collection indicated a total of 55 different patterns within
the digitized 15-character ship type field, ctship.  These were mapped into a
2-character designation, cts2 (1-51, plus blank for missing) as follows.  In
three cases (blank, 29, and 34) two apparently equivalent patterns were mapped
to the same cts2 value:

cts2 ctship (first)   ctship (second)   cts2 ctship (first)   ctship (second)
12   123456789012345  123456789012345   12   123456789012345  123456789012345
--   ---------------  ---------------   --   ---------------  ---------------
             (blank)  NOT LISTED         1   3 MAST CLIPPER 
 2   BARK                                3   BARQUE         
 4   BRIG                                5   BRIGANTINE     
 6   BRIT. SCHOONER                      7   BRITISH        
 8   BRITISH BARK                        9   BRITISH BARQUE 
10   BRITISH RMS                        11   CHILIAN        
12   CHILIAN BARK                       13   CLIPPER        
14   CUTTER                             15   DUTCH BARK     
16   DUTCH FRIGATE                      17   FINNISH        
18   FRENCH                             19   FRENCH SLOOP   
20   FRIGATE                            21   GERMAN         
22   GERMAN BRIG                        23   PACKET         
24   PILOT                              25   PILOT BOAT     
26   PORTUG.CORVETTE                    27   PORTUGUESE BRIG
28   PRUSSIAN                           29   R.M.S.BRITISH    R.M.S.S.BRITISH
30   REVENUE                            31   RUSSIAN CORVET 
32   RUSSIAN STEAMER                    33   SARDINI. FRIGAT
34   SCHOONER         SCOONER           35   SCHOONER,HMS   
36   SCREW SLOOP                        37   SHIP           
38   SLOOP                              39   SLOOP OF WAR   
40   SPANISH                            41   STEAM FRIGATE  
42   STEAMER                            43   STEAMSHIP      
44   SURVEY SHIP                        45   SWEDISH BRIG   
46   TRANSPORT                          47   U.S. SHIP      
48   U.S. SQUADRON                      49   U.S. STORE SHIP
50   U.S.FRIGATE                        51   WHALER         
--   ---------------  ---------------   --   ---------------  ---------------


[6] Truncation of Commander field (comm)
To save space, the 24-character field was truncated after the sixteenth
character.  In general this eliminated only blanks in positions 17-24,
except it resulted in non-blank truncation of the 46 following names:
        # 1234567890123456|78901234        # 1234567890123456|78901234
       -- ----------------|--------       -- ----------------|--------
        1 ALFRED A. ENGVIS|T              24 NATHANIEL BROWN |SR.     
        2 ALVIN O.BLACKIST|ON             25 NATHANIEL J.KINS|MAN     
        3 ANTONIO RICARDO |GRACA          26 NATHANIEL PUTNAM| JR     
        4 BENJ.LOWNDES JOH|NSTON          27 NATHANIEL PUTNAM| JR.    
        5 CAPT-LIEUT TERIA|EFF            28 OLIVER H.SAUNDER|S       
        6 CHARLES H.KENNED|Y              29 P.A.MARTINS DE S|ILVA    
        7 CHRISTOPHER GILP|ATRICK         30 P.V.COSTANEIRO E| PINTAO 
        8 E.G.JILION COMMO|S              31 RICHARD F.CORNIN|G       
        9 FERDINAND CROCKE|R              32 RICHARD J.HOFFNE|R       
       10 FRANCIS A.BEERSL|EY             33 RICHARD T. CORNI|NG      
       11 FRANCIS F.NICKER|SON            34 ROB'T B. CUNNING|HAM     
       12 FRANKLIN BUCHANA|N              35 SAM HUTCHINSON J|R       
       13 HUMPHREY W.SEABU|RY             36 SAM'L EASTERBROO|K       
       14 ISAAC HARDING JR|.              37 SAM'L HUTCHINSON| JR.    
       15 JACOB L.CLEVELAN|D              38 SAMUEL BARTLETT |JR.     
       16 JAMES F. ARMSTRO|NG             39 STEPHEN JEFFERSO|N       
       17 JAMES LEMASSURIE|R              40 STEPHEN JELLERSO|N       
       18 JOCIO EUSEBIO D'|OLIVEIRA       41 STEPHEN MICKERSO|N       
       19 JOHN C. HUBBARD |JR.            42 STEPHEN NICKERSO|N       
       20 JOHN PETER LUNDB|ERG            43 THORNTON B.RENNE|LL      
       21 JOSIAH RICHARDSO|N              44 WASHINGTON PLUME|R       
       22 LEFTENANT MOTELE|V              45 WASHINGTON T.WAL|KER     
       23 LT.CMDR. B.J. LO|TTEN           46 WILLIAM RICHARDS|ON      
       -- ----------------|--------       -- ----------------|--------


{References}

NCDC (National Climatic Data Center), 1998: The Maury Collection: Global Ship
      Observations, 1792-1910 (CD-ROM, Version 1.0, February 1998).  NCDC,
      Asheville, NC.
Elms, J.D., 1999: Digitizing U.S. historical marine collections (1792-1976).
      Proceedings of the International Workshop on Digitization and Preparation
      of Historical Surface Marine Data and Metadata (Toledo, Spain, 15-17
      September 1997). H.F.  Diaz and S.D. Woodruff, Eds., WMO/TD-No.957, MMROA
      Report No.  43, World Meteorological Organization, Geneva, 7-13.
Oliver, J., and J.A. Kington, 1970: The usefulness of ships' log-books in
      the synoptic analysis of past climates.  Weather, 25, 520-528.