Ocean Surface Winds Drive Dynamics of Transoceanic Aerial Movements
QuikSCAT winds on 7 September 2002 (4A) and 15 November 2002 (4B) showing the migratory “gate” located at 10°–15° N blocked and opened, respectively. Wind speed in the background increases from fuchsia (0 m·s−1) to green (6 m·s−1) to red (15 m·s−1), and arrows show wind direction. 4C, Migration (hatched red bars) starts when the frequency of blocking winds drops (black bars; winds blow towards 75°–115°). In the returning trip (range: February 11–March 10), there are no westerlies blocking the passage to the breeding areas in the Northern Hemisphere (not shown).