Absolute Calibration of Jason-1 and Jason-2 Altimeters in Corsica during the Formation Flight Phase

Bonnefond, Pascal; Exertier, P.; Laurain, O.; Jan, Gwénaële

doi:10.1080/01490419.2010.487790

Cited by 63 publications

(24 citation statements)

References 8 publications

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“…In this framework, the use of ICESat and Cryosat-2 data was fundamental since they allow calculating relative biases between each of the missions. The calculated water level time series from each satellite are biased for two main reasons: First, there is an instrumental bias of each altimeter: This is well documented in the literature (Bonnefond et al 2010;Mertikas et al 2010). The second reason is that the geoid variations over a lake are not precisely known on a short wavelength of several kilometers, and as the tracks are not located exactly over the same region of a given lake, it adds a relative bias between each time series obtained from individual altimeter (Cretaux et al 2013a;Cheng et al 2010).…”

Section: Combination Of Multi-satellite Datamentioning

confidence: 76%

Lake Volume Monitoring from Space

Crétaux¹,

et al. 2016

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Lakes are integrators of environmental change occurring at both the regional and global scale. They present a wide range of behavior on a variety of timescales (cyclic and secular) depending on their morphology and climate conditions. Lakes play a crucial role in retaining and stocking water, and because of the significant global environmental changes occurring at several anthropocentric levels, the necessity to monitor all morphodynamic characteristics [e.g., water level, surface (water contour) and volume] has increased substantially. Satellite altimetry and imagery are now widely used together to calculate lake and reservoir water storage changes worldwide. However, strategies and algorithms to calculate these characteristics are not straightforward, and specific approaches need to be developed. We present a review of some of these methodologies by using lakes over the Tibetan Plateau to illustrate some critical aspects and issues (technical and scientific) linked to the observation of climate change impact on surface waters from remote sensing data. Many authors have measured water variation using the limited remote sensing measurements available over short time periods, even though the time series are probably too short to directly link these results with climate change. Indeed, there are many processes and factors, like the influence of lake morphology, that are beyond observation and are still uncertain. The time response for lakes to reach a new state of equilibrium is a key aspect that is often neglected in current literature. Observations over a long period of time, including maintaining a constellation of comprehensive and complementary satellite missions with service continuity over decades, are therefore necessary especially when the ground gauge network is too limited. In addition, the design of future satellite missions with new instrumental concepts (e.g., SAR, SARin, Ka band altimetry, Ka interferometry) will also be suitable for complete monitoring of continental waters.

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Section: Combination Of Multi-satellite Datamentioning

confidence: 76%

Lake Volume Monitoring from Space

Crétaux¹,

et al. 2016

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“…The main difference in the processing in this study, compared to previous studies [1][2][3]6], is the difference in the footprint area in over which the geoid height is interpolated. In the case of LRM (low resolution mode, e.g., Jason missions), the footprint is defined as a circle using the significant wave height to define the diameter [14], while in the case of SAR (synthetic aperture radar, e.g., Sentinel-3A) the footprint is defined as a rectangle with a width of 300 m along-track and a length across-track that is also a function of SWH with the same formula as LRM (see Figure 5 or Figure 8 for an illustration).…”

Section: Methodsmentioning

confidence: 78%

“…First, it shows that the SSH bias for SAR is very stable with a standard deviation of 24 mm. Concerning the PLRM, as expected due to data processing issues (reconstruction of pseudo LRM waveforms from original SAR measurements that make the PLRM measurements noisier than real LRM), the standard deviation of 42 mm is higher than the classical LRM missions (e.g., 38 and 37 mm for Jason-1 and Jason-2 respectively [2]). Second, the 13 mm difference in the SSH bias between SAR and PLRM comes mainly from the differences in the altimeter range.…”

Section: Radiometer-gpsmentioning

confidence: 97%

“…Since 1998, the successful calibration process used to calibrate many oceanographic satellite altimeter missions has been regularly updated, see details in [1][2][3]. General configuration of the Corsica calibration site with all of the satellite altimeter missions ground tracks that have been monitored since 1998 (the black frame on the left bottom corresponds to the zoom on the right map).…”

Section: Introductionmentioning

confidence: 99%

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Calibrating the SAR SSH of Sentinel-3A and CryoSat-2 over the Corsica Facilities

et al. 2018

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Initially developed to monitor the performance of TOPEX/Poseidon and to follow the Jason legacy satellite altimeters at Senetosa Cape, Corsica, this calibration/validation site has been extended to include a new location at Ajaccio. This addition enables the site to monitor Envisat and ERS missions, CryoSat-2 and, more recently, the SARAL/AltiKa mission and Sentinel-3A satellites. Sentinel-3A and CryoSat-2 carry altimeters that use a synthetic aperture radar (SAR) mode that is different to the conventional pulse-bandwidth limited altimeters often termed "low resolution mode" (LRM). The aim of this study is to characterize the sea surface height (SSH) bias of the new SAR altimeter instruments and to demonstrate the improvement of data quality close to the coast. Moreover, some passes of Sentinel-3A and CryoSat-2 overfly both Senetosa and Ajaccio with only a few seconds time difference, allowing us to evaluate the reliability and homogeneity of both ground sites in term of geodetic datum. The Sentinel-3A and CryoSat-2 SSH biases for the SAR mode are respectively +22 ± 7 mm and −73 ± 5 mm (for CryoSat-2 baseline C products). The results show that the stability of the SAR SSH bias time series is better than standard LRM altimetry. Moreover, compared to standard LRM data, for which the measurements closer than~10 km from the coast were generally unusable, SAR mode altimeters provide measurements that are reliable at less than few hundred meters from the coast.

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“…When this empirical correction is applied to the J1 SSH measurements it effectively levels them to those from J2. Absolute calibrations show that the J2 SSH measurements are biased 84-88 mm higher than those from J1, due principally to systematic differences in the altimeter range measurements (e.g., Haines et al 2010;Bonnefond et al 2010). Meanwhile, global comparisons indicate a relative SSH bias of 75 mm (Willis 2009).…”

Section: Orbit Altitude Correction = A(t) + B(t)cos(ωt) + C(t)sin(ωt)mentioning

confidence: 97%

Precise Near-Real-Time Sea Surface Height Measurements from the Jason-1 and Jason-2/OSTM Missions

Desai¹,

Haines²

2010

Marine Geodesy

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Precise measurements of sea surface height from the Jason-1 and Jason-2/Ocean Surface Topography Mission satellite altimeter missions are being generated within seven and four hours, respectively, of real time by applying high accuracy orbit altitudes to their near-real-time altimetry products. The near-real-time orbit altitudes have respective accuracies of <2 and <1 cm (RMS), and the corresponding sea surface height measurements have accuracies of <4.0 and <3.5 cm, respectively. These near-real-time orbit solutions are computed using GPS-based precise orbit determination for Jason-2, and Jason-1/Jason-2 sea surface height crossover differences for Jason-1.

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Absolute Calibration of Jason-1 and Jason-2 Altimeters in Corsica during the Formation Flight Phase

Cited by 63 publications

References 8 publications

Lake Volume Monitoring from Space

Lake Volume Monitoring from Space

Calibrating the SAR SSH of Sentinel-3A and CryoSat-2 over the Corsica Facilities

Precise Near-Real-Time Sea Surface Height Measurements from the Jason-1 and Jason-2/OSTM Missions

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