1 ISSN 0001-4370, Oceanology, 2016, Vol. 56, No. 1, pp. 1–5. © Pleiades Publishing, Inc., 2016. Original Russian Text © N.D. Tilinina, S.K. Gulev, A.V. Gavrikov, 2016, published in Okeanologiya, 2016, Vol. 56, No. 1, pp. 5–9. Formation of Extreme Surface Turbulent Heat Fluxes from the Ocean to the Atmosphere in the North Atlantic N. D. Tilinina, S. K. Gulev, and A. V. Gavrikov Shirshov Institute of Oceanology, Russian Academy of Sciences 117218 Russia e-mail: tilinina@sail.msk.ru Received June 8, 2015; in final form, August 13, 2015 Abstract—The role of extreme surface turbulent fluxes in total oceanic heat loss in the North Atlantic is stud- ied. The atmospheric circulation patterns enhancing ocean–atmosphere heat flux in regions with significant contributions of the extreme heat fluxes (up to 60% of the net heat loss) are analyzed. It is shown that extreme heat fluxes in the Gulf Stream and the Greenland and Labrador Seas occur in zones with maximal air pres- sure gradients, i.e., in cyclone–anticyclone interaction zones. DOI: 10.1134/S0001437016010215 INTRODUCTION Turbulent sensible and latent heat fluxes from the ocean to the atmosphere in the middle and subpolar latitudes are characterized by high spatiotemporal variability. They can vary by hundreds and thousands W/m 2 on the synoptic scale (from several hours to days in time and from tens to hundreds kilo- meters in space) [10, 13]. The synoptic variability of turbulent heat fluxes is much stronger than seasonal and interannual variability [1, 2, 9, 11]; it forms sur- face extreme turbulent heat fluxes. Extreme turbu- lent heat fluxes play an important role in the forma- tion of ocean convection and mixing, affecting the lower troposphere and the baroclinity of the lower air layers [3, 4]. Therefore, the creation of reliable esti- mates of extreme heat fluxes and comprehension of how they occur is very important. It was shown [13] that extreme heat fluxes are associated with atmo- spheric cyclones, which rapidly propagate over the inhomogeneous ocean surface. However, the authors of work [7] have shown that atmospheric cyclones itself do not provide conditions for the formation of ocean–atmosphere extreme heat fluxes, and only 43% of all winter cyclones in the North Atlantic are characterized by heat fluxes integral to a cyclone area higher than the North Atlantic average flux. This agrees with studies [5, 12], which show that most of the heat loss in the Southern Ocean is occurs outside of cyclone areas. In this work, we analyze the mechanisms of extreme heat flux formation in the midlatitudes. The main aim of this study is a description of large-scale atmospheric circulation, which has resulted in the for- mation of ocean–atmosphere extreme heat fluxes for the past several decades. Hereinafter, extreme heat flux is understood as a total turbulent heat flux (sensible + latent heat) exceeding the 90th percentile of the empirical distri- bution for a given point. We consider only Januaries from 1979 to 2010, since the ocean–atmosphere tur- bulent heat exchange is maximal precisely in January. DATA AND TECHNIQUES OF THE STUDY In this work, we used 6-hourly data sea-level pres- sure fields (slp) and surface turbulent sensible (Qh) and latent (Qe) heat fluxes from NCEP CFSR reanalysis [8] for 1979–2010, with a spatial resolution of 0.5° × 0.5°, which corresponds to ~55.5 km at the equator. The empirical total heat flux (Qe + Qh, Fig. 1) probability distributions were calculated for each grid point from a time series one month long (124 time steps of the reanalysis), which allowed the estimation of the 90th percentile and the analysis of fluxes that exceed it. We thus identified the time points and intensities of extreme surface turbulent heat flux in the North Atlantic in three regions: the Gulf Stream, the Greenland Sea, and the Labrador Sea, which are characterized by high flux values and oceanological processes that strongly depend on air– sea interaction processes. At the next step, we ana- lyzed the large-scale atmospheric circulation typical for time points with extreme heat fluxes and con- structed composite patterns of sea level pressure that allowed the description of atmospheric synoptic con- ditions resulting in the formation of ocean–atmo- MARINE PHYSICS