Polar Motion Information
Entry ID: OES_GL_POLAR_MOTION

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Summary
Abstract: The POLARIS (Polar Motion Analysis by Radio Interferometric Surveying)
network monitors the location of the Earth's axis of rotation using
the method of Very Long Baseline Interferometry (VLBI). Extragalactic
radio sources are observed to determine polar motion, universal time,
precession and nutation. Estimates of x and y components of the
position of the pole, and formal uncertainties are tabulated according
to observational dates. Currently, the nominal interval between
entries is five days. The POLARIS Earth orientation information has
applications in high accuracy satellite and space geodesy, geodynamics
research, and climatology.

Data are available in machine-readable form from NOAA via telephone
modem or through INTERNET - specifically, Earth Orientation Parameters
(EOP), UT1 (Rotational Orientation of the Earth), and Length of Day
(LOD). The following files are available:

Monthly: IRIS** EOP from current adjustment of IRIS data series, from 9/27/80
UT1MC** UT1 from Intensive series, from 4/24/84
LODR** LOD, uncorrected/corrected for tidal variations, from 1/1/86
Weekly: IRISW* Rapid Calculation of recent IRIS EOP
UT1RS* Rapid calculation of recent intensive UT1

(For fuller information on the nature and content of these files,
speak with the Technical Contact for this data set.) To access these
files from modem, first set your terminal for 1200 baud, full duplex,
any parity, and then dial (301) 881-6358. Enter and
wait for response. Respond to 'user ID' with IRIS-NGS; to 'password'
with NGS. Respond to 'who are you?' your organization name. Finally,
respond to : prompt with LI,name where 'name' is the file name. To
avoid further interrupts, respond with rather than . Exit
with EX before disconnecting the modem. Subscribers to the GE Mark
III system may also access these files, and should use their usual
system procedures.

These files are now available via INTERNET using FTP protocols. The
INTERNET address where the files can be found is 'ray.grdl.noaa.goc'
or '192.64.69.197 The user should log in as 'anonymous' and give
his/her own name when the system asks for a password. After logging
on, the user should change to the appropriate directory with the
command 'cd /dist/vlbi' and use the FTP command 'get' to transfer the
appropriate files. The file names are identical to those described
above (for modem access), but without the asterisks, which can cause
difficulty on UNIX systems.

Geographic Coverage
 N: 90.0 S: -90.0  E: 180.0  W: -180.0

Temporal Coverage
Start Date: 1978-01-01


Location Keywords
GEOGRAPHIC REGION > GLOBAL


Science Keywords
SOLID EARTH >GRAVITY/GRAVITATIONAL FIELD >CRUSTAL MOTION    [Definition]
SOLID EARTH >GRAVITY/GRAVITATIONAL FIELD >POLAR MOTION    [Definition]
SOLID EARTH >GRAVITY/GRAVITATIONAL FIELD >SATELLITE ORBITS/REVOLUTION    [Definition]


ISO Topic Category
GEOSCIENTIFIC INFORMATION


Keywords
OES/GL_POLAR_MOTION


Originating Center
NOAA/NOS/OES/GL


Data Center
National Geodetic Survey, National Ocean Service, NOAA, U.S. Department of Commerce    [Information]
Data Center URL: http://www.ngs.noaa.gov/

Data Center Personnel
Name: INFORMATION SERVICES BRANCH NATIONAL GEODETIC SURVEY
Phone: 301-713-3242
Fax: 301-713-4172
Email: ngs.infocenter at noaa.gov
Contact Address:
National Geodetic Survey, NOAA
Information Services Branch
1315 East-West Highway
City: Silver Spring
Province or State: MD
Postal Code: 20910-3282
Country: USA



Distribution
Distribution_Media: Online, Digital


Publications/References
IRIS Bulletin-A; Earth Orientation (available from NOAA N/OES13, 11400
Rockville Pike, Rockville MD 20852)

Carter, W.E., D.S. Robertson, J.E.Pettey, B.D. Tapley, B.E. Schultz,
R.J. Eanes, and Miao Lufeng, 'Variations in the Rotation of the Earth,'
Science, vol 224, pp. 957-961, 1 June, 1984.

Creation and Review Dates
Last DIF Revision Date: 2012-12-21

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