The NASA-SSH Simple Gridded Sea Surface Height from Standardized Reference Missions Only Version 1 dataset produced by NASA provides 2-D maps of sea surface height, or sea level, anomaly once every 7 days. The grids are based on observations of sea surface height from the radar altimeter satellites in the reference mission orbits, including TOPEX/Poseidon, the Jason series, and Sentinel-6. The data begin in Oct 1992 and continue through the present. They are created using the NASA-SSH Along-Track Sea Surface Height from Standardized Reference Missions Version 1 dataset. The grids consist of 10-days worth of observations, which covers approximately 1 complete repeat cycle of observations from the reference missions. The grids are produced on a 0.5-degree latitude and longitude grid, by taking a simple gaussian weighted spatial average with a width of 100 km. The grids are produced every 7 days to allow for easy interpolation in time. However, since they are created using 10-days of data, there is some overlap of information between adjacent time steps. The grids are also created using the basin flags to avoid mixing data from distinct ocean basins (for example, to avoid mixing observations from the Caribbean Sea with observations from the Pacific across the Isthmus of Panama). Connected basins are allowed to share data, however. This is accomplished by using a table of connections between basins. The basin connection table is available (https://archive.podaac.earthdata.nasa.gov/podaac-ops-cumulus-docs/web-misc/nasa-ssh/basin_connection_table.txt). The basin definitions can be downloaded as a shape file from https://archive.podaac.earthdata.nasa.gov/podaac-ops-cumulus-docs/web-misc/nasa-ssh/basin_polygon_files.tar.gz, or as a kml file https://archive.podaac.earthdata.nasa.gov/podaac-ops-cumulus-docs/web-misc/nasa-ssh/NASA-SSH_Basins.kmz. A new grid will be released approximately once per week, with a latency of a few weeks.

NetCDF file result_s3b_sarm_stack.nc contains longitude, latitude, number of cycles, sigma, and stacked sea surface height records for 770 Sentinel-3B Synthetic Aperture Radar Mode (SARM) satellite altimeter passes. Repeat cycles were aligned to a common position along a synthetic track having 20239 records between +/-81.419 latitude. Stacking is the median sea surface height profile from multiple repeat cycles. Sigma is the expected one sigma error in a single measurement. The number of cycles is the quantity that passed selection criteria and were included in a stack. Repeat cycles 19 to 38 were used. The interleaved ground track started with cycle 19.

NetCDF file result_s3a_sarm_stack.nc contains longitude, latitude, number of cycles, sigma, and stacked sea surface height records for 770 Sentinel-3A Synthetic Aperture Radar Mode (SARM) satellite altimeter passes. Repeat cycles were aligned to a common position along a synthetic track having 20239 records between +/-81.419 latitude. Stacking is the median sea surface height profile from multiple repeat cycles. Sigma is the expected one sigma error in a single measurement. The number of cycles is the quantity that passed selection criteria and were included in a stack. Repeat cycles 1 to 56 were used.

NetCDF file result_s3b_plrm_stack.nc contains longitude, latitude, number of cycles, sigma, and stacked sea surface height records for 770 Sentinel-3B Pseudo-Low Rate Mode (PLRM) satellite altimeter passes. Repeat cycles were aligned to a common position along a synthetic track having 20239 records between +/-81.419 latitude. Stacking is the median sea surface height profile from multiple repeat cycles. Sigma is the expected one sigma error in a single measurement. The number of cycles is the quantity that passed selection criteria and were included in a stack. Repeat cycles 19 to 38 were used. The interleaved ground track started with cycle 19.

This file contains an indicator for the Indian Ocean Dipole (IOD), based on satellite observations of sea surface height anomaly, measured by radar altimeter missions such as TOPEX/Poseidon, the Jason series, and Sentinel-6. The indicator values were calculated using NASA-SSH Simple Gridded Sea Surface Height from Standardized Reference Missions Only Version 1 https://podaac.jpl.nasa.gov/dataset/NASA_SSH_REF_SIMPLE_GRID_V1 . Indicator values were calculated using cyclostationary empirical orthogonal functions (CSEOFs; Kim et al., 2015) computed by decomposing the gridded sea surface height anomalies over the time period from 1993 to 2019. After removing the linear trend from each individual gridded location, three sets of regional CSEOFs were generated, one each for the El Nino-Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO) and (IOD). In each case, the dominant statistical mode represents the seasonal cycle. The second most dominant mode represents the variability explained by each respective indicator and is referred to as the “indicator mode”. The seasonal mode and indicator mode are then projected onto the along-track sea surface height anomalies to produce the indicator time series through the most current date. In this case, the IOD mode was used to produce the time series contained in this file.

This file contains a time series of globally-averaged sea level change, or "global mean sea level" (GMSL) in units of centimeters. The estimate is based on satellite observations of sea surface height anomaly, measured by reference radar altimeter missions such as TOPEX/Poseidon, the Jason series, and Sentinel-6. The indicator values were calculated using NASA-SSH Simple Gridded Sea Surface Height from Standardized Reference Missions Only Version 1 https://podaac.jpl.nasa.gov/dataset/NASA_SSH_REF_SIMPLE_GRID_V1 . GMSL was calculated as the area-weighted average over each map in the time series of Simple Gridded Sea Surface Height. Because maps are computed using 10-days of observations, but are computed once every 7 days, there is a small amount of overlap between data used to compute successive time steps. A version of the estimate smoothed over 60 days is also provided. Expert users, please note that this estimate has NOT been adjusted for Glacial Isostatic Adjustment, to account for the slight long-term depression of the sea floor. Users who study the sea level budget will need to account for this effect in order to properly evaluate closure of the budget.

NetCDF file result_stack.nc contains longitude, latitude, number of cycles, sigma, and stacked sea surface height records for 1002 AltiKa satellite altimeter passes. Repeat cycles were aligned to a common position along a synthetic track having 20005 records between +/-81.498 latitude with equator crossings from the AltiKa median equator crossing table. Stacking is the median sea surface height profile from multiple repeat cycles. Sigma is the expected one sigma error in a single measurement. The number of cycles is the quantity that passed selection criteria and were included in a stack. Cycles were restricted to 1 through 32 due to orbital drift off the nominal ground track after a hardware issue in 2015.

These data are near-real-time (NRT) (within 7-9 hours of measurement) sea surface height anomalies (SSHA) from the AltiKa altimeter onboard the Satellite with ARgos and ALtiKa (SARAL). SARAL is a French(CNES)/Indian(SARAL) collaborative mission to measure sea surface height using the Ka-band AltiKa altimeter and was launched February 25, 2013. The major difference between these data and the Operational Geophysical Data Record (OGDR) data produced by the project is that the orbit from SARAL has been adjusted using SSHA differences with those from the OSTM/Jason-2 GPS-OGDR-SSHA product at inter-satellite crossover locations. This produces a more accurate NRT orbit altitude for SARAL with accuracy of 1.5 cm (RMS), taking advantage of the 1 cm (radial RMS) accuracy of the GPS-based orbit used for the OSTM/Jason-2 GPS-OGDR-SSHA product. This dataset also contains all data from the project (reduced) OGDR, and improved altimeter wind speeds and sea state bias correction. More information on the SARAL mission can be found at: http://www.aviso.oceanobs.com/en/missions/current-missions/saral.html

The Integrated Multi-Mission Ocean Altimeter Sea Surface Height (SSH) Version 5.2 dataset provides level 2 along track sea surface height anomalies (SSHA) for 10-day cycles from the TOPEX/Poseidon, Jason-1, OSTM/Jason-2, Jason-3, and Sentinel-6A missions geo-referenced to a mean reference orbit. It is produced by NASA Sea Surface Height (NASA-SSH) project investigators at Goddard Space Flight Center and Jet Propulsion Laboratory with support from NASA’s Physical Oceanography program, and was developed originally as an Earth System Data Record (ESDR) under the Making Earth System Data Records for Use in Research Environments (MEaSUREs) program, which supported forward processing and incremental refinements through version 5.1 (released in April 2022). Geophysical Data Records (GDRs) from each altimetry mission were interpolated to a common reference orbit with biases and cross-calibrations applied so that the derived SSHA are consistent between satellites to form a single homogeneous climate data record. The entire multi-mission data record covers the period from September 1992 to present; it is extended to include new observations approximately once each quarter. The previous release (version 5.1) integrated Jason-3 data and applied revised internal tides and pole tide across missions (GDR_F standard). The current release (version 5.2) includes the following revisions: a) GSFC std2006_cs21 orbit for all missions, b) GOT5.1 ocean tide model, c) TOPEX/Poseidon GDR_F data, d) Sentinel-6 LR version F08 data, e) Jason-3 re-calibrated radiometer wet troposphere correction. More information about the data content and derivation can be found in the v5.2 User’s Handbook (https://doi.org/10.5067/ALTUG-TJ152). Please note that this collection contains the same data as https://doi.org/10.5067/ALTTS-TJA52, re-organized into one netCDF file per cycle for convenience.

Provides low resolution (LR) non-time critical (NTC; 60-day latency) measurements of sea surface height anomaly (SSHA), Significant Wave Height (SWH), and Wind Speed. The NTC product is analogous to the Jason-3 GDR product.