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IERS Message No. 175                                  September 22, 2010
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Information on the updates to the IERS Conventions


The IERS Conventions Center informs of the following updates:

Three chapters of the IERS Conventions have been updated:

* Chapter 6 "Geopotential" has been updated on 19 September 2010, 
see http://tai.bipm.org/iers/convupdt/convupdt_c6.html.

The section 6.3 "Effect of the ocean tides" has been rewritten, and the
tide model FES2004 is described (main contributors are S. Bettadpur,
R. Biancale and J. Ries). The introduction has been expanded to present
general notions.


* Chapter 7 "Displacement of reference points" has been updated on 21
September 2010, see http://tai.bipm.org/iers/convupdt/convupdt_c7.html.

The chapter has been reorganized to consider three kinds of
displacements, see the chapter's introduction for details. A new section
treats "S1-S2 atmospheric pressure loading" based on the work of T. van
Dam and R. Ray; the model is implemented at
http://geophy.uni.lu/ggfc-about/tide-loading-calculator.html, see the
text for details.


* Chapter 9 "Models for propagation delays" has been updated on 21
September 2010: see http://tai.bipm.org/iers/convupdt/convupdt_c9.html.

A mean a priori model for gradients is given along with information on
its use for radio techniques (provided by J. Boehm).


Gerard Petit and Brian Luzum
IERS Conventions Center


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