北赤道洋流（North Equatorial Current）為一支由東向西流動的海流，到了菲律賓東邊以後，分成兩支，一支往北形成黑潮（Kuroshio），一支往南形成民答那峨海流（Mindanao Current），而海流分開的地方一般就稱為分支點（Bifurcation Point）。黑潮會將高溫高鹽水由低緯度往高緯度輸送，對於所經過區域如呂宋海峽、台灣、東海及日本的氣候變化，漁場分布等，都會產生很大的影響。所以對於黑潮上游及其源頭-北赤道洋流的變化，就值得探討。本研究是利用一個已經建構完成且有良好模擬結果的數值模式，來探討北赤道洋流與黑潮上游的流況。
透過模式的結果，我們瞭解到分支點會隨著時間的不同而有所改變。一般來說當它移動到較低緯度時，是在六月，移動到較高緯度時，是在十二月。另外北赤道洋流以及黑潮的傳輸量（Volume Transport）一樣也會隨著時間而有所改變，不過兩者都是呈現春夏較強，秋冬較弱的情形。而當聖嬰發生時，北赤道洋流的傳輸量會變多，分支點會往北移動，黑潮傳輸量會變少；當反聖嬰時，北赤道洋流傳輸量會變少，分支點往南移動，黑潮傳輸量變多。
黑潮上游的傳輸量，一直以來幾乎都是以18°N作為代表，對於18°N以南的黑潮流況，並不是很清楚，所以利用模式來對18°N以南的黑潮流況做一個探討。得到當緯度越來越接近18°N時，黑潮的傳輸量也就越來越多，而這主要是因為迴流（Recirculation）所導致的。
北赤道洋流與赤道反流兩者的主軸在聖嬰時會相距較遠，由動力高度圖來看可以發現北赤道洋流主軸兩側的高度差異較大；反聖嬰時，則是剛好相反，兩者主軸則是靠得比較近，北赤道洋流主軸兩側高度差異較小。透過動力高度圖，當海表面高度差異越大，海流流速就會越快，當差異越小，海流流速就會變小。

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