Analysis of the skewness of characteristics of the upper layer of the North Atlantic according to the ORA-S3 reanalysis

by

P.A. Sukhonos

 Institute of Natural and Technical Systems, RF, Sevastopol, Lenin St., 28

E-mail: pasukhonis@mail.ru

DOI: 10.33075/2220-5861-2022-4-15-24

UDC 551.465.7(261.1)                                              

Abstract:

   It is shown that the interannual anomalies of the upper mixed layer (UML) temperature and depth, the net surface heat flux and the wind stress modulus in a number of regions of the North Atlantic exhibit non-Gaussian variability according to the ORA-S3 oceanic reanalysis monthly data for the period 1980–2011. In the area south of the Azores, the distribution of all these characteristics has a significant positive skewness. In this region, a close negative relationship between the anomalies of the UML temperature partial derivative and the anomalies of the net surface heat flux is confirmed. Anomalies of the net surface heat flux and wind stress modulus, which possess a significant positive skewness, have a close positive relationship with each other. The anomalies of these parameters when leading for 1 month are accompanied by the formation of the UML temperature anomalies of the opposite sign. An analysis of the terms of the closed UML heat balance equation has shown that in the area south of the Azores, the processes of local interaction between the ocean and the atmosphere play an important role in the formation of the UML temperature anomalies. The variability of net surface heat flux, normalized to the UML depth, is a significant part of the total variance of the UML heat balance in the annual cycle. In the summer months, the value of this contribution is maximal and amounts to ~50%. Thus, the positive skewness of the UML temperature anomalies in the region south of the Azores mainly arises due to the presence of positive skewness in the variability of the net surface heat flux and the UML depth, which are the components of the main UML heat balance term.

Keywords: non-Gaussianity, heat balance, upper mixed layer, North Atlantic.

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