Manned Station and Unmanned Buoy Drift Positions
                 Coordinated Eastern Arctic Experiment (CEAREX)

                              Miles G. McPhee
                          McPhee Research Company
                          450 Clover Springs Road
                        Naches, Washington 98937 USA


1.  Description

     This data set contains a summary of CEAREX manned station and unmanned
buoy drift positions.  There are 24 ASCII data files, each with one header
record followed by "position fix" records with (1) time in decimal days of
the year; (2) latitude in decimal degrees; (3) longitude in decimal degrees
(east positive); and, for the manned camps, (4) an integer source code
described in sections 3.4, 3.5 and 3.6, below.  The data were perused, and
any obvious outliers were marked with asterisks.
 
     In addition, there are hourly listings of position and velocity for
the manned camps (PBHOURLY.POS = Polarbjorn drift, OHOURLY.POS = O Camp,
AHOURLY.POS = A Camp) from the complex demodulation algorithm as described in
the reports distributed at the CEAREX Workshop and Publications Planning
Meeting, 8-10 February 1990, Long Beach, Mississippi. (McPhee, M.G., 1988,
Analysis and prediction of short term ice drift. Transactions of the ASME,
Journal of Offshore Mechanics and Arctic Engineering, vol. 110, p. 94-100.)

2.  Complex Demodulation Procedure.  

     Briefly, the complex demodulation procedure moves a 24-hour window 
through the data at 6 hour intervals, calculating a least-squares fit of 6 
complex coefficients, from which position and velocity are derived.  If there
are not enough fixes (12) in the window, or if there is a gap of more than
6 hours, the complex demodulation is replaced with a linear fit for position.
In the hourly files, this causes a step structure in the velocity, since it 
is constant over the 6 hours.
  
     In order to keep the amount of data manageable, results of complex 
demodulation for the buoys are not included; however, the subdirectory 
"programs" contains both the required routines and a UNIX session for 
generating the file `AHOURLY.POS'.  

     [Special Notes About Filenames: Filenames on this CD-ROM are in upper 
case because the directory structure is based on MS-DOS.  Take this into 
account when transferring files to a Unix environment.  See section 4 for an 
additional note about the programs.]
  
3. File Contents.

3.1. POLARBJORN Drift, O Camp Drift, A Camp Drift Data Files

3.1.1.  Filenames and Headers

     Data files on this CD-ROM are numbered [4nnn.POS, 6nnn.POS, 
7nnn.POS, 8441.POS] or named [PBDRIFT.POS, OCAMP.POS, ACAMP.POS, 
PBHOURLY.POS (POLARBJORN drift hourly), OHOURLY.POS (O Camp hourly), and 
AHOURLY.POS (A Camp hourly)].  MS-DOS conventions limit filenames to 
eight characters.  

     Headers for these files contain information about the file contents:
original filename, `0' (zero), year, start time (in decimal days of the 
year), end time (in decimal days of the year), number of fixes, and PI for 
data collection.  

3.1.2.  POLARBJORN Drift, James Morison, PI

 Filename: PBDRIFT.POS   [hourly file: PBHOURLY.POS]
 
 Header:  65-character record providing information about the start and end
 times and the source of the data.  This is not a traditional "field" header.

 pbdrift 0  1988 start 260.37153 end 335.1278 fixes  4776 PI bunch
     ERIM satnav fixes = code 0
     PSC Salargos buoy = code 1
     ERIM dead reckoning estimates = code 2
     Scripps ADCP satnav fixes = code 3
        
 Flag is `*' to indicate outlying data points.

 Data records are 65 characters.

3.1.3.  O Camp Drift, Miles McPhee, PI

 Filename: OCAMP.POS    [hourly file: OHOURLY.POS]
 
 Header:  62-character record providing information about the start and end
 times and the source of the data.  This is not a traditional "field" header.

  ocamp 0  1989 start  78.4306 end 120.7347 fixes  753 PI McPhee
     PSC satnav fixes = code 0
     PSC Salargos buoy = code 1
     MFO log from satellite navigator = code 2

 Flag is `*' to indicate outlying data points.

 Data records are 62 characters.

3.1.4.  Alpha Camp Drift, Arthur Baggeroer, PI

 Filename: ACAMP.POS    [hourly file: AHOURLY.POS]

 Header:  67-character record providing information about the start and end
 times and the source of the data.  This is not a traditional "field" header.

 alpha 0  1989 start  82.27431 end 110.43775 fixes  680 PI Baggeroer
     MIT satnav fixes

     Code is not used because all fixes are from MIT satnav.
     Flag is `*' to indicate outlying data points.

 Data records are 67 characters.

3.2.  Buoy Data Files

3.2.1.  The headers shown below for each of the data files provide 
information about the file contents:  type, filename, year, start date 
(in decimal days of the year), end date (in decimal days of the year), 
number of fixes, and PI for data collection.  All the filenames beginning 
with numbers have the same format, although the record size varies.  

3.2.2.  Robin D. Muench and Arthur Baggeroer

 Filenames: 4886.POS ==> 4899.POS

 Header:
 ptt 4886 1989 start  96.09881 end 107.94616 fixes   67 PI Baggeroer/Muench
 ptt 4890 1989 start  90.99833 end 109.32020 fixes  207 PI Baggeroer/Muench
 ptt 4897 1989 start  91.03516 end 109.50545 fixes  361 PI Baggeroer/Muench
 ptt 4899 1989 start  90.96494 end 103.06101 fixes  232 PI Baggeroer/Muench

 Data and headers: 74-character records

3.2.3.  Jean-Claude Gascard

 Filenames: 6110.POS ==> 6119.POS

 Header:
 ptt 6110 1989 start  91.56365 end 184.83350 fixes 2143 PI Gascard
 ptt 6111 1989 start  90.50036 end 200.79429 fixes 2421 PI Gascard
 ptt 6112 1989 start  93.49718 end 296.27713 fixes 1369 PI Gascard
 ptt 6113 1989 start  95.53391 end 214.66140 fixes 2559 PI Gascard
 ptt 6114 1989 start  94.68361 end 232.67072 fixes 2966 PI Gascard
 ptt 6115 1989 start  91.56296 end 198.14800 fixes 2386 PI Gascard
 ptt 6116 1989 start  88.71596 end 142.05626 fixes 1159 PI Gascard
 ptt 6117 1989 start  93.63753 end 267.06992 fixes 1875 PI Gascard
 ptt 6118 1989 start  88.65594 end 214.73418 fixes 2790 PI Gascard
 ptt 6119 1989 start  90.50072 end 186.94223 fixes 2276 PI Gascard

 Data and headers: 65-character records.

3.2.4.  James Overland

 Filenames: 7100.POS ==> 7105.POS

 Header:
 ptt 7100 1988 start 260.68355 end 324.72720 fixes 1234 PI Overland
 ptt 7101 1988 start 261.58638 end 486.91866 fixes 4002 PI Overland
 ptt 7102 1988 start 260.75404 end 425.88196 fixes 3096 PI Overland
 ptt 7103 1988 start 261.51644 end 425.88208 fixes 3324 PI Overland
 ptt 7104 1988 start 261.38729 end 407.35451 fixes 2765 PI Overland
 ptt 7105 1988 start 261.65786 end 425.88211 fixes 3060 PI Overland

 Data and headers: 66-character records.

4.  How to Use the Programs.  

     The programs provided on this CD-ROM were written in the C programming
language by M.G. McPhee, for use on a SUN workstation.  They are written on
the CD-ROM as received from the author, with some minor changes in
filenames for MS-DOS compatibility.  [See the following paragraph for 
information on the record size and padding.]  Please note that the programs
contain references to SUN Unix utilities and assume SUN Unix conventions.

     Special Notes on Using the Programs on this CD-ROM:  

     The filenames on this CD-ROM all have 3-character extensions, a 
function of the software used to produce this CD-ROM.  Because of this, the 
C programs in the directory \POSITION\POSPRG have extensions .CXX or .HXX 
rather than .C or .H as you would expect.  You will need to copy the program 
files to your hard (or floppy) disk with the normal .C or .H extensions 
before attempting to use the programs.  

     Also note the use of lower case within the programs and upper case in 
the DOS-compatible filenames on the CD-ROM.

     The programs are not supported by NSIDC, the distributor of this 
CD-ROM.  Questions concerning the programs should be addressed to M.G. 
McPhee at the address given at the beginning and end of this file.

4.1  Program File Formats.

     Each program file is stored on the CD-ROM as 79-character
records.  The program files were padded with blanks to 79 characters in the
cases where the record length was shorter or was variable.  

4.2. Steps for using the complex demodulation routines in the subdirectory
"PROGRAMS" follow:
 
4.2.1. Compile the tools modules: dcomplex.c randomio.c tricks.c
 mrc% cc -c dcomplex.c
 mrc% cc -c randomio.c
 mrc% cc -c tricks.c

4.2.2. Compile the "efile" program which makes a data record file from the
  text files, eliminating lines with asterisks
         (a) copy the makefile lines from efile.c to Makefile
         (b) make the object file
mrc% make
cc  -c efile.c
cc  -o efile efile.o randomio.o tricks.o -lm

4.2.3. Compile the "fitpos" program, which performs the complex demodulation
  fit (it will also do a polynomial fit) on the data file made by efile
   (a) copy the makefile lines from fitpos.c to Makefile
   (b) make the object file
mrc% make
cc  -c fitpos.c
cc  -c pfit4.c
cc  -c polyfit4.c
cc  -c demod4.c
cc  -o fitpos fitpos.o pfit4.o polyfit4.o demod4.o dcomplex.o randomio.o 
  tricks.o -lm

4.2.4. Copy the "alpha" file from parent directory
 mrc% cp ../alpha 
 
4.2.5. Run efile:
mrc% efile alpha
alpha 0  1989 start  82.27431 end 110.43775 fixes  680 PI Baggeroer
ignore entries flagged with *? y
list? n
mrc% 
  -- this produces a second data file named alpha.e that has the same 
  information (less asterisked lines) as alpha
 
4.2.6. Now do the complex demodulation-- note that the time base for the 
  phasors depends on the start time you specify, so that if you want to
  compare phasors from one station to another start with the same time--
  if no data are present, it will fill with blanks (actually -99.0)
  
mrc% fitpos alpha
Data go from  82.274 to 110.438
Input fit start and end times (decimal day): 80 120
Input the time between fits and the fitting period:0.25 1.0
Input 0 for complex demodulation, 1 for polynomial fit: 0
Input nterm: 6
Input max error (km) (0 for no checking): 1.5
Input max time gap for successive data samples (e.g., 0.25): 0.25
Input coord system longitude offset (e.g., 30 for 30E): 0
nfits= 161
size of ff: 27048
istart,npoints: 1, 679, tref  80.000
sample at  91.245 rejected, data: (-12.07,-870.61)   fit: (-10.75,-869.81)
sample at 105.610 rejected, data: (-16.77,-995.43)   fit: (-18.21,-993.90)
The output file is named falpha.d,   80.00 to  120.00
rec   1,  80.000 (-99.00,-99.00) (-99.00,-99.00) rms:   0.000 from 0 sam 0

************ plus output listing ***********************

rec 161, 120.000 (-99.00,-99.00) (-99.00,-99.00) rms:   0.000 from 0 sam 0

4.2.7. There now exist two files spawned from the original text file, alpha:
 alpha.e, falpha.d, which is the file of fit coefficients.
 
4.2.8. These can be listed to stdout (i.e., can be redirected)  with pv_list

      copy the makefile lines from list_pv.c to Makefile
mrc% make
cc  -c list_pv.c
cc  -c fitutil.c
cc -o list_pv list_pv.o fit_utilities.o dcomplex.o  randomio.o tricks.o -lm
 
4.2.9.  And run: 
mrc% list_pv falpha.d > alpha_hourly

5. References

McPhee, M.G. (1988) Analysis and prediction of short term ice drift.
Transactions of the ASME, Journal of Offshore Mechanics and Arctic
Engineering, vol. 110, p. 94-100.

6. Contact Information

Dr. Miles G. McPhee
McPhee Research Company
450 Clover Springs Road
Naches, WA   98937 USA
Telephone: 509-658-2575
Omnet: M.MCPHEE

Data files used to compile this data base of manned station and unmanned
buoy drift positions were provided to Miles McPhee by the following
CEAREX investigators:

Dr. Arthur Baggeroer
Massachusetts Institute of Technology
Ocean Engineering Department, Room 5-204
Cambridge, MA   02139

Dr. Jean-Claude Gascard
Laboratoire Oceanographie Physique
Museum d'Histoire Naturelle
43 rue Cuvier
75231 Paris CEDEX 05
France

Dr. James Morison
Polar Science Center
University of Washington
1013 NE 40th Street
Seattle, WA   98105

Dr. Robin D. Muench
Science Applications International Corporation
13400B Northrup Way, Suite 36
Bellevue, WA   98005

Dr. Robert Onstott
Environmental Research Institute of Michigan
PO Box 8618
Ann Arbor, MI   48017

Dr. James Overland
NOAA PMEL
7600 Sand Point Way NE
Building 3
Seattle, WA   98115

Dr. Robert Pinkel
Scripps Institution of Oceanography
A-025
La Jolla, CA   92093

19 October 1990 (revised 4/91)