Uncertainties of monthly ocean bottom pressure from Gravity Recovery and Climate Experiment (GRACE): a case study at the Drake Passage

Several studies reported some aliasing errors of Ocean bottom pressure (OBP) data from Gravity Recovery and Climate Experiment (GRACE), although this data have been widely used to estimate the oceanic transports. In this study, the performances of monthly OBP data from six GRACE products with two different solutions are evaluated by comparisons with the observed records at the Drake Passage. Result shows that spherical harmonic products have a better ability to capture monthly OBP variability than mascon products at the Drake Passage. In all GRACE products, higher skills occur to the south of Polar Front than those in the northern Drake Passage, and the correlations with observations reach minimum in the Local Dynamics Array (LDA) region. Such spatial differences are mainly attributed to local mesoscale processes, accompanied with high-frequency bottom eddy kinetic energy (EKE). It indicates that the monthly OBP variations from GRACE products are not reliable in the eddy-rich regions.