NASA, through its Earth Science Data Systems, supports the NASA Earth Science research community in providing Earth science data products and services driven by NASA’s Earth Science goals. NASA’s Earth Science Program is dedicated to advancing Earth remote sensing and pioneering the scientific use of satellite measurements to improve human understanding of our home planet in order to inform economic and policy decisions and improve operational services of benefit to the Nation. Through the Making Earth Science Data Records for Use in Research Environments (MEaSUREs) Program, NASA is continuing its commitment to expand understanding of the Earth system using consistent records. NASA has begun to deploy new types of sensors to provide three-dimensional profiles of Earth’s atmosphere and surface. Emphasis is placed on linking together multiple satellites into a constellation, developing the means of utilizing a multitude of data sources to form coherent time series, and facilitating the use of extensive data in the development of comprehensive Earth system models.
The MEaSUREs projects are focused on product generation, availability, and utility. During the life of MEaSUREs projects, each project is responsible for making its Earth Science Data Records (ESDRs) available to the user community. At the end of the MEaSUREs projects, the generated ESDRs will be archived and distributed by the EOSDIS data centers. More information about the archives supporting MEaSUREs projects is available at: https://earthdata.nasa.gov/our-community/community-data-system-programs/measures-projects.
The CDDIS is an Earth Observing System Data and Information System) (EOSDIS) Distributed Active Archive Center. CDDIS has been designated as the DAAC for one MEaSUREs project, the Solid Earth Science ESDR System (SESES), a collaborative activity between JPL and the Scripps Orbit and Permanent Array Center (SOPAC). The archived products are time series of geodetic station positions, velocity fields, strain and strain rate, and time series offsets. Weekly updates are issued by the project. In addition, the project has developed the GPS Explorer data portal, which provides tools to access and explore these GPS data products.
The CDDIS provides ftp-only access to products. Files of daily coordinate time series for western North America are now archived at the CDDIS (since July 2012). Tar files created through processes at the SOPAC contain complete, cleaned files of time series solutions.
The starting directory for these files is:
ftp://cddis.gsfc.nasa.gov/pub/GPS_Explorer/latest/ (latest solution)
ftp://cddis.gsfc.nasa.gov/pub/GPS_Explorer/archive/ (prior solutions)
Append the following file names to the starting directory:
as described in the table below.
|SOLN||Solution (WNAM=Western North America, GLB=Global)|
|TYPE||Clean or Filter|
|SOURCE||Solution source (comb=combined, JPL, SOPAC)|
|YYYY||3-digit day of year|
|DD||2-digit day of month|
- Cleaned ("Clean"): Outliers are removed from the trended and detrended time series
- Filtered ("Filter"): Principal Component Analysis (PCA) filter is generated and then applied to the cleaned time series
- Trended ("Trend"): Mean, coseismic and seismic jumps are removed from this time series
- Detrended ("Detrend"): Mean, trend, coseismic and seismic jumps are removed from this time series
- Residuals ("Resid"): Difference between all estimated model values and the cleaned or filtered time series points
More information about these solutions is available in readme files:
- CDDIS archive location: ftp://cddis.gsfc.nasa.gov/pub/GPS_Explorer/
- GPS Explorer portal: http://geoapp.ucsd.edu
- JPL timeseries information: https://gipsy-oasis.jpl.nasa.gov/index.php?page=pppdata
- SIO/SOPAC information: http://sopac.ucsd.edu