INTERNAL METRICS
459
3.2. Class 1 metrics
Class 1 diagnostics gathers 2-D and 3-D fields interpolated on the
MERSEA grid. Two dimensions fields are:
x The zonal and meridional wind stress (Pa),
x The total net heat flux including relaxation term (W/m
2 ),
x The freshwater flux including relaxation term (kg/m
2 /s),
x The
Barotropic
Streamfunction
(henceforth
BSF)
(Sverdrup=10
6
m
3 /s). The BSF characterizes the wind-driven
circulation established in response to wind forcing. One year mean
Sverdrup BSF can also be computed using the provided Class 1
wind stress fields. At 25°N, it is commonly assumed that the
vertically integrated transport is governed by a flat-bottom Sverdrup
balance (Towsend et al. 2000; Boning et al. 1991) at least in the
eastern basin. The DYNAMO (Willebrand et al, 2001, their figure
15) five years mean numerical simulations without data assimilation
at this latitude showed a good agreement in the eastern basin
between models and Sverdrup for all models except the Sigma
coordinates models.
x The Mixed Layer Depth (henceforth MLD) (m). Two kinds of
MLD diagnostics are provided in the Atlantic basin: MLD(T) with a
1 °C criteria and MLD(U) with a 0.05kg/m
3 surface potential density
criteria. In the Mediterranean Sea, one MLD(U) with a 0.011kg/m
3
surface potential density criteria is provided. Hovmuller plots of the
MLD behaviour in chosen regions can show convection time
periods. In the mediterranean basin for example, in convection areas
as the Levantine Basin, the MLD maximum depth could be plotted.
Volume of newly formed Levantine Intermediate Water could be
estimated (Castellari et al. 2000).
x The Sea Surface Height (SSH) (m). For instance, a zonal section at
48°N of the one year mean SSH can show whether systems have a
realistic North Atlantic Current (Willebrand et al. 2001, their figure
13). The path of major currents can also be derived from SSH
averaged over several months using the Le Provost and Bremond
(2003) algorithm which allows to display path location associated
with geostrophic currents. True current position which are well
known from compilation of in situ data and remote sensing
observations (Auer, 1987) can also be displayed. SSH time series at
some moorings locations can also be compared to available observed
tide gauge measurements (Smedstad et al. 2002; Tokmakian and
McClean, 2003).
459
3.2. Class 1 metrics
Class 1 diagnostics gathers 2-D and 3-D fields interpolated on the
MERSEA grid. Two dimensions fields are:
x The zonal and meridional wind stress (Pa),
x The total net heat flux including relaxation term (W/m
2 ),
x The freshwater flux including relaxation term (kg/m
2 /s),
x The
Barotropic
Streamfunction
(henceforth
BSF)
(Sverdrup=10
6
m
3 /s). The BSF characterizes the wind-driven
circulation established in response to wind forcing. One year mean
Sverdrup BSF can also be computed using the provided Class 1
wind stress fields. At 25°N, it is commonly assumed that the
vertically integrated transport is governed by a flat-bottom Sverdrup
balance (Towsend et al. 2000; Boning et al. 1991) at least in the
eastern basin. The DYNAMO (Willebrand et al, 2001, their figure
15) five years mean numerical simulations without data assimilation
at this latitude showed a good agreement in the eastern basin
between models and Sverdrup for all models except the Sigma
coordinates models.
x The Mixed Layer Depth (henceforth MLD) (m). Two kinds of
MLD diagnostics are provided in the Atlantic basin: MLD(T) with a
1 °C criteria and MLD(U) with a 0.05kg/m
3 surface potential density
criteria. In the Mediterranean Sea, one MLD(U) with a 0.011kg/m
3
surface potential density criteria is provided. Hovmuller plots of the
MLD behaviour in chosen regions can show convection time
periods. In the mediterranean basin for example, in convection areas
as the Levantine Basin, the MLD maximum depth could be plotted.
Volume of newly formed Levantine Intermediate Water could be
estimated (Castellari et al. 2000).
x The Sea Surface Height (SSH) (m). For instance, a zonal section at
48°N of the one year mean SSH can show whether systems have a
realistic North Atlantic Current (Willebrand et al. 2001, their figure
13). The path of major currents can also be derived from SSH
averaged over several months using the Le Provost and Bremond
(2003) algorithm which allows to display path location associated
with geostrophic currents. True current position which are well
known from compilation of in situ data and remote sensing
observations (Auer, 1987) can also be displayed. SSH time series at
some moorings locations can also be compared to available observed
tide gauge measurements (Smedstad et al. 2002; Tokmakian and
McClean, 2003).