Principal Investigator (PI): Felix Landerer, NASA's Jet Propulsion Laboratory
The data record of sea surface height from the altimeter series will soon exceed a quarter century in length, and time-variable gravity from Gravity Recovery and Climate Experiment (GRACE) now spans more than 15 years, with the GRACE Follow-On (GRACE-FO) mission launched on May 22, 2018. Lower-resolution observations of Earth’s gravity changes from Satellite Laser Ranging (SLR) extend back to the 1970s. Together, these observations provide the satellite-geodetic basis for tracking and quantifying several key metrics of our changing planet:
- The sea level budget, consisting of ocean mass and steric changes as well as full-depth ocean heat gain,
- the adjustment of the solid Earth to mass redistribution, and
- the variation of key large-scale ocean transport indices.
Together, these data records are perhaps the most important metrics for the overall state and long-term trajectory of the planetary climate.
A big challenge in combining the different observing systems to derive these key Earth Science Data Records (ESDRs) in a robust and coherent way lies in accurately identifying and applying systematic and correlated biases and corrections, as well as estimating uncertainties in the combined data products. Therefore, we are combining satellite observations to create a set of ESDRs that provide a homogeneous basis for an accurate and current quantification of the planetary sea level budget, ocean heat content, and large-scale ocean transport variations.
Over the last few years, algorithms and concepts have been developed and sufficiently matured to generate individual components of the sea level and heat budget and large-scale transport estimates. To date, however, these components have not been combined into a climate data record within a coherent framework, nor are they produced on a regular basis. By closing this gap, our data products will uniquely inform on full-depth global ocean heat gain, support non-expert assessments and monitoring of the global sea level budget, and contribute data records to infer volume transport variations of two key ocean currents: the Antarctic Circumpolar Current (ACC), and the Atlantic Meridional Overturning Circulation (AMOC).
By judiciously merging different data types (i.e., altimetry, gravimetry, and in-situ floats) and providing uncertainty estimates, these ESDRs will also inform model development and calibration.