CAJ | 학술논문

观测事实显示,在El Nino发生期间,伴随着赤道中东太平洋的增暖,中纬度北太平洋中部表层海温(SST)常出现冷距平,而北美大陆西海岸SST则出现暖距平.借助观测资料分析和海气耦合模式模拟两种手段,检验了北太平洋对ENsO事件的上述响应.观测证据和数值模拟都支持有关学者提出的"大气桥"概念,即大气对赤道中东太平洋SST异常增暖的响应,随后强迫中纬度北太平洋,并导致那里SST的变冷,从而起到了连接热带和热带外特别是中纬度北太平洋的"桥梁"的作用.关于其机制,本文认为主要是海洋对大气强迫的动力响应导致那里的SST变冷,尽管潜热通量的贡献也很显著.至少模式结果证明短波辐射、长波辐射和感热通量的贡献都是次要的.进一步的分析揭示,北太平洋存在着线性独立于ENSO事件的所谓"北太平洋模态",在空间型上,它和线性地依赖于ENSO事件的模态非常相近,即它们的纬向结构都呈现出扁平的"双极"型,只是彼此间SST距平极大值的中心位置不同.模拟结果表明,北太平洋模态与大气的耦合作用,主要是通过海气热通量交换实现的,其中短波辐射和长波辐射的作用居主导地位,而潜热通量的贡献则基本可以忽略.
관측사실현시,재El Nino발생기간,반수착적도중동태평양적증난,중위도북태평양중부표층해온(SST)상출현랭거평,이북미대륙서해안SST칙출현난거평.차조관측자료분석화해기우합모식모의량충수단,검험료북태평양대ENsO사건적상술향응.관측증거화수치모의도지지유관학자제출적"대기교"개념,즉대기대적도중동태평양SST이상증난적향응,수후강박중위도북태평양,병도치나리SST적변랭,종이기도료련접열대화열대외특별시중위도북태평양적"교량"적작용.관우기궤제,본문인위주요시해양대대기강박적동력향응도치나리적SST변랭,진관잠열통량적공헌야흔현저.지소모식결과증명단파복사、장파복사화감열통량적공헌도시차요적.진일보적분석게시,북태평양존재착선성독립우ENSO사건적소위"북태평양모태",재공간형상,타화선성지의뢰우ENSO사건적모태비상상근,즉타문적위향결구도정현출편평적"쌍겁"형,지시피차간SST거평겁대치적중심위치불동.모의결과표명,북태평양모태여대기적우합작용,주요시통과해기열통량교환실현적,기중단파복사화장파복사적작용거주도지위,이잠열통량적공헌칙기본가이홀략.
During El Nino events, the warm anomalies in the eastern tropical Pacific are seen to occur in conjunction with prominent warm anomalies in the North Pacific SSTs off the west coast of North America as well as with cold anomalies in the central North Pacific. This kind of North Pacific response to ENSO is examined in observational data and IPSL air-sea coupled model simulations. Analyses based on observational data and the model output data both support the hypothesis of an "atmospheric bridge concept", i.e., the atmospheric response to ENSO, in turn, forces the extra-tropical SST anomalies associated with the El Ninno event, thereby serving as a bridge between the tropical and extra-tropical Pacific. Regarding the mechanism responsible for this, the ocean dynamical response to the atmospheric forcing is suggested to be active, while the contribution of latent heat flux is also significant. The role of solar radiation, longwave radiation, and sensible heat flux are of minor importance however, as indicated in the model.Further analysis shows that the North Pacific mode, which is linearly independent of ENSO, resembles the El Nino-type SST mode in the northern Pacific, i.e. both take the pattern ora zonally-oriented dipole in the subtropical Pacific, though differ slightly in the location of the anomaly center. The coupling between the North Pacific mode and the atmosphere is found to be mainly via air-sea heat flux exchange in the model. Both solar radiation and longwave radiation play important roles, while the contribution of latent heat flux is nearly negligible.