Toward Marine Environrnental Predictions in the Mediterranean Sea Coastal Areas
371
1'"
. _
r.:.
.r.'- ~",:,;,~. r.'"~'.' ....... ' . ."J .neste
~, ~'"'j~-m~if.y+ţg;~~>·
44.5
44
Italia
122
12.4
12.6
12.6
13
+
+ + +
',.',".1; ,' ,',' +
+ +
+
, ' .,' ,'.,'.
+
+
+ +
+
13.2
13.4
14
Fig. 17.10 The computational grid points ofthe nested 1.5 lan shelfmode1 (ASHELF) ofthe
Northem Adriatic Sea within the 5 km regional model (AREG) of the Adriatic Sea. The
latter is nested at the Northem Ionian boundary within the large scale-forecasting model of
the Mediterranean Sea. Both grids are plotted every other points. Crosses: AREG model.
Dots: ASHELF model. The arrows near Venice and on the Croatian coasts indicate the start
of the section illustrated in Fig. 17.11.
that the initialization of ASHELF from AREG tields has to consider extrapolation.
In order to overcome this difficulty Auclair et al (2000a) proposed a 3D variational
method that limits the amplitude ofthe transient processes following the initialization. The tangent linear equations to the ASHELF are used to decrease the initial
time step tendency of the model physical parameters down to realistic values. The
amplitude ofsome ofthe model biases, like the horizontal pressure gradient truncation error due to the use of sigma coordinates in regions with large topographic
slopes (Auclair et al, 2000b), is also drastically reduced. A comparison ofthe time
evolution ofthe surface elevation anomaly along a section in the Northem Adriatic
basin with and without the tangent linear model initialization method is given on
Fig. 17.11. The results obtained with the initialization technique (Fig. 17.11 b) show
a drastic de crease of the amplitude of the external gravity waves with respect to a
crude initialization (Fig. 17.l1a). The consequences of these transients on a 15days forecast are studied in details in Auclair (1999). This initialization method is
the tirst step toward an initialization/assimilation scheme that should in a near
371
1'"
. _
r.:.
.r.'- ~",:,;,~. r.'"~'.' ....... ' . ."J .neste
~, ~'"'j~-m~if.y+ţg;~~>·
44.5
44
Italia
122
12.4
12.6
12.6
13
+
+ + +
',.',".1; ,' ,',' +
+ +
+
, ' .,' ,'.,'.
+
+
+ +
+
13.2
13.4
14
Fig. 17.10 The computational grid points ofthe nested 1.5 lan shelfmode1 (ASHELF) ofthe
Northem Adriatic Sea within the 5 km regional model (AREG) of the Adriatic Sea. The
latter is nested at the Northem Ionian boundary within the large scale-forecasting model of
the Mediterranean Sea. Both grids are plotted every other points. Crosses: AREG model.
Dots: ASHELF model. The arrows near Venice and on the Croatian coasts indicate the start
of the section illustrated in Fig. 17.11.
that the initialization of ASHELF from AREG tields has to consider extrapolation.
In order to overcome this difficulty Auclair et al (2000a) proposed a 3D variational
method that limits the amplitude ofthe transient processes following the initialization. The tangent linear equations to the ASHELF are used to decrease the initial
time step tendency of the model physical parameters down to realistic values. The
amplitude ofsome ofthe model biases, like the horizontal pressure gradient truncation error due to the use of sigma coordinates in regions with large topographic
slopes (Auclair et al, 2000b), is also drastically reduced. A comparison ofthe time
evolution ofthe surface elevation anomaly along a section in the Northem Adriatic
basin with and without the tangent linear model initialization method is given on
Fig. 17.11. The results obtained with the initialization technique (Fig. 17.11 b) show
a drastic de crease of the amplitude of the external gravity waves with respect to a
crude initialization (Fig. 17.l1a). The consequences of these transients on a 15days forecast are studied in details in Auclair (1999). This initialization method is
the tirst step toward an initialization/assimilation scheme that should in a near