| Journal of Physical Oceanography (2007) | |||||||||||||
Abstract | |||||||||||||
| The North Pacific thermocline (250m to 400m) is studied using XBT observations acquired during the 1970s and 1980s. Interannual variations (3-5 year time scales) in thermocline temperature, with O(0.1 ffi C) amplitude at 400m, are found to exhibit westward propagation throughout the extra-tropical North Pacific up to 45N. Southwards of 30N, the features propagate intact across the basin from the eastern boundary to the western boundary. Northwards of 30N, the features can be observed to propagate only as far as the dateline. The observed midlatitude thermocline anomalies are often related to tropical ENSO events in that they occur most strongly after the development of tropical El Nino or La Nina conditions and propagate westward from near the eastern boundary in the midlatitudes. But it is found that the observed midlatitude thermocline anomalies have larger phase speeds than theoretically predicted free baroclinic Rossby waves. Also, the observed anomalies have larger wavelength and faster propagation speeds than baroclinic Rossby waves that radiate from | |||||||||||||
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