Russian Federation
Russian Federation
We consider the decomposition of water temperature fields into the Empirical Orthogonal Functions (EOFs), also known as Principal Components (PCs). We use the GREP data (Global Reanalysis Ensemble Product) in this study and we examine water temperature at the horizon of 457 m for the period 1993–2019 in the area limited to 50°–80°N, 50°W–20°E. It is shown that the first two Principal Components of decomposition (PC1 and PC2) are responsible for 48% of the total variance, and all subsequent ones are smaller by an order of magnitude. The time series of PC1 and PC2 are further considered as indicators responsible for the transfer of Atlantic heat to the Arctic. Transport and heat fluxes have been calculated through the cross-section 64.5°N, which connects Iceland with Scandinavia. It is shown that PC1 characterizes transport through the cross-section, and PC2 is responsible for heat fluxes. The analysis of the spatial distribution of PC1 and PC2 loadings allowed us to introduce three new NAT, NAHT1, and NAHT2 indices determined by water temperature anomalies. The NAT index is responsible for the transport of Atlantic waters to the Arctic, and two identical indices NAT1 and NAT2 characterize the corresponding heat transfer by these waters. The time series responsible for heat transfer to the Arctic [https://doi.org/10.2205/2022ES000792-data] in text format are available at the website of Earth Science Data Base (ESDB) repository [http://esdb.wdcb.ru/] located in Geophysical Center RAS.
Atlantic Ocean; Arctic; AMOC; climate; transport; heat fluxes; empirical orthogonal functions; EOF; principal components; indicators; GREP
1. Alekseev, G.V., Kuzmina, S.I., Urazgildeeva, A.V., Bobylev, L.P. Impact of atmos-pheric heat and moisture on Arctic warming in winter. Fundamental'naya i prikladnaya klimatologiya [Fundamental and applied climatology]. 1, 43-63.https://doi.org/10.21513/2410-8758-2016-1-43-63. (In Russian) (2016).
2. Belonenko,T.V. and Fedorov A.M. Steric Level Fluctuations and Deep Convection in the Labrador and Irminger Seas. Izvestiya, Atmospheric and Oceanic Physics, Vol. 54, No. 9, pp. 1039-1049. DOI:https://doi.org/10.1134/S0001433818090086. (2018).
3. Belonenko, T.V., Koldunov, A.V. Trends of Steric Sea Level Oscillations in the North Atlantic. Izvestiya, Atmospheric and Oceanic Physics, 55 (9), 1106-1113. DOI:https://doi.org/10.1134/S0001433819090081. (2019).
4. Beszczynska-Möller, A., Fahrbach, E., Schauer, U., & Hansen, E. Variability in Atlan-tic water temperature and transport at the entrance to the Arctic Ocean, 1997-2010. IC-ES Journal of Marine Science, 69(5), 852-863. doihttps://doi.org/10.1093/icesjms/fss056. (2012).
5. Biri, S., & Klein, B. North atlantic sub-polar gyre climate index: A new approach. Journal of Geophysical Research: Oceans, 124, 4222-4237. doi:https://doi.org/10.1029/2018JC014822. (2019).
6. Bryden, H. L., Johns, W. E., King, B. A., McCarthy, G., McDonagh, E. L., Moat, B. I., & Smeed, D. A. Reduction in ocean heat transport at 26°N since 2008 cools the eastern subpolar gyre of the North Atlantic Ocean. Journal of Climate. doihttps://doi.org/10.1175/jcli-d-19-0323.1. (2019).
7. Bekryaev, R.V. Interrelationships of the North Atlantic multidecadal climate variability characteristics, Russ. J. Earth Sci., 19, ES3004, doihttps://doi.org/10.2205/2018ES000653. (2019).
8. Buckley, M. W., & Marshall, J. Observations, inferences, and mechanisms of the At-lantic Meridional Overturning Circulation: A review. Reviews of Geophysics, 54(1), 5-63. doihttps://doi.org/10.1002/2015rg000493. (2016).
9. Caesar, L., McCarthy, G. D., Thornalley, D. J. R., Cahill, N., & Rahmstorf, S. Current Atlantic Meridional Overturning Circulation weakest in last millennium. Nature Geo-science, 14(3), 118-120. doihttps://doi.org/10.1038/s41561-021-00699-z. (2021).
10. Cheng, W., Chiang, J. C. H., & Zhang, D. Atlantic Meridional Overturning Circulation (AMOC) in CMIP5 Models: RCP and Historical Simulations. Journal of Climate, 26(18), 7187-7197. doihttps://doi.org/10.1175/jcli-d-12-00496.1. (2013).
11. Chiang, J. C. H., and Vimont, D. J. Analogous meridional modes of atmosphere-ocean variability in the tropical Pacific and tropical Atlantic. Journal of Climate, 17(21), 4143-4158. (2004).
12. Dong, S., Goni, G., Domingues, R., Bringas, F., Goes, M., Christophersen, J., & Ba-ringer, M. Synergy of in situ and satellite ocean observations in determining meridional heat transport in the Atlantic Ocean. Journal of Geophysical Research: Oceans, 126, e2020JC017073. https://doi.org/10.1029/2020JC017073. (2021).
13. Frajka-Williams, E., Ansorge, I. J., Baehr, J., Bryden, H. L., Chidichimo, M. P., Cun-ningham, S. A., … Wilson, C. Atlantic Meridional Overturning Circulation: Observed Transport and Variability. Frontiers in Marine Science, 6. doihttps://doi.org/10.3389/fmars.2019.00260. (2019).
14. Grigorieva, V. and S. K. Gulev Wave climate in subarctic seas from Voluntary Observ-ing Ships: 1900-2020, Russ. J. Earth. Sci., 20, ES14015, doihttps://doi.org/10.2205/2020ES000729. (2020).
15. Gordeeva, S. M., T. V. Belonenko (2022), New indicators responsible for heat transfer from the Atlantic to the Arctic, ESDB repository, GCRAS,
16. Hurrell et al. The North Atlantic Oscillation: Climate Significance and Environmental Impact, Geophysical Monograph 134, American Geophysical Union. DOI:https://doi.org/10.1029/GM134. (2003)
17. IPCC 2019. Climate Change and Land: an IPCC special report on climate change, des-ertification, land degradation, sustainable land management, food security, and green-house gas fluxes in terrestrial ecosystems. 874 p. https://www.ipcc.ch/site/assets/uploads/2019/11/SRCCL-Full-Report-Compiled-191128.pdf. (2019).
18. Koul, V., Tesda, J.-E., Bersch1, M., Hátún, H., Brune, S., Borchert, L., Haak, H., Schrum, C., & Baehr, J. Unraveling the choice of the north Atlantic subpolar gyre in-dex. Scientific Reports 10:1005. DOI:https://doi.org/10.1038/s41598-020-57790-5 1. (2020).
19. Kuznetsova, D. A., Bashmachnikov, I. L. On the Mechanisms of Variability of the At-lantic Meridional Overturning Circulation (AMOC). Oceanology. 61 (6), 843-855. DOI:https://doi.org/10.31857/S0030157421060071. (2021).
20. Larson S. M., Buckley M. W., Clement A. C. (2020). Extracting the Buoyancy-Driven Atlantic Meridional Overturning Circulation. Journal of Climate. 33. 4697-4714.
21. Loose, N., Heimbach, P., Pillar, H. R., & Nisancioglu, K. H. Quantifying dynamical proxy potential through shared adjustment physics in the North Atlantic. Journal of Geophysical Research: Oceans, 125, e2020JC016112. DOI:https://doi.org/10.1029/2020JC016112. (2020).
22. Pnyushkov, A. V., Polyakov, I. V., Rember, R., Ivanov, V. V., Alkire, M. B., Ashik, I. M., … Sundfjord, A. Heat, salt, and volume transports in the eastern Eurasian Basin of the Arctic Ocean from 2 years of mooring observations. Ocean Sci., 14(6), 1349-1371, https://doi.org/10.5194/os-14-1349-2018. (2018).
23. Rahmstorf, S., Box, J. E., Feulner, G., Mann, M. E., Robinson, A., Rutherford, S., & Schaffernicht, E. J. Exceptional twentieth-century slowdown in Atlantic Ocean over-turning circulation. Nature Climate Change, 5(5), 475-480. doihttps://doi.org/10.1038/nclimate2554. (2015).
24. Smith, G. C., Haines, K., Kanzow, T., and Cunningham, S. Impact of hydrographic da-ta assimilation on the modelled Atlantic meridional overturning circulation, Ocean Sci., 6, 761-774, https://doi.org/10.5194/os-6-761-2010. (2010).
25. Tsubouchi, T., Våge, K., Hansen, B., Larsen, K. M. H., Østerhus, S., Johnson, C., … Valdimarsson, H. Increased ocean heat transport into the Nordic Seas and Arctic Ocean over the period 1993-2016. Nature Climate Change. doihttps://doi.org/10.1038/s41558-020-00941-3. (2020).
26. Volodin, E. M., V. Ya. Galin, N. A. Diansky, V. P. Dymnikov, and V. N. Lykossov. Mathematical modeling of potential catastrophic climate changes, Russ. J. Earth Sci., 10, ES2004, doihttps://doi.org/10.2205/2007ES000231. (2008).
27. Weijer, W., Cheng, W., Drijfhout, S. S., Fedorov, A. V., Hu, A., Jackson, L. C., … Zhang, J. Stability of the Atlantic Meridional Overturning Circulation: A Review and Synthesis. Journal of Geophysical Research: Oceans. doihttps://doi.org/10.1029/2019jc015083. (2019).
28. Yamamoto, A., Tatebe, H., & Nonaka, M. On the emergence of the Atlantic multide-cadal SST signal: A key role of the mixed layer depth variability driven by North Atlan-tic Oscillation. Journal of Climate. doihttps://doi.org/10.1175/jcli-d-19-0283.1. (2020).
29. Zhang, R. Coherent surface-subsurface fingerprint of the Atlantic meridional overturn-ing circulation. Geophysical Research Letters, 35(20). doihttps://doi.org/10.1029/2008gl035463. (2008).
30. Zhang, R., Sutton, R., Danabasoglu, G., Kwon, Y., Marsh, R., Yeager, S. G., … Little, C. M. A Review of the Role of the Atlantic Meridional Overturning Circulation in At-lantic Multidecadal Variability and Associated Climate Impacts. Reviews of Geophysics. doihttps://doi.org/10.1029/2019rg000644. (2019).
