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Full-Text Articles in Engineering
Toward Realistic Nonstationarity Of Semidiurnal Baroclinic Tides In A Hydrodynamicmodel, Arin D. Nelson, Brian K. Arbic, Edward Zaron, Anna Savage, James G. Richman, Maarten C. Buijsman, Jay F. Shriver
Toward Realistic Nonstationarity Of Semidiurnal Baroclinic Tides In A Hydrodynamicmodel, Arin D. Nelson, Brian K. Arbic, Edward Zaron, Anna Savage, James G. Richman, Maarten C. Buijsman, Jay F. Shriver
Civil and Environmental Engineering Faculty Publications and Presentations
Semidiurnal baroclinic tide sea surface height (SSH) variance and semidiurnal nonstationary variance fraction (SNVF) are compared between a hydrodynamic model and altimetry for the low- to middle-latitude global ocean. Tidal frequencies are aliased by ∼10-day altimeter sampling, which makes it impossible to unambiguously identify nonstationary tidal signals from the observations. In order to better understand altimeter sampling artifacts, the model was analyzed using its native hourly outputs and by subsampling it in the same manner as altimeters. Different estimates of the semidiurnal nonstationary and total SSH variance are obtained with the model depending on whether they are identified in the …
Surface Kinetic Energy Distributions In The Global Oceans From A High-Resolution Numerical Model And Surface Drifter Observations, Xiaolong Yu, Aurelien Ponte, Shane Elipot, Dimitris Menemenlis, Edward Zaron, Ryan Abernathey
Surface Kinetic Energy Distributions In The Global Oceans From A High-Resolution Numerical Model And Surface Drifter Observations, Xiaolong Yu, Aurelien Ponte, Shane Elipot, Dimitris Menemenlis, Edward Zaron, Ryan Abernathey
Civil and Environmental Engineering Faculty Publications and Presentations
The surface kinetic energy of a 1/48◦ global ocean simulation and its distribution as a function of frequency and location are compared with the one estimated from 15,329 globally distributed surface drifter observations at hourly resolution. These distributions follow similar patterns with a dominant low-frequency component and well-defined tidal and near-inertial peaks globally. Quantitative differences are identified with deficits of low-frequency energy near the equator (factor 2) and at near-inertial frequencies (factor 3) and an excess of energy at semidiurnal frequencies (factor 4) for the model. Owing to its hourly resolution and its near-global spatial coverage, the array of surface …
Ocean And Ice Shelf Tides From Cryosat-2 Altimetry, Edward Zaron
Ocean And Ice Shelf Tides From Cryosat-2 Altimetry, Edward Zaron
Civil and Environmental Engineering Faculty Publications and Presentations
A new empirical model of ocean tides has been developed for the Weddell Sea, south of 668S, between 908W and 08, using six years of radar altimeter data from the CryoSat-2 satellite mission. Because of its long groundtrack repeat period (368 days) and its diverse measurement modes, low-rate mode (LRM) over the ocean and synthetic aperture radar interferometric mode (SARin) over ice surfaces and parts of the ocean, the CryoSat2 data pose a number of challenges for tidal analysis. The space and time sampling properties of the exact repeat, near-repeat, and crossover ground tracks have been analyzed to discover which …
Nonstationary Internal Tides Observed Using Dual-Satellite Altimetry, Edward D. Zaron
Nonstationary Internal Tides Observed Using Dual-Satellite Altimetry, Edward D. Zaron
Civil and Environmental Engineering Faculty Publications and Presentations
Dual-satellite crossover data from the Jason-2 and Cryosat-2 altimeter missions are used in a novel approach to quantify stationary and nonstationary tides from time-lagged mean square sea surface height (SSH) differences, computed for lags from 1 to 1440 h (60 days). The approach is made feasible by removing independent estimates of the stationary tide and mesoscale SSH variance, which greatly reduces the sampling error of the SSH statistics. For the semidiurnal tidal band, the stationary tidal variance is approximately 0.73 cm(2), and the nonstationary variance is about 0.33 cm(2), or 30% of the total. The temporal correlation of the nonstationary …
An Analysis Of Secular Change In Tides At Open-Ocean Sites In The Pacific, Edward D. Zaron, David A. Jay
An Analysis Of Secular Change In Tides At Open-Ocean Sites In The Pacific, Edward D. Zaron, David A. Jay
Civil and Environmental Engineering Faculty Publications and Presentations
Hourly sea level is examined at 25 open-ocean stations in the Pacific Ocean with records longer than 30 yr. A search for trends finds that the amplitude of the dominant semidiurnal tide M2 is increasing at 12 of the 13 sites where a statistically significant trend can be identified. It is also found that nontidal variance in the neighborhood of M2 is decreasing at all 12 of the sites where a significant increase in M2 tide is occurring. The trend in amplitude of the dominant diurnal tide K1 is significant at six stations, and it is …
Regional Models Of Internal Tides, Glenn S. Carter, Oliver B. Fringer, Edward D. Zaron
Regional Models Of Internal Tides, Glenn S. Carter, Oliver B. Fringer, Edward D. Zaron
Civil and Environmental Engineering Faculty Publications and Presentations
Internal tides are ubiquitous in the ocean, and they play an important role in a range of ocean processes, for example, particle dispersal, acoustics, and vertical buoyancy flux. The wavelength of internal tides can be as much as 250 km in the open ocean, but as the generation of these tides depends on the angle between the depth-averaged current and the topography, there can be considerable local spatial variability. This range of scales makes it difficult to develop a comprehensive understanding of the processes involved from observations alone. Regional numerical modeling provides a way to study the generation and early …
Non-Stationary Internal Tides Observed With Satellite Altimetry, Richard D. Ray, Edward D. Zaron
Non-Stationary Internal Tides Observed With Satellite Altimetry, Richard D. Ray, Edward D. Zaron
Civil and Environmental Engineering Faculty Publications and Presentations
Temporal variability of the internal tide is inferred from a 17-year combined record of Topex/Poseidon and Jason satellite altimeters. A global sampling of along-track sea-surface height wavenumber spectra finds that non-stationary variance is generally 25% or less of the average variance at wavenumbers characteristic of mode-1 tidal internal waves. With some exceptions the non-stationary variance does not exceed 0.25 cm2. The mode-2 signal, where detectable, contains a larger fraction of non-stationary variance, typically 50% or more. Temporal subsetting of the data reveals interannual variability barely significant compared with tidal estimation error from 3-year records. Comparison of summer vs. winter conditions …