U.S. DEPARTMENT OF COMMERCE
NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
NATIONAL ENVIRONMENTAL SATELLITE, DATA, AND INFORMATION SERVICE
THE AROMAGNETIC SURVEYS HEADER FORMAT - "ARO88"
COMPILED BY THE ARO88 TASK GROUP
Dan R. Metzger
Ron H. Buhmann
National Geophysical Data Center
Boulder, Colorado
December 1993
INTRODUCTION........................I
GENERAL DESCRIPTION................II
THE ARO88 HEADER RECORD...........III
THE DATA RECORDS...................IV
10 DEGREE ID CODES.........APPENDIX A
NGDC CONTACTS..............APPENDIX B
I. INTRODUCTION
During 1988 the National Geophysical Data Center decided
to integrate it's collection of worldwide aeromagnetic survey
data into the already existing GEODAS (GEOphysical DAta System)
data managment system. In doing this NGDC created a digital
header to document key information about these surveys. As can be
seen below, the ARO88 header was patterned after the ever popular
MGD77 exchange format header. (It was decided not to attempt to
introduce a common format for the aeromagnetic data records.)
Integrating NGDC's aeromagnetic data into GEODAS systems allows
for assimilation into an already developed system and a standardized
software interface for the user.
II. GENERAL DESCRIPTION
The digital format presented, and referred to as "ARO88",
is a format for aeromagnetic survey headers. It is intended to
be used for the transmission of data to and from a data center
and may be useful for the exchange of data between marine
institutions. This meta-data can be exchanged as a companion file to
the aeromagnetic data files, which have various formats, generally being
in the original format as recieved by NGDC from the source contributor.
Data may be exchanged on various mass storage devices such as floppy
disks, 8mm tape, or optical media or over the Internet. The National
Geophysical Data Center uses CD/DVD disks as its chief method of
distribution of these data.
III. THE ARO88 HEADER RECORD
The purpose of the Header Record is to document both
the content and structure of the aeromagnetic data contained
within the data records. In general, documentation that is
constant throughout the cruise will be in the Header Record,
while documentation that is variable will be in the Data Records.
On mass storage media, the ARO88 Header consists of a file
of 24 80-character sequential records.
The Header Record contains fields which are both fixed
and freely formatted. All field lengths within the Header
that have not been coded with information should be blank-
filled, and all plain language statements should be left-
justified. The Header consists of a "sequence" of twenty-
four 80-character images.
*** CHANGES SINCE LAST REVISION ***
Several changes in the ARO88 Format were required in order to
make the format "Year 2000 Compliant" (Y2K Compliant):
SEQUENCE DESCRIPTOR CHANGE
______________________________________________-
01 RECORD TYPE Change from "1" to "4"
01 FILE CREATION DATE Change to include century
From 6 digits (col 32-37)
to 8 digits (col 32-39)
01 SOURCE INSTITUTION Change from 41 chars (col 38-78)
to 39 chars (col 40-78)
04 SURVEY DEPARTURE DATE Change to include century
From 6 digits (col 1-6)
to 8 digits (col 1-8)
04 AIRPORT OF DEPARTURE Change from 34 chars (col 7-40)
to 32 chars (col 9-40)
04 SURVEY ARRIVAL DATE Change to include century
From 6 digits (col 41-46)
to 8 digits (col 41-48)
04 AIRPORT OF ARRIVAL Change from 32 chars (col 47-78)
The following is a detailed description of the Header
Record.
Length
Character of
Nos. Field Type Description
_____________________________________________________
Sequence No. 1
1 1 integer RECORD TYPE - ("4")
2-9 8 char SURVEY IDENTIFIER
identifier supplied by the contributing
organization, else given by NGDC in a
manner which represents the data.
10-14 5 char FORMAT ACRONYM ("ARO88")
15-22 8 integer DATA CENTER FILE NUMBER
survey identifier bestowed by the data
center. First 4 chars indicate the
project as defined by NGDC.
27-31 5 char PARAMETERS SURVEYED CODE
if code is present, parameter is
contained in file.
__________________________________
|COLUMN|CODE| PARAMETER SURVEYED |
|______|____|______________________|
| 1 | F | Total Field |
| 2 | X | xyz Components |
| 3 | D | dhz Components |
| 4 | R | Residual Field |
| 5 | O | Other (radiometrics) |
|______|___________________________|
32-39 8 integer FILE CREATION DATE (YYYYMMDD)
date data records were last
altered.
40-78 39 char SOURCE INSTITUTION
organization which collected the data.
Include contributor if different from
collector.
79-80 2 integer SEQUENCE NUMBER - ("01")
Sequence No. 2
1-18 18 char COUNTRY
19-39 21 char PLATFORM NAME
40 1 integer PLATFORM TYPE CODE
0 - Unspecified Platform
1 - Surface ship
2 - Submersible ship
3 - Aircraft
4 - Buoy
5 - Mobile land
6 - Fixed land
7 - Deep tow
8 - Anchored seafloor
9 - Other, specify
41-46 6 char PLATFORM TYPE
(e.g. "SHIP","PLANE",
"SUB", etc.)
47-78 32 char CHIEF SIENTIST(S)
79-80 2 integer SEQUENCE NUMBER - ("02")
Sequence No. 3
1-78 78 char PROJECT
(e.g. "China Sea, high density,
1 min")
79-80 2 integer SEQUENCE NUMBER - ("03")
Sequence No. 4
1-8 8 char SURVEY DEPARTURE DATE (YYYYMMDD)
9-40 32 char AIRPORT OF DEPARTURE
city, country
41-48 8 char SURVEY ARRIVAL DATE (YYYYMMDD)
49-78 30 char AIRPORT OF ARRIVAL
city, country
79-80 2 integer SEQUENCE NUMBER - ("04")
Sequence No. 5
1-40 40 char FLIGHT LINE SPACINGS
(e.g. NW-SE 37 km.)
41-78 38 char MAGNETOMETER(S) USED
(e.g. Geometrics G801/3 Proton
Precession)
79-80 2 integer SEQUENCE NUMBER ("05")
Sequence No. 6
1-20 20 char AIRCRAFT ALTITUDE
(e.g. 11000 Feet BAR)
21-34 14 char AIRCRAFT VELOCITY
(e.g. 120 Knots)
35-37 3 integer SAMPLING RATE
in seconds
38-44 7 char SENSOR TOW DISTANCE
45-57 13 char REFERENCE FIELD
field used to calculate Residual
Magnetics. (e.g. IGRF-85)
58-67 10 integer TOTAL OBSERVATIONS
68-78 11 char MAGNETIC SENSITIVITY
(e.g. 0.001)
79-80 2 integer SEQUENCE NUMBER - "06"
Sequence No. 7-11
1-78 78 char DATA PARAMETER FORMAT
AND UNITS DESCRIPTION
defines format of the data file;
uses Fortran edit descriptors.
(e.g. "TOTAL-MAG-FIELD-nT(F6.1),")
79-80 2 integer SEQUENCE NUMBER
"07" thru "11"
Sequence No. 12
1-2 2 integer NUMBER OF 10-DEGREE IDENTIFIERS
number of 4-digit 10-degree identifiers,
(excluding "9999"), which will follow this
field (see appendix 1)
4-78 75 integers 15 10-DEGREE IDENTIFIERS
a series of 4-digit codes, seperated
by commas or space, which identify the
10-degree squares through which the survey
collected data. Last ID is "9999".
(see appendix 1)
79-80 2 integer SEQUENCE NUMBER - "12"
Sequence No. 13-15
1-75 75 integers 15 10-DEGREE IDENTIFIERS
continued
79-80 2 integer SEQUENCE NUMBER
("13" thru "15")
Sequence No. 16
1-49 49 integers 10 10-DEGREE IDENTIFIERS
continued
65-67 3 integer TOPMOST LATITUDE OF SURVEY
expand to next whole degree
68-70 3 integer BOTTOMMOST LATITUDE
71-74 4 integer LEFTMOST LONGITUDE
75-78 4 integer RIGHTMOST LONGITUDE
79-80 2 integer SEQUENCE NUMBER - ("16")
Sequence No. 17
1 1 integer ARCHIVE NGDC TAPE LETTER
2-78 77 char ARCHIVE NGDC TAPE NUMBERS
79-80 2 integer SEQUENCE NUMBER - ("08")
Sequence Nos. 18-24
1-78 78 char ADDITIONAL DOCUMENTATION
information concerning this
survey not contained in header
fields.
79-80 2 integer SEQUENCE NUMBER
("18" thru "24")
IV. THE DATA RECORDS
The Aeromagnetic Survey records at NGDC are organized by survey
operation, one survey per file. The data records have been kept in the
same format as they were recieved in. They may have been re-worked, but
generally not re-formatted. To find out more about these files please
contact Ron Buhmann or Stuart Racey. (see NGDC CONTACTS below)
___________________________________________________________
APPENDIX A 10-DEGREE-SQUARE IDENTIFIER CODE
A 10-degree-square area can be easily identified by
constructing a four-digit number. The components of this
number, in order of their construction are described as
follows:
Quadrant - A one-digit number identifies the quadrant of the
world with the following significance to each digit:
1st digit = Quadrant number
Qc Code Latitude Longitude
_______ ________ _________
1 North East
3 South East
5 South West
7 North West
10-Degree Square - The next three digits identify a unique
10-degree square; thus, the significant digits consist of:
2nd digit = Tens digit of degrees latitude
3rd digit = Hundreds digit of degrees longitude
4th digit = Tens digit of degrees longitude
10-DEGREE SQ IDENT. CODE
________________________
EXAMPLES: Qc Lat Long Long
(i) 37 degrees 48'S, 4 degrees 13'E 3 3 0 0
(ii) 21.6 degrees S, 14.3 degrees W 5 2 0 1
(iii) 34 degrees 28'N, 143 degrees 27'W 7 3 1 4
(iv) 75 degrees N, 43 degrees E 1 7 0 4
__________________________________________________________________
APPENDIX B NGDC CONTACTS
Dan R. Metzger: (303) 497-6542 Dan.R.Metzger@noaa.gov
or
Ron W. Buhmann: (303) 497-3158 Ron.W.Buhmann@noaa.gov
National Geophysical Data Center
NOAA, E/GC3
325 Broadway
Boulder, CO 80305-3328
TELEX 592811 NOAA MASC BDR
FAX (303) 497-6513
__________________________________________________________________________