| The air-sea interaction in the North Atlantic Ocean is studied in three parts. In the first part, we use the historical dataset from Ocean Weather Station (OWS) Bravo to characterize the air-sea fluxes occurring in the Labrador Sea. The Labrador Sea is one of a handful of locations where deep ocean convection is known to occur. We find that there is significant high frequency variability (which would get masked with monthly mean analyses) in the buoyancy flux attributable to the passage of synoptic weather systems. We also highlight the importance of precipitation as it is an important source of positive buoyancy flux at high latitudes. The buoyancy flux temporarily becomes positive during the passage of a cyclone. The timescale for this change in buoyancy flux is similar to the timescale for the convective plumes in the ocean, suggesting that the variability of the high frequency variability in the atmosphere could modify deep ocean convection.; In the second part, we introduce a novel way to quantify the variance of a time series and apply it to the OWS Bravo dataset. The method involves first filtering the time series using filters with different temporal characteristics, and then using a moving window to calculate the variances in each filtered time series. The use of a moving window allows the original temporal resolution to be retained, as well as allowing one to study how the variance changes with time. We find that the variance during the winter months is strongly influenced by weather systems in the bandpass and the lowpass frequency range. The variance during the summer months, on the other hand, is dominated by the shortwave radiation in the highpass frequency range.; Finally, in the third part, using a global meteorological dataset, we examine basin scale signals in the North Atlantic. Using a trigger point in the Greenland, Iceland and Norwegian Sea, we identify a basin scale regime shift that resembles the North Atlantic Oscillation (NAO) spatial pattern. Unlike the NAO signal which occurs on an annual timescale, this regime shift occurs on intra-month time scales. Composites of the “before” and “after” regimes illustrate the respective flow patterns and the associated changes in the heat fluxes. |
