Suitable region of dynamic optimal interpolation for efficiently altimetry sea surface height mapping

Abstract

The dynamic optimal interpolation (DOI) method is a technique based on quasi-geostrophic dynamics for merging multi-satellite altimeter along-track observations to generate gridded absolute dynamic topography (ADT). Compared with the linear optimal interpolation (LOI) method, the DOI method can improve the accuracy of gridded ADT locally but with low computational efficiency. Consequently, considering both computational efficiency and accuracy, the DOI method is more suitable to be used only for regional applications. In this study, we propose to evaluate the suitable region for applying the DOI method based on the correlation between the absolute value of the Jacobian operator of the geostrophic stream function and the improvement achieved by the DOI method. After verifying the LOI and DOI methods, the suitable region was investigated in three typical areas: the Gulf Stream (25°N-50°N, 55°W-80°W), the Japanese Kuroshio (25°N-45°N, 135°E−155°E), and the South China Sea (5°N-25°N, 100°E−125°E). We propose to use the DOI method only in regions outside the equatorial region and where the absolute value of the Jacobian operator of the geostrophic stream function is higher than 1 × 10−11.