Water mass formation in the Gulf of California
Water mass formation in the Gulf of California
复制标题
加利福尼亚湾水团的形成
DOI：
10.1029/jc093ic08p09223
复制
发表时间：
1988
影响因子：
--
通讯作者：
N. Bray
中科院分区：
文献类型：
--
作者：
N. Bray
加利福尼亚湾是位于下加利福尼亚半岛和墨西哥大陆之间的狭长边缘海。由于多山的下加利福尼亚半岛与太平洋在地理上隔离，海湾中的海气通量增强了。在北部海湾，年蒸发率约为 1 m y−1。然而，与大多数蒸发盆地不同，海湾以年平均 20 至 80 W m−2 的速度从大气中获取热量（Bray，1988）。鉴于海湾不寻常的海气强迫，水团的形成应采取什么形式？每年的水分损失和热量增加需要将高盐度的地表水向下输送到中间深度，并将冷的新鲜水向上输送到中间深度。这是通过多种机制实现的。 (1) 冬季对流：仅发生在有限的地理区域，即遥远北部海湾的瓦格纳盆地，但厄尔尼诺-南方涛动年份除外，此时对流似乎更为广泛。 (2) 对流水在小涡流状特征中的扩散：这发生在可能由与大气通量相关的大尺度密度梯度驱动的大规模向南输送中。 (3) 北部海湾的反气旋环流：它位于对流区以南，将高盐度的水从浅层陆架输送到较深的地方，在那里它可能与海湾中部的水混合。 (4)潮汐混合：北部湾可用于混合的能量大部分来自潮汐。特别是，岛屿地区海床的潮汐混合是导致北部湾水域进入中部海湾时盐度大幅降低的原因。
The Gulf of California is a long, narrow marginal sea lying between the Baja California peninsula and the mainland of Mexico. Air-sea fluxes of heat and moisture in the gulf are enhanced because of geographical isolation from the Pacific provided by the mountainous Baja California peninsula. In the northern gulf, annual evaporation rates are about 1 m y−1. Unlike most evaporative basins, however, the gulf gains heat from the atmosphere at an annual average rate of 20 to 80 W m−2 (Bray, 1988). Given the unusual air-sea forcing of the gulf, what form or forms should water mass formation take? The annual moisture loss and heat gain require that high-salinity surface water be transported downward to an intermediate depth and that cold, fresh inflow be transported upward to an intermediate depth. This is accomplished through several mechanisms. (1) Winter convection: this occurs only in a limited geographical region, the Wagner Basin of the far northern gulf, except in El Nino–Southern Oscillation years, when convection appears to be more widespread. (2) Dispersion of convected water in small eddylike features: this occurs within a large-scale southward transport possibly driven by the large-scale density gradient associated with atmospheric fluxes. (3) An anticyclonic circulation in the northern gulf: this is found south of the convection region and transports high-salinity water off the shallow shelves and to substantial depths, where it may mix with water of central gulf origin. (4) Tidal mixing: most of the energy available for mixing in the northern gulf derives from the tides. In particular, tidal mixing over the sill in the island region is responsible for the substantial reduction in salinity of northern gulf waters as they enter the central gulf.