Swot Mission Performance and Error Budget

Peral, Eva; Esteban-Fernández, Daniel

doi:10.1109/igarss.2018.8517385

Cited by 32 publications

(30 citation statements)

References 1 publication

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“…The SWOT correlated errors, to a large part specific to the satellite and instrument design (Peral and Esteban-Fernandez 2018), are particularly challenging for the mapping of altimetry because they can present significant amplitudes but cannot be easily filtered out using conventional filters. Hopefully, these strong spatially correlated errors are expected to have a much lower signature on j than on SSH (Gómez-Navarro et al 2018).…”

Section: Observational Scenariosmentioning

confidence: 99%

Mapping Altimetry in the Forthcoming SWOT Era by Back-and-Forth Nudging a One-Layer Quasigeostrophic Model

Guillou

Metref

Ubelmann

et al. 2021

Journal of Atmospheric and Oceanic Technology

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During the past 25 years, altimetric observations of the ocean surface from space have been mapped to provide two dimensional sea surface height (SSH) fields which are crucial for scientific research and operational applications. The SSH fields can be reconstructed from conventional altimetric data using temporal and spatial interpolation. For instance, the standardDUACS products are created with an optimal interpolation method which is effective for both low temporal and low spatial resolution. However, the upcoming next-generation SWOT mission will provide very high spatial resolution but with low temporal resolution.The present paper makes the case that this temporal-spatial discrepancy induces the need for new advanced mapping techniques involving information on the ocean dynamics. An algorithm is introduced, dubbed the BFN-QG, that uses a simple data assimilation method, the back-and-forth nudging, to interpolate altimetric data while respecting quasigeostrophic dynamics. The BFN-QG is tested in an observing system simulation experiments and compared to the DUACS products. The experiments consider as reference the high-resolution numerical model simulation NATL60 from which are produced realistic data: four conventional altimetric nadirs and SWOT data. In a combined nadirs and SWOT scenario, the BFN-QG substantially improves the mapping by reducing the root-mean-square errors and increasing the spectral effective resolution by 40km. Also, the BFN-QG method can be adapted to combine large-scale corrections from nadirs data and small-scale corrections from SWOT data so as to reduce the impact of SWOT correlated noises and still provide accurate SSH maps.

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Section: Observational Scenariosmentioning

confidence: 99%

Mapping Altimetry in the Forthcoming SWOT Era by Back-and-Forth Nudging a One-Layer Quasigeostrophic Model

Guillou

Metref

Ubelmann

et al. 2021

Journal of Atmospheric and Oceanic Technology

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“…As described in the document of SWOT error budget (Peral and Esteban-Fernandez, 2018), there are various error sources, including systematic error, random noise, and media error. The details can be found at "https://swot.jpl.nasa.gov/resources/ documents/".…”

Section: "Guanlan" Observation Simulationmentioning

confidence: 99%

“…Taking "Guanlan" mission as an example (Chen et al, 2019), the effective swath in the cross-track direction is between 15 km to 100 km. Based on the HEBR and HEBL calculation model in (Peral and Esteban-Fernandez, 2018), 0.1 mm baseline length error would bring about 8.4 cm range error on the outer edges of the swath. Generally, a roll error of only 1/3,600 deg (1arcsec) will result in a height error of 48 cm on the outer edge position of 100 km.…”

Section: Introductionmentioning

confidence: 99%

Overlapping-calibration of wide-swath altimeter baseline errors using two satellites formation flying design

Wang

Gao

et al. 2022

Front. Mar. Sci.

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The sea surface height (SSH) measured by future wide-swath altimetry satellites contains observation error due to baseline measurement, which is called SSH_Error_Baseline. It is a huge challenge for satellite engineering to maintain such high accuracies of the baseline roll and length in orbit to ensure that the SSH_Error_Baseline can be maintained below 1 cm. Therefore, how to effectively reduce the SSH_Error_Baseline is extremely important. In order to solve the existing problem, an innovative overlapping-calibration method is proposed based on two-satellite formation flight design with overlapping swath. In this study, the differences of SSH data observed by these two satellites in the overlapping area is so small that it can be ignored, and the SSH_Error_Baseline dominates the difference. Then, the baseline parameters of the two satellites can be well estimated by adopting an optimal inverse method. A total of 9 groups of observing system simulation experiments (OSSEs) have been carried out, and they respectively indicate different pessimistic theoretical scenarios of baseline measurement systems. According to the results, this design can effectively reduce the SSH_Error_Baseline in most scenarios. Regarding the advantage of this method, it can be applied to all along-track observation data without requiring the application of additional auxiliary data (i.e. model data, SSH derived from nadir altimetry). Therefore, when two wide-swath altimetry satellites are simultaneously designed, the formation flight scheme proposed in this paper is recommended, especially when the measurements of the baseline cannot meet the expected accuracies.

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“…This unprecedented set of measurements would allow characterization of ocean mesoscale and sub-mesoscale dynamic processes [9][10][11] that are crucial to understanding and quantifying the exchange of energy between ocean layers and their impact on local and global carbon and energy budgets as well as nutrient transport [12,13]. The primary instrument on board the SWOT observatory enabling this unique set of measurements is KaRIn [14,15], a Ka-band (35 GHz) near-nadir radar interferometer capable of measuring sea-surface height with centimetric accuracy at kilometer scale resolutions [16], complemented with a nadir altimeter [17], GPS and DORIS [18] receivers and a three-frequency radiometer [19].…”

Section: Introductionmentioning

confidence: 99%

Analytical Models for Multipath and Switch Leakage for the SWOT Interferometer

Ahmed

Esteban-Fernández

Hensley

2022

Sensors

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The Ka-Band Radar Interferometer (KaRIn) instrument on the Surface Water and Ocean Topography (SWOT) mission is a single-pass synthetic aperture radar (SAR) interferometer tasked with, among others, measuring ocean topography to within a few centimeters over kilometer scale resolutions. A SAR interferometer relies on very precise phase difference measurements between two spatially distant antennas to estimate topography. Multipath phase caused by unintended scattering off the spacecraft structure is a known error source for radar interferometers and takes up a significant portion of the KaRIn error budget. This paper outlines some analytical multipath models that were used for instrument design, performance analysis and mitigation of the multipath signal.

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Swot Mission Performance and Error Budget

Cited by 32 publications

References 1 publication

Mapping Altimetry in the Forthcoming SWOT Era by Back-and-Forth Nudging a One-Layer Quasigeostrophic Model

Mapping Altimetry in the Forthcoming SWOT Era by Back-and-Forth Nudging a One-Layer Quasigeostrophic Model

Overlapping-calibration of wide-swath altimeter baseline errors using two satellites formation flying design

Analytical Models for Multipath and Switch Leakage for the SWOT Interferometer

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