A New Climate Data Record of the Ocean Surface Winds, Stress and Their Dynamically-Significant Derivatives – Vorticity and Divergence: Supporting Studies of Trends and Variability in the Large-Scale Circulation
Ocean surface winds and wind stress are key components of the Earth climate system. After more than 20 years of continuous scatterometer observation of the ocean surface vector winds by a variety of instruments we are now positioned to address three still outstanding issues of great importance: i) creation of a consistent long-term Earth Science Data Record (ESDR) that includes observations from all different missions while eliminating inconsistencies between them; ii) development of the dynamically-significant derived products – the surface wind stress and the curl and divergence of the surface wind and stress; iii) development of scatterometer-only user-friendly uniformly gridded products (Level 3 products, with space/time gaps between observations), to fill an unmet user need and complement existing gap-free L4 products (blending models and observations), which have their own roles.
Indeed, these are the goals of our NASA MEaSUREs-funded project. This effort is not the first of its kind, following with the traditions of others. Here we provide new state-of-the-art set of retrieved products based on different retrieval algorithms, thus providing an additional ESDR of climate quality. Only through analyses of a number of different ESDRs can we obtain a better understanding of the uncertainties associated with the retrieval approaches and the creation of the climate-quality ESDRs.
Our products bring some new elements: i) equivalent neutral (EN), surface-relative wind vector retrievals homogenized across the retrievals from the different instruments/missions; ii) estimation of the 10 m true wind vectors; iii) estimation of the wind stress vector; iv) computation of the divergence and vorticity of the wind and the stress; v) uncertainty estimation; vi) providing collocated data from ERA-5, IMERG and GlobeCurrents to support the product evaluation.
We will begin the presentation by outlining our goals and motivation, followed by a short overview on what is new, and a summary on how some of the new products were developed. We will then provide initial evaluation and validation of the products. Finally, we will illustrate how a long-term data record of the scatterometer-derived ocean surface wind vectors can be used to study the trends and variability in the large-scale circulation, as depicted by its lower branch.
