Mechanisms of Climate Variability in the North Atlantic Ocean

为了了解一些可能与年代际气候变化有关的海洋过程，该项目将对北大西洋环流的1摄氏度模式进行伴随敏感性分析，以研究控制海表温度（SST）的机制。1度模式的行为还将与1/3度和1/6度模式的前向整合进行比较，以研究不可预测的内部过程的重要性，如中尺度涡旋的输送。伴随的研究将用于确定海温对先前地表强迫的敏感性。这项工作的一个假设是，表面强迫的变化可以导致温跃层深度的变化，这种变化随后在斜压时间尺度上通过海洋传播，并可能在随后的年份影响它们上面的海温。这项工作将基于麻省理工学院开发的z坐标海洋环流模型。该方法包括首先进行1950-2000年50年的后置实验，使用1度分辨率版本的模型。将通过比较模型海表温度和COADS海表温度来评估其保真度。然后将利用模型系统的线性化，围绕由后投运行给出的基准轨迹进行三组20年长的伴随灵敏度计算。伴随的三个计算将对应于NAO的不同阶段- 60年代初，90年代初，接近零至70年代中期。将检验其敏感性的变量是冬季末海洋表面0 （10,000 Km^2）区域的空间平均海温。模型计算将在JHU的Beowulf集群和一个国家超级计算中心进行。

0136327/HaineIn an effort to understand some of the oceanic processes that may be involved in decadal climate variability, this project will apply adjoint sensitivity analysis to 1-degree models of the N. Atlantic Ocean circulation to look at mechanisms that control sea-surface temperature (SST). The behavior of the 1-degree model will also be compared to forward integrations with 1/3-degree and 1/6-degree models in order to investigate the importance of unpredictable internal processes such as transport by mesoscale eddies. The adjoint study will be used to determine the sensitivity of SST to prior surface forcing. One of the hypotheses underlying this work is that changes to surface forcing can lead to changes in the depth of the thermocline which subsequently propagate through the ocean on baroclinic time scales and which may affect the SST above them in subsequent years. The work will be based on a z-coordinate ocean circulation model developed at MIT. The approach involves first conducting a 50-year hind-cast experiment for 1950-2000 with a 1-degree resolution version of the model. The fidelity of this will be assessed by comparing model SST with COADS SST. Three sets of 20-year long adjoint sensitivity calculations will then be made using the a linearization of the model system around the fiducial trajectory given by the hind-cast run. The three adjoint calculations will correspond to during different phases of the NAO -- low - early 60s, high - early 90s, near zero - mid-70s. The variable whose sensitivity will be examined will be the end-of-winter SST spatially averaged over O(10,000 Km^2) regions of the ocean surface. Model calculations will be performed on a Beowulf cluster at JHU and at one of the national supercomputing centers.