Climate Fluctuations and Climate Sensitivity Studies

对具有理想地理条件的NCAR CCM长期模式运行的初步检验表明，地表温度场可以解释为一个受时空噪声影响的系统。线性系统可以解释为具有扩散水平热输运和线性辐射阻尼的能量平衡气候模式。两个模型中的表面温度场都有几个有趣的性质。例如，在几千公里的距离上，空间相关统计基本上是各向同性的，在1500公里左右的特征长度上，空间相关下降，这与EBM和地表温度数据一致。线性理论认为，对点热源的气候（=时间平均）响应应表现出与等倍空间自相关函数相同的空间模式。CCM地表数据似乎就是这种情况。这些证据有助于解释为什么与数据和gcm相比，EBM在早期的季节周期研究中，甚至在各种古气候情景中都取得了如此大的成功。本研究将利用简单模式研究气候变率和变化的潜在机制。该项目将系统地考察通量和相关气象场，以阐明气候波动和响应现象具有明显线性的原因。这项研究很重要，因为它可以让我们深入了解气候系统是如何工作的——这是对未来气候进行更可信预测的先决条件。

Preliminary examination of a long model run of the NCAR CCM with idealized geography indicates that the surface temperature field can be interpreted as an system forced by noise in space- time. The linear system can be interpreted as an energy-balance climate model (EBM) with diffusive horizontal heat transport and linear radiation damping. The surface temperature field in both models has several interesting properties. For example, the spatial correlation statistics are essentially isotropic over distances of a few thousand km. The spatial correlations fall off with a characteristic length of about 1500 km which agrees with the EBM and with surface temperature data. Linear theory suggests that climatological (=time averaged) responses to point heat sources should exhibit a spatial pattern identical to the equal times spatial auto correlation function. This appears to be the case in the CCM surface data. These pieces of evidence help to explain why the EBM has been so successful in earlier studies of the seasonal cycle and even in various paleoclimate scenarios compared to data and GCMs. This research will study the underlying mechanisms of climate variability and change using simple models. The PI will systematically examine the fluxes and related meteorological fields in order to clarify the reasons for the apparant linearity of climate fluctuation and response phenomena. This research is important because it may give insight into how the climate system works - a pre-requisite for more credible predictions of future climates.