Research Satellite Missions

Abstract

Satellites view the surface of the world oceans in days to weeks, and can repeat such measurements for many years. Among the Essential Climate Variables (ECVs), those that can be measured from space are sea surface temperature, height, vector winds, colour, as well as sea state and sea ice. In addition, there are emerging ECVs: ocean mass and sea surface salinity. Our recommendations can be summarized as follows  Sea Surface Temperature. Continue the high resolution infrared record, and the all-weather microwave record. Research: obtain better blended products with improved, well characterized accuracy.  Sea Surface Height. Continue the climate record of the Jason-series, and the operational use of the high inclination altimeters. Make these sustained, systematic observations useful for both applications and research. Use CryoSat for improved resolution, and approve the Surface Water Ocean Topography (SWOT) mission for launch no later than 2016. Research: improve the accuracy for climate record.  Ocean Vector Winds. Continue the observations obtained by the European Space Agency's Advanced Scatterometer (ASCAT). Replace QuikSCAT as soon as possible. Develop sustained, systematic observations to follow on QuikSCAT. Research: a constellation, with improved spatial resolution and sensitivity, and creation of a true climate record from the set of diverse scatterometers..  Ocean Colour. Continue the data record, fly climatequality, well calibrated instruments. Research: improved analyses enabled by sensitive, wellcharacterized instruments. Derive new parameters, for example distinguish between plankton species, using existing and planned instruments with increased spectral band coverage, such the European Medium Resolution Imaging Spectrometer (MERIS) and the planned US Hyperspectral Infrared Imager (HyspIRI).  Sea State. Improve coverage. Derive new quantities. Continue the data record for both altimeter and SAR derived sea state quantities. Create a real climate record for wave products.  Sea Ice. Continue the climate record of sea ice coverage. Research: improved resolution. Add sea ice thickness and dynamics. For all of the above, the concept of constellations must be followed: voluntary coordination of the observing systems from different countries to improve accuracy, resolution and overall coverage for any one parameter. Inherent in this concept is the need to cross-calibrate the various observing systems and remove any systematic differences in order to yield true climate records.  Sea Surface Salinity. An emerging ECV. Research: use the Soil Moisture and Ocean Salinity (SMOS) mission, launched in November 2009, and the future Aquarius/SAC-D mission to begin a climate record.  Ocean Mass and Geoid. An emerging ECV. Continue to improve the accuracy of the first 7 years of this climate record of total ocean mass, and time changes of ocean bottom pressure from the Gravity Recovery and Climate Experiment (GRACE) mission. Ensure continuity of this new measurement. Improve the time-averaged geoid using GOCE, aided by GRACE, CHAMP, and historical laser-tracked geodetic satellites. The previous decade saw these ECVs be used primarily on their own. We fully expect interdisciplinary use of two or more ECVs to become the norm in the next decade.