Lagrangian flow in the California Undercurrent, an observation and model comparison

During the period 1992-1998, 38 isobaric RAFOS floats were deployed to samp le the subsurface flow of the California Undercurrent. The deployments, rel eased over the California continental slope west of San Francisco, have sam pled robust year-round poleward subsurface flow associated with the Undercu rrent most seasons and the combined inshore current and Undercurrent in win ter. Two other types of flow have been seen: a region of weak flow with lit tle net displacement just west of the California Undercurrent, and an activ e westward propagating eddy field. This eddy field appears to be the primar y mechanism for moving floats from the Undercurrent into the ocean interior . The observations and statistics from the RAFOS floats are compared with L agrangian estimates of particles tracked in a global high resolution ocean simulation in order to evaluate the fidelity of the model along an eastern boundary. The results show that the model reproduces the general character of the flow reasonably well, but underestimates both the mean and eddy ener gies by a substantial amount. (C) 2001 Published by Elsevier Science B.V.