Sponsor
This project was supported by NASA Grants NNX17AJ35G and NNX16AH88G, and National Geospatial-Intelligence Agency Grant HM01771310008.
Published In
Journal of Atmospheric and Oceanic Technology
Document Type
Article
Publication Date
12-2018
Subjects
Sea level -- Measurement, Sea level -- Maps, Oceanography -- Measurement -- Remote sensing, Baroclinic models
Abstract
Sea level anomaly (SLA) maps are routinely produced by objective analysis of data from the constellation of satellite altimeter missions in operation since 1992. Beginning in 2014, changes in the Data Unification and Altimeter Combination System (DUACS) used to create the SLA maps resulted in improved spatial resolution of mesoscale variability, but it also increased the levels of aliased tidal variability compared to the methodology employed prior to 2014. The present work investigates the magnitude and spatial distribution of these tidal signals, which are typically smaller than 1 cmin the open ocean but can reach tens of centimeters in the coastal ocean. In the open ocean, the signals are caused by a combination of phase-locked and phase variable baroclinic tides. In the coastal ocean, the signals are a combination of aliased high-frequency nontidal variability and aliased variability caused by erroneous tidal corrections applied to the along-track altimetry prior to objective analysis. Several low-pass and bandpass filters are implemented to reduce the tidal signals in the mapped SLA, and independent tide gauge data are used to provide an objective assessment of the performance of the filters. The filter that attenuates both the small-scale (less than 200 km) and the high frequency (period shorter than 108 days) components of SLA removes aliased baroclinic tidal variability and improves the accuracy of tidal analysis in the open ocean while also performing acceptably in the coastal ocean.
DOI
10.1175/JTECH-D-18-0089.1
Persistent Identifier
https://archives.pdx.edu/ds/psu/27210
Citation Details
Zaron, E. D., & Ray, R. D. (2018). Aliased Tidal Variability in Mesoscale Sea Level Anomaly Maps. Journal of Atmospheric and Oceanic Technology, (2018).
Description
To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the American Meteorological Society and can be found at: https://doi.org/10.1175/JTECH-D-18-0089.1.
Originally appeared in the Journal of Atmospheric and Oceanic Technology, December 2018. May be found at https://journals.ametsoc.org/doi/abs/10.1175/JTECH-D-18-0089.1.