Combining airborne remote, in situ, and expendable probe sensors with air-deployed ocean platforms provides a strategy for expanding knowledge of illusive high-wind air-sea fluxes in difficult-to-predict storms.
[1] An array of instruments air-deployed ahead of Hurricane Frances measured the three-dimensional, time dependent response of the ocean to this strong (60 ms À1 ) storm. Sea surface temperature cooled by up to 2.2°C with the greatest cooling occurring in a 50-km-wide band centered 60 -85 km to the right of the track. The cooling was almost entirely due to vertical mixing, not air-sea heat fluxes. Currents of up to 1.6 ms À1 and thermocline displacements of up to 50 m dispersed as near-inertial internal waves. The heat in excess of 26°C, decreased behind the storm due primarily to horizontal advection of heat away from the storm track, with a small contribution from mixing across the 26°C isotherm. SST cooling under the storm core (0.4°C) produced a 16% decrease in air-sea heat flux implying an approximately 5 ms À1 reduction in peak winds.
Abstract. Breaking waves at the ocean's surface inject bubbles and turbulence into the water column. During periods of rough weather the scales of wave breaking will increase with increasing sea states and result in mixing of the surface waters and the turbulent transport of bubbles to depth. Depending on their concentrations and size distribution, the entrained bubbles can significantly change the optical properties of water, introducing potentially significant errors in retrieval of remotely sensed hyperspectral data products. In this paper, the effects of bubbles on optical scattering in the upper ocean are investigated through optical scattering calculations based on field measurements of bubble populations.
The Coupled Air–Sea Processes and Electromagnetic Ducting Research (CASPER) project aims to better quantify atmospheric effects on the propagation of radar and communication signals in the marine environment. Such effects are associated with vertical gradients of temperature and water vapor in the marine atmospheric surface layer (MASL) and in the capping inversion of the marine atmospheric boundary layer (MABL), as well as the horizontal variations of these vertical gradients. CASPER field measurements emphasized simultaneous characterization of electromagnetic (EM) wave propagation, the propagation environment, and the physical processes that gave rise to the measured refractivity conditions. CASPER modeling efforts utilized state-of-the-art large-eddy simulations (LESs) with a dynamically coupled MASL and phase-resolved ocean surface waves. CASPER-East was the first of two planned field campaigns, conducted in October and November 2015 offshore of Duck, North Carolina. This article highlights the scientific motivations and objectives of CASPER and provides an overview of the CASPER-East field campaign. The CASPER-East sampling strategy enabled us to obtain EM wave propagation loss as well as concurrent environmental refractive conditions along the propagation path. This article highlights the initial results from this sampling strategy showing the range-dependent propagation loss, the atmospheric and upper-oceanic variability along the propagation range, and the MASL thermodynamic profiles measured during CASPER-East.
Analysis of coastal surface currents measured off the coast of San Diego for two years suggests an anisotropic and asymmetric response to the wind, probably as a result of bottom/coastline boundary effects, including pressure gradients. In a linear regression, the statistically estimated anisotropic response explains approximately 20% more surface current variance than an isotropic wind-ocean response model. After steady wind forcing for three days, the isotropic surface current response veers 428 6 28 to the right of the wind regardless of wind direction, whereas the anisotropic analysis suggests that the upcoast (onshore) wind stress generates surface currents with 108 6 48 (718 6 38) to the right of the wind direction. The anisotropic response thus reflects the dominance of alongshore currents in this coastal region. Both analyses yield winddriven currents with 3%-5% of the wind speed, as expected. In addition, nonlinear isotropic and anisotropic response functions are considered, and the asymmetric current responses to the wind are examined. These results provide a comprehensive statistical model of the wind-driven currents in the coastal region, which has not been well identified in previous field studies, but is qualitatively consistent with descriptions of the current response in coastal ocean models.
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