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1. Decomposition of the Multimodal Multidirectional M ₂ Internal Tide Field

   https://doi.org/10.1175/JTECH-D-19-0022.1  

   Zhao, Zhongxiang; Wang, Jinbo; Menemenlis, Dimitris; Fu, Lee-Lueng; Chen, Shuiming; Qiu, Bo (June 2019, Journal of Atmospheric and Oceanic Technology)

   The M₂internal tide field contains waves of various baroclinic modes and various horizontal propagation directions. This paper presents a technique for decomposing the sea surface height (SSH) field of the multimodal multidirectional internal tide. The technique consists of two steps: first, different baroclinic modes are decomposed by two-dimensional (2D) spatial filtering, utilizing their different horizontal wavelengths; second, multidirectional waves in each mode are decomposed by 2D plane wave analysis. The decomposition technique is demonstrated using the M₂internal tide field simulated by the MITgcm. This paper focuses on a region lying off the U.S. West Coast ranging 20°–50°N, 220°–245°E. The lowest three baroclinic modes are separately resolved from the internal tide field; each mode is further decomposed into five waves of arbitrary propagation directions in the horizontal. The decomposed fields yield unprecedented details on the internal tide’s generation and propagation, which cannot be observed in the harmonically fitted field. The results reveal that the mode-1 M₂internal tide in the study region is dominantly from the Hawaiian Ridge to the west but also generated locally at the Mendocino Ridge and continental slope. The mode-2 and mode-3 M₂internal tides are generated at isolated seamounts, as well as at the Mendocino Ridge and continental slope. The Mendocino Ridge radiates both southbound and northbound M₂internal tides for all three modes. Their propagation distances decrease with increasing mode number: mode-1 waves can travel over 2000 km, while mode-3 waves can only be tracked for 300 km. The decomposition technique may be extended to other tidal constituents and to the global ocean. 

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2. Satellite Investigation of the M ₂ Internal Tide in the Tasman Sea

   https://doi.org/10.1175/JPO-D-17-0047.1  

   Zhao, Zhongxiang; Alford, Matthew H.; Simmons, Harper L.; Brazhnikov, Dmitry; Pinkel, Rob (March 2018, Journal of Physical Oceanography)
3. Internal tide oceanic tomography

   https://doi.org/10.1002/2016GL070567  

   Zhao, Zhongxiang (September 2016, Geophysical Research Letters)
4. Propagation of the Semidiurnal Internal Tide: Phase Velocity Versus Group Velocity

   https://doi.org/10.1002/2017GL076008  

   Zhao, Zhongxiang (December 2017, Geophysical Research Letters)
5. Examination of the structures, energetics, and vibrational frequencies of small sulfur‐containing prototypical dimers, (H ₂ S) ₂ and H ₂ O/H ₂ S

   https://doi.org/10.1002/jcc.25578  

   Dreux, Katelyn M.; Tschumper, Gregory S. (October 2018, Journal of Computational Chemistry)

   The optimized geometries, vibrational frequencies, and dissociation energies from MP2 and CCSD(T) computations with large correlation consistent basis sets are reported for (H₂S)₂and H₂O/H₂S. Anharmonic vibrational frequencies have also been computed with second‐order vibrational perturbation theory (VPT2). As such, the fundamental frequencies, overtones, and combination bands reported in this study should also provide a useful road map for future spectroscopic studies of the simple but important heterogeneous H₂O/H₂S dimer in which the hydrogen bond donor and acceptor can interchange, leading to two unique minima with very similar energies. Near the CCSD(T) complete basis set limit, the HOH⋯SH₂configuration (H₂O donor) lies only 0.2 kcal mol⁻¹below the HSH⋯OH₂structure (H₂S donor). When the zero‐point vibrational energy is included, however, the latter configuration becomes slightly lower in energy than the former by <0.1 kcal mol⁻¹. © 2018 Wiley Periodicals, Inc. 

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