Effects of increased isopycnal diffusivity mimicking the unresolved equatorial intermediate current system in an earth system climate model
Effects of increased isopycnal diffusivity mimicking the unresolved equatorial intermediate current system in an earth system climate model
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DOI：
10.1002/grl.50419
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发表时间：
2013-05-28
影响因子：
5.2
通讯作者：
Dietze, Heiner
中科院分区：
文献类型：
--
作者：
Getzlaff, Julia;Dietze, Heiner
地球系统气候模式通常低估了赤道太平洋东部深层的溶解氧浓度。这个问题与Najjar等人[1992]描述的营养物捕获问题有关，至少部分是由于赤道中间流系统（EICS）的代表性不足造成的。在这里，我们模拟的UVic地球系统气候模式中的未解决的EICS局部增加纬向等密度扩散。近似50，000 m（2）s（-1）的各向异性扩散系数产生温度、盐度和氧气的改进的全局表示。此外，它（1）解决了赤道东太平洋的大部分局部营养物捕获和相关的氧气不足，（2）减少了等密度线上的假纬向温度梯度，而不影响其他物理指标，如纬向翻转或海气热通量。最后，低含氧沃茨和相关的反硝化作用的气候预测改变的迹象，显然变得更加合理。
Earth system climate models generally underestimate dissolved oxygen concentrations in the deep eastern equatorial Pacific. This problem is associated with the nutrient trapping problem, described by Najjar et al. [1992], and is, at least partially, caused by a deficient representation of the Equatorial Intermediate Current System (EICS). Here we emulate the unresolved EICS in the UVic earth system climate model by locally increasing the zonal isopycnal diffusivity. An anisotropic diffusivity of approximate to 50,000 m(2) s(-1) yields an improved global representation of temperature, salinity and oxygen. In addition, it (1) resolves most of the local nutrient trapping and associated oxygen deficit in the eastern equatorial Pacific and (2) reduces spurious zonal temperature gradients on isopycnals without affecting other physical metrics such as meridional overturning or air-sea heat fluxes. Finally, climate projections of low-oxygenated waters and associated denitrification change sign and apparently become more plausible.