A Model that Explains the Contrasting SST Trends in the Southern Pacific Ocean
DOI:
https://doi.org/10.61173/xnag2k18Keywords:
SST trends, Ocean-Atmoshpere-Ice Interaction, the Southern Pacific OceanAbstract
Sea surface temperature (SST) of the southern Pacific Ocean plays an important role in ocean-atmospheric interactions, influencing both regional and global climate and ecosystems. The contrasting SST trends in the southern Pacific Ocean during 1993-2021 are noted by analyzing satellite and in-situ datasets, consisting of SST warming trend (0.05℃·yr−1) in the region of 80°W-180,30°S-50°S and cooling trend (−0.04℃·yr−1) in the area of 60°W-150°W, 55°S-70°S. A detailed trend analysis for the wind and sea ice concentration suggest that Ekman transport and sea ice radiative positive feedback are the two key contributors to the contrasting SST trends. The intensified downwelling (upwelling), induced by the Ekman transport and strengthened westerlies, gives rise to warm (cold) water swarming in (upturning) from lower latitudes (deeper ocean), which causes SST warming (cooling). Moreover, the sea ice increase at higher latitudes, due to both the cold water transport from deeper ocean layers and broken ice transport from polar regions, strengthens the cooling trend through sea ice positive radiative feedback. In conclusion, these findings underscore the complexity of SST trends in the southern Pacific Ocean, highlighting the critical roles of Ekman transport and sea ice radiative feedback in shaping regional climate dynamics.Plain Language Summary: The southern Pacific Ocean is an indispensable part in the climate system while it still remained poorly observed. The SST trend is regarded as a critical indicator of global climate change. Using the satellite and in-situ datasets, we find that the contrasting SST trends from 1993 to 2021, one area in this region is warmed by 0.3℃ per decade, while another area is cooled by -0.1℃ per decade. Considering impacts of various factors such as wind, sea ice and radiation, the primarily explanation is that wind-driven warm (cold) water from the subtropics (deeper ocean) flows in and goes downward (goes upward and flow away) in the warm (cold) area through oceanic circulation and leads to the SST warming (cooling). Additionally, the cooling trend is also related to the cold water that flows to higher latitudes and forms ice there and at the same time, trash ice from polar regions driven by enhanced south wind speed will be transported there. As a result, ice increases, reflects more shortwave radiation to space, and surface downward shortwave radiation decreases which contributes to SST decreases.
References
[1] Bowen, M., Markham,J., Sutton, P., Zhang, X., Wu, Q., Shears, N. T., & Fernandez, D. (2017). Inter- annual Variability of Sea Surface Temperature in the Southwest Pacific and the Role of Ocean Dynamics. Journal of Climate, 30(18), 7481– 7492. https://doi.org/10.1175/JCLI-D-16-0852.1
[2] Cushman-Roisin, B., & Beckers, J.-M. (2011). Chapter 8 - The Ekman Layer. In B. Cushman-Roisin & J.-M. Beckers (Eds.), Introduction to Geophysical Fluid Dynamics (Vol. 101, pp. 239–270). Academic Press. https://doi.org/10.1016/B978-0-12- 088759-0.00008-0
[3] Fernandez, Denise, Bowen, Melissa, Sutton, & Philip. (2022). South Pacific Ocean Dynamics Redis- tribute Ocean Heat Content and Modulate Heat Exchange With the Atmosphere. Geophysical Research Letters, 49(23), e2022GL100965. https:// doi.org/10.1029/2022GL100965
[4] Haumann, Alexander, F., Gruber, Nicolas, & Münnich, M. (2020). Sea-Ice Induced Southern Ocean Subsurface Warming and Surface Cooling in a Warming Climate. AGU Advances, 1(2), e2019AV000132. https://doi.org/10.1029/2019AV000132
[5] Hobbs, W. R., Massom, R., Stammerjohn, S., Reid, P., Williams, G., & Meier, W. (2016). A review of recent changes in Southern Ocean sea ice, their drivers and forcings. Global and Planetary Change, 143, 228–250. https://doi.org/https://doi. org/10.1016/j.gloplacha.2016.06.008
[6] Jones, R. N., & Ricketts,J. H. (2021). The Pacific Ocean heat engine. Earth System Dynamics Discus- sions, 1–47. https://api. semanticscholar.org/CorpusID:236783792
[7] Kalnay, E., Kanamitsu, M., Kistler, R. E., Collins,W. D., Deaven, D. G., Gandin, L. S., Iredell, M., Saha, S., White, G. H., Woollen,J. S., Zhu,Y., Chelliah, M., Ebisuzaki,W., Higgins,W.J., Janowiak,J. E., Mo, K. C., Ropelewski, C., Wang,J., Leetmaa, A., … Joseph, D. (1996). The NCEP/NCAR 40-Year Reanalysis Dean&Francis Project. Renewable Energy. https://api.semanticscholar.org/ CorpusID:124135431
[8] Kato, S., Rose, F. G., Rutan, D. A., Thorsen, T. J., Loeb, N. G., Doelling, D. R., Huang, X., Smith, W. L., Su, W., & Ham, S.- H. (2018). Surface Irradiances of Edition 4.0 Clouds and the Earth’s Radiant Energy System (CERES) Energy Balanced and Filled (EBAF) Data Product. Journal of Climate, 31(11), 4501– 4527. https://doi.org/10.1175/JCLI-D-17-0523.1
[9] Kieu, C. Q., Zhao, M., Tan, Z., Zhang, B., & Knutson, T. R. (2023). On the Role of Sea Surface Temperature in the Clustering of Global Tropical Cyclone Formation. Journal of Climate. https://api. semanticscholar.org/CorpusID:256294860
[10] Li,Q., Luo, Y., Lu,J., & Liu, F. (2022). The Role of Ocean Circulation in Southern Ocean Heat Uptake, Transport and Storage Response to Quadrupled CO2. Journal of Climate. https://api.semanticsc holar.org/CorpusID:251083035
[11] Loeb, N. G., Doelling, D. R., Wang, H., Su, W., Nguyen, C., Corbett, J. G., Liang, L., Mitrescu, C., Rose, F. G., & Kato, S. (2018). Clouds and the Earth’s Radiant Energy System (CERES) Energy Balanced and Filled (EBAF) Top-of-Atmosphere (TOA) Edition-4.0 Data Product. Journal of Climate, 31(2), 895–918. https://doi.org/10.1175/JCLI-D-17-0208.1
[12] Meier, N., W., Fetterer, F., W., K., A., Stewart, & S., J. (2021). Near-Real-Time NOAA/NSIDC Climate Data Record of Passive Microwave Sea Ice Concentration, Version 2. https:// doi.org/10.7265/tgam-yv28
[13] Merchant, C.J., Embury, O., Bulgin, & C.E. (2019). Satellite-based time-series of sea-surface temperature since 1981 for climate applications. Sci Data, 6(223). https://doi. org/10.1038/s41597-019-0236-x
[14] Saurral, D.-R. F. &. G.-S. J., R.I. (2018). Observed modes of sea surface temperature variability in the South Pacific region. Clim Dyn, 50, 1129–1143. https://doi.org/10.1007/ s00382-017-3666-1
[15] Seager, R., Henderson,N., & Canea,M. (2022). Persistent Discrepancies between Observed and Modeled Trends in the Tropical Pacific Ocean. https://api.semanticscholar.org/ CorpusID:253501859
[16] Serratosa, J., Hyrenbach, K. D., Miranda-Urbina, D., Portflitt-Toro, M., Luna, N., & Luna-Jorquera, G. (2020). Environmental Drivers of Seabird At-Sea Distribution in the Eastern South Pacific Ocean: Assemblage Composition Across a Longitudinal Productivity Gradient. Frontiers in Marine Science, 6. https://doi.org/10.3389/fmars.2019.00838
[17] Sutton,H., P.J., Rickard,J., G., Roemmich, & H., D. (2024). Southwest Pacific Ocean Warming Driven by Circulation Changes. Geophysical Research Letters, 51(13), e2024GL109174. https://doi.org/10.1029/2024GL109174
[18] Turner, John, Holmes, Caroline, Harrison, C., Thomas, Phillips, Tony, Jena, Babula, Reeves-Francois, Tylei, Fogt, Ryan, Thomas, E. R., & Bajish, C. C. (2022). Record Low Antarctic Sea Ice Cover in February 2022. Geophysical Research Letters, 49(12), e2022GL098904. https://doi. org/10.1029/2022GL098904
[19] Xu, Xiaoqi,Liu, Jiping, Huang, & Gang. (2022). Understanding Sea Surface Temperature Cooling in the Central- East Pacific Sector of the Southern Ocean During 1982–2020. Geophysical Research Letters, 49(10), e2021GL097579. https:// doi.org/10.1029/2021GL097579
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