Chapter 1 Satellite Altimetry

Chelton, Dudley B.; Ries, John; Haines, Bruce; Fu, Lee‐Lueng; Callahan, Philip S.

doi:10.1016/s0074-6142(01)80146-7

Cited by 348 publications

(245 citation statements)

References 294 publications

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“…The TOPEX, JASON1/JASON2/JASON3 missions all operate simultaneously at 13.575 GHz (Ku band) and 5.3 GHz (C band), flying at an identical orbit altitude (approximately 1336 km) with an inclination angle of 66 • and a period of 112 min [15,31,32]. By measuring the range on two different frequencies, the T/J altimeter can provide a direct vTEC VTEC T/J over the oceans (worst case of GNSS-derived vTEC) up to the T/J orbit altitude [17,22,33,34]. If Ku band ionospheric range correction is calculated as presented by Brunini et al [22], then the vTEC can be expressed as follows:…”

Section: Gnss-derived Vtec Data and Jason Vtec Datamentioning

confidence: 99%

“…Jee et al [15] compared GPS vTEC and T/J vTEC for 1998-2009, and reported a positive relative TEC difference (i.e., GPS vTEC > T/J vTEC) in the PEC contribution to the ionosphere, which was largest in the early morning sector (up to 100%). However, many studies have found that T/J vTEC has a positive systematic bias of 2-5 TECu above real ionospheric TEC values when compared to other independent sources (i.e., T/J vTEC > GPS vTEC) [17][18][19][20][21][22][23]. This is paradoxical because GPS satellite altitude (~20,000 km) is higher than that of T/J satellites (~1336 km); thus, GPS vTEC should be larger than T/J vTEC due to it including the plasmasphere contribution above the T/J satellite orbital altitude.…”

Section: Introductionmentioning

confidence: 95%

“…This is paradoxical because GPS satellite altitude (~20,000 km) is higher than that of T/J satellites (~1336 km); thus, GPS vTEC should be larger than T/J vTEC due to it including the plasmasphere contribution above the T/J satellite orbital altitude. Chelton et al [17] pointed out that the relative TEC bias indicates a systematic error in the T/J sea state bias (SSB) correction, which is an empirical model with limited accuracy, and SSB assembles corrections for the sum of the electromagnetic (EM) bias, skewness bias and tracker bias. Meza et al [20] performed a comparison of GPS-based la plata ionospheric model (LPIM) with T/J estimates during quiet geomagnetic days in 1997.…”

Section: Introductionmentioning

confidence: 99%

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Plasmaspheric Electron Content Inferred from Residuals between GNSS-Derived and TOPEX/JASON Vertical TEC Data

et al. 2018

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Abstract:The plasmasphere, which is located above the ionosphere, is a significant component of Earth's atmosphere, and the plasmasphere electron content (PEC) distribution is determined by different physical mechanisms to those of the ionosphere electron content (IEC). However, the observation for the PEC is very limited. In this study, we introduced a methodology (called zero assumption method, which is based on the assumption that PEC can reach zero) to extract the PEC over TOPEX/JASON (T/J) and global navigation satellite system (GNSS) overlapping areas. Results show that the daily systematic bias (T/J vertical TEC > GNSS-derived vertical TEC) for both low (2009) and high (2011) solar activity condition is consistent, and the systematic bias for JASON2 and JASON1 is different. We suggest that systematic biases predominantly arise from the sea state bias (SSB), especially the tracker bias. After removing the systematic bias, we extracted reliable PEC inferred from differences between GNSS-derived vertical TEC and T/J vertical TEC data. Finally, the characteristics of the plasmaspheric component distribution for different local times, latitudes, and seasons were investigated.

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Section: Gnss-derived Vtec Data and Jason Vtec Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

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Plasmaspheric Electron Content Inferred from Residuals between GNSS-Derived and TOPEX/JASON Vertical TEC Data

et al. 2018

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“…The Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) sensor on-board the Aqua spacecraft had an effective footprint of 56 km [Chelton and Wentz, 2005], a swath width of approximately 1450 km [Martin, 2004] and provided approximately 89% coverage of the globe each day and 98% coverage every 2 days [Chelton and Wentz, 2005]. In contrast, the repeat orbit of satellite altimeters occurs at most once every 10 days and distances between altimeter tracks can be large-e.g., greater than 300 km for TOPEX/Poseidon tracks [Chelton et al, 2001]. The merger and optimal interpolation of altimeter data overcomes this limitation to some degree by combining measurements from multiple spacecraft but assumes certain temporal and spatial decorrelation scales during interpolation [Ducet et al, 2000;Le Traon et al, 2003].…”

Section: Microwave Sstmentioning

confidence: 99%

Global observations of quasi‐zonal bands in microwave sea surface temperature

et al. 2014

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Global observations of quasi-zonal jet-like structures have recently been reported in estimates of upper ocean circulation. To date, these observations have come primarily from float-derived and altimeter-derived estimates of zonal velocity. Here, we explore the existence of similar structures in the ocean using satellite-derived estimates of sea surface temperature (SST) from the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E). Applying an ocean front detection algorithm globally to microwave measurements of SST, we find that repeated ocean fronts occur along quasizonal bands in a multiyear (2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011) average of detections. Such a pattern is also observed in SST gradient magnitude. Composite analyses of SST, sea surface height (SSH), and upper ocean temperatures from Argo profiling floats suggest repeated fronts in the subtropics occur as a result of neighboring anticyclonic and cyclonic eddies. Horizontal advection in the presence of a background temperature gradient likely plays a role as evidenced by the tilt of temperature anomalies with depth. High gradient events found within the bands are observed to propagate westward with speed comparable to mesoscale eddies and we estimate these events explain 20% of the observed variance in SST gradient magnitude (2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011). In a final analysis, we regress the decay of the bands with averaging period and observe mild-to-strong persistence throughout much of the World Ocean. These findings support the view that propagating eddies help give rise to the bands. Whether or not eddies follow preferred paths remain unanswered.

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“…This estimation comprises the geoid (an equipotential of the earth gravity field to which a motionless ocean would exactly conform) and the ocean dynamic topography. The geoid has variations of up to 100 m and the ocean dynamic topography (the parameter of interest here) has variations of up to 1 m. For a comprehensive description of altimeter measurement principles, the reader is referred to Chelton et al (2001).…”

Section: Principle Of Satellite Altimetrymentioning

confidence: 99%

From satellite altimetry to Argo and operational oceanography: three revolutions in oceanography

Traon

2013

Ocean Sci.

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Abstract. The launch of the French/US mission Topex/Poseidon (T/P) (CNES/NASA) in August 1992 was the start of a revolution in oceanography. For the first time, a very precise altimeter system optimized for largescale sea level and ocean circulation observations was flying. T/P alone could not observe the mesoscale circulation. In the 1990s, the ESA satellites ERS-1/2 were flying simultaneously with T/P. Together with my CLS colleagues, we demonstrated that we could use T/P as a reference mission for ERS-1/2 and bring the ERS-1/2 data to an accuracy level comparable to T/P. Near-real-time high-resolution global sea level anomaly maps were then derived. These maps have been operationally produced as part of the SSALTO/DUACS system for the last 15 yr. They are now widely used by the oceanographic community and have contributed to a much better understanding and recognition of the role and importance of mesoscale dynamics. Altimetry needs to be complemented with global in situ observations. At the end of the 90s, a major international initiative was launched to develop Argo, the global array of profiling floats. This has been an outstanding success. Argo floats now provide the most important in situ observations to monitor and understand the role of the ocean on the earth climate and for operational oceanography. This is a second revolution in oceanography. The unique capability of satellite altimetry to observe the global ocean in near-real-time at high resolution and the development of Argo were essential for the development of global operational oceanography, the third revolution in oceanography. The Global Ocean Data Assimilation Experiment (GODAE) was instrumental in the development of the required capabilities. This paper provides an historical perspective on the development of these three revolutions in oceanography which are very much interlinked. This is not an exhaustive review and I will mainly focus on the contributions we made together with many colleagues and friends.

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Chapter 1 Satellite Altimetry

Cited by 348 publications

References 294 publications

Plasmaspheric Electron Content Inferred from Residuals between GNSS-Derived and TOPEX/JASON Vertical TEC Data

Plasmaspheric Electron Content Inferred from Residuals between GNSS-Derived and TOPEX/JASON Vertical TEC Data

Global observations of quasi‐zonal bands in microwave sea surface temperature

From satellite altimetry to Argo and operational oceanography: three revolutions in oceanography

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