Five research cruises were conducted over the continental shelf and sl
ope near the Farallon Islands, California, in February, May, August, a
nd October/November 1991 and February 1992. The observations consisted
of shipboard hydrographic and acoustic Doppler current profiler data
and moored current meter measurements. Water mass anomalies were calcu
lated for each cruise by subtracting seasonal means based on historica
l data. In general, the maximum anomalies were observed subsurface in
the 100-to 150-m range. In May 1991, equatorward, upwelling favorable
winds elevated the thermocline resulting in cold, salty anomalies near
shore, with cold, fresh anomalies offshore associated with the advecti
on of Pacific Subarctic Water into the region from the north. Warm, fr
esh anomalies and a strongly depressed thermocline were observed durin
g the February 1992 cruise. A combination of coastal sea level and win
d stress data and output from the Los Alamos National Laboratory paral
lel ocean program model was used to explain the cause of these anomali
es. The February 1992 anomalies were shown to be due to both the deepe
ning of the Aleutian low in the North Pacific associated with the 1991
-1993 El Nino/Southern Oscillation event in the equatorial Pacific and
poleward propagating intraseasonal coastal trapped Kelvin waves also
arising from this event. The anomalous poleward wind forcing produced
onshore flow, deepening of the thermocline, and downwelling at progres
sively southward locations. The ''downwelling'' Kelvin waves propagate
d northward with the two signals meeting somewhere near the cruise reg
ion. Both the model and the coastal sea level data showed the phase sp
eed of the waves to slow by about 50% after passing the Gulf of Califo
rnia. This may be due to the scattering of energy from the fastest bar
oclinic mode into a slower mode. The strongest wave signal in the equa
torial Pacific did not necessarily produce the strongest anomalies off
central California.