Satellite-based datasets of surface turbulent fluxes over the global oceans are being evaluated and improved.O cean surface fluxes of heat, moisture, and momentum observed during field experiments show strong variability on temporal scales that range from the diurnal cycle to the life cycle of storms, and on spatial scales as small as that of an individual convective cloud. High-frequency variability (e.g., diurnal, storm scale) in tropical air-sea fluxes has been hypothesized to influence intraseasonal and interannual variability of the monsoon (e.g., Webster et al. 1998) and the Pacific Ocean warm pool and El Nino (e.g., Sui and Lau 1997;Fasullo and Webster 2000). At high latitudes, large variations in surface fluxes and sea surface temperature are seen in response to storms, which impact the temperature, density, and mixing in the upper ocean, further influencing the atmospheric dynamics and thermodynamics. Storm-scale events have been hypothesized (e.g., Marshall et al. 1998;Nardelli and Salusti 2000) to be associated with ocean convection in the high-latitude water mass formation regions, contributing to deep water formation and the global ocean thermohaline circulation. Ocean mixing induced by tropical cyclones might play an important role in driving the global ocean thermohaline circulation and, thereby,

[1] This paper presents a first attempt to analyze C-band RADARSAT-2 measurements of the normalized radar cross sections (NRCS) in quad-polarization acquisition mode (HH, VV, HV, and VH) over the ocean. NRCS in copolarizations and cross-polarizations are found to be different; the latter is independent of radar incidence angles and wind directions, but is quite linear with respect to wind speeds. We also investigate the properties of the polarization ratio, denoted PR, and show that it is dependent on incidence angle and azimuth angle as well as wind speed. It also correlates well with wave steepness and significant wave height. Moreover, the polarization difference shows a linear relationship with wind speed. Two new analytical models are proposed to estimate PR; one is a function of incidence angle only, while the other has additional dependence on wind speed. Comparisons are presented with theoretical and empirical PR models from the literature; the new PR model which includes wind speed dependence is shown to best compare with observed RADARSAT-2 data. An assessment of this PR model is given using different CMOD algorithms and RADARSAT-2 images. Results show that the wind speeds retrieved from this PR model and CMOD5.N are in good agreement with buoy measurements (standard deviation, 1.37 m/s). This joint GMF-PR approach constitutes a promising hybrid model for wind speed retrievals from HH-polarized RADARSAT-2 images.Citation: Zhang, B., W. Perrie, and Y. He (2011), Wind speed retrieval from RADARSAT-2 quad-polarization images using a new polarization ratio model,

Nonlinear transfer due to wave-wave interactions was first described by the Boltzmann integrals of Hasselmann (1961) and has been the subject of modelling ever since. We present an economical method to evaluate the complete integral, which uses selected scaling properties and symmetries of the nonlinear energy transfer integrals to construct the integration grid. An important aspect of this integration is the inherent smoothness and stability of the computed nonlinear energy transfer. Energy fluxes associated with the nonlinear energy transfers and their behaviour within the equilibrium range are investigated with respect to high-frequency power law, peak frequency, peakedness, spectral sharpness and angular spreading. We also compute the time evolution of the spectral energy and the nonlinear energy transfers in the absence of energy input by wind or dissipated by wave breaking. The response of nonlinear iterations to perturbations is given and a formulation of relaxation time in the equilibrium range is suggested in terms of total equilibrium range energy and the nonlinear energy fluxes within the equilibrium range.