Sensitivity of simulated extent and future evolution of marine suboxia to mixing intensity
Sensitivity of simulated extent and future evolution of marine suboxia to mixing intensity
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DOI：
10.1029/2011gl046877
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发表时间：
2011-03-31
影响因子：
5.2
通讯作者：
Oschlies, A.
中科院分区：
文献类型：
--
作者：
Duteil, O.;Oschlies, A.
地质和水文记录包含了过去全球海洋氧化作用发生重大变化的证据。数值模型预测，在全球变暖的情况下，未来海洋氧气水平会下降。利用一个全球海洋地球化学-气候模式，在该模式中，底流混合被参数化为区域非均匀潮汐和均匀背景垂直混合的总和，我们在这里表明，模拟的海洋总氧含量和海洋低氧的程度都敏感的背景垂直混合的强度。在工业化前的条件下，针对不同的垂直扩散率（范围从0.01 cm（2）/s到0.5 cm（2）/s的背景值），旋转了8个其他方面相同的模型配置。这一范围对应于各种观测估计值和目前在海洋环流数值模式中使用的数值。尽管模拟的海洋总氧含量在较大的混合强度下较大，但模拟的亚氧体积在大约0.2 cm（2）/s的中等扩散率下显示出最大值。垂直混合的强度也决定了21世纪二氧化碳排放量预测下的亚氧区的演变：虽然所有模式配置都预测海洋氧气总量会下降，但模拟的海洋亚氧区范围仅在混合速率高于0.2 cm（2）/s时才显示出21世纪的扩张，而尽管海洋氧气总体损失，但混合速率较低时，亚氧区体积会下降。因此，在约束不佳的混合参数化的差异，可能会导致定性不同的估计未来的演变海洋suboxia预测气候变化。引文：Duteil，O.，和A. Oschlies（2011年），模拟范围的敏感性和海洋亚低氧对混合强度的未来演变，地球物理学。保留信函：38，L06607，doi：10.1029/2011GL046877。
Geological and hydrographic records contain evidence of substantial past variations in the oxygenation of the global ocean. Numerical models predicts a future decrease of marine oxygen levels under global warming. Using a global biogeochemical-climate model in which diapycnal mixing is parametrised as the sum of the regionally heterogenous tidal and homogenous background vertical mixing, we here show that simulated total oceanic oxygen content and the extent of marine suboxia are both sensitive to the strength of background vertical mixing. Eight otherwise identical configurations of the model were spun up under pre-industrial conditions for different vertical diffusivities ranging from background values of 0.01 cm(2)/s to 0.5 cm(2)/s. This range corresponds to various observational estimates and to values currently used in numerical ocean circulation models. Whereas the simulated total oceanic oxygen content is larger for larger mixing intensities, the simulated suboxic volume displays a maximum at intermediate diffusivities of about 0.2 cm(2)/s. The intensity of vertical mixing also determines the evolution of suboxic areas under projected 21st century CO2 emissions: while all model configurations predict a decline in total oceanic oxygen, the simulated extent of marine suboxia shows a 21st century expansion only for mixing rates higher than 0.2 cm(2)/s, whereas the suboxic volume declines for lower mixing rates despite an overall loss of marine oxygen. Differences in the poorly constrained mixing parameterisation can thus lead to qualitatively different estimates about the future evolution of marine suboxia under projected climate change. Citation: Duteil, O., and A. Oschlies (2011), Sensitivity of simulated extent and future evolution of marine suboxia to mixing intensity, Geophys. Res. Lett., 38, L06607, doi: 10.1029/2011GL046877.