Polar orbiting satellites

Jason-1 is a joint french/american follow-on to the successful TOPEX/Poseidon mission. It provides precise sea surface height measurements (within 2 cm accuracy) in order to support operational oceanography at modelling and forecasting ocean circulation, currents, water temperature,... and to monitor sea level change at climatological scale. Sea surface height, wave height or wind speed can be measured by the onboard radar altimeter, complemented by additional instruments for improved atmospheric and orbit correction.

QuikSCAT (Quik SCATterometer) is a satellite launched by the NASA the 19th of June 1999. The onboard SeaWinds instrument is a rotating scatterometer designed for the measurement of the surface wind speed and direction over the ocean. Thanks to its higher resolution and its wider sample pattern, value-added products with higher time and space resolution, compared to ERS, can be generated. These data are used daily in weather forecasting models and have many application in ocean research.

The ERS Program (European Remote Sensing satellite system) of the European Space Agency is one of the most essential part of an important european earth observation program concerning : meteorology, climatology, oceanography, land resource management...ERS-1 was the first of two twin earth observing satellites launched by ESA respectively in July 1991 and April 1995. It included, in addition to other instruments, several sensors relevant for oceanography such as the RA radar altimeter (measurement of the sea surface topography, the wave height,...), the AMI-Wind scatterometer (measurement of the surface wind speed and direction over the ocean), the SAR (measurement of wave spectra) and the MW micro-wave sounder (brightness temperature, atmospheric vapour content,...). The ERS-1 mission ended on 10th March 2000 (its sensors had been on stand-by since 1995). Nevertheless, thanks to the length of the ERS mission (more than 15 years), an impressive continuous and homogeneous series of sea surface parameters could be collected all along the mission.

The Japanese satellite ADEOS-1 (Advanced Earth Observing Satellite) was launched in August 2006. Its main relevant onboard sensor for oceanography is NSCAT, a double-swath scatterometer (measurement of the surface wind speed and direction over the ocean), built by NASA. Compared to the ERS scatterometer, this sensor provides more measurements, in another frequency band (Ku). Unfortunately, due to a failure in its solar array, ADEOS was lost on June 30th 1997.

The ERS Program (European Remote Sensing satellite system) of the European Space Agency is one of the most essential part of an important european earth observation program concerning : meteorology, climatology, oceanography, land resource management...ERS-2 is the second of two twin earth observing satellites launched by ESA respectively in July 1991 and April 1995. It included, in addition to other instruments, several sensors relevant for oceanography such as the RA radar altimeter (measurement of the sea surface topography, the wave height,...), the AMI-Wind scatterometer (measurement of the surface wind speed and direction over the ocean), the SAR (measurement of wave spectra) and the MW micro-wave sounder (brightness temperature, atmospheric vapour content,...). Despite a reduced coverage since the failure of an onboard recorder in 2001, and an initially expected lifetime of three years, it is still operational, providing (together with ERS-1) an impressive 15-years continuous and homogeneous series of sea surface parameters could be collected all along the mission.

Envisat, a follow-on to ERS series, is the largest Earth Observation spacecraft ever built. Onboard instruments relevant for oceanography include an Advanced Synthetic Aperture Radar (ASAR) providing measurement of sea surface (wind, wave spectra, roughness), a imaging spectrometer (MERIS) prodviding ocean color data and an Advanced Along Track Scanning Radiometer (AATSR) providing measurement of sea surface temperature (complementing the ATSR onboard ERS-1 and ERS-2).

DMSP (Defense Meteorological Satellites Program) is a series of environmental and weather satellites operated by US Air Force, whose first element was launched in June 2007. Onboard instruments relevant for oceanography include the SSM/I microwave imager, a passive sensor measuring brightness temperature over the sea surface which can be used to determine sea ice concentration or surface wind speeds.

The Meteorological Operational satellite programme (MetOp) is a new series of three weather satellites that has been jointly established by ESA and the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT). The first satellite of this serie, METOP-A, includes several sensors of interest for oceanography such as an AVHRR for sea surface temperature and the ASCAT scatterometer for the retrieval of ocean surface wind vectors and the observation of sea-ice.

AQUA is a US polar orbiting satellite for earth observation, focusing espcially on the water cycle. It embed six sensors, two of them of major interest for the oceanographic community :the Advanced Microwave Scanning Radiometer (AMSR-E), a microwave radiometer with the unique ability to provide sea surface temperature data through cloud coverage (if no rain contamination), and the Moderate-Resolution Imaging Spectroradiometer (MODIS) which provides high resolution sea surface temperature and ocean color observations.

TRMM is a US/Japanese earth obervation satellite, focusing mainly on the observation and measurement of tropical and subtropical rainfalls. It embeds several instruments, including the TRMM Microwave Imager (TMI) that is especially useful for oceanography thanks to its ability to provided an estimation of sea surface temperature including over cloudy areas (like AQUA AMSR-E).