北冰洋次表层暖水形成机制的研究

分析了北冰洋加拿大海盆上层海水温度结构特征,针对在海冰覆盖区域普遍发生的次表层暖水现象,建立了冰海耦合的一维柱形模式,成功模拟了次表层暖水的垂向结构和形成机制,证明了太阳辐射加热和表层冷却是次表层暖水的成因。通过数值实验定量分析了形成次表层暖水各因子的作用,表明太阳辐射是形成次表层暖水的能量来源;长波辐射、气温和比湿等其他大气因子对次表层暖水强度有较大影响;在厚冰区不能形成次表层暖水,海冰越薄,水道面积越大,则冰下次表层海水温度升高得就越快,薄冰和冰间水道是形成次表层暖水的主要能量通道;通过模式的拟合给出湍扩散系数垂向变化的估值,冰下表层海水垂向湍扩散系数为5.0×10-3m2/s左右,而次表层垂向湍扩散系数却快速降低到1.0×10-6m2/s,表明跃层导致的稳定性增大是形成次表层暖水尖峰的关键因素。

Theoretical study on modulating group velocity of light inphotonic crystal coupled cavity optical waveguide

We present a novel mechanism,which is formed by periodically changing the radii of dielectric rods in the middle row of a photonic crystal, to control and stop light. Using the Bloch theory and coupled-mode theoryl the dispersion characteristic of such a photonic crystal coupled cavity optical waveguide is obtained. We also theoretically demonstrate that the group velocity of a light pulse in this system can be modulated by dynamically changing the refractive index or radii of the selected dielectric rods, and the light stopping can be achieved.