臺灣博碩士論文加值系統

本研究藉由分析NODC長達九十五年與NCOR長達十八年的水文資料，由呂宋海峽鄰近海域的動力地形圖來了解其上層流場在時間與空間上的變化；並利用北太平洋熱帶水(North Pacific Tropical Water ,簡稱NPTW)的高鹽度特徵以追蹤水團在研究區域中所分布的深度來了解其季節變化。
研究結果顯示，呂宋海峽年平均流速之垂直剖面分布(沿120.25˚E，相對400 m)，最大向西的流速位於海峽中央，深度分布在0∼100 m，在海峽的南北兩端為東向海流，最大向東的流速出現於海峽北端，深度分布於0∼50 m。流場之水平分布(100 m╱400 m) 顯示北太平洋水整年皆經由呂宋海峽入侵南海，約於20∼21˚N有明顯分歧的西向海流，在南海海域中整年皆存在一逆時鐘向的渦流，核心約位於18˚N，118˚E，其強度隨著東北季風逐漸增強，在1、2月時達到最強。
呂宋海峽上層流量(0∼400 m)的年平均值為向西3.5 Sv，最大值為向西6.5 Sv (12月)，最小值約為向西1.1 Sv (6月)。上層流場主要受季風影響，在東北季風盛行時由於上層海水受艾克曼效應的作用，形成呂宋海峽為南低北高的壓力梯度，造成西向入侵的海流。另一方面，在東北季風期間由於呂宋海峽同時存在兩個較強且反向的風應力旋度，分別為北部的反氣旋與南部的氣旋，在這兩個反向的風應力旋度作用下，海流沿著位於海峽中央的零度等值線匯集成一股較強的西向海流。
NPTW(σθ=23.5∼25.5 kg/m3，S >34.5 psu)於南海海域內大多分布於水深120∼130 m。NPTW 於水深125 m處之季節變化顯示，整年皆經由呂宋海峽進入南海，其路徑約沿中國大陸南方的陸棚進入南海，在12∼2月時入侵達到最強，水團可分布至南海盆地中。

This study analyzed historical hydrographic data consist of 95 years of NODC data and 18 years of NCOR data. Variations of upper-layer current in Luzon Strait and its neighboring Northern South China Sea are investigated by the method of dynamical topography. On the other hand, higher salinity characteristic of the North Pacific Tropical Water (NPTW) is used to trace the water mass distribution and its seasonal variations in the studied area.
The result shows that the maximum of x-component velocity (along 120.25˚E, relative to 400 m ) in the Luzon Strait occurs in the middle of the strait, the flow direction is westward and the speed increases toward the surface. At the north and south ends of the strait flows are eastward and the maximum speed core is at the depth of 0~50 m. Horizontal distribution of flow fields indicates that intrusion of the north Pacific waters into the South China Sea through the Luzon Strait in the whole year. Westward bifurcation of the intrusion flows occurs at 20~21˚N. A cyclonic eddy exists in the South China Sea all year-round, and its core is located at about 18˚N, 118˚E. This eddy strengthens as the monsoon prevails with its speed reached in January and February.
Annual mean upper-layer transport (0~ 400 m) of the Luzon Strait is estimated to be about 3.5 Sv (positive value means westward) with a maximum value of about 6.5 Sv in December and a minimum value of 1.1 Sv in June. The Upper-layer current of the SCS is dominated by the monsoon. When the northeast monsoon prevails, the currents are affected by the Ekman effect to form high sea surface height in the north and low sea surface height in the south to produce a westward current. On the other hand, strong two coexistent wind stress curls with reversing signs during the northeast monsoon produce a westward current along the line of zero curl in the middle of the strait.
The distribution of the NPTW(σθ=23.5∼25.5 kg/m3,S >34.5 psu) is mostly at a depth of 120∼130 m in the South China Sea. NPTW were traced at 125 m depth, and the result indicates that this water mass enters the South China Sea through the Luzon strait all year-round. The intrusion path is along the continental slope of south China. The extent of intrusion reaches the maximum between December and February, and the water mass can spread into the South China Sea basin.

中文摘要　……………………………………………… I
英文摘要　……………………………………………… III
目錄　…………………………………………………… V
圖目錄　………………………………………………… VIII
一、 前言　………………………………………… 1
二、 資料與分析方法　…………………………… 5
2.1　水文資料來源　…………………………………… 5
2.1.1　NODC　…………………………………………… 5
2.1.2　NCOR　…………………………………………… 6
2.2　水文資料之空間與時間分布　…………………… 6
2.2.1　溫度剖面資料之空間與時間分布　…………… 6
2.2.2　溫鹽剖面資料之空間與時間分布　…………… 8
2.3　水文資料分析方法　……………………………… 9
2.3.1　除錯　…………………………………………… 9
2.3.2　散亂資料點網格化　…………………………… 10
2.3.3　圓滑　…………………………………………… 11
2.4　風場資料來源與時空分布　……………………… 11
2.5　風場資料分析方法　……………………………… 12
2.6　地形資料　………………………………………… 13
三、 結果　………………………………………… 14
3.1　平均狀態　………………………………………… 14
3.1.1 動力高度　…………………………………… 14
3.1.2 地衡流量　…………………………………… 16
3.1.3 地衡流速　…………………………………… 18
3.1.4 當地風場　…………………………………… 23
3.1.5 水團　………………………………………… 25
3.2　季節變化　………………………………………… 29
3.2.1 動力高度　…………………………………… 29
3.2.2 地衡流量　…………………………………… 31
3.2.3 地衡流速　…………………………………… 34
3.2.4 當地風場　…………………………………… 38
3.2.5 水團　………………………………………… 42
四、 討論　………………………………………… 44
4.1 壓力梯度　…………………………………… 44
4.2 測線與流量　………………………………… 48
4.2.1 變化A測站　………………………………… 48
4.2.2 變化B測站　………………………………… 51
4.3 環流　………………………………………… 53
五、 結論　………………………………………… 55
參考文獻　……………………………………………… 58

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