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An OGCM assessment of blended OSCAT winds
Author(s) -
Chakraborty Abhisek,
Sharma Rashmi,
Kumar Raj,
Basu Sujit
Publication year - 2014
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2013jc009406
Subject(s) - scatterometer , buoy , environmental science , climatology , meteorology , numerical weather prediction , empirical orthogonal functions , wind speed , forcing (mathematics) , satellite , geology , geography , engineering , oceanography , aerospace engineering
Ensemble optimal interpolation technique has been used to blend winds for the years 2011–2012, derived by OSCAT, a scatterometer onboard the satellite Oceansat‐2, with winds from two different numerical weather prediction (NWP) centers, namely, National Center for Environmental Prediction (NCEP) and European Centre for Medium Range Weather Forecast (ECMWF). These blended winds, when compared with buoy winds, show higher correlations and lower root‐mean‐square errors (RMSE) than the standalone NWP winds. Analysis of divergence and curl of wind stresses also suggests that the blending is physically realistic. Comparisons of blended winds with buoy winds and analysis of divergence and curls as also the subsequent spectral analysis show that the blended ECMWF wind is the best among all the wind products. Consequent assessment of the impact of blended ECMWF wind product has been done using an ocean general circulation model (OGCM). The technique of empirical orthogonal function (EOF) analysis has been used to assess the impact on sea level and surface currents. The dominant modes of simulated variability in the case of forcing by blended winds are found to be more faithfully reproducing the well‐known features of global ocean circulation. Validation of the depth of the 20°C isotherm (D20) also establishes the relative superiority of the blended wind product.