A Weak Constraint 4D-Var Assimilation System for the Navy Coastal Ocean Model Using the Representer Method - Data Assimilation for Atmospheric, Oceanic and Hydrologic Applications - page 371

MODAS minus FG Temperature at prf1 MODAS minus FG Salinity at prf1

0
100
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500

3
2.5
2
1.5
1
0.5
0

0
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0.25
0.2
0.15
0.1
0.05
0

5 10 15 20 25 30 5 10 15 20 25 30

Days of August, 2003 Days of August, 2003

MODAS minus 4DVR Temperature at prf1 MODAS minus 4DVR Salinity at prf1

0
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3
2.5
2
1.5
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0

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0.25
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0.1
0.05
0

5 10 15 20 25 30 5 10 15 20 25 30

Days of August, 2003 Days of August, 2003

Fig. 15.3 Time evolution of the absolute value of the innovation ( top ) and the analysis error
( bottom ) at profile location 1, for temperature ( left ) and salinity ( right )

MODAS minus FG Temperature at prf 3

MODAS minus FG Salinity at prf 3

0.25
0.2
0.15
0.1
0.05
0

0
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50

3
2.5
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0

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Days of August, 2003 Days of August, 2003

MODAS minus 4DVR Temperature at prf 3 MODAS minus 4DVR Salinity at prf 3

0
10
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50

3
2.5
2
1.5
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0

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0.25
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0

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Days of August, 2003 Days of August, 2003

Fig. 15.4 Same as Fig. 15.3 , except for location 3

mixed layer could also be incompatible with MODAS data. Yet both the data and
the forcing fields are purposefully chosen in order to test the assimilation's ability
to efficiently reduce these discrepancies while estimating a reasonable (magnitude-
wise) correction to the surface fluxes. The assimilation effectively reduces all the
discrepancies to within the data standard deviation for both temperature and salinity.
The maximum depth at location 3 inside the bay is 28 m. Results at this location,
shown in Fig. 15.4 , indicate that high salinity discrepancies sometimes exceeding
.25psu are distributed through the water column during the first 5-day assimilation
period. Some large salinity discrepancies also appear between days 18-20. Temper-
ature discrepancies on the other hand are more prevalent, distributed over space and
time. It appears that the initialization of the model using the previous 5-day analysis
has less influence on the current 5-day first-guess. This may be due to the fact that in
this shallow location, temporal variability of the solution is mostly governed by the