中文摘要：

到增加的 CO2 集中和联系机制的 ENSO 频率的反应与提交到 IPCC 的四个联合气候模型(GFDL/CM2.0， CNRM/CM3， IPSL/CM4 和 INM/CM3.0 ) 的产量被检验第四份评价报告(IPCC AR4 ) 。结果作为对增加的 CO2 集中的反应揭示 ENSO 频率的一个重要变化。然而，如此的一个变化展出明显的模型依赖。ENSO 频率趋于在 IPSL/CM4 和 INM/CM3.0 模型在 GFDL/CM2.0 和 CNRM/CM3 模型和减少增加。模型依赖被发现热带太平洋的模型 climatological 背景状态怎么对增加的 CO2 集中作出回应决定。这被表明在赤道和离开赤道之间的上面的海洋温度坡度是的地带地平均、垂直地平均的 climatological 背景的变化为 ENSO 频率变化关键地负责。作为对增加的 CO2 集中的反应， climatological 背景温度坡度在 GFDL/CM2.0 和 CNRM/CM3 模型被增加并且在 IPSL/CM4 和 INM/CM3.0 模型减少了。以为 ENSO 的再装分泌物振荡器理论，增加(减少)在赤道和离开赤道之间的 climatological 背景温度坡度导致一更快(更慢)在赤道和离开赤道之间的海洋的热内容的交换，因此产生一更短(更长) ENSO timescale 并且一更高(更低) ENSO 频率。

英文摘要：

The response of ENSO frequency to the increasing CO2 concentration and associated mechanism are examined with outputs of four coupled climate models （GFDL/CM2.0, CNRM/CM3, IPSL/CM4 and INM/CM3.0） submitted to the IPCC Fourth Assessment Report （IPCC AR4）. Results reveal a significant change of ENSO frequency as response to the increasing CO2 concentration However, such a change exhibits an evident model dependence. The ENSO frequency tends to increase in GFDL/CM2.0 and CNRM/CM3 models and decreases in IPSL/CM4 and INM/CM3.0 models. The model dependence is found to be determined by how the model climatological background state of the tropical Pacific responds to the increasing CO2 concentration. It is demon- strated that the change of zonally- and vertically-averaged climatological background upper ocean temperature gradient between the equator and off-equator is crucially responsible for the ENSO frequency change. As response to the increasing CO2 concentration, the climatological background temperature gradient is increased in GFDL/CM2.0 and CNRM/CM3 models and decreased in IPSL/CM4 and INM/CM3.0 models. In terms of the recharge-discharge oscillator theory for ENSO, the increased （decreased） climatological background temperature gradient between the equator and off-equator induces a faster （slower） exchange of oceanic heat content between the equator and off-equator, thus giving rise to a shorter （longer） ENSO timescale and a higher （lower） ENSO frequency.