Spatial and Temporal Variability of a Latent Heat Flux in the Northwest Pacific Ocean Based on the ERA5 Reanalysis Data

G. V. Shevchenko1, 2, ✉, D. M. Lozhkin1

1 Sakhalin Branch of the Russian Federal Research Institute of Fisheries and Oceanography, Yuzhno-Sakhalinsk, Russian Federation

2 Institute of Marine Geology and Geophysics, Far Eastern Branch of Russian Academy of Sciences, Yuzhno-Sakhalinsk, Russian Federation

✉ e-mail: Shevchenko_zhora@mail.ru

Abstract

Purpose. The paper is aimed at studying the spatial and temporal variability of a latent heat flux – one of the important components of heat balance in the Northwest Pacific Ocean and the Far Eastern seas based on the ERA5 reanalysis data.

Methods and Results. The ERA5 reanalysis data on a latent heat flux in the area limited by the coordinates 42°−60°N and 135°–180°E and including the Far Eastern seas and the Northwest part of the Pacific Ocean constituted the material for the study. The array of monthly averages at a quarter-degree spatial resolution was analyzed using the standard statistical methods. The average long-term distributions of latent heat flux values for each month were constructed; the amplitudes and phases of annual and semi-annual cycles, and the linear trend coefficients were calculated in each spatial cell, and the decomposition was performed using the empirical orthogonal functions. The range of seasonal variations is significant in the zone of warm currents, and it decreases sharply in the northern part of the area under study in the Pacific Ocean as well as in the Okhotsk and Bering seas. The interannual variations are manifested in the quasi-cyclic changes of the envelope based on the maximum values with a period of about 6 years. The unidirectional trends in the interannual latent heat flux variations are weakly shown.

Conclusions. Among the seasonal variations of a latent heat flux, the annual cyclicity is predominant and most pronounced in the southern part of the Northwest Pacific Ocean (the area influenced by the warm Kuroshio Current) off the Japan Sea coast of the Honshu Island in the Tsushima Current zone. This is conditioned by a significant evaporation increase in these areas during a cold season that, in its turn, is related to a sharper temperature contrast as well as to the impact of a winter monsoon characterized by the strong and stable northwesterly winds bringing dry cold air from the continent. The latent heat flux values are positive in some areas of the studied area in a warm period that indicates the important role of water vapor condensation in the areas with high cloudiness and in the zones of quasi-stationary upwellings.

Keywords

heat balance, latent heat flux, annual cycle, linear trend, empirical orthogonal functions, Northwest Pacific Ocean

Acknowledgements

The study was carried out within the framework of state assignment of the FSBSI “VNIRO” on theme “Study of influence of variability of climatic and oceanological conditions on the main objects of Russian fisheries”.

Original russian text

Original Russian Text © G. V. Shevchenko, D. M. Lozhkin, 2024, published in MORSKOY GIDROFIZICHESKIY ZHURNAL, Vol. 40, Iss. 3, pp. 426–437 (2024)

For citation

Shevchenko, G.V. and Lozhkin, D.M., 2024. Spatial and Temporal Variability of a Latent Heat Flux in the Northwest Pacific Ocean Based on the ERA5 Reanalysis Data. Physical Oceanography, 31(3), pp. 387-397.

References

  1. Ponomarev, V.I., Petrova, V.A. and Dmitrieva, E.V., 2012. Climatic Variability of the Heat Balance Components at the Sea Surface in the North Pacific. Izvestiya TINRO, 169, pp. 67-76 (in Russian).
  2. Ayina, L.-H., Bentamy, A., Mestas-Nuñez, A.M. and Madec, G., 2006. The Impact of Satellite Winds and Latent Heat Fluxes in a Numerical Simulation of the Tropical Pacific Ocean. Journal of Climate, 19(22), pp. 5889-5902. https://doi.org/10.1175/JCLI3939.1
  3. Wang, Yu and Wu, R., 2021. Factors of Boreal Summer Latent Heat Flux Variations over the Tropical Western North Pacific. Climate Dynamics, 57(9–10), pp. 2753-2765. https://doi.org/10.1007/s00382-021-05835-4
  4. Pichugin, M.I. and Ponomarev, V.I., 2013. Variability of Sensible and Latent Heat Fluxes over the Northwest Part of the Sea of Japan in Cold Season. Vestnik of Far Eastern Branch of Russian Academy of Sciences, (6), pp. 22-29 (in Russian).
  5. Lappo, S.S., Gulev, S.K. and Rozdestvensky, A.E., 1990. Large-Scale Heat Interaction in the Ocean-Atmosphere System and Energetically Active Zones of the World Ocean. Leningrad: Gidrometeoizdat, 336 p. (in Russian).
  6. Surkova, G.V. and Romanenko, V.A., 2021. Seasonal and Long-Term Changes of Turbulent Heat Fluxes between Sea and Atmosphere in Western Sector of the Russian Arctic. Vestnik Moskovskogo Universiteta. Seria 5, Geografia, (4), pp. 74-82 (in Russian).
  7. Vlasova, G.A. and Polyakova, A.M., 2013. Energy-Active Zone of the Ocean and Atmosphere in Nw Pacific. Izvestia: Herzen University Journal of Humanities & Sciences, 163, pp. 128-140 (in Russian).
  8. Bagrov, N.A., 1959. [Analytical Representation of Meteorological Field Series by Natural Orthogonal Components]. Trudy TsIP [Transactions of the Central Institute of Forecasts], 74, pp. 3-24 (in Russian).

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