 |
 |
 |
|
ILRS Home  Science & Analysis Analysis Products
|
|
 |
|
 |
Analysis Products
The ILRS provides a service to utilize Satellite and Lunar Laser Ranging data to generate geodetic, geodynamic, and geophysical scientific products.
Currently, five SLR analysis
groups (ASI, DGFI, GFZ, JCET and NSGF)
provide direct input for the official ILRS products (station
coordinates and Earth Orientation Parameters, EOPs). The results of the ILRS
POS+EOP pilot project were evaluated during the AWG
meeting in San Fernando.
The five contributors were acknowledged and given an official
status.
In addition, ASI was selected as the official ILRS primary
combination center, and DGFI was selected as the official ILRS
backup combination center, each for a two-year term. As well
as the contributors of individual solutions, these combination
centers must follow strict timelines and provide routine products
of the highest possible quality. Weekly, official ILRS products
from these two combination centers are now available in SINEX
format each Wednesday at CDDIS and EDC.
Analysis centers will again compete for the ILRS combination
and backup center in mid-2006, at the International Laser Ranging
Workshop in Australia. All groups are encouraged to develop
(the quality of) their contributions further.
The ILRS now generates weekly, unconstrained solutions for station coordinates (valid for the mid-point of each 7-day interval) and EOPs (x-pole, y-pole and Length-Of-Day (LOD), all of them for 1-day intervals). These results are stored in subdirectories of the form "pos+eop/YYMMDD", where "YYMMDD" is the date (YY=2 digit year, MM=2 digit month, and DD=2 digit day) of the end of each 7-day interval. Within each subdirectory, one finds so-called individual solutions and combination solutions, that are explained below. For the individual contributions to the POS+EOP project filenames are of the form (examples reflect CDDIS archive):
ftp://cddis.gsfc.nasa.gov/pub/slr/products/pos+eop/YYMMDD/CENTER.pos+eop.YYMMDD.v1.snx.Z
Here, "CENTER" is replaced by the name of the actual contributor. It is the first solution that is generated for this period and by this analysis center, hence "v1". If re-computations are necessary, the version number will be increased by one; solutions for new weeks will start with "v1", however. The results are stored in the SINEX format (".snx"). The reader is refered to the COMMENTS section of each solution (in the file itself) or more general explanations of SINEX for further details of the solution and/or the format.
The official ILRS primary product on POS+EOP is labeled as:
ftp://cddis.gsfc.nasa.gov/pub/slr/products/pos+eop/YYMMDD/ilrsa.pos+eop.YYMMDD.v1.snx.Z
In a similar fashion, the EOP solutions (w.r.t. ITRF2000) generated by the official ILRS primary combination center are named:
ftp://cddis.gsfc.nasa.gov/pub/slr/products/pos+eop/YYMMDD/ilrsa.eop.YYMMDD.v1.snx.Z
The ILRS also has an official backup combination center, and its products are labeled
ftp://cddis.gsfc.nasa.gov/pub/slr/products/pos+eop/YYMMDD/ilrsb.pos+eop.YYMMDD.v1.snx.Z
ftp://cddis.gsfc.nasa.gov/pub/slr/products/pos+eop/YYMMDD/ilrsb.eop.YYMMDD.v1.snx.Z
Currently, the ILRS AWG is in the process of computing similar solutions for the years before the workshop in San Fernando. At this moment, the AWG works on solutions going back to the launch date of LAGEOS-2 (i.e. November 1992). It is foreseen that this will (at a later stage) be followed by computations for the time frame extending back to September 1983, the beginning of the MERIT campaign.
Historic products include:
- Earth Orientation Parameters (EOP)
- GSFC 98L01 solution
- CSR 95L01 solution
- Delft University of Technology 92L01 solution
- GeoForschungsZentrum 95L01 solution
- Centro di Geodesia Spaziale solutions
- Coordinates and velocities of the tracking stations
- Geocenter coordinates - thanks to IERS Geocenter campaign results
- On the determination of terrestrial reference frame by SLR and GPS techniques, by H. Montag, G. Gendt and P. Wilson
- CSR Geocenter from Lageos-1&2, by R. Eanes gives a time series of SLR estimates from 30 Oct. 1992 to 02 Jan. 1997.
- Geocenter variation comparisons, by J. Chen, shows results from two SLR solutions compared with effects produced by variations in sea surface, land water, and atmospheric pressure.
- Geocenter variations from TOPEX SLR, by M. Cheng, gives a time series of 10-day estimates otained using 174 cycles of SLR ranging to TOPEX.
- Preliminary times series from LAGEOS 1 & 2 SLR data, by E. Pavlis, gives estimates at 15-day intervals from the launch of LAGEOS 2 in 1993 to end of 1996.
- CGS geocenter motion estimations, by P. Rutigliano and F. Vespe, gives estimates at 28-day intervals from January 1994 to January 1997 using combined Lageos-I and Lageos-II data.
- AGU Poster Data & Postscript files, by E. Pavlis describes anonymous ftp access to the data and the postscript files presented at the Fall AGU Meeting. Please refer to the README file.
- CGS geocenter motion estimations, by P. Rutigliano and C. Luceri, gives two new, independent solutions, each at 14-day intervals from January 1993 to December 1996 using combined Lageos-I and Lageos-II data. A free-network approach with minimal inner constraints was used.
Responsible Government Official: Carey Noll
NASA's Privacy Policy and Important Notices
Send us your comments
