Abstract:
Temperature, salinity, and dissolved oxygen concentration
measured in an estuary were analyzed to determine if the effects of
coastal upwelling could be observed and used to effectively monitor
the degree of upwelling.
Hydrographic data collected weekly at a point four miles from
the entrance of Yaquina Bay (Buoy 15) were analyzed for their applicability as indicators of coastal upwelling. Only data collected during
the known upwelling season off Oregon of May through October were
considered. Low temperature, low dissolved oxygen concentration,
and high salinity occurred when the wind was strongly from the north--
conditions expected during times of active upwelling.
A regression analysis was performed to establish the relationship
between water temperature and wind velocity averaged over a three
day period. The two were significantly related. Various weighting
schemes were applied to the wind observations to obtain an average
wind which would provide the best correlation between wind and
temperature. A wind averaged over four days and weighted heaviest
during the third 24 hour period prior to the temperature observation
resulted in the best correlation.
A prediction model was formulated to allow for the prediction of
water temperature 24 hours in advance based upon the known wind
field during times of active upwelling.
Comparisons of temperature and salinity from five miles off
the coast with that in the estuary established that the upwelled water
entering the estuary on the flood tide originated from a depth of about
20 meters at three-five miles off the coast.
Measuring the temperature, salinity, and oxygen concentration
of the bottom water near the mouth of an estuary does provide an
effective, reliable, and simple method of monitoring the stage of
upwelling occurring outside the estuary.
