Results from Deployment of MBARI Drifter #4
Drifter #4 instrumentation included an osmotically-pumped nitrate analyzer,
fluorometer, scatterometer, CTD, and GPS receiver. Figure 1 shows a time series of
measurements made by the drifter.
Figure 1: Parameters measured during deployment of Drifter #4
The vertical lines on Figure 1 mark the times of AVHRR
sea surface temperature images.
"Backscatter" is approximately proportional to concentration of suspended
The drifter was deployed at the upwelling center near 37N 122.3W. This water was
characterized by high nitrate and particulates, and low chlorophyll. The drifter went
south, passing very close to MBARI mooring M1; particulates decreased steadily
during this phase. The drifter then crossed into warm, high chloropyll, low nutrient
Monterey Bay water early on April 22; (AVHRR image #7
and image #8 ).
Several drifters deployed during CoOP '95 exhibited this front-crossing behavior; it is
likely related to the subduction of recently-upwelled water under warmer, fresher, more
productive waters. These frontal features were studied carefully in the following weeks,
and further work is ongoing to confirm or reject this hypothesis.
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