Surface wind speed probability distribution in the Southeast Pacific of Marine Stratus and Stratocumulus regions

Abstract

Abstract Probability distributions of surface wind speeds (SWS) near coastal regions are needed for applications such as estimating offshore wind power and ocean surface fluxes and for offshore wind risk assessments. Ocean surface wind speed probability distribution (PDF) is characterized using three-year QuikSCAT and AIRS satellite observations in the southeast Pacific of marine stratus and stratocumulus (MSC) regions. Seasonal variation is removed from wind statistics. It was found that the observed SWS standard deviation has a linear positive relationship with its mean SWS; while the SWS skewness decreases with mean SWS in regimes of strong winds and increases with mean SWS in regimes of weak winds. A simple 1D conceptual model is developed near the Peruvian region, which successfully reproduces the observed relationship between higher moments of SWS and its mean value. The model based physical picture among ocean surface winds, SST, and marine boundary clouds are supported by three-year QuikSCAT surface wind observations and fifteen-year ERA40 re-analysis data. Model sensitive tests suggest that large-scale divergence, and strengths of momentum and cloud fluctuations have significant effects on the ocean SWS-PDF in marine stratus and stratocumulus regions.