Fortnightly atmospheric tides forced by spring and neap tides in coastal waters

Recently, oceanic influences on atmospheric processes via sea surface temperature (SST) have been well recognized over the various open oceans. Meanwhile, atmospheric responses to SST in coastal waters are poorly understood. The oceanic stratification (hence, SST) largely depends on the fortnightly springs-neaps cycle of coastal tides because of the difference of vertical tidal mixing. Here we consider how SST varying in the fortnightly tidal cycle affects the lower-level atmosphere over the Seto Inland Sea, Japan, using a combination of in-situ measurements, satellite observations, and a regional atmospheric model. We find that the SST in summer has cool (warm) anomalies mostly over the inland sea during spring (neap) tides. In addition, surface air temperature is positively correlated with the SST varying in the fortnightly tidal cycle. Moreover, the fortnightly springs-neaps fluctuation is also found in the surface wind speed because the atmospheric boundary layer becomes neutral (stabilized) by the difference between air temperature and SST.