# Presentation: 437412

## Current Status of the IGS Reprocessing

**Peter Steigenberger**
- Technische Universität München
**Gerd Gendt **
- GeoForschungsZentrum Potsdam
**Remi Ferland**
- National Resources Canada
**Ignacio Romero**
- European Space Operations Centre, Darmstadt

## Motivation

**Significant** and **numerous improvements** in ACs’ processing strategies and modeling have been implemented since the official start of the IGS in January 1994
- Therefore, time series of **operational IGS products** are **inhomogeneous** and affected by reference frame changes.
- Geophysical interpretation of these inhomogeneous IGS time series is difficult
- Major discontinuity introduced in November 2006 (Week 1400)
- absolute antenna phase center model
- ITRF2005 (IGS05)
- Inclusion of **more stations**:
- Processing limitations in the early years
- Data not available in time for operational processing

## PPP with IGS Final Orbits and Clocks

## Major Goals of the IGS Reprocessing

- Generate **homogeneous** and **consistent** long time series of combined **IGS products** computed with up-to-date models and standards:
- station coordinates,
- Earth rotation parameters,
- satellite orbits,
- satellite and station clocks
- for the time period **January 1994 till December 2007**
- Provide **input** for the next **realization of the ITRS**
- Basis for the generation of a **new satellite antenna phase center model** (satellite antenna offsets are given in the SINEX files of some ACs)

## History of the IGS Reprocessing

| 2004 Workshop | Recommendation 2.9:  “The ACs should be prepared to reprocess the IGS data. The detailed procedure should be discussed after the absolute antenna phase center variation models are decided (see Antenna session).” |
| --- | --- |
| July 2005 | Call for Participation (IGSMAIL-5175) |
| November 2005 | Station operator asked to check data archives |
| 2006 Workshop | Session “Reprocessing Issues, Standardization, New models” |
| Summer 2007 | first results for a 3 months test period in 2000 |
| February 2008 | Start of the 1st IGS reprocessing campaign |

## Reprocessing Analysis Centers

| Abb. | Analysis Center | Country |
| --- | --- | --- |
| em1 | National Resources Canada | Canada |
| es1 | European Space Operations Center  | Germany |
| gf1 | GeoForschungsZentrum Potsdam | Germany |
| jp1 | Jet Propulsion Laboratory | USA |
| mi1 | Massachusetts Institute of Technology  | USA |
| ng1 | National Geodetic Service | USA |
| pd1  | Potsdam Dresden Reprocessing | Germany |
| si1 | Scripps Institution of Oceanography  | USA |

## Reprocessing Combination Centers

- _Natural Resources Canada (NRCan) _
- weekly SINEX combination	Talk by R. Ferland
- Terrestrial Reference Frame
- _GeoForschungsZentrum (GFZ) Potsdam_
- Orbit combination
- Clock combination
- _Naval Research Laboratory (NRL)_
- Timescale (not yet available)

- Talk by G. Gendt

## Products of the 1st IGS Reprocessing Campaign

- Weekly **SINEX** files (***.snx**)
- Station coordinates
- Earth rotation parameters: polar motion + rates, LOD
- Apparent geocenter
- Satellite antenna offsets
- 	(only some ACs, not included in combined files)
- Daily **orbit** files (***.sp3**)
- satellite positions and clocks with 15 min time resolution
- Daily **clock** files (***.clk**)
- satellite and receiver clocks with 30 s or 5 min time resolution (AC dependent, 5 min for combined clocks)
- Weekly **Earth rotation parameter** files (***.erp**)
- 24 h time resolution

## /wwww/repro#/cc#wwwwd.typ.Z

**ftp://cddis.gsfc.nasa.gov/gps/products/**

| # | Reprocessing campaign number: 1, 2, ... |
| --- | --- |
| cc | first two characters of the AC code
ig# for combined IGS products |
| wwww | GPS week |
| d | Day of week |
| typ | File type: snx, ssc, sp3, clk, erp, sum |

**/wwww/repro****#****/****cc****#****wwwwd.****typ****.Z**

## /repro#

- 		week 1400, day 3

**File Naming (2)**

- Concatenated Earth rotation parameters: ** ****ig108p01.erp**
- Links to weekly directories **/wwww/repro****#****/**

**ftp://cddis.gsfc.nasa.gov/gps/products/**

**/repro****#**

- Primary Data Center: **CDDIS**
- + distribution to Global Data Centers **IGN**, **SIO** and **KASI**

**/1400/repro****1****/****ig****1****14003.****sp3****.Z**

## File Archiving

**Operational files** will be moved to:
**...****/wwww/orig**** **
- Files of the 1st reprocessing campaign will be linked through week 1459 (December 2007)
-  	from 	**.../wwww/repro****1****/****cc****1****wwwwd.typ.Z** to 	**.../wwww/****ccc****wwwwd.typ.Z**
- Users can always access the **latest IGS products** at
- 		**...****/wwww/****ccc****wwwwd.typ.Z**
- The same procedure will be valid for future reprocessing campaigns

- As soon as the 1st reprocessing campaign is concluded

## Current Status

| AC | 2000 | 2007 | sp3 | erp | clk | snx | sum |
| --- | --- | --- | --- | --- | --- | --- | --- |
| em1 | -- | -- | x | x | 5 min | x |  |
| es1 | 1042-1055 | 1408-1459 | x | x | 5 min | x | x |
| gf1 | 1043 | 1410-1459* | x | x | 5 min | x | x |
| jp1 | -- | -- | x | x | 30 sec | x |  |
| mi1 | 1042-1061 | 1408-1459 | x | x | 30 sec | x | x |
| ng1 | 1042-1060 | 1448-1459 | x | x | - | x | x |
| pd1 | 1042-1060 | 1408-1459 | x | x | - | x | - |
| si1 | 1042-1060 | 1408-1459 | x | x | - | x | x |

- * 7 week missing during that time period

- Files available at CDDIS/GFZ Potsdam:

- Status: 29 May 2008

## Current Status

| AC | 2000 | 2007 | sp3 | erp | clk | snx | sum |
| --- | --- | --- | --- | --- | --- | --- | --- |
| em1 | -- | -- | x | x | 5 min | x |  |
| es1 | 1042-1055 | 1408-1459 | x | x | 5 min | x | x |
| gf1 | 1043 | 1410-1459* | x | x | 5 min | x | x |
| jp1 | -- | -- | x | x | 30 sec | x |  |
| mi1 | 1042-1061 | 1408-1459 | x | x | 30 sec | x | x |
| ng1 | 1042-1060 | 1448-1459 | x | x | - | x | x |
| pd1 | 1042-1060 | 1408-1459 | x | x | - | x | - |
| si1 | 1042-1060 | 1408-1459 | x | x | - | x | x |

- * 7 week missing during that time period

- Files available at CDDIS/GFZ Potsdam:

- Status: 29 May 2008

## Timetable

| AC | Time/year | Start | End |
| --- | --- | --- | --- |
| em1 | 1-2 month | July 2008 | end of 2009 |
| es1 | 4 days (single PC) |  | end of 2008 |
| gf1 | 1 week |  | October 2008 |
| jp1 | 1 week | end of June | end of 2008 |
| mi1 |  |  |  |
| ng1 |  |  |  |
| pd1 | 1 week |  | autumn 2008 |
| si1 |  |  |  |

- Combined weekly SINEX files: 1 month/year

**Notes:**
PDR: September 2008 für F7/F3 in igs05

## Recommendations: Antenna Model

**REPRO-4**: 	The IGS absolute antenna calibration file should be updated before the start of each new reprocessing campaign, in-cluding all available robot calibrations for receiver antennas and satellite-specific antenna offsets available in the SINEX files of the previous reprocessing campaign.

- Currently 6 GPS satellites with preliminary z-offsets (block mean)

- ANTEX file used for the current reprocessing: igs05_1461.atx

- _Recent changes for receiver antennas:_
- 7 converted calibrations from NGS added
- 6 robot calibrations from GEO++ added
- 5 converted NGS calibrations replaced by robot calibrations

## Recommendations: SLR Orbit Validation

**REPRO-5**: 	(Refreshment of WS06-REPR10): Reprocessed orbits should be validated computing SLR residuals.

- AC capability to compute SLR range residuals with their AC software

| EMR | ESA | GFZ | JPL | MIT | NGS | PDR | SIO |
| --- | --- | --- | --- | --- | --- | --- | --- |
| -- |  | -- |  |  |  |  |  |

| EMR | ESA | GFZ | JPL | MIT | NGS | PDR | SIO |
| --- | --- | --- | --- | --- | --- | --- | --- |
| x |  | x |  |  |  |  |  |

- AC willing to provide SLR range residuals for SVN 35 and 36

**Who will do the analysis of these residuals?**

## Posters/Further Information

_**Posters:**_
- Rohde et al.: *The GPS data reanalysis campaign at the National Geodetic Survey*
- Steigenberger et al.: *PDR GPS satellite orbits*
- Thomas et al.: *Water vapour estimates over Antarctica from 12 years of globally reprocessed GPS solutions*
- T.A. Springer et al.: ESOC IGS reprocessing (details)

- Further information and preliminary results: IGS ACC webpage
**http://www.ngs.noaa.gov/igsacc/WWW/reprocess.html**

- Discussion of all recommendations at the end of the session

## Summary

- After several tests, the **first IGS reprocessing** campaign has started in February 2008
**First results** for a three months period in 2000 and for 2007 are **available** (some ACs still missing), more details in the following talks
- First complete AC series for the time period 1994 – 2007 will be available by the **end of 2008**
**Preliminary combined products** are expected to be available by the **end of 2009**
- First IGS reprocessing campaign is expected to be **concluded in 2010**

**Notes:**
Preliminary combination will start start as soon as ~half of the Acs are available. 

## Recommendations

**REPRO-3**	Discontinuity table shall be updated to be consistent with reprocessed solutions in coordination with the users.

**REPRO-1**	All reprocessing ACs have to follow the rules for ge-nerating IGS Final products, i.e. all products have to be consistent (especially the orbits have to be in the system given in the SINEX files; and the clocks shall be consistent with the orbits and with the frame center of the IGS05 [WS 2004 Recommendation RFM10]).

**REPRO-2**	Future IGS reference frame realizations should in-clude active and inactive high quality stations, going back to the IGS beginning. This way the stability over time, having sufficient RF stations in early years, should be improved.

## Recommendations

**REPRO-6**: 	Correct  IERS domes numbers shall be used for the SINEX files. For the clock solutions the unique 4-character ID (RINEX file name) shall be used.

**REPRO-4**: 	The IGS absolute antenna calibration file should be updated before the start of each new reprocessing campaign, in-cluding all available robot calibrations for receiver antennas and satellite-specific antenna offsets available in the SINEX files of the previous reprocessing campaign.

**REPRO-5**: 	(Refreshment of WS06-REPR10): Reprocessed orbits should be validated computing SLR residuals.

## Discussion

- _Open issues from the 2006 workshop:_
- Troposphere product and combination
- Differential Code Biases back to 1994

- _Other issues_
- How best to deal with other densification needs: what is IGS role in providing PPP & other services?
- Ionosphere maps
- 30 s clocks: at least 3 ACs needed for combination (currently 2 ACs)