海洋对大气风应力强迫响应的数值模拟及其与El Ninño的关系

THE NUMERICAL SIMULATION ON OCEANIC FORCING RESPONSE TO ATMOSPHERIC WIND STRESS AND THE RELATION WITH EL NIÑO

中文摘要:

      本文设计了一个一层的等效非线性浅水模式,用此模式进行了有关海洋对表面风应力强迫的试验,并用于解释El Ninño的形成过程。结果表明,当西太平洋东部的偏东风突然减弱,并转变为偏西风时,能引起太平洋东部海面高度及温度的升高。该非线性浅水模式及相应的线性浅水模式都较成功地模拟了中东太平洋大范围增暖的这类广义El Ninño事件^[1]。试验结果还表明,东部海域海面高度的升高及增暖强度与西部海域西风的强度、持续时间和扩展的范围有关,即海域西部西风愈强、持续时间愈久、扩大范围愈大,产生的El Ninño就愈强。并对用线性模式得到的结果同用非线性模式的结果进行比较,结果表明非线性平流项能影响波的传播速度,使得逆基本气流传播的波的传播速度减慢,而非线性平流项对形成El Ninño这种行星尺度的超低频事件所起的作用可能不大。

英文摘要:

      A one layer model of equivalent nonlinear shallow water has been designed. Using this model the simulation on oceanic forcing response to surface wind stress is conducted. The results showed that while the east wind intensity over east part of western Pacific Ocean are suddenly reduced and are changed to west wind, it induced to the increase of the sea surface height and the temperature on the east Pacific Ocean. The nonlinear shallow water model and the linear shallow water model successfully simulated these broad sense El Ninño events of large scape on the central-east Pacific Ocean. The simulated results also showed that the increase of height and temperature of sea surface on the east Pacific Ocean egion are related to the intensity, duration, and scape of extension of west wind on the west Pacific Ocean region, that is, the west wind on the west part of sea region is stronger, the duration is longer, the scape of extension is larger, the productive El Ninño is stronger. Moreover, the results of the linear model with the results of the nonlinear model are compared. The results showed that the nonlinear advection term can have effect on propagate velocity of wave, the propagate velocity of wave of counter basic-flow have been decreaced, but the role of nonlinear advection term on forming El Ninño events may be little.