Discrete precipitation effects on seasonal mixed layer dynamics in the North Pacific Ocean.

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Author
Livezey, Mendal S.
Date
1988-09Advisor
Garwood, Roland W., Jr.
Chu, Pecheng
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Show full item recordAbstract
This study was conducted to examine the effects of discrete precipitation events on
the short-term and seasonal evolution of ocean mixed layer temperature and salinity
structure. This study was located at Ocean Station "P" (50°N, 145°W) in the Northeast
Pacific Ocean. Two numerical modeling experiments were performed. The first was to
simulate the response of the mixed layer to hypothetical discrete (isolated) precipitation
events. This experiment showed that the effect of a single discrete rain event can van'
with season, with the mixed layer depth (MLD) at onset of the rain event, and with the
strength of wind stress forcing. A single rain event can have lasting effects on mixed
layer depth and temperature for up to 55 days after the event, depending upon the season.
The second experiment simulated quasi-realistic "complex" precipitation forcing,
with a realistic distribution of synoptic events over a 13-month period. For this experiment,
four different precipitation "intensities" were tested. The values of temperature,
salinity, and MLD predicted by the model were compared with observed Conductivity
Temperature Depth measurements and with the values predicted using constant precipitation
forcing. In all experiments, the modelled MLD's approximated the observed
MLD and temperature cycle. MLD's for all cases were too deep while temperature was
estimated well in winter and was too cool in summer. Predicted salinity provided the
greatest discrepancy between the modeled and the observed cycle. The 96 cm, 400-day
quasi-realistic precipitation forced case best approximated the salinity observations
though predicted salinity was fresher than observed in winter and saltier than observed
in summer. Model results suggest that the amount of precipitation observed at Ocean
Station "P" was too low to explain the observed and simulated ocean salinity and temperature
structure for the year.
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This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.Collections
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