Seasonal variations in the horizontal structure of the Amazon Plume inferred from historical hydrographic data
Seasonal variations in the horizontal structure of the Amazon Plume inferred from historical hydrographic data
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DOI：
10.1029/94jc01847
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发表时间：
1995-02
影响因子：
--
通讯作者：
S. Lentz
中科院分区：
文献类型：
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作者：
S. Lentz
美国国家海洋数据中心水文数据档案对4°S-10°N， 60-40°W区域的近地表盐度观测表明，亚马逊河的流量形成了一股低盐度水羽流，向西北延伸至热带北大西洋西部。羽流内的平均近地表盐度在远离亚马逊河口的地方增加，这与每1°纬度的海水平均夹带2×105 m3/s相一致。有两个显著的季节变化。在亚马逊河口附近（0-2°N），从6月到12月，烟羽向东延伸约200-300公里。然而，从3月到5月，在河口附近的羽流通常要宽得多（400-500公里），这可能是由于接近最大的河流流量和东南风向的结合。在北纬5度以北，亚马逊羽流扇形展开，覆盖了北大西洋热带西部的广阔地区。在1月至6月期间，5°N以北的低盐度亚马逊羽流主要分布在52°W以西，向西北向加勒比海扩散。通常从5月开始，一些亚马逊河羽流的水在北巴西洋流（NBC）的反射下向东偏转。从8月到10月，地表盐度表明约70%的亚马逊羽流水在NBC反射中向东流动，而剩余的约30%向西北方向流向加勒比海。
Near-surface salinity observations from the National Oceanographic Data Center hydrographic data archive for the region 4°S–10°N, 60–40°W show that the Amazon River discharge forms a plume of low-salinity water that extends northwestward into the western tropical North Atlantic. The average near-surface salinity within the plume increases away from the Amazon River mouth consistent with an average entrainment of oceanic water of 2×105 m3/s every 1° of latitude. There are two notable seasonal variations. In the vicinity of the Amazon River mouth (0–2°N) the plume extends about 200–300 km eastward from June through December. However, from March to May the plume was often much wider (400–500 km) in the vicinity of the river mouth, possibly due to the combination of near-maximum river discharge and winds with a southeastward component. North of 5°N, the Amazon Plume fans out over a broad region of the western tropical North Atlantic. During January through June, low-salinity Amazon Plume water north of 5°N is primarily found west of 52°W, spreading northwestward toward the Caribbean. Beginning typically in May, some of the Amazon Plume water is deflected eastward in the North Brazil Current (NBC) retroflection. From August through October, surface salinities suggest ∼70% of the Amazon Plume water is carried eastward in the NBC retroflection, while the remaining ∼30% flows northwestward toward the Caribbean.