Accuracy of integral migration transformation in dependence on space-time sampling

The Surface Water and Ocean Topography (SWOT) satellite mission, expected to launch in 2022, will enable near global river discharge estimation from surface water extents and elevations. However, SWOT’s orbit specifications provide non-uniform space–time sampling. Previous studies have demonstrated that SWOT’s unique spatiotemporal sampling has a minimal impact on derived discharge frequency distributions, baseflow magnitudes, and annual discharge characteristics. In this study, we aim to extend the analysis of SWOT’s added value in the context of hydrologic model calibration. We calibrate a hydrologic model using previously derived synthetic SWOT discharges across 39 gauges in the Ohio River Basin. Three discharge timeseries are used for calibration: daily observations, SWOT temporally sampled, and SWOT temporally sampled including estimated uncertainty. Using 10,000 model iterations to explore predefined parameter ranges, each discharge timeseries results in similar optimal model parameters. We find that the annual mean and peak flow values at each gauge location from the optimal parameter sets derived from each discharge timeseries differ by less than 10% percent on average. Our findings suggest that hydrologic models calibrated using discharges derived from SWOT’s non-uniform space–time sampling are likely to achieve results similar to those based on calibrating with in situ daily observations.

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The 25-Day-Period Large-Scale Oscillations in the Argentine Basin Revisited

Journal of Physical Oceanography ◽

10.1175/jpo2766.1 ◽

2005 ◽

Vol 35 (8) ◽

pp. 1473-1479 ◽

Cited By ~ 11

Author(s):

Chang-Kou Tai ◽

Lee-Lueng Fu

Keyword(s):

Simulation Study ◽

Large Scale ◽

Space Time ◽

Sea Surface ◽

Time Sampling ◽

Numerical Studies ◽

In Situ Observations ◽

Ocean Topography ◽

Argentine Basin

Abstract From sea surface height measurements made by the Ocean Topography Experiment (TOPEX)/Poseidon satellite, Fu et al. found and described large-scale oscillations at the period of 25 days in the Argentine Basin of the South Atlantic Ocean. These oscillations were previously hinted at by in situ observations. Only the extensive space–time sampling capability of TOPEX/Poseidon, however, was able to give a complete description of the phenomenon as a counterclockwise-rotating dipole centered at 45°S, 317°E over the Zapiola Rise. Fu et al. also undertook theoretical and numerical studies to suggest that the phenomenon is a resonantly excited barotropic normal mode of the locally closed f/H contour. In a simulation study, however, they also found that the space–time smoothing scheme employed would probably lower the amplitude of the estimated phenomenon by 30%–40%. By reprocessing the data using a different method and showing the amplitude to be almost 2 times as large, in this note it is confirmed that this is indeed the case. The original 5-yr study has also been extended to nearly 10 yr, demonstrating that the same phenomenon has persisted for almost 10 yr.

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Space-Time Sampling for Network Observability

IFAC-PapersOnLine ◽

10.1016/j.ifacol.2018.12.070 ◽

2018 ◽

Vol 51 (23) ◽

pp. 408-413

Author(s):

Hossein K. Mousavi ◽

Qiyu Sun ◽

Nader Motee

Keyword(s):

Space Time ◽

Time Sampling

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