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The detection of duct height has a significant effect on marine radar or wireless apparatus applications. The paper presents two models to verify the adaptation of evaporation duct models in the SCS in winter. A meteorological gradient instrument used to measure evaporation ducts was fabricated using hydrological and meteorological sensors at different heights. An experiment on the adaptive characteristics of evaporation duct models was carried out over the SCS. The heights of the evaporation ducts were measured by means of log-linear fit, Paulus-Jeske (PJ) and Naval Postgraduate School (NPS) models. The results showed that NPS model offered significant advantages in stability compared with the PJ model. According the collected data computed by the NPS model, the mean deviation (MD) was -1.7 m, and the Standard Deviation (STD) of the MD was 0.8 m compared with the true value. The NPS model may be more suitable for estimating the evaporation duct height in the SCS in winter due to its simpler system characteristics compared with meteorological gradient instruments. [ABSTRACT FROM AUTHOR]

Measurements of turbulence in the deep ocean, particularly close to the bottom, are extremely sparse because of the difficulty and operational risk of obtaining deep profiles near the seafloor. A newly developed expendable instrument-the VMP-X (Vertical Microstructure Profiler-Expendable)-carries two microstructure shear probes to measure the fluctuations of vertical shear into the dissipation range and can profile down to a depth of 6000 m. Data from nine VMP-X profiles in the western Pacific Ocean near 11.6°N over rough topography display bottom-intensified turbulence with dissipation rates increasing by two factors of 10 to 4 W kg-1 within 200 m above the bottom. In contrast, over smooth topography in the southern South China Sea near 11°N, three profiles show that turbulence in the bottom boundary layer increases only slightly, with dissipation rates reaching 1 W kg-1. The eddy diffusivity over rough topography reached to 5 m2 s-1. The average diffusivity over all depths was 0.3 and 0.9 m2 s-1 for the tests in the southern South China Sea and in the western Pacific Ocean, respectively, and these values are much larger than previous estimates of less than ≈0.1 m2 s-1 for the main thermocline. [ABSTRACT FROM AUTHOR]