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Background
Ph.D. Physical Oceanography, Oregon State University, 1995
B.S. Applied Mathematics, Harvey Mudd College, 1988
Dr. Zaron joins our Department in the summer 2006 as part of Dr. David Jay’s research team, and will work with Dr. Jay on research funded by the NSF, US Army Corps of Engineers and the Bonneville Power Administration. Dr. Zaron’s research has emphasized using inverse methods to validate numerical ocean models and improve their predictive capability. Applications have ranged from scales of tens of kilometers (tidal internal waves) to thousands of kilometers (basin scale general circulation). He is also interested in the dynamical links between small-scale mixing processes and the mesoscale ocean circulation.
Projects
Check out all of Dr. Zaron’s research endeavors on his personal faculty page here.
Publications
Devlin, A; Jay, D A; Talke, S A; Zaron, E D; Pan, J; Lin, H Coupling of sea level and tidal range changes, with implications for future water levels Journal Article In: Scientific Reports, 7 , 2017. @article{articleb, title = {Coupling of sea level and tidal range changes, with implications for future water levels}, author = {A. Devlin and D. A. Jay and S. A. Talke and E. D. Zaron and J. Pan and H. Lin}, url = {https://www.nature.com/articles/s41598-017-17056-z}, doi = {10.1038/s41598-017-17056-z}, year = {2017}, date = {2017-12-05}, booktitle = {Scientific Reports}, journal = {Scientific Reports}, volume = {7}, abstract = {Are perturbations to ocean tides correlated with changing sea-level and climate, and how will this affect high water levels? Here, we survey 152 tide gauges in the Pacific Ocean and South China Sea and statistically evaluate how the sum of the four largest tidal constituents, a proxy for the highest astronomical tide (HAT), changes over seasonal and interannual time scales. We find that the variability in HAT is significantly correlated with sea-level variability; approximately 35% of stations exhibit a greater than ±50 mm tidal change per meter sea-level fluctuation. Focusing on a subset of three stations with long records, probability density function (PDF) analyses of the 95% percentile exceedance of total sea level (TSL) show long-term changes of this high-water metric. At Hong Kong, the increase in tides significantly amplifies the risk caused by sea-level rise. Regions of tidal decrease and/or amplification highlight the non-linear response to sea-level variations, with the potential to amplify or mitigate against the increased flood risk caused by sea-level rise. Overall, our analysis suggests that in many regions, local flood level determinations should consider the joint effects of non-stationary tides and mean sea level (MSL) at multiple time scales.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Are perturbations to ocean tides correlated with changing sea-level and climate, and how will this affect high water levels? Here, we survey 152 tide gauges in the Pacific Ocean and South China Sea and statistically evaluate how the sum of the four largest tidal constituents, a proxy for the highest astronomical tide (HAT), changes over seasonal and interannual time scales. We find that the variability in HAT is significantly correlated with sea-level variability; approximately 35% of stations exhibit a greater than ±50 mm tidal change per meter sea-level fluctuation. Focusing on a subset of three stations with long records, probability density function (PDF) analyses of the 95% percentile exceedance of total sea level (TSL) show long-term changes of this high-water metric. At Hong Kong, the increase in tides significantly amplifies the risk caused by sea-level rise. Regions of tidal decrease and/or amplification highlight the non-linear response to sea-level variations, with the potential to amplify or mitigate against the increased flood risk caused by sea-level rise. Overall, our analysis suggests that in many regions, local flood level determinations should consider the joint effects of non-stationary tides and mean sea level (MSL) at multiple time scales. |
Devlin, A T; Jay, D A; Zaron, E D; Talke, S A; Pan, J; Lin, H Tidal Variability Related to Sea Level Variability in the Pacific Ocean Journal Article In: Journal of Geophysical Research: Oceans, pp. n/a–n/a, 2017, ISSN: 2169-9291. @article{JGRC:JGRC22519, title = {Tidal Variability Related to Sea Level Variability in the Pacific Ocean}, author = {A. T. Devlin and D. A. Jay and E. D. Zaron and S. A. Talke and J. Pan and H. Lin}, url = {http://dx.doi.org/10.1002/2017JC013165}, doi = {10.1002/2017JC013165}, issn = {2169-9291}, year = {2017}, date = {2017-09-30}, journal = {Journal of Geophysical Research: Oceans}, pages = {n/a--n/a}, abstract = {Ocean tides are changing worldwide for reasons unrelated to astronomical forcing. Changes in tidal properties coupled with altered mean sea level (MSL) may yield higher peak water levels and increased occurrence of short-term exceedance events such as storm surge and nuisance flooding. Here we investigate the hypothesis that changes in relative sea-level are correlated with alterations in tidal amplitudes. Our approach focuses on the correlation between short-term (monthly to interannual) fluctuations in sea-level with changes in tidal properties of major ocean tides (M2, and K1; S2 and O1) at 152 gauges. Results suggest that sea-level variability is correlated to inter-annual tidal variability at most (92%) of tide gauges in the Pacific, with statistically significant rates between ±10 and ±500 mm per meter sea-level rise observed. These tidal anomalies, while influenced by basin-scale climate processes and sea-level changes, appear to be locally forced (in part) and not coherent over amphidromic or basin-wide scales. Overall, the Western Pacific shows a greater concentration of tide/sea level correlations at interannual time scales than the Eastern Pacific; 44% and 46% of gauges are significant in K1 and O1 in the west compared to 29% and 30% in the east, and 63% and 53% of gauges in the west are significant in M2 and S2 versus 47% and 32% in the east. Seasonal variation in tidal properties is less apparent in the empirical record, with statistically significant seasonal variations observed at only 35% of all gauges, with the largest concentrations in Southeast Asia.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Ocean tides are changing worldwide for reasons unrelated to astronomical forcing. Changes in tidal properties coupled with altered mean sea level (MSL) may yield higher peak water levels and increased occurrence of short-term exceedance events such as storm surge and nuisance flooding. Here we investigate the hypothesis that changes in relative sea-level are correlated with alterations in tidal amplitudes. Our approach focuses on the correlation between short-term (monthly to interannual) fluctuations in sea-level with changes in tidal properties of major ocean tides (M2, and K1; S2 and O1) at 152 gauges. Results suggest that sea-level variability is correlated to inter-annual tidal variability at most (92%) of tide gauges in the Pacific, with statistically significant rates between ±10 and ±500 mm per meter sea-level rise observed. These tidal anomalies, while influenced by basin-scale climate processes and sea-level changes, appear to be locally forced (in part) and not coherent over amphidromic or basin-wide scales. Overall, the Western Pacific shows a greater concentration of tide/sea level correlations at interannual time scales than the Eastern Pacific; 44% and 46% of gauges are significant in K1 and O1 in the west compared to 29% and 30% in the east, and 63% and 53% of gauges in the west are significant in M2 and S2 versus 47% and 32% in the east. Seasonal variation in tidal properties is less apparent in the empirical record, with statistically significant seasonal variations observed at only 35% of all gauges, with the largest concentrations in Southeast Asia. |
Zaron, E D; Ray, R D Using an altimeter-derived internal tide model to remove tides from in situ data Journal Article In: Geophysical Research Letters, 44 (9), pp. 4241–4245, 2017, ISSN: 1944-8007, (2017GL072950). @article{GRL:GRL55764, title = {Using an altimeter-derived internal tide model to remove tides from in situ data}, author = {E. D. Zaron and R. D. Ray}, url = {http://dx.doi.org/10.1002/2017GL072950}, doi = {10.1002/2017GL072950}, issn = {1944-8007}, year = {2017}, date = {2017-01-01}, journal = {Geophysical Research Letters}, volume = {44}, number = {9}, pages = {4241--4245}, abstract = {Internal waves at tidal frequencies, i.e., the internal tides, are a prominent source of variability in the ocean associated with significant vertical isopycnal displacements and currents. Because the isopycnal displacements are caused by ageostrophic dynamics, they contribute uncertainty to geostrophic transport inferred from vertical profiles in the ocean. Here it is demonstrated that a newly developed model of the main semidiurnal (M2) internal tide derived from satellite altimetry may be used to partially remove the tide from vertical profile data, as measured by the reduction of steric height variance inferred from the profiles. It is further demonstrated that the internal tide model can account for a component of the near-surface velocity as measured by drogued drifters. These comparisons represent a validation of the internal tide model using independent data and highlight its potential use in removing internal tide signals from in situ observations.}, note = {2017GL072950}, keywords = {}, pubstate = {published}, tppubtype = {article} } Internal waves at tidal frequencies, i.e., the internal tides, are a prominent source of variability in the ocean associated with significant vertical isopycnal displacements and currents. Because the isopycnal displacements are caused by ageostrophic dynamics, they contribute uncertainty to geostrophic transport inferred from vertical profiles in the ocean. Here it is demonstrated that a newly developed model of the main semidiurnal (M2) internal tide derived from satellite altimetry may be used to partially remove the tide from vertical profile data, as measured by the reduction of steric height variance inferred from the profiles. It is further demonstrated that the internal tide model can account for a component of the near-surface velocity as measured by drogued drifters. These comparisons represent a validation of the internal tide model using independent data and highlight its potential use in removing internal tide signals from in situ observations. |
Zaron, E D On the observability of bottom topography from measurements of tidal sea surface height Journal Article In: Ocean Modelling, 102 , pp. 55-63, 2016. @article{Zaron2016b, title = {On the observability of bottom topography from measurements of tidal sea surface height}, author = {E. D. Zaron}, url = {https://www.sciencedirect.com/science/article/pii/S1463500316300221}, doi = {10.1016/j.ocemod.2016.04.008}, year = {2016}, date = {2016-04-23}, journal = {Ocean Modelling}, volume = {102}, pages = {55-63}, abstract = {The question of whether features of the ocean bottom topography can be identified from measurements of water level is investigated using a simplified one-dimensional barotropic model. Because of the nonlinear dependence of the sea surface height on the water depth, a linearized analysis is performed concerning the identification of a Gaussian bump within two specific depth profiles, (1) a constant depth domain, and, (2) a constant depth domain adjoining a near-resonant continental shelf. Observability is quantified by examining the estimation error in a series of identical-twin experiments varying data density, tide wavelength, assumed (versus actual) topographic correlation scale, and friction. For measurements of sea surface height that resolve the scale of the topographic perturbation, the fractional error in the bottom topography is approximately a factor of 10 larger than the fractional error of the sea surface height. Domain-scale and shelf-scale resonances may lead to inaccurate topography estimates due to a reduction in the effective number of degrees of freedom in the dynamics, and the amplification of nonlinearity. A realizability condition for the variance of the topography error in the limit of zero bottom depth is proposed which is interpreted as a bound on the fractional error of the topography. Appropriately designed spatial covariance models partly ameliorate the negative impact of shelf-scale near-resonance, and highlight the importance of spatial covariance modeling for bottom topography estimation.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The question of whether features of the ocean bottom topography can be identified from measurements of water level is investigated using a simplified one-dimensional barotropic model. Because of the nonlinear dependence of the sea surface height on the water depth, a linearized analysis is performed concerning the identification of a Gaussian bump within two specific depth profiles, (1) a constant depth domain, and, (2) a constant depth domain adjoining a near-resonant continental shelf. Observability is quantified by examining the estimation error in a series of identical-twin experiments varying data density, tide wavelength, assumed (versus actual) topographic correlation scale, and friction. For measurements of sea surface height that resolve the scale of the topographic perturbation, the fractional error in the bottom topography is approximately a factor of 10 larger than the fractional error of the sea surface height. Domain-scale and shelf-scale resonances may lead to inaccurate topography estimates due to a reduction in the effective number of degrees of freedom in the dynamics, and the amplification of nonlinearity. A realizability condition for the variance of the topography error in the limit of zero bottom depth is proposed which is interpreted as a bound on the fractional error of the topography. Appropriately designed spatial covariance models partly ameliorate the negative impact of shelf-scale near-resonance, and highlight the importance of spatial covariance modeling for bottom topography estimation. |
Zaron, E D; deCarvalho, R Identification and Reduction of Retracker-Related Noise in Altimeter-Derived Sea Surface Height Measurements Journal Article In: Journal of Atmospheric and Oceanic Technology, 33 (1), 2016. @article{Zaron2016, title = {Identification and Reduction of Retracker-Related Noise in Altimeter-Derived Sea Surface Height Measurements}, author = {E. D. Zaron and R. deCarvalho}, year = {2016}, date = {2016-01-29}, journal = {Journal of Atmospheric and Oceanic Technology}, volume = {33}, number = {1}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Zaron, E D Laser Doppler velocimetry using a modified computer mouse Journal Article In: American Journal of Physics, 84 (10), pp. 810-813, 2016. @article{doi:10.1119/1.4960466, title = {Laser Doppler velocimetry using a modified computer mouse}, author = {E. D. Zaron}, url = {https://doi.org/10.1119/1.4960466}, doi = {10.1119/1.4960466}, year = {2016}, date = {2016-01-01}, journal = {American Journal of Physics}, volume = {84}, number = {10}, pages = {810-813}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Ray, R D; Zaron, E D M2 Internal Tides and Their Observed Wavenumber Spectra from Satellite Altimetry Journal Article In: Journal of Physical Oceanography, 46 (1), pp. 3-22, 2016. @article{doi:10.1175/JPO-D-15-0065.1, title = {M2 Internal Tides and Their Observed Wavenumber Spectra from Satellite Altimetry}, author = {R. D. Ray and E. D. Zaron}, url = {https://doi.org/10.1175/JPO-D-15-0065.1}, doi = {10.1175/JPO-D-15-0065.1}, year = {2016}, date = {2016-01-01}, journal = {Journal of Physical Oceanography}, volume = {46}, number = {1}, pages = {3-22}, abstract = {AbstractA near-global chart of surface elevations associated with the stationary M2 internal tide is empirically constructed from multimission satellite altimeter data. An advantage of a strictly empirical mapping approach is that results are independent of assumptions about ocean wave dynamics and, in fact, can be used to test such assumptions. A disadvantage is that present-day altimeter coverage is only marginally adequate to support mapping such short-wavelength features. Moreover, predominantly north–south ground-track orientations and contamination from nontidal oceanographic variability can lead to deficiencies in mapped tides. Independent data from Cryosphere Satellite-2 (CryoSat-2) and other altimeters are used to test the solutions and show positive reduction in variance except in regions of large mesoscale variability. The tidal fields are subjected to two-dimensional wavenumber spectral analysis, which allows for the construction of an empirical map of modal wavelengths. Mode-1 wavelengths show good agreement with theoretical wavelengths calculated from the ocean’s mean stratification, with a few localized exceptions (e.g., Tasman Sea). Mode-2 waves are detectable in much of the ocean, with wavelengths in reasonable agreement with theoretical expectations, but their spectral signatures grow too weak to map in some regions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } AbstractA near-global chart of surface elevations associated with the stationary M2 internal tide is empirically constructed from multimission satellite altimeter data. An advantage of a strictly empirical mapping approach is that results are independent of assumptions about ocean wave dynamics and, in fact, can be used to test such assumptions. A disadvantage is that present-day altimeter coverage is only marginally adequate to support mapping such short-wavelength features. Moreover, predominantly north–south ground-track orientations and contamination from nontidal oceanographic variability can lead to deficiencies in mapped tides. Independent data from Cryosphere Satellite-2 (CryoSat-2) and other altimeters are used to test the solutions and show positive reduction in variance except in regions of large mesoscale variability. The tidal fields are subjected to two-dimensional wavenumber spectral analysis, which allows for the construction of an empirical map of modal wavelengths. Mode-1 wavelengths show good agreement with theoretical wavelengths calculated from the ocean’s mean stratification, with a few localized exceptions (e.g., Tasman Sea). Mode-2 waves are detectable in much of the ocean, with wavelengths in reasonable agreement with theoretical expectations, but their spectral signatures grow too weak to map in some regions. |
Zaron, E D; Fitzpatrick, P J; Cross, S L; Harding, J M; Bub, F L; Wiggert, J D; Ko, D S; Woodard, K; Mooers, C N K Initial Evaluations of a Gulf of Mexico/Caribbean ocean forecast system in the context of the Deepwater Horizon disaster Journal Article In: Frontiers of Earth Science, accepted , 2015. @article{Hardingetal:2015, title = {Initial Evaluations of a Gulf of Mexico/Caribbean ocean forecast system in the context of the Deepwater Horizon disaster}, author = {E. D. Zaron and P. J. Fitzpatrick and S. L. Cross and J. M. Harding and F. L. Bub and J. D. Wiggert and D. S. Ko and K. Woodard and C. N. K. Mooers}, doi = {10.1007/s11707-014-0508-x}, year = {2015}, date = {2015-01-01}, journal = {Frontiers of Earth Science}, volume = {accepted}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Zaron, E D Properties of non-stationary tides inferred from dual-satellite crossovers Journal Article In: Journal of Physical Oceanography, submitted , 2015. @article{Zaron:2015a, title = {Properties of non-stationary tides inferred from dual-satellite crossovers}, author = {E. D. Zaron}, year = {2015}, date = {2015-01-01}, journal = {Journal of Physical Oceanography}, volume = {submitted}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Zaron, E D Nonstationary Internal Tides Observed Using Dual-Satellite Altimetry Journal Article In: Journal of Physical Oceanography, 45 (9), pp. 2239-2246, 2015. @article{doi:10.1175/JPO-D-15-0020.1, title = {Nonstationary Internal Tides Observed Using Dual-Satellite Altimetry}, author = {E. D. Zaron}, url = {https://doi.org/10.1175/JPO-D-15-0020.1}, doi = {10.1175/JPO-D-15-0020.1}, year = {2015}, date = {2015-01-01}, journal = {Journal of Physical Oceanography}, volume = {45}, number = {9}, pages = {2239-2246}, abstract = {AbstractDual-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 cm2, and the nonstationary variance is about 0.33 cm2, or 30% of the total. The temporal correlation of the nonstationary tide is examined by complex demodulation and found to be oscillatory with first 0 crossing at 400 h (17 days). Because a significant fraction of the time-variable mesoscale signal is resolved at time scales of roughly 150 h by the present constellation of satellite altimeters, the results suggest that it may be feasible to predict the nonstationary tide from modulations of the resolved mesoscale, thus enhancing the efficacy of tidal corrections for planned wide-swath altimeters such as the Surface Water and Ocean Topography (SWOT) mission.}, keywords = {}, pubstate = {published}, tppubtype = {article} } AbstractDual-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 cm2, and the nonstationary variance is about 0.33 cm2, or 30% of the total. The temporal correlation of the nonstationary tide is examined by complex demodulation and found to be oscillatory with first 0 crossing at 400 h (17 days). Because a significant fraction of the time-variable mesoscale signal is resolved at time scales of roughly 150 h by the present constellation of satellite altimeters, the results suggest that it may be feasible to predict the nonstationary tide from modulations of the resolved mesoscale, thus enhancing the efficacy of tidal corrections for planned wide-swath altimeters such as the Surface Water and Ocean Topography (SWOT) mission. |