On 31 October 2020, anonymous ftp access will officially be discontinued at CDDIS. Beginning October 1, 2020, CDDIS will bandwidth limit ALL IPs using anonymous ftp to just 50KB/s and will limit simultaneous downloads to only 3 per IP address. CDDIS is STRONGLY recommending all users begin to transition to using alternate method of access to the CDDIS archive. Examples of alternate methods can be found at: https://cddis.nasa.gov/Data_and_Derived_Products/CDDIS_Archive_Access.html.

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SLR data holdings

The SLR data in the CDDIS are in the form of on-site normal point and full-rate data. In the early days of laser ranging data analysis, scientists typically required SLR full-rate data; these data included all valid points or returns from the satellite. Since 1988, SLR normal points have been produced from the global full-rate data set. Normal point data are compressed data using sampling over time based upon the presence of some minimum number of data points in the sampling interval. The monthly data volume is considerably reduced. Since the early 1990's, normal point are generated on-site by laser ranging systems and transmitted daily (and sometimes hourly) to a regional processing center via electronic means.

The data from each satellite are stored in separate files and directories, by satellite. Each file contains all data received during the last 24-hour period. Additionally, a single file containing all data received during the last 24 hours is available.

Data from the global laser ranging network are organized in subdirectories by

  • File content (normal points, full-rate)
  • Satellite
  • Year

Spatial coverage

Temporal coverage

Data volume

  • Normal point data: ~1.25 Mbyte/day, 40 Mbyte/month
  • Full-rate SLR data: ~10 Mbytes/day (compressed)

Data Formats