Jet Alignment in a 2 Layer Quasi-Geostrophic Channel Using One-Dimensional Grid Warping

Traditional methods of data assimilation can deform jets and other flow structures leading to reduced forecast skill. Here we develop and test a technique to assimilate properties of coherent structures. Focusing on jets, the technique identifies jets in both the modeled and observed fields and warps the model grid so that the jet positions are better aligned prior to further assimilation of observations. We test the technique using optimal interpolation on the flow in a two-layer quasi-geostrophic channel. The results show that a simple and fast jet position correction algorithm can significantly improve the skill of a 12-hour forecast. Furthermore results indicate that this method of position correction maintains its utility when observations become sparse.