Responses of seasonal cycles of the mixed layer depth and subduction rate to global warming in the subtropical Northeast Pacific

Wang Yishan; Xia Ruibin

doi:10.12284/hyxb2022202

Volume 44 Issue 10

Oct. 2022

Turn off MathJax

Article Contents

Article Navigation > Haiyang Xuebao > 2022 > 44(10): 35-48

Wang Yishan，Xia Ruibin. Responses of seasonal cycles of the mixed layer depth and subduction rate to global warming in the subtropical Northeast Pacific[J]. Haiyang Xuebao，2022, 44(10)：35–48 doi: 10.12284/hyxb2022202

Citation:

PDF( 2442 KB)

Responses of seasonal cycles of the mixed layer depth and subduction rate to global warming in the subtropical Northeast Pacific

doi: 10.12284/hyxb2022202

Wang Yishan^1
,,
Xia Ruibin^{1, 2
,
,}

1.
School of Marine Science, Nanjing University of Information Science and Technology, Nanjing 210044, China
2.
Nanjing Xinda Institute of Safety and Emergency Management, Nanjing 210044, China

Received Date: 2021-12-04
Rev Recd Date: 2022-07-13

Available Online: 2022-07-29

Publish Date: 2022-10-01

Abstract

Abstract

Based on the Earth System Model (ESM2M) of the Coupled Model Intercomparison Project 5 (CMIP5), combined with Argo observation data and the reanalysis dataset compiled by Ishii et al., this paper presents the seasonal variation characteristics of mixed layer depth (MLD) and subduction process in the subtropical Northeast Pacific Ocean (10°−40°N, 110°−160°W) under the present climate background and extreme enhancement of radiative forcing are presented, to study its response to global warming. Under the current climate background, both of MLD and subduction rate reach their maximum values in winter. The main contribution items of subduction rate have significant seasonal variation. From January to May, the subduction rate is mainly controlled by the change of lateral induction rate, while from June to December, the main mechanism is the change of Ekman pumping velocity controlled by wind stress curl. After global warming, the main control elements of seasonal signals remain unchanged. However, under the influences of wind stress curl and other factors, the MLD in each season decreased and the range of the core maximum region shrinks. As the decrease in winter is much larger than that in summer, the seasonal fluctuation range (amplitude) of MLD is significantly smaller. In the long run, MLD shows a trend of continuous shallower, and the weakening of MLD front caused by the weakening of its spatial non-uniformity is the key to control the weakening of lateral induction rate and eventually lead to the weakening of the subduction rate. Since the seasonal variation signal of Ekman pumping velocity has little response to global warming, subduction rate is most strongly affected in winter. The results show that the contribution proportion of the two key factors to the subduction rate changes with the seasons: when the MLD front is strong in winter, the influence of the lateral induction rate will be significantly enhanced. The different variations of the two factors before and after global warming will significantly change the seasonal amplitude of the subduction rate, which may have a profound impact on the formation and transport of mode water in the region.
- mixed layer depth,
- subduction rate,
- subtropical Northeast Pacific,
- global warming

FullText(HTML)

References(44)

References

[1]	Kara A B, Rochford P A, Hurlburt H E. Mixed layer depth variability and barrier layer formation over the North Pacific Ocean[J]. Journal of Geophysical Research: Oceans, 2000, 105(C7): 16783−16801. doi: 10.1029/2000JC900071
[2]	Deser C, Alexander M A, Timlin M S. Upper-ocean thermal variations in the North Pacific during 1970–1991[J]. Journal of Climate, 1996, 9(8): 1840−1855. doi: 10.1175/1520-0442(1996)009<1840:UOTVIT>2.0.CO;2
[3]	Alexander M A, Timlin M S, Scott J D. Winter-to-winter recurrence of sea surface temperature, salinity and mixed layer depth anomalies[J]. Progress in Oceanography, 2001, 49(1/4): 41−61.
[4]	Hanawa K, Sugimoto S. ‘Reemergence’ areas of winter sea surface temperature anomalies in the world’s oceans[J]. Geophysical Research Letters, 2004, 31(10): L10303.
[5]	Iwasaka N, Kobashi F, Kinoshita Y, et al. Seasonal variations of the upper ocean in the western North Pacific observed by an Argo float[J]. Journal of Oceanography, 2006, 62(4): 481−492. doi: 10.1007/s10872-006-0070-6
[6]	Suga T, Hanawa K. The mixed-layer climatology in the northwestern part of the North Pacific subtropical gyre and the formation area of subtropical mode water[J]. Journal of Marine Research, 1990, 48(3): 543−566. doi: 10.1357/002224090784984669
[7]	Suga T, Motoki K, Aoki Y, et al. The North Pacific climatology of winter mixed layer and mode waters[J]. Journal of Physical Oceanography, 2004, 34(1): 3−22. doi: 10.1175/1520-0485(2004)034<0003:TNPCOW>2.0.CO;2
[8]	Stommel H. Determination of water mass properties of water pumped down from the Ekman layer to the geostrophic flow below[J]. Proceedings of the National Academy of Sciences of the United States of America, 1979, 76(7): 3051−3055. doi: 10.1073/pnas.76.7.3051
[9]	Woods J D. The physics of thermocline ventilation[J]. Elsevier Oceanography Series, 1985, 40: 543−590.
[10]	Sprintall J, Tomczak M. Evidence of the barrier layer in the surface layer of the tropics[J]. Journal of Geophysical Research: Oceans, 1992, 97(C5): 7305−7316. doi: 10.1029/92JC00407
[11]	Sprintall J, Roemmich D. Characterizing the structure of the surface layer in the Pacific Ocean[J]. Journal of Geophysical Research: Oceans, 1999, 104(C10): 23297−23311. doi: 10.1029/1999JC900179
[12]	Holte J, Talley L. A new algorithm for finding mixed layer depths with applications to Argo data and subantarctic mode water formation[J]. Journal of Atmospheric and Oceanic Technology, 2009, 26(9): 1920−1939. doi: 10.1175/2009JTECHO543.1
[13]	Kraus E B, Turner J S. A one-dimensional model of the seasonal thermocline II. The general theory and its consequences[J]. Tellus, 1967, 19(1): 98−106. doi: 10.3402/tellusa.v19i1.9753
[14]	Qiu B, Kelly K A. Upper-ocean heat balance in the Kuroshio extension region[J]. Journal of Physical Oceanography, 1993, 23(9): 2027−2041. doi: 10.1175/1520-0485(1993)023<2027:UOHBIT>2.0.CO;2
[15]	Qiu B. The Kuroshio extension system: its large-scale variability and role in the midlatitude ocean-atmosphere interaction[J]. Journal of Oceanography, 2002, 58(1): 57−75. doi: 10.1023/A:1015824717293
[16]	Keerthi M G, Lengaigne M, Drushka K, et al. Intraseasonal variability of mixed layer depth in the tropical Indian Ocean[J]. Climate Dynamics, 2016, 46(7/8): 2633−2655.
[17]	Chen S Y, Qiao F L, Huang C J, et al. Effects of the non-breaking surface wave-induced vertical mixing on winter mixed layer depth in subtropical regions[J]. Journal of Geophysical Research: Oceans, 2018, 123(4): 2934−2944. doi: 10.1002/2017JC013038
[18]	Panassa E, Völker C, Wolf-Gladrow D, et al. Drivers of interannual variability of summer mixed layer depth in the Southern Ocean between 2002 and 2011[J]. Journal of Geophysical Research: Oceans, 2018, 123(8): 5077−5090. doi: 10.1029/2018JC013901
[19]	Alraddadi T M, Alsaafani M A, Albarakati A M, et al. Seasonal variability of mixed layer depth from Argo floats in the central Red Sea[J]. Arabian Journal of Geosciences, 2021, 14(6): 496. doi: 10.1007/s12517-021-06862-5
[20]	Gaube P, McGillicuddy Jr D J, Moulin A J. Mesoscale eddies modulate mixed layer depth globally[J]. Geophysical Research Letters, 2019, 46(3): 1505−1512. doi: 10.1029/2018GL080006
[21]	Wang R, Cheng X H, Xu L X, et al. Mesoscale eddy effects on the subduction of North Pacific eastern subtropical mode water[J]. Journal of Geophysical Research: Oceans, 2020, 125(5): e2019JC015641.
[22]	Huang R X, Qiu B. Three-dimensional structure of the wind-driven circulation in the subtropical North Pacific[J]. Journal of Physical Oceanography, 1994, 24(7): 1608−1622. doi: 10.1175/1520-0485(1994)024<1608:TDSOTW>2.0.CO;2
[23]	Ohno Y, Iwasaka N, Kobashi F, et al. Mixed layer depth climatology of the North Pacific based on Argo observations[J]. Journal of Oceanography, 2009, 65(1): 1−16. doi: 10.1007/s10872-009-0001-4
[24]	Xia R B, Liu Q Y, Xu L X, et al. North Pacific eastern subtropical mode water simulation and future projection[J]. Acta Oceanologica Sinica, 2015, 34(3): 25−30. doi: 10.1007/s13131-015-0630-y
[25]	Xia R B, Liu C Y, Cheng C. On the subtropical Northeast Pacific mixed layer depth and its influence on the subduction[J]. Acta Oceanologica Sinica, 2018, 37(3): 51−62. doi: 10.1007/s13131-017-1102-3
[26]	Xia R B, Li B R, Cheng C. Response of the mixed layer depth and subduction rate in the subtropical Northeast Pacific to global warming[J]. Acta Oceanologica Sinica, 2021, 40(4): 1−9. doi: 10.1007/s13131-021-1818-y
[27]	Kawasaki T, Tanaka S, Toba Y, et al. Long-term variability of pelagic fish populations and their environment[C]//Proceedings of the International Symposium. New York: Pergamon Press, 1991.
[28]	Mantua N J, Hare S R, Zhang Y, et al. A Pacific interdecadal climate oscillation with impacts on salmon production[J]. Bulletin of the American Meteorological Society, 1997, 78(6): 1069−1080. doi: 10.1175/1520-0477(1997)078<1069:APICOW>2.0.CO;2
[29]	Toyoda T, Fujii Y, Kuragano T, et al. Interannual-decadal variability of wintertime mixed layer depths in the North Pacific detected by an ensemble of ocean syntheses[J]. Climate Dynamics, 2017, 49(3): 891−907. doi: 10.1007/s00382-015-2762-3
[30]	Hautala S L, Roemmich D H. Subtropical mode water in the Northeast Pacific Basin[J]. Journal of Geophysical Research: Oceans, 1998, 103(C6): 13055−13066. doi: 10.1029/98JC01015
[31]	Oka E, Qiu B. Progress of North Pacific mode water research in the past decade[J]. Journal of Oceanography, 2012, 68(1): 5−20. doi: 10.1007/s10872-011-0032-5
[32]	Richards K J, Whitt D B, Brett G, et al. The impact of climate change on ocean submesoscale activity[J]. Journal of Geophysical Research: Oceans, 2021, 126(5): e2020JC016750.
[33]	Ishii M, Kimoto M, Sakamoto K, et al. Steric sea level changes estimated from historical ocean subsurface temperature and salinity analyses[J]. Journal of Oceanography, 2006, 62(2): 155−170. doi: 10.1007/s10872-006-0041-y
[34]	Dunne J P, John J G, Adcroft A J, et al. GFDL’s ESM2 global coupled climate-carbon earth system models. Part I: physical formulation and baseline simulation characteristics[J]. Journal of Climate, 2012, 25(19): 6646−6665. doi: 10.1175/JCLI-D-11-00560.1
[35]	Taylor K E, Stouffer R J, Meehl G A. An overview of CMIP5 and the experiment design[J]. Bulletin of the American Meteorological Society, 2012, 93(4): 485−498. doi: 10.1175/BAMS-D-11-00094.1
[36]	Luo Y Y, Liu Q Y, Rothstein L M. Simulated response of North Pacific mode waters to global warming[J]. Geophysical Research Letters, 2009, 36(23): L23609. doi: 10.1029/2009GL040906
[37]	Williams R G. The role of the mixed layer in setting the potential vorticity of the main thermocline[J]. Journal of Physical Oceanography, 1991, 21(12): 1803−1814. doi: 10.1175/1520-0485(1991)021<1803:TROTML>2.0.CO;2
[38]	Xie S P, Xu L X, Liu Q Y, et al. Dynamical role of mode water ventilation in decadal variability in the central subtropical gyre of the North Pacific[J]. Journal of Climate, 2011, 24(4): 1212−1225. doi: 10.1175/2010JCLI3896.1
[39]	Xu L X, Xie S P, Liu Q Y, et al. Response of the North Pacific subtropical countercurrent and its variability to global warming[J]. Journal of Oceanography, 2012, 68(1): 127−137. doi: 10.1007/s10872-011-0031-6
[40]	Cushman-Roisin B. Exact analytical solutions for elliptical vortices of the shallow-water equations[J]. Tellus A, 1987, 39(3): 235−244. doi: 10.3402/tellusa.v39i3.11756
[41]	Pond S, Pickard G L. Introductory Dynamical Oceanography[M]. Oxford: Pergamon Press, 1983.
[42]	Toyoda T, Awaji T, Ishikawa Y, et al. Preconditioning of winter mixed layer in the formation of North Pacific eastern subtropical mode water[J]. Geophysical Research Letters, 2004, 31(17): L17206.
[43]	Hu H B, Liu Q Y, Zhang Y, et al. Variability of subduction rates of the subtropical North Pacific mode waters[J]. Chinese Journal of Oceanology and Limnology, 2011, 29(5): 1131−1141. doi: 10.1007/s00343-011-0237-x
[44]	Liu F K, Lu J, Luo Y Y, et al. On the oceanic origin for the enhanced seasonal cycle of SST in the midlatitudes under global warming[J]. Journal of Climate, 2020, 33(19): 8401−8413. doi: 10.1175/JCLI-D-20-0114.1