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Climate feedback analysis of the GFDL IPCC AR4 global warming simulation.

机译：GFDL IPCC AR4全球变暖模拟的气候反馈分析。

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摘要

Both observed and modeled global warming pattern shows a large surface polar warming and a large upper atmospheric warming in the tropics. This pattern leads to an amplification (reduction) of the temperature gradient at upper levels (surface). Physical processes behind this temperature change are the external radiative forcing, and subsequent feedback processes that may amplify or dampen the climate response. This unique warming pattern suggests that high latitudes are very sensitive to climate change and also the area where the largest warming projection uncertainties occur. The objective of this study is to apply a new coupled atmosphere-surface climate feedback-response analysis method to quantify the contributions of the external forcing alone (doubling of carbon dioxide), and subsequent feedback processes to the 3-D global warming pattern in the GFDL_CM2.0 model. The feedbacks under consideration include the water vapor feedback, surface albedo feedback, surface turbulent heat flux feedback, and the sum of the change in cloud radiative forcing (CRF), vertical convective, and large-scale scale dynamical feedback. The partial temperature changes due to the external forcing and due to individual feedbacks are additive and their sum converges toward the temperature change produced by the original GFDL_CM2.0 global warming simulations. Therefore, our attributions of the global warming patter to individual thermodynamic and dynamical processes are mathematically robust and physically meaningful.The partial temperature change due to the water vapor feedback is found to be the largest contributor to the globally averaged surface warming. It is twice as large as the warming due to the external radiative forcing alone. The surface albedo feedback and change in surface cloud radiative forcing increase the surface temperature by a smaller amount. In addition, the changes in atmospheric cloud forcing and large-scale dynamics, as well as the surface turbulent heat flux feedback, contribute to an overall damping the surface warming.In terms of spatial pattern of global warming, the external forcing alone would cause a large surface warming in the extratropics. The water vapor feedback strengthens the tropical warming substantially and the ice/snow albedo feedback contributes to polar warming amplification. The atmospheric dynamical feedbacks associated with the enhancement of vertical convection in the tropics acts to amplify the warming in the upper troposphere at the expense of reducing the warming in the lower troposphere and at the surface in the tropics. The dynamical feedbacks due to the strengthening of the poleward energy transport contribute to a warming in the entire troposphere and the surface in high latitudes. At the surface and in the lower troposphere, the additional warming brought by the change in circulations strengthens the warming due to thermodynamical forcings (e.g., external forcing, water vapor feedback, and ice albedo feedback). In the upper troposphere, the warming brought by the change in circulations dominates the cooling due to thermodynamical forcings. As a result, the entire troposphere becomes warmer. The stratospheric cooling is entirely due to the external radiative forcing.
机译：观测到的和模拟的全球变暖模式均显示热带地区存在较大的表面极地变暖和​​较大的高层大气变暖。该模式导致在较高水平（表面）的温度梯度增大（减小）。温度变化背后的物理过程是外部辐射强迫，其后的反馈过程可能会放大或减弱气候响应。这种独特的变暖模式表明，高纬度地区对气候变化以及变暖预估不确定性最大的地区非常敏感。这项研究的目的是应用一种新的耦合的大气-地表气候反馈-响应分析方法来量化仅外部强迫作用（二氧化碳加倍）的贡献，以及随后的反馈过程对全球3D全球变暖模式的影响。 GFDL_CM2.0模型。正在考虑的反馈包括水蒸气反馈，地表反照率反馈，地表湍流热通量反馈以及云辐射强迫（CRF），垂直对流和大规模动态反馈的变化之和。由于外部强迫和由于个别反馈而导致的部分温度变化是相加的，它们的总和收敛于由原始GFDL_CM2.0全球变暖模拟产生的温度变化。因此，我们将全球变暖模式归因于各个热力学和动力学过程在数学上是稳健的并且在物理上有意义。发现水蒸气反馈导致的部分温度变化是造成全球平均表面变暖的最大因素。仅由于外部辐射强迫，它就变暖了两倍。表面反照率反馈和表面云辐射强迫的变化使表面温度升高的幅度较小。此外，大气云强迫和大规模动力学的变化以及地表湍流热通量反馈有助于整体减缓地表变暖。就全球变暖的空间格局而言，仅外部强迫会导致气候变暖。温带地区的地表温度升高。水蒸气反馈极大地增强了热带变暖，而冰/雪反照率反馈有助于极地变暖。与热带垂直对流的增强相关的大气动力反馈，以扩大对流层上层的变暖为代价，减少了对流层下层和热带表面的变暖。由于加强了极向能量传输而产生的动态反馈促使整个对流层和高纬度地区变暖。在地表和对流层较低处，由于热力学强迫（例如外部强迫，水汽反馈和冰反照率反馈），循环变化带来的额外变暖加剧了变暖。在对流层上部，由于热力学强迫，循环变化带来的变暖主导了冷却。结果，整个对流层变暖。平流层冷却完全归因于外部辐射强迫。

著录项

  • 作者

    Castet, Christelle.;

  • 作者单位

    The Florida State University.;

  • 授予单位 The Florida State University.;
  • 学科 Climate Change.Atmospheric Sciences.Meteorology.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 137 p.
  • 总页数 137
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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