3 SMOS and Aquarius/SAC-D Missions
55
<0.1 K be achieved with such large hardware dimensions? These are the types of
over-arching technical challenges for the future, for which SMOS and Aquarius
will provide vital technical data to consider the best options.
The other key consideration for future missions, of course, is data continuity.
Aquarius and SMOS will provide unprecedented benchmark measurements of an
essential climate variable at a time when the planet appears to be experiencing dramatic climate change. As we analyze the satellite SSS data in the next few years,
the scientific benefit and need to maintain a climate data record for decades to come
will become obvious.
Two opportunities for SSS measurement continuity beyond SMOS and
Aquarius/SAC-D are likely. ESA has begun considering possible improvements on
the basic MIRAS design to propose a series of operational satellites (SMOSops,
SMOS Operational System) that could follow SMOS with similar characteristics.
Options are also being studied to augment MIRAS to provide a simultaneous
roughness measurement. Several preparatory studies have been carried out in
2007–2008 to analyze some of these possible improvements, although no decision will be taken until an evaluation of the SMOS mission achievements can
be made.
In the United States, NASA is developing the Soil Moisture Mapping mission
(SMAP) for possible launch in 2015. This is a conically scanning system with a
large 6 m offset mesh antenna with a radiometer footprint size of ∼40 km. It offers
the only viable option in NASA for follow-on salinity measurements, although it
is primarily designed for soil moisture measurement. Like Aquarius, SMAP will
have an integrated L-band radiometer and radar sensor which will provide simultaneous brightness and roughness measurements over the ocean. The sample rate
will be much higher than for Aquarius, although the radiometric accuracy will
not be as good. A simulation study is planned for early 2010 to analyze how
well the SMAP design could perform to meet the Aquarius science measurement
requirements.
We believe that Oceans from Space 2010 is witness to the start of a new era
in ocean remote sensing; one that will include ocean salinity as a fully functional
component of the array of space borne ocean measurements. The next decade will
bring important new discoveries and oceanographic insights. What shall we wager
for Oceans from Space 2020 regarding ocean salinity? Will we have a decade of
satellite SSS data to analyze? Will ENSO forecast skill be measurably improved as a
result? Will the global marine freshwater balance be known to within a few percent?
Will upper ocean mixing process be much better understood as a result, and new
parameterizations be imbedded in our best ocean general circulation and climate
models? Will we have found some significant ocean features and phenomena that
we did not anticipate? All of these speculations are certainly worth about
1 / 2 pinch
of salt in a bottle of wine.
Acknowledgements This chapter is partly a contribution to the SMOS Barcelona Expert Centre
on Radiometric Calibration and Ocean Salinity (SMOS-BEC) funded through grant ESP200705667-C04 from the Spanish Ministry of Science and Innovation.
55
<0.1 K be achieved with such large hardware dimensions? These are the types of
over-arching technical challenges for the future, for which SMOS and Aquarius
will provide vital technical data to consider the best options.
The other key consideration for future missions, of course, is data continuity.
Aquarius and SMOS will provide unprecedented benchmark measurements of an
essential climate variable at a time when the planet appears to be experiencing dramatic climate change. As we analyze the satellite SSS data in the next few years,
the scientific benefit and need to maintain a climate data record for decades to come
will become obvious.
Two opportunities for SSS measurement continuity beyond SMOS and
Aquarius/SAC-D are likely. ESA has begun considering possible improvements on
the basic MIRAS design to propose a series of operational satellites (SMOSops,
SMOS Operational System) that could follow SMOS with similar characteristics.
Options are also being studied to augment MIRAS to provide a simultaneous
roughness measurement. Several preparatory studies have been carried out in
2007–2008 to analyze some of these possible improvements, although no decision will be taken until an evaluation of the SMOS mission achievements can
be made.
In the United States, NASA is developing the Soil Moisture Mapping mission
(SMAP) for possible launch in 2015. This is a conically scanning system with a
large 6 m offset mesh antenna with a radiometer footprint size of ∼40 km. It offers
the only viable option in NASA for follow-on salinity measurements, although it
is primarily designed for soil moisture measurement. Like Aquarius, SMAP will
have an integrated L-band radiometer and radar sensor which will provide simultaneous brightness and roughness measurements over the ocean. The sample rate
will be much higher than for Aquarius, although the radiometric accuracy will
not be as good. A simulation study is planned for early 2010 to analyze how
well the SMAP design could perform to meet the Aquarius science measurement
requirements.
We believe that Oceans from Space 2010 is witness to the start of a new era
in ocean remote sensing; one that will include ocean salinity as a fully functional
component of the array of space borne ocean measurements. The next decade will
bring important new discoveries and oceanographic insights. What shall we wager
for Oceans from Space 2020 regarding ocean salinity? Will we have a decade of
satellite SSS data to analyze? Will ENSO forecast skill be measurably improved as a
result? Will the global marine freshwater balance be known to within a few percent?
Will upper ocean mixing process be much better understood as a result, and new
parameterizations be imbedded in our best ocean general circulation and climate
models? Will we have found some significant ocean features and phenomena that
we did not anticipate? All of these speculations are certainly worth about
1 / 2 pinch
of salt in a bottle of wine.
Acknowledgements This chapter is partly a contribution to the SMOS Barcelona Expert Centre
on Radiometric Calibration and Ocean Salinity (SMOS-BEC) funded through grant ESP200705667-C04 from the Spanish Ministry of Science and Innovation.