US CLIVAR plays a central role in motivating and utilizing in-situ and satellite ocean and atmosphere observing systems to monitor, understand and model climate variability. Key observing systems beneficial to US CLIVAR research include:
- The Global Tropical Moored Buoy Array of over 110 fixed moorings spanning the tropical Pacific (TAO/TRITON), Atlantic (PIRATA) and Indian Ocean (RAMA) basins instrumented to measure both upper ocean and surface meteorological variables involved in ocean-atmosphere interactions, providing knowledge of critical processes important to monitoring, understanding and prediction of ENSO and PDO in the Pacific, the meridional gradient mode and equatorial warm events in the Atlantic, the Indian Ocean Dipole and intraseasonal Madden-Julian Oscillation in the Indian Ocean, the mean seasonal cycle and monsoon circulation, and decadal trends that may be related to global warming.
- Ocean Reference Stations, a global array of 60 moored surface and subsurface buoys instrumented to provide the most accurate possible long-term climate data records of heat, momentum, freshwater, and gas (e.g., CO2) exchanges across the air-sea interface, ocean currents and transport to a depth of 5000m, and biogeochemical properties within the water column in key ocean regimes (e.g., narrow Western Boundary Currents, trade-wind sites) to detect sudden changes and events, to calibrate remotely sensed measurements, to elucidate climatically sensitive processes, and to evaluate and improve models.
- The Global Expendable Bathythermograph (XBT) Network comprised of over 30 fixed transects spanning all ocean basins along which measurements of water temperature from the surface to 850m are made every 25km and at least 4 times a year (for high-density transects), resolving both the oceanic boundary currents and the corresponding interior heat and mass circulations of the global oceans.
- The US Global Ocean Carbon and Repeat Hydrography Program and the international Global Ocean Ship-Based Hydrographic Investigations Program (GO-SHIP) providing systematic and global re-occupation of select World Ocean Circulation Experiment (WOCE)/Joint Global Ocean Flux Study (JGOFS) hydrographic sections (currently 46 lines globally) that measure pressure, temperature, salinity, carbon, nitrogen, oxygen and other biogeochemistry variables from the surface to the deep ocean, providing the ability to quantify full depth changes in storage and transport of heat, fresh water, and CO2 globally on decadal timescales.
- The global Argo Array of 3,000 free-drifting profiling floats that measure temperature, salinity, and velocity of the upper 2000m of the ocean, providing a quantitative description of the changing state of the upper ocean, sea level, and the patterns of ocean climate variability from months to decades, including heat and freshwater storage and transport.
- The Global Drifter Program array of 1250 satellite-tracked free-drifting surface drifting buoys that measure mixed layer currents, sea surface temperature, atmospheric pressure, winds and salinity, supporting climate monitoring, research, seasonal-to-interannual predictions, and satellite SST measurement calibration.
- Satellite data products crucial for monitoring and studying climate variability and change and for improving the descriptive and predictive skill of climate models, e.g., the TOPEX/Poseidon altimeter and Jason-1 (sea level); infrared and microwave channels (sea surface temperature), the NASA Quick Scatterometer (QuikSCAT; ocean surface vector winds); the Gravity Recovery and Climate Experiment (GRACE; spatial mass changes), Aquarius (salinity), passive radiometers, such as Special Sensor Microwave Imager (SSM/I) and Advanced Microwave Scanning Radiometer (AMSR; sea ice), the Ice, Cloud, and land Elevation Satellite laser altimeter (ICESat; ice sheet topography and sea ice freeboard), and the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC; precipitable water vapor), in addition to measurements of total solar irradiance, stratospheric aerosols, and land-cover and land-use change.