Chapter 9
Determining Ocean Circulation and Sea Level
from Satellite Altimetry: Progress
and Challenges
Lee-Lueng Fu
9.1 Introduction
The idea of flying a radar altimeter in space to measure the height of sea surface
for a variety of geophysical studies was quickly developed after the first launch of
artificial satellite. Seasat, launched in 1978, carried the first radar altimeter with a
precision capable of revealing the variability of ocean currents. After the premature
demise of the mission after only 3 months’ data collection, the oceanographic community realized the potential of satellite altimetry for making global observation
of the ocean. The military community also realized the utility of the measurement
for naval operations and hence launched Geosat in 1985. The instrument itself was
a copy of Seasat, but without the correction for the effects of tropospheric water
vapor due to the lack of an onboard radiometer. The oceanographic community was
more ambitious in developing a mission specifically designed for studying the ocean
circulation and its variability, leading to the Franco-American collaboration in the
TOPEX/Poseidon Mission (T/P), launched in 1992.
While T/P was in development, the data from Geosat, although not as accurate
as oceanographers had desired, provided nonetheless the first multi-year altimetry
data for the study of ocean dynamics as well as a test bed for processing altimetry data. As part of the payload of the European Remote Sensing satellite (ERS-1),
a radar altimeter similar to Seasat was launched by the European Space Agency
(ESA) in 1991. The launch of T/P then started an era in which at least two satellite altimeters were flying simultaneously. The era has continued as of the writing
of the article today. Results from these missions cover a wide range of earth sciences: oceanography, geophysics, geodesy, and hydrology. Fu and Cazenave (2001)
provided a comprehensive review. There has been tremendous progress made since
that review. The scope of this paper, however, is focused on recent progress in the
study of ocean circulation and sea level change, including some recap of earlier
results to provide a historic perspective. At the end, the limitation of the present
approach and the challenges for future development are addressed.
L.-L. Fu (B)
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099, USA
e-mail: lee-lueng.fu@jpl.nasa.gov
147
V. Barale et al. (eds.), Oceanography from Space,
DOI 10.1007/978-90-481-8681-5_9, C
Springer Science+Business Media B.V. 2010
Determining Ocean Circulation and Sea Level
from Satellite Altimetry: Progress
and Challenges
Lee-Lueng Fu
9.1 Introduction
The idea of flying a radar altimeter in space to measure the height of sea surface
for a variety of geophysical studies was quickly developed after the first launch of
artificial satellite. Seasat, launched in 1978, carried the first radar altimeter with a
precision capable of revealing the variability of ocean currents. After the premature
demise of the mission after only 3 months’ data collection, the oceanographic community realized the potential of satellite altimetry for making global observation
of the ocean. The military community also realized the utility of the measurement
for naval operations and hence launched Geosat in 1985. The instrument itself was
a copy of Seasat, but without the correction for the effects of tropospheric water
vapor due to the lack of an onboard radiometer. The oceanographic community was
more ambitious in developing a mission specifically designed for studying the ocean
circulation and its variability, leading to the Franco-American collaboration in the
TOPEX/Poseidon Mission (T/P), launched in 1992.
While T/P was in development, the data from Geosat, although not as accurate
as oceanographers had desired, provided nonetheless the first multi-year altimetry
data for the study of ocean dynamics as well as a test bed for processing altimetry data. As part of the payload of the European Remote Sensing satellite (ERS-1),
a radar altimeter similar to Seasat was launched by the European Space Agency
(ESA) in 1991. The launch of T/P then started an era in which at least two satellite altimeters were flying simultaneously. The era has continued as of the writing
of the article today. Results from these missions cover a wide range of earth sciences: oceanography, geophysics, geodesy, and hydrology. Fu and Cazenave (2001)
provided a comprehensive review. There has been tremendous progress made since
that review. The scope of this paper, however, is focused on recent progress in the
study of ocean circulation and sea level change, including some recap of earlier
results to provide a historic perspective. At the end, the limitation of the present
approach and the challenges for future development are addressed.
L.-L. Fu (B)
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099, USA
e-mail: lee-lueng.fu@jpl.nasa.gov
147
V. Barale et al. (eds.), Oceanography from Space,
DOI 10.1007/978-90-481-8681-5_9, C
Springer Science+Business Media B.V. 2010