Kucukosmanoglu Murat

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Last Name
Kucukosmanoglu
First Name
Murat
ORCID
0000-0003-3611-7692

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  • Article
    Observations of the space/time scales of Beaufort sea acoustic duct variability and their impact on transmission loss via the mode interaction parameter
    (Acoustical Society of America, 2023-05-02) Kucukosmanoglu, Murat ; Colosi, John A. ; Worcester, Peter F. ; Dzieciuch, Matthew A. ; Sagen, Hanne ; Duda, Timothy F. ; Zhang, Weifeng Gordon ; Miller, Christopher W. ; Richards, Edward L.
    The Beaufort duct (BD) is a subsurface sound channel in the western Arctic Ocean formed by cold Pacific Winter Water (PWW) sandwiched between warmer Pacific Summer Water (PSW) and Atlantic Water (AW). Sound waves can be trapped in this duct and travel long distances without experiencing lossy surface/ice interactions. This study analyzes BD vertical and temporal variability using moored oceanographic measurements from two yearlong acoustic transmission experiments (2016–2017 and 2019–2020). The focus is on BD normal mode propagation through observed ocean features, such as eddies and spicy intrusions, where direct numerical simulations and the mode interaction parameter (MIP) are used to quantify ducted mode coupling strength. The observations show strong PSW sound speed variability, weak variability in the PWW, and moderate variability in the AW, with typical time scales from days to weeks. For several hundreds Hertz propagation, the BD modes are relatively stable, except for rare episodes of strong sound speed perturbations. The MIP identifies a resonance condition such that the likelihood of coupling is greatest when there is significant sound speed variability in the horizontal wave number band ⁠1/11 < kh < 1/5 km-1. MITgcm ocean model results are used to estimate sound speed fluctuations in this resonance regime.
  • Article
    Observations of sound-speed fluctuations in the Beaufort Sea from summer 2016 to summer 2017
    (Acoustical Society of America, 2021-03-05) Kucukosmanoglu, Murat ; Colosi, John A. ; Worcester, Peter F. ; Dzieciuch, Matthew A. ; Torres, Daniel J.
    Due to seasonal ice cover, acoustics can provide a unique means for Arctic undersea communication, navigation, and remote sensing. This study seeks to quantify the annual cycle of the thermohaline structure in the Beaufort Sea and characterize acoustically relevant oceanographic processes such as eddies, internal waves, near-inertial waves (NIWs), and spice. The observations are from a seven-mooring, 150-km radius acoustic transceiver array equipped with oceanographic sensors that collected data in the Beaufort Sea from 2016 to 2017. Depth and time variations of the sound speed are analyzed using isopycnal displacements, allowing a separation of baroclinic processes and spice. Compared to lower latitudes, the overall sound speed variability is small with a maximum root mean square of 0.6 m/s. The largest source of variability is spice, most significant in the upper 100 m, followed by eddies and internal waves. The displacement spectrum in the internal wave band is time dependent and different from the Garret-Munk (GM) spectrum. The internal wave energy varied with time averaging 5% of the GM spectrum. The spice sound-speed frequency spectrum has a form very different from the displacement spectrum, a result not seen at lower latitudes. Because sound speed variations are weak, observations of episodic energetic NIWs with horizontal currents up to 20 cm/s have potential acoustical consequences.