Fig. 5
From: Benefits of radar-derived surface current assimilation for South of Africa ocean circulation
Maps of differences of FREE and 4DVAR geostrophic velocities RMSE (against altimeter derived velocities) during April 2020. a corresponds to the 1\(^{st}\) to 10\(^{th}\) of April, b corresponds to the 11\(^{th}\) to the 20\(^{th}\) of April and c corresponds to the 21\(^{th}\) to the 30\(^{th}\) of April. Blue color means RMSE reduction in 4DVAR solution. Dotted contour shows where HF radar data are assimilated