Attention GNSS Data Users: Please review the IGSMail messages related to the "Transition to ISO-3166 Alpha-3 codes in the IGS metadata." The changes go into effect on December 4, 2024. See https://lists.igs.org/pipermail/igsmail/2024/008454.html and https://lists.igs.org/pipermail/igsmail/2024/008518.html.
Other IGS products, such as troposphere and ionosphere products, have been developed through working groups (https://igs.org/wg/troposphere and https://igs.org/wg/ionosphere) or pilot project activities and are stored using separate directory structures within the GNSS products area of the archive. These products include troposphere ZPD estimates, along with statistics about the product, derived from GNSS measurements and ionosphere vertical total electron content maps for climate research and atmospheric studies.
Troposphere
IGS associate analysis centers generate troposphere products from ground-based GNSS data. These products include five-minute estimates of zenith path delay (ZPD) and north and east troposphere gradient components. Data are available in daily files by site for over 400 GNSS stations in the IGS network. Measurements of surface pressure and temperature at GNSS sites allow the extraction of precipitable water vapor from the total zenith path delay. Final troposphere estimates for over 400 stations in the IGS network. The final troposphere estimate products utilize the IGS final satellite, orbit, and EOP combination products and are therefore available approximately three weeks following the observation day. Troposphere products are available in a standard IGS format.
Since the inception of the troposphere product, three analysis groups (GFZ, JPL, and currently USNO) have generated the IGS final troposphere solution each using different methodologies. Therefore, the resulting file types have changed through the years. GFZ and JPL produced the IGS final troposphere estimates as a combination product of contributing analysis centers. In 2007, JPL switched to producing the estimates with a precise point positioning (PPP) method. The current product, produced by USNO, consists of files containing daily ZPD estimates from PPP processing for selected sites in the IGS network. The original product consisted of one file per site per GPS week.
Historical tropospheric products are also available. These products are no longer updated.
The starting directory for the current troposphere solution files is:
At the end of 2022, the IGS made the decision to change the name format going forward of many of its products archived at the CDDIS.
Name Format Since GPS Week 2238
Append the following directory and file names to the starting directory:
WWWW/IGS0OPSFIN_YYYYDDDHHMM_01D_05M_SITENAME_TRO.TRO.gz
as described in the table below.
Code | Meaning |
---|---|
WWWW | GPS week |
YYYY | 4-digit year |
DDD | 3-digit day of year |
HH | 2-digit hour |
MM | 2-digit minute |
SITENAME | 9-digit IGS monument name |
.gz | gzip compressed file |
Name Format Before GPS Week 2237
Append the following directory and file names to the starting directory for current files:
YYYY/DDD/SSSSDDD#.YYzpd.gz
as described in the table below.
Code | Meaning |
---|---|
YYYY | 4-digit year |
SSSS | IGS monument name |
DDD | 3-digit day of year |
# | file number for the day, typically 0 |
YY | 2-digit year |
.gz | gzip compressed file |
The starting directories for the historical troposphere product files are:
Starting Directory | Products |
---|---|
https://cddis.nasa.gov/archive/gnss/products/troposphere/cmp/ | Comparison results between initial IGS troposphere product (generated by GFZ) and JPL solution (through 2009) |
https://cddis.nasa.gov/archive/gnss/products/troposphere/old/ | Earlier versions of IGS troposphere products, produced by GFZ |
https://cddis.nasa.gov/archive/gnss/products/troposphere/rpt/ | Product reports by GPS week, produced by JPL (through 2010) |
https://cddis.nasa.gov/archive/gnss/products/troposphere/sta/ | Reports and supporting information on station troposphere products, produced by JPL (through 2007) |
Ionosphere
Since 1998, IGS associate analysis centers have provided products containing ionosphere vertical total electron content (TEC) maps and daily GNSS satellite differential code bias (DCB) values derived from the dual-frequency GNSS data. Daily ionospheric fluctuation maps are also available. The IGS product is derived from analysis center solutions, both rapid and final. These ionosphere products are available in rapid solutions with a latency of less than 24 hours, a final solution with a latency of approximately 11 days, and a predicted solution, available both one and two days prior. Ionosphere products are provided in IONEX (ionosphere exchange) format.
The starting directory for the current ionospheric solution files is:
https://cddis.nasa.gov/archive/gnss/products/ionex/
At the end of 2022, the IGS made the decision to change the name format going forward of many of its products archived at the CDDIS. A table is available on the IGS website which compares the old and new name formats. The table can be found on the following page:
https://igs.org/products/#ionosphere
Name Format Since GPS Week 2238
Append the following directory and file names to the starting directory:
WWWW/IGS0OPSTYP_YYYYDDDHHMM_01D_SMP_CNT.INX.gz
as described in the table below.
Code | Meaning |
---|---|
WWWW | GPS week |
TYP | solution type identifier - FIN (Final solution combination) RAP (Rapid solution combination |
YYYY | 4-digit year |
DDD | 3-digit day of year |
HH | 2-digit hour |
MM | 2-digit minute |
SMP | temporal product sampling resolution |
CNT | content type - GIM (global ionosphere (TEC) maps) ROT (rate of TEC index maps) |
.gz | gzip compressed file |
Name Format Before GPS Week 2237
Append the following directory and file names to the starting directory for current files:
YYYY/DDD/AAAgDDD#.YYi.Z
Vertical total electron content (TEC) maps
YYYY/DDD/rotiDDD0.YYf.Z
Daily ROTI (rate of TEC index) product
as described in the table below.
Code | Meaning |
---|---|
c1p | 1-day predicted solution (CODE) |
c2p | 2-day predicted solution (CODE) |
cod | Final solution (CODE) |
cor | Rapid solution (CODE) |
e1p | 1-day predicted solution (ESA) |
e2p | 2-day predicted solution (ESA) |
ehr | Rapid high-rate solution, one map per hour, (ESA) |
esa | Final solution (ESA) |
esr | Rapid solution (ESA) |
ilp | 1-day predicted solution (IGS combined) |
i2p | 2-day predicted solution (IGS combined) |
igr | Rapid solution (IGS combined) |
igs | Final combined solution (IGS combined) |
jpl | Final solution (JPL) |
u2p | 2 day predicted solution (UPC) |
upc | Final solution (UPC) |
uhr | Rapid high-rate solution, one map per hour, (UPC) |
upr | Rapid solution (UPC) |
uqr | Rapid high-rate solution, one map per 15 minutes, (UPC) |
Code | Meaning |
---|---|
YYYY | 4-digit year |
DDD | 3-digit day of year |
AAA | Analysis center name |
# | file number for the day, typically 0 |
YY | 2-digit year |
.Z | Unix compressed file |
The IGS analysis centers re-processed the historical IGS data set (from 1994 to 2007 for repro1, from 1994 through 2012/2013 for repro2, from 1994 through 2022 for repro3) to produce a fully consistent set of products utilizing the most recent models and updated processing strategies.