Impact of Errors in Environmental Correction on Gravity Field Recovery Using Interferometric Radar Altimeter Observations

Wan, Xiaoqiao; Wang, Fei; Guo, Hengyang; Liu, Bo

doi:10.3390/rs14246299

Cited by 4 publications

(3 citation statements)

References 26 publications

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“…The error sources of InIRA in SSH measurement mainly include ionosphere/troposphere delay errors, sea-state bias (SSB), geophysical errors, interferometric phase error, baseline error and system error [34,[50][51][52][53]. The error sources of InIRA are quite different from those of CA although they have some common error sources, e.g., ionosphere/troposphere delay errors, geophysical errors and SSB.…”

Section: Correction Of Errorsmentioning

confidence: 99%

Preliminary Results of Marine Gravity Recovery by Tiangong-2 Interferometric Imaging Radar Altimeter

Sun,

Zhang,

Dong

et al. 2023

Remote Sensing

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This paper presents for the first time the results of marine gravity recovery using the ocean observation data acquired by Tiangong-2 interferometric imaging radar altimeter (TG2 InIRA) which demonstrate not only the balanced accuracies of the north and east components of deflection of the vertical (DOV) as envisaged, but also the improved spatial resolutions of DOV compared with that by conventional altimeters (CAs). Moreover, much higher measurement efficiency owing to the wide-swath capability and the great potential in accuracy improvement of marine gravity field are also demonstrated. TG2 InIRA adopts the interferometry with short baseline and takes small incidence angles, by which wide-swath sea surface height (SSH) can be measured with high accuracy. Gravity recovery experiments in the Western Pacific area are conducted to demonstrate the performance, advantages and capability of TG2 InIRA. SSH data processing algorithms and DOV calculation have been designed by taking the wide-swath feature into account, based on which, the gravity anomalies are then calculated using the inverse Vening Meinesz formula. The derived gravity anomalies are compared with both the published gravity models and the shipborne gravity measurements. The results show that the accuracy of TG2 InIRA is equivalent to, or even a little better than, that of CAs. The fused gravity result using equal TG2 InIRA data and CAs data performs better than those using TG2 InIRA data alone or CAs data alone. Due to the signal bandwidth of TG2 InIRA is only 40 MHz which is much smaller than that of CAs, much higher accuracy can be hopefully achieved for future missions if larger signal bandwidth is used.

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Section: Correction Of Errorsmentioning

confidence: 99%

Preliminary Results of Marine Gravity Recovery by Tiangong-2 Interferometric Imaging Radar Altimeter

Sun,

Zhang,

Dong

et al. 2023

Remote Sensing

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“…Tian [6] and Jin et al [4] have analyzed the instrumental errors of interferometric radar altimeters and their impact on DOV. Wan et al [7] investigated the influence of environmental errors on the recovery of DOV and gravity anomalies (GA) based on wide-swath observations. Yu et al [8] simulated observations of SWOT and recovered the GA using the Inverse Vening-Meinesz formula (IVM) and the Inverse Stokes Integral Method (ISM).…”

Section: Introductionmentioning

confidence: 99%

Validation of Just-Released SWOT L2 KaRIn Beta Prevalidated Data Based on Restore the Marine Gravity Field and Its Application

Guo,

Wan,

Wang

2024

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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A part of the pre-processed Beta Ka-band Radar Interferometer (KaRIn) data (September 7 -November 21, 2023) for the Surface Water and Ocean Topography (SWOT) mission has been released. To validate the performance of SWOT L2 KaRIn Beta Pre-Validated data (Beta data), this study conducted various experiments, including inverting the ocean gravity field and seafloor topography from these data. Validating the accuracy of deflections of the vertical (DOV) by DOV products of Scripps Institution of Oceanography (SIO). The RMS of differences of north-south and east-west components is about 1.83 urad and 2.71 urad, respectively. The precision of gravity anomaly (SWOT_GA) is about 5.07 mGal compared with shipborne gravity. The results derived from 1-cycle data are comparable to those obtained from a substantial dataset accumulated by traditional nadir altimeters. The accuracy of seafloor topography inverted from SWOT_GA is about 68 m validated by shipborne depth, which is almost the same as the topography obtained from SIO_GA and SDUST2021GRA. The results of multiple experiments have demonstrated that Beta data can be used to compute high-precision ocean gravity fields and seafloor topography products. This proves the success of the first operational run of KaRIn and the capability of SWOT to support studies related to ocean science. The current evaluation results are based on Beta data. The Pre-Validated data will be more accurate after further calibration, which will lead to higher accuracy of the inverted gravitational field products in the future.

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“…The root mean square (RMS) compared to the VGG model provided by SIO is 7.69 E (1E = 1 × 10 −9 /s 2 ). Wan et al [28] investigated the impact of environment errors based on Tian's method [29] on the recovery of DOV and GA from wide-swath altimetry data.…”

Section: Introductionmentioning

confidence: 99%

Expected Precision of Gravity Gradient Recovered from Ka-Band Radar Interferometer Observations and Impact of Instrument Errors

Guo,

Wan,

Wang

et al. 2024

Remote Sensing

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Full tensor of gravity gradients contains extremely large amounts of information, which is one of the most important sources for research on recovery seafloor topography and underwater matching navigation. The calculation and accuracy of the full tensor of gravity gradients are worth studying. The Ka-band interferometric radar altimeter (KaRIn) of surface water and ocean topography (SWOT) mission enables high spatial resolution of sea surface height (SSH), which would be beneficial for the calculation of gravity gradients. However, there are no clear accuracy results for the gravity gradients (the gravity gradient tensor represents the second-order derivative of the gravity potential) recovered based on SWOT data. This study evaluated the possible precision of gravity gradients using the discretization method based on simulated SWOT wide-swath data and investigated the impact of instrument errors. The data are simulated based on the sea level anomaly data provided by the European Space Agency. The instrument errors are simulated based on the power spectrum data provided in the SWOT error budget document. Firstly, the full tensor of gravity gradients (SWOT_GGT) is calculated based on deflections of the vertical and gravity anomaly. The distinctions of instrument errors on the ascending and descending orbits are also taken into account in the calculation. The precision of the Tzz component is evaluated by the vertical gravity gradient model provided by the Scripps Institution of Oceanography. All components of SWOT_GGT are validated by the gravity gradients model, which is calculated by the open-source software GrafLab based on spherical harmonic. The Tzz component has the poorest precision among all the components. The reason for the worst accuracy of the Tzz component may be that it is derived by Txx and Tyy, Tzz would have a larger error than Txx and Tyy. The precision of all components is better than 6 E. Among the various errors, the effect of phase error and KaRIn error (random error caused by interferometric radar) on the results is greater than 2 E. The effect of the other four errors on the results is about 0.5 E. Utilizing multi-cycle data for the full tensor of gravity gradients recovery can suppress the effect of errors.

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Impact of Errors in Environmental Correction on Gravity Field Recovery Using Interferometric Radar Altimeter Observations

Cited by 4 publications

References 26 publications

Preliminary Results of Marine Gravity Recovery by Tiangong-2 Interferometric Imaging Radar Altimeter

Preliminary Results of Marine Gravity Recovery by Tiangong-2 Interferometric Imaging Radar Altimeter

Validation of Just-Released SWOT L2 KaRIn Beta Prevalidated Data Based on Restore the Marine Gravity Field and Its Application

Expected Precision of Gravity Gradient Recovered from Ka-Band Radar Interferometer Observations and Impact of Instrument Errors

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