Aeromagnetics

Project Magnet Data (19531994)

**CD-ROM User\'s Manual**

by

**Allen M. Hittelman**

**Ronald W. Buhmann**

**Stewart D. Racey**

National Geophysical Data Center, Boulder, CO

February 1996

> **UNITED STATES DEPARTMENT OF COMMERCE**
>
> **Ronald H. Brown, Secretary**
>
> **National Oceanic and Atmospheric Administration**
>
> Dr. James Baker, Administrator
>
> **National Geophysical Data Center**
>
> Michael S. Loughridge, Acting Director

## [Disclaimer]{.smallcaps}

While every effort has been made to ensure that these data are accurate
and reliable within the limits of the current state of the art, NOAA
cannot assume liability for any damages caused by any inaccuracies in
the data or as a result of the failure of the data to function on a
particular system. NOAA makes no warranty, expressed or implied, nor
does the fact of distribution constitute such a warranty.

The user must be cautious when using these data and computer programs.
These programs are for display and information purposes only. As in many
complex scientific endeavors, errors can be expected.

## [Trademark Acknowledgments]{.smallcaps}

In this documentation, trademarked commercial products and companies are
named. Mention of a commercial company or product does not imply
endorsement by NOAA or the Department of Commerce. Use for publicity or
advertising purposes of information from this publication concerning
proprietary products or the tests of such products is not authorized.

Throughout the publication, rather than put a trademark symbol in every
occurrence of a trademarked name, we state that we are using the names
only in an editorial fashion with no intention of infringement of the
trademark.

**[Contents]{.smallcaps}**

**Introduction** 4

**Chapter 1: The Project Magnet Program** 6

A Brief History 6

The Aircraft and Instrumentation 8

The Surveys 13

**Chapter 2: Technical Specifications** 15

The Compact Disc Format 15

Directory Structure of the CD-ROM 15

**Chapter 3: Trackline Inventory System** 17

Aeromagnetic Survey Inventory 17

Setting Up the Trackline Inventory 25

Sample Search 25

**Chapter 4: Accessing Data with GeoVu** 27

Hardware and Software Requirements 27

GeoVu Loading Instructions 27

Overview of GeoVu Access Software 28

Hints on Using GeoVu 30

**Chapter 5: Acknowledgments** 31

Program Support 31

Staff Credits 33

**References** 34

[Introduction]{.smallcaps}

The purpose of this compilation is to provide, in one complete
collection, Project Magnet, developed by the U.S. Department of
Defense's, Naval Oceanographic Office. This set consists of aircraft
derived aeromagnetic data which were collected world wide to aid the
geomagnetic field modeling efforts of the U.S. Navy. This manual
provides data documentation and explains how to use GeoVu (access
software developed by the National Geophysical Data Center).

The compact disc contains approximately 600 megabytes (4.1 million
statute miles) of trackline data in binary form, dating from 1953 to
1994. The majority of the data consists of flight surveys in binary
(.bin) files. Many other documentation (.txt, .doc, .wp), and meta-data
(.lst,.cst,.hdr,.hlp) support files are also included.

The National Oceanic and Atmospheric Administration (NOAA) appreciates
the value of integrated data management, and has assembled data for this
compact disc in order to simplify the work of scientists performing
regional and global geophysical studies. The primary application for
this disc is research into the nature of the Earth\'s magnetic field.

Questions, comments, and suggestions for improvement of this data
product may be sent to:

Allen M. Hittelmen

National Geophysical Data Center

NOAA, E/GC1

325 Broadway

Boulder, Colorado 80303-3328

USA

Fax: 1-303-497-6513

**User support and** Ronald W. Buhmann

**Data management:** Phone: 1-303-497-6128

Internet: rbuhmann@ngdc.noaa.gov

Stewart D. Racey

Phone: 1-303-497-6118

Internet: sracey@ngdc.noaa.gov

**Concept:** Allen M. Hittelman

Phone: 1-303-497-6591

Internet: ahittelman@ngdc.noaa.gov

[Chapter 1]{.smallcaps}

The Project Magnet Program

A Brief History

From 1951 through 1994, the U.S. Navy, under its Project MAGNET program,
continuously collected vector aeromagnetic survey data to support the
U.S. Defense Mapping Agency's world magnetic modeling and charting
program. The high-level survey coverage during this period is presented
in Figure 1. Early test flights began in 1951. Full operational
capability was established in 1953. Since that time five separate
aircraft have been employed as the survey platform. Each succeeding
aircraft represented a significant improvement in range, speed, or
altitude. The flight capabilities and deployment dates of these aircraft
are summarized in Table 1.

![](media/image1.emf){width="4.372916666666667in"
height="3.0194444444444444in"}

Figure 1. Survey coverage of Project Magnet

![](media/image2.emf){width="4.378472222222222in" height="7.0625in"}

![](media/image3.emf){width="4.374305555555556in"
height="1.1298611111111112in"}

Figure 2. Last Project MAGNET Aircraft.

The primary purpose of the high-level Project MAGNET aeromagnetic
surveys is to supply data in support of the World Magnetic Modeling
(WMM) program, which in turn supports civilian and military global
navigation needs. Most Global Positioning System (GPS) receivers made in
the United States incorporate the WMM either as a piece of hardware in
the form of a computer chip, or as a piece of software. The model also
is used to control drift rates in inertial navigation systems. Other
applications of the WMM include its use as a control measurement for the
Earth's core-mantle boundary, and as an aid for geophysical prospecting
and resource evaluation.

**The Aircraft and Instrumentation**

Between 1953 and 1970, the survey did not fly much higher than 15,000
feet and, since most surveys were conducted in remote ocean areas,
navigation was limited to periodic celestial fixes, some Loran and dead
reckoning. By today's standards, therefore, navigation during this
period was rather poor, with accuracies no better than about five
nautical miles (±5 nm). Table 2 summarizes the capabilities of the early
magnetic survey system. The data acquisition system consisted primarily
of strip chart recorders and navigation logs. Consequently, the majority
of these data were hand digitized. All vector magnetic data collected
during this early period is now summarized in the U.S. Naval
Oceanographic Office (NAVOCEANO) Special Publication #66 (SP-66) and is
also digitized on this CD-ROM at five minute intervals. The analog
magnetograms (strip charts as mentioned above), were transferred to
micro film and are available from the National Geophysical Data Center.

During the last twenty years, after the introduction of the Orion
aircraft, the high-level vector aeromagnetic surveys were conducted
above 15,000 feet, usually between 20,000 feet and 25,000 feet.
Navigational accuracy during this period was generally within ±1 nm,
although some flights since the introduction of GPS receivers in 1987
have positioning accuracies on the order of 30 to 100 meters whenever
there was a good GPS window.

![](media/image4.emf){width="4.378472222222222in"
height="7.020138888888889in"}

The fluxgate vector magnetometer and the electrically suspended gyro
(ESG) are shockmounted on a rigid aluminum beam in a magnetically clean
area at the rear of the aircraft. The ESG has been the primary inertial
navigation and attitude determination instrument during most of the past
twenty years. It has been augmented, first with two ASN-84 inertial
systems and later by two Litton inertial systems which were located on
shock mounts toward the middle of the aircraft.

The two Litton inertial systems are referred to as INS-1 and INS-2.
These inertial systems were not mounted on the rigid beam with the
magnetometer or the ESG. Therefore, due to the flexure of the fuselage
of the aircraft, attitude as specified by these instruments did not as
accurately represent the orientation of the magnetometer in space as did
the ESG. Nevertheless, they provided a sufficiently accurate redundant
attitude capability to be used in data reduction in the event of ESG
failure.

The scalar magnetometer used during the past twenty years has been the
ASQ-81 optically pumped metastable helium magnetometer. Its purpose is
to calibrate the vector magnetic data collected from the fluxgate
magnetometer, which has a tendency to drift. The ASQ-81 magnetometer is
located in the stinger at the rear of the aircraft, which can be seen in
figure 2. Table 3 summarizes the Project MAGNET survey capabilities for
the period 1971-1990.

Since mid-1990, the Project MAGNET aircraft has undergone extensive
maintenance and reconfiguration which was completed in early 1992. The
old fluxgate magnetometer was replaced with a NAROD, ring-core fluxgate
vector magnetometer, while the ASG-81 scalar magnetometer was retained.
The ESG and the two Litton inertial systems was replaced with one
ring-laser gyro (RLG) inertial system which was shockmounted on a rigid
beam along with the ring-core fluxgate vector magnetometer in the
magnetically clean area in the rear of the aircraft. A spare RLG was
carried aboard the aircraft for use in case of failure of the other RLG.
The RLG was used primarily for attitude, while GPS, which is now
becoming globally available, is the primary navigational system.

Due to the inclusion of aerogravimetric surveying capability on the
aircraft, more accurate and redundant altitude instrumentation has been
included. These instruments and their accuracies, along with other
details of the Replacement Geophysical Airborne Survey System (RGASS)
are given in table 4.

![](media/image5.emf){width="4.378472222222222in"
height="7.045138888888889in"}

![](media/image6.emf){width="4.378472222222222in"
height="7.028472222222222in"}

**The Surveys**

A full survey lasts approximately two and a half months during which
twenty to twenty-five, ten to twelve hour flights are scheduled. This
group of flights is referred to as a "project" and is assigned a project
designation such as C32-452. The "C32" is an accounting designation
which changes about once a decade. The "452" indicates the project was
conducted in FY84 using the fifth Project MAGNET aircraft during the
second quarter of the fiscal year.

Each flight of a project is also tagged with an identifying number. For
example, flight 4061 indicates that this flight took off from an airport
in area 4 of a world divided into seven areas. This would be the
sixty-first flight to have taken off in this area during the existence
of the Project MAGNET program. Flights in the 9000 series are low-level
flights below 15,000 feet and are usually constrained to a small
geographical area.

A typical project begins with a low-level (approximately 1,000 feet)
calibration flight, called an airswing, over a geomagnetic observatory.
Usually the observatory in Fredericksburg, Virginia, which is nearest to
the Patuxent River Naval Air Station where the Project MAGNET aircraft
was based, was used for airswing purposes at the beginning and at the
end of a project. Other airswings are flown during the course of a
project, as observatory proximities permit. Usually, three to four
airswings are performed during each project. It is particularly
important to fly airswings in both the North and South geomagnetic
hemispheres if surveying covers both hemispheres.

A calibration flight consists of a roll maneuver in each of the four
cardinal directions, and a yaw maneuver in all four cardinal directions.
Additionally, the aircraft performs straight and level passes over the
observatory in all four cardinal and intercardinal directions. The
straight and level passes are sometimes flown at a somewhat higher
altitude than the maneuvers. The yaw, pitch, and roll maneuvers are
automatically controlled at ±5. The purpose of these maneuvers is to
provide data to compute the coefficients of a phenomenological magnetic
compensation model. This model characterizes the contaminating magnetic
fields associated with:

1.  The permanently magnetized portion of the aircraft.

2.  The magnetic fields induced in the aircraft's metal parts by the
    Earth's main (core-generated) field.

3.  The magnetic fields generated by eddy-currents that are driven by
    the changes in the Earth's main and crustal field as the aircraft
    travels through them.

Of course, there is also a certain amount of feedback and coupling among
these fields which also interfere with the magnetic field as seen in the
absence of the aircraft. The aircraft is primarily made of aluminum.
However, many other metals such as copper and iron may be found in and
around the aircraft.

Details of the airswing data flow and the compensation model used by the
Project Magnet aircraft program can be found in the PCX images called
N_CP_215.PCX through N_CP_248.PCX which are located in the
\\document\\images directory on this CD-ROM.

Chapter 2

Technical Specifications

The Compact Disc Format

The data on the CD-ROM are in the International Organization for
Standardization (ISO) 9660 format. Mastering of the CD-ROM disc and
replication of the copies were done by Disc Manufacturing, Inc.,
Anaheim, California, under contract to NGDC.

Handle the CD-ROM carefully to avoid damage. Dust, scratches, ink,
paint, and fingerprints may obscure some of the data. With careful
handling, one can expect at least a 10-year lifetime for the data disc.

Directory Structure of the CD-ROM

The compact disc contains approximately 600 megabytes of data. The
majority of the data consists of 528 flight surveys.

GeoVu has standard file extensions used when writing and reading files
and these may also appear on CD-ROM products:

.BIN binary data files

.FMT format descriptions

.HDR header files documenting grid data

.MEN menu file

.TXT documentation in ASCII

.CST character histogram file

.LST integer histogram file

.GIF graphics file

.PCX graphics file

.PS postscript file

**GENERALIZED DIRECTORY**

DOCUMENT Documentation Directory

3153_NAS.A NASA Conference Publication #3153

Excerpt from "Project Magnet High Level Vector

Survey Data Reduction"

HELP Metadata (documenting survey characteristics)

GRAPHICS Graphics Directory

GIF GIF images of flight coverage

PCX PCX images of flight coverage

POSTSCRP Postscript images of flight coverage

GRIDS

VIETNAM Gridded data for Southern Vietnam

JOHN_ATL Gridded data for Johnston's Atoll

HI_ALT High altitude aeromagnetic vector survey data

0NNN-NNN 479 flight surveys (NGDC assigned numbers)

LISTS Histograms of survey parameters

LO_ALT Low altitude aeromagnetic survey data

95_SURV 5 Seamount surveys (1995)

ICELAND Iceland survey data (1978)

JOHN_ALT Johnstons Atoll survey data(1989)

JUAN_DE 12 Juan De Fuca surveys (1991)

PM_53_70 29 global flight surveys (1953 - 1970)

PM_76_77 U.S. flight survey data (1976 - 1977)

SOFTWARE

GEODAS Trackline Inventory Software & Database

GEOVU GeoVu Access and Browse Software

PC MS Windows Software

UNIX_SGI UNIX Software for SGI

UNIX_SUN UNIX Software for SUN

MAC Macintosh Software

Chapter 3

**Trackline Inventory System**

**Aeromagnetic Survey Inventory**

NGDCs Aeromagnetic Survey Trackline Inventory Database, found in the
software directory, is searchable with the GEODAS (GEOphysical DAta
System) software. The aeromagnetic data records are not available
directly using the GEODAS. Each header file contains 24 80-character
ASCII records, each containing survey documentation in specific fields.
The survey Headers are described in file ARO88.TXT.

GEODAS is an interactive database management system developed by NGDC
for use in the assimilation, storage and retrieval of geophysical data.
The GEODAS software is presently being used with three types of data:
Marine Trackline Geophysical Data, Hydrographic (bathymetric) Survey
Data, and Aeromagnetic Survey Data. Searches by geographic area, year of
survey, source, platform/project, survey identifier, or data type are
available.

You can perform On-Line Searches on the World Wide Web (WWW), and a new
UNIX XWINDOWS version of GEODAS which is now available.

-   WWW http://www.ngdc.noaa.gov/mgg/mggd.html

-   ftp ftp.ngdc.noaa.gov

-   gopher gopher.ngdc.noaa.gov

The purpose of the Header Record is to document 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. The data records are not in a common format, rather we
have retained the format in which they were submitted to NGDC.

**Format Conventions for the Header Record:**

1\. All decimal points are explicit.

2\. Leading zeros and blanks are equivalent.

3\. Unknown or unused fields are to be blank filled.

The following is a detailed description of the Header Record. Fields can
be of type integer, real (or floating point) or character. Fields that
represent whole numbers are integers Fields that contain a decimal
component are real, and fields that are alphanumeric are character.

Character Length

Nos. of Field Type Description

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Sequence No. 1

1 1 integer RECORD TYPE - (\"1\")

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.

COL CODE PARAMETER SURVEYED

1 F Total Field

2 X xyz Components

3 D dhz Components

4 R Residual Field

5 O Other (radiometrics)

32-37 6 integer FILE CREATION DATE (YYMMDD)

date data records were last altered.

38-78 41 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 SCIENTIST(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**

1-6 6 char SURVEY DEPARTURE DATE

(YYMMDD)

7-40 34 char AIRPORT OF DEPARTURE

city, country

41-46 6 char SURVEY ARRIVAL DATE (YYMMDD)

47-78 32 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 table A below)

4-78 75 integer 15 10-DEGREE IDENTIFIERS

a series of 4-digit codes, separated by commas or space, which identify
the

10-degree squares through which the survey collected data. Last ID is
\"9999\". (see table A)

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 - (\"17\")

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\")

**TABLE 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: Quad Lat Long Long

37 deg 48\'S, 4 deg 13\'E 3 3 0 0

21.6 deg S, 14.3 deg W 5 2 0 1

34 deg 28\'N, 143 deg 27\'W 7 3 1 4

75 deg N, 43 deg E 1 7 0 4

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

**Setting Up the Trackline Inventory**

1.  In WINDOWS click on FILE RUN. Enter the name of your CD-ROM drive
    and path name for the setup file. (e.g.,
    L:\\SOFTWARE\\GEODAS\\WIN31\\setup.exe)

2.  For a minimal run, install the GEODAS\\ARODAS SOFTWARE, COASTLINES
    files and the Project Magnet Inventory File.

The trackline inventory will automatically setup a directory on your
hard drive and a window with icons for you.

**Sample Search**

1.  Open the GEODAS/ARODAS window.

2.  Click on the GEODAS icon.

3.  Click on FILE, NEW SEARCH.

4.  Enter a search key (8 characters or less).

5.  Enter a title. This can say anything that you want (40 character
    maximum).

6.  The database line should already have the Project Magnet
    Aeromagnetics line highlighted.

There are many parameters to choose from now. For example purposes, we
will choose SEARCH AREA(S).

7.  Click on AREA.

8.  Once the map displays, several options are available. Click on
    SELECT-AREA(S)

9.  Click on LAT/LON BOX(S)

10. Click on DIALOG LAT/LON ENTRY

11. Enter the following area: 44 North, -120 West, -60 West and 20
    North.

NOTE: Use the tab key to go on to the next option or click on it. DO NOT
hit the return key. Western and Southern Hemispheres are denoted as
negative values.

12. Click OK. A box covering the southern half of the North American
    continent should be displayed on the terminal.

13. Click on FILE, ACCEPT. This enters the values into memory. The
    SEARCH CRITERIA screen should now be displayed with a check mark
    next to the Select Area button.

14. Click on RUN, SEARCH.

15. Choose a location to put your metadata. (default is C:\\GDAS)

16. When the search is complete click OK.

17. A summary listing window should appear and there should be 100 files
    listed at the bottom.

18. Click on PROGRAM, PLOT SEARCH. This will bring up a plotting window
    and the options are self explanatory. Choose COLORS and then COLOR
    CODE BY PROJECT.

19. Click on SCREEN PLOT. A summary plot of the area with quite a few
    flight lines should appear on the screen. One of the options on this
    level is the ability to zoom in or out of an area.

From here the user can create a PostScript file of the map if they so
desire.

NOTE: All of the search material is written to the hard drive and can
eventually take up quite a bit of space. When exiting the program either
save the files or delete them.

Chapter 4

Accessing Data with GeoVu

Hardware and Software Requirements

The access software provided with this package will operate on any
IBM-PC/AT or compatible personal computer, with MS Windows (3.1) and a
compatible CD-ROM reader. The software is not fully tested to operate on
other types of computers; however, prototype UNIX-Motif versions (SUN &
SGI) and a Macintosh version are included in the "Software/GeoVu"
directory. As available, updated releases of these and other
system-ports can be found in the "Access_Tools" directory of our on-line
system:

-   http://www.ngdc.noaa.gov/ngdc.html

-   gopher.ngdc.noaa.gov

-   ftp.ngdc.noaa.gov

Three (3) megabytes of hard disk space are required to load and execute
the software. A high capacity hard disk is needed if large files are to
be copied from the CD, or if many screen images are to be saved. We
recommend using a computer with a minimum of eight (8) megabytes of RAM.
A math coprocessor should significantly speed up the application.

GeoVu Loading Instructions

The GeoVu software is provided on the CD-ROM in the Software/GeoVu
directory.

1\. Insert the CD-ROM into the reader.

2\. With Windows operating, choose the Program Manager FILE menu and
select RUN. BROWSE the CD-ROM to locate within the software directory
the appropriate setup file and launch in standard manner (e.g.
L:\\SOFTWARE\\GEOVU\\PC\\setup.exe).

3\. Follow the installation instructions on the screen. The contents of
the GeoVu directory will be copied to your hard drive in the directory
of your choice. The install default will create a directory, GEOVU, in
the same drive as your Windows directory (e.g., C:\\GEOVU). The install
will also create a file, FREEFORM.INI, in your Windows directory, and
create a GeoVu Program Manager Group and icon.

Overview of GeoVu Access Software

There are several ways to run GeoVu:

To start GeoVu as a Windows desktop application, double-click on the
GeoVu icon. Remember that GeoVu help is available through either a HELP
key or F1.

Pull-down menus are a familiar part of any Windows application. They
appear at the top of the application window, and each one displays a
family of commands when you click on it. The GeoVu menus are File, Edit,
Search, GeoRef, Utilities, Windows and Help.

There are three major components of GeoVu: (1) the data description
layer, known as FREEFORM, (2) the data navigation layer, known as the
"Menu Guide", and (3) the data browse and retrieval layer, referenced as
GeoVu.

When a user requests data, GeoVu searches for a format description using
the FREEFORM layer (descriptions exist within the data compilation in
the form of format files, .FMT). For data not previously defined, the
user is prompted for format information.

Data are often described in CD-ROMs in obscure ways, leaving users to
guess the exact meaning of a cryptic file name. GeoVu\'s Menu Guide
removes this obstacle by providing understandable navigation throughout
the data compilation. The actual menu guide is written in an ASCII text,
which GeoVu translates into screen dialogues with companion help panels.
Using the Menu Guide, data producers are provided with a mechanism of
integrating data documentation with the data itself; data users are
provided with context-sensitive help and information.

The browse and retrieval capabilities of GeoVu were designed to provide
users with a quick-look and data extraction capabilities. GeoVu was not
designed to provide GIS-level or sophisticated analysis level features,
since numerous commercial products serve this function well. Rather,
GeoVu was conceived of as a link between data compilations and the
researcher\'s analytic application of choice. The following descriptions
highlight GeoVu\'s major capabilities:

1\. Display grids and images---with pan, zoom, profile, value look-up,
color manipulation and histogram support

2\. Display tabular data sets---with two-dimensional plots of any
combination of parameters

3\. Display correlative documentation---in the form of scrollable text
boxes

4\. Extract data---in multi-platform representations, with choices of
data content and structure.

> Caution: Sometimes users open too many files, resulting in
>
> unfriendly computer memory messages. To help
>
> manage this situation, a STATUS display window is
>
> always available while running GeoVu. This helps you
>
> keep track of your open data and search definitions.
>
> The WINDOWS menu also helps by providing a list
>
> of all top-level display windows.

Hints on Using GeoVu to Display Aeromagnetic Data

The data are accessible through a menu system that allows the user to:

• select a specific data set

• browse data set documentation

• browse field-value distributions as histograms

• identify a geographic area-of-interest

• define the desired output (screen display, data to disk or floppy)

• view the selected data (using standard or user defined palettes)

To familiarize yourself with GeoVu capabilities, the following exercises
are suggested:

1.  Explore the help facility. (Note: This can be reviewed by selecting
    HELP from the menu bar. Also, a "GeoVu Users Guide" exists in the
    form of a PostScript file, GVHELP.PS. You may wish to print out this
    file.

2.  Review metadata by exploring the VIEW HISTOGRAM and FACTS. (Hint:
    After opening a data file, view histograms and examine "Terms".
    "Terms" in a histogram window provides definitions of terms.)

3.  Examine a graphic overview of the CD data collection by using the
    SLIDE SHOW option.

4.  Output a 1-degree region from a data set. (Hint: Define a SEARCH and
    select the WRITE TO FILE option.)

Chapter 5

Acknowledgments

Program Support

The National Geophysical Data Center (NGDC), Boulder, Colorado, USA is
now the custodian of the Project Magnet digital Data. These data have a
very long history and were used as the primary input to the US/UK World
Magnetic Model (several epochs). The below acknowledgments section is
excerpted from DOD Technical Report 314 and identifies many of the
individuals responsible for both the Project Magnet and Polar Orbiting
Geomagnetic Satellite data collections. The significant efforts of this
group are evident in the data collections and the resultant WMM-95
model.

**ACKNOWLEDGMENTS**

Overall coordination and production of the joint US/UK World Magnetic
Model for the 1995 Epoch (WMM‑95) were the responsibilities of David R.
Barraclough and Susan Macmillan of the British Geological Survey (BGS)
and John M. Quinn and Rachel J. Coleman of the Naval Oceanographic
Office (NAVOCEANO). Key NAVOCEANO Senior Scientists responsible for
planning and executing the Project MAGNET survey flights were Virgil
Bettencourt, Donald Wilson, Fred Valentine, and Jesus Anglero. The
calibration and processing of aeromagnetic data are complicated affairs.
Key geophysicists concerned with this aspect of Project MAGNET data
analyses were John Nigro and Dave Irwin. Donald Shiel was the principle
geophysicist responsible for deploying and maintaining the Polar
Orbiting Geomagnetic Survey (POGS) satellite ground stations and
collecting, calibrating, and editing the POGS data from these stations.
He also coordinated with the Defense Mapping Agency (DMA) to assure the
continuous flow of accurate satellite‑tracking data from DMA\'s TRANET
network. Many other NAVOCEANO geophysicists, engineers, and technicians
have been involved in the many and varied aspects of Project MAGNET and
POGS data collection and data processing.

Special recognition must go to the military officers and personnel of
the VXN‑8 Naval Air Squadron located at the Patuxent River Naval Air
Station, Maryland, who safely flew and maintained the Project MAGNET
aircraft (a Lockheed RP3D Orion) during the many years of surveying
covered by the data used in this and in previous US/UK World Magnetic
Models.

Of course, this model could not have been produced without the tireless
efforts of those many unnamed individuals around the world who collect
and process magnetic field data on a day‑to‑day basis at the geomagnetic
observatories. The Dst indices which were provided by M. Sugiura of the
University of Kyoto, Japan, and the Kp indices which were provided by
Helen Coffey of NGDC, are both based on observatory data. These indices
were key factors in selecting subsets of POGS data for input to this
model.

A special effort has been made to preserve the several million Project
MAGNET and POGS magnetic field measurements collected for use in the
1995 Epoch World Magnetic Model at NOAA/NGDC. This effort has been
coordinated by Bob Jones and John Weaver of NAVOCEANO and Ronald
Buhmann, Stewart Racey and Susan McLean of NGDC. The entire high‑level
data set from Project MAGNET, going back to its origins in 1951, will be
placed on its own CD‑ROM by NGDC, as will the entire POGS data set. Both
CD‑ROM\'s will then be made available to the general public in this
convenient form through NGDC.

Many government agencies were responsible for placing the POGS satellite
in space. Among these were the Office of Naval Research, the Navy Space
Systems Activity, the Space Test Program, and the U.S. Air Force. The
satellite itself was built by Defense Systems Incorporated, of McLean,
Virginia.

Staff Credits

Many workers in the National Oceanic and Atmospheric Administration
(NOAA) were involved in the preparation of the Project Magnet CD-ROM and
the related access software:

Project Authorization: Herb Meyers and Allen M. Hittelman

Project Management: Ronald W. Buhmann and Stewart D. Racey

Data Preparation: Stewart D. Racey

Access Software: Ray E. Habermann, Deborah Sinay, Dan R. Metzger, and
Allen M. Hittelman

Documentation: Allen M. Hittelman, Stewart D. Racey, Ronald W. Buhmann,
and Joy Ikelman

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