Air-sea interaction in the vicinity of an oceanic front in East China Sea during spring time is firstly investigated with high-resolution satellite measurements. The analyses reveal a significant positive correlation between sea surface temperature and surface wind speed. This positive correlation becomes even more significant when the SST front is intensified. The satellite measurements also indicate that in spring the oceanic front is strongest and the collocation of SST and wind speed anomalies is most significant. Then, a high-resolution mesoscale atmospheric model with state-of-the-art physical parameterizations is used to investigate the mechanisms by which the ocean can influence the atmosphere. The control run successfully reproduces the SST-wind positive correlation in the vicinity of the oceanic front. The simulated vertical structure of the Planetary Boundary Layer (PBL) indicates that the changes of SST can cause large differences in static stability and vertical mixing between cold and warm sides of the SST front and thus confirm the existence of vertical mixing mechanism. The analyses of the momentum budgets in the control and smoothed SST runs indicate that the pressure gradient force induced by the oceanic front is also important for the acceleration of cross-frontal winds. All in all, satellite observations and simulation results suggest that the ocean-to-atmosphere forcing plays a key role in air-sea interactions over the SST frontal area in East China Sea during spring time. Both the SLP (sea level pressure) mechanism and the vertical mixing mechanism are responsible for this ocean-to-atmospheric forcing.