Modeling of the Teleconnections in the African Climate

大量实证研究表明， 大陆尺度的气候异常在 决定了非洲气候的多变性。 其中一 十年尺度的气候异常制度涉及的同时， 在降水距平分布中， 赤道非洲和热带非洲之间。 这种大陆规模的 尽管在雨季， 大陆上的每个纬度带 年周期的各个阶段。 显然，一个大陆规模的 遥相关机制似乎参与了 发展和维持这些气候条件。 的 PI的解是从一个稳态多水平线性 模型，表明大规模之间的相互作用 非洲地形和气候波动的基本 国家可以帮助产生观察到的遥相关在 非洲气候 私家侦探会把他之前的调查 通过执行一系列基于NCAR的数值模拟， 社区气候模式（CCM）。 这次调查将针对两个不同但密切相关的 相关和互补的目标，可以说是 如下(1)美国国家大气研究中心（National Center for Atmospheric Research） （NCAR）社区气候模型（CCM），以调查观察到的 全球海表温度的三向联系 (SST)非洲大陆尺度遥相关 气候和萨赫勒地区的干旱。 数值 综合将基于两个版本的NCAR GCM，一个 早期型号指定为CCM 1，以及新版本CCM 2，其中 已进行了广泛的改进。 (2)引进和 测试一个新的假设， 非洲大尺度地形和平均纬向 在促进非洲观测到的遥相关方面的流动 气候 通过这次调查，PI希望澄清一些 重要的物理机制，负责大陆- 非洲气候的遥相关 另外该 研究将有助于评估CCM 1的相对性能， CCM 2在模拟热带气候变率方面， 为模型的进一步改进做出贡献。

A Significant body of empirical studies indicated that continental-scale climate anomalies play an important part in determining the variability of the African climate. One of these decadal-scale climate anomaly regimes concerns the simultaneous phase reversal, in the precipitation anomaly distribution, between equatorial and tropical Africa. This continental-scale concurrence happens despite the fact that the rainy season in each latitudinal band over the continent comes at different phases of the annual cycle. Clearly, a continental-scale teleconnection mechanism appears to be involved in the development and maintenance of these climatic conditions. The PI's solutions obtained form a steady-state multi-level linear model, indicate that the interaction between the large-scale African orography and the climatic fluctuations in the basic state could help to produce the observed teleconnections in the African climate. The PI will extend his previous investigations by performing a series of numerical simulations based on the NCAR Community Climate Model (CCM). This investigation will be aimed at two distinct but closely related and complementary objectives which may be stated as follows. (1) Employ the National Center for Atmospheric Research (NCAR) Community Climate Model (CCM) to investigate the observed three-way connection between the global sea surface temperature (SST), the continental-scale teleconnections in the African climate, and the regional Sahelian droughts. The numerical integrations will be based on two versions of the NCAR GCM, an earlier model designated CCM1, and a new version CCM2, in which extensive enhancements have been implemented. (2) Introduce and test a new hypothesis concerning the role of the interaction between the large-scale orography of Africa and the mean zonal flow in promoting the observed teleconnections in the African climate. Through this investigation the PI hopes to clarify some of the important physical mechanisms responsible for the continental- scale teleconnections in the African climate. In addition this study will help to assess the relative performances of CCM1 and CCM2 in simulating the variability of the tropical climate, thus contributing toward further improvements in the models.