


Next: 8.4 SMOOTH: Smoothing And
Up: 8. Ocean State Estimation
Previous: 8.2 PROFILES: modeldata comparisons
Contents
8.3 CTRL: Model Parameter Adjustment Capability
The parameters available for configuring generic cost terms in data.ctrl are given in table 8.9.
Table 8.9:
Parameters in ctrl_nml_genarr namelist in data.ctrl. The * can be replaced by arr2d, arr3d, or tim2d for timeinvariant two and three dimensional controls and timevarying 2D controls, respectively. Parameters for genarr2d, genarr3d, and gentime2d are arrays of length maxCtrlArr2D, maxCtrlArr3D, and maxCtrlTim2D, respectively, with one entry per term in the cost function.
parameter 
type 
function 
xx_gen*_file 
character(*) 
Name of control. Prefix from table 8.10 + suffix. 
xx_gen*_weight 
character(*) 
Weights in the form of

xx_gen*_bounds 
real(5) 
Apply bounds 
xx_gen*_preproc 
character(*) 
Control preprocessor(s) (see table 8.11) 
xx_gen*_preproc_c 
character(*) 
Preprocessor character arguments 
xx_gen*_preproc_i 
integer(*) 
Preprocessor integer arguments 
xx_gen*_preproc_r 
real(*) 
Preprocessor real arguments 
gen*Precond 
real 
Preconditioning factor (
by default) 
mult_gen* 
real 
Cost function multiplier
(
by default) 
xx_gentim2d_period 
real 
Frequency of adjustments (in seconds) 
xx_gentim2d_startdate1 
integer 
Adjustment start date 
xx_gentim2d_startdate2 
integer 
Default: model start date 
xx_gentim2d_cumsum 
logical 
Accumulate control adjustments 
xx_gentim2d_glosum 
logical 
Global sum of adjustment (output is still 2D) 

Table 8.10:
Generic control prefixes implemented as of checkpoint 65x.

name 
description 
2D, timeinvariant controls 
genarr2d 


xx_etan 
initial sea surface height 

xx_bottomdrag 
bottom drag 

xx_geothermal 
geothermal heat flux 
3D, timeinvariant controls 
genarr3d 


xx_theta 
initial potential temperature 

xx_salt 
initial salinity 

xx_kapgm 
GM coefficient 

xx_kapredi 
isopycnal diffusivity 

xx_diffkr 
diapycnal diffusivity 
2D, timevarying controls 
gentim2D 


xx_atemp 
atmospheric temperature 

xx_aqh 
atmospheric specific humidity 

xx_swdown 
downward shortwave 

xx_lwdown 
downward longwave 

xx_precip 
precipitation 

xx_uwind 
zonal wind 

xx_vwind 
meridional wind 

xx_tauu 
zonal wind stress 

xx_tauv 
meridional wind stress 

xx_gen_precip 
globally averaged precipitation? 

Table 8.11:
xx_gen????d_preproc options implemented as of checkpoint 65x. Notes:
: If noscaling is false, the control adjustment is scaled by one on the square root of the weight before being added to the base control variable; if noscaling is true, the control is multiplied by the weight in the cost function itself.
name 
description 
arguments 
WC01 
Correlation modeling 
integer: operator type (default: 1) 
smooth 
Smoothing without normalization 
integer: operator type (default: 1) 
docycle 
Average period replication 
integer: cycle length 
replicate 
Alias for docycle 
(units of xx_gentim2d_period) 
rmcycle 
Periodic average subtraction 
integer: cycle length 
variaweight 
Use timevarying weight 
 
noscaling

Do not scale with xx_gen*_weight 
 
documul 
Sets xx_gentim2d_cumsum 
 
doglomean 
Sets xx_gentim2d_glosum 
 

The control problem is nondimensional by default, as reflected in the omission of weights in control penalties [(
in (8.1)]. Nondimensional controls (
) are scaled to physical units (
) through multiplication by the respective uncertainty fields (
), as part of the generic preprocessor
in (8.4). Besides the scaling of
to physical units, the preprocessor
can include, for example, spatial correlation modeling (using an implementation of Weaver and Coutier, 2001) by setting xx_gen*_preproc = 'WC01'. Alternatively, setting xx_gen*_preproc = 'smooth' activates the smoothing part of WC01, but omits the normalization. Additionally, bounds for the controls can be specified by setting xx_gen*_bounds. In forward mode, adjustments to the
th
control are clipped so that they remain between xx_gen*_bounds(i,1) and xx_gen*_bounds(i,4). If xx_gen*_bounds(i,1)
xx_gen*_bounds(i+1,1) for
, then the bounds will ``emulate a local minimum;''^{8.3} otherwise, the bounds have no effect in adjoint mode.
For the case of timevarying controls, the frequency is specified by xx_gentim2d_period. The generic control package interprets special values of xx_gentim2d_period in the same way as the exf package: a value of
implies cycling monthly fields while a value of 0
means that the field is steady. Time varying weights can be provided by specifying the preprocessor variaweight, in which case the xx_gentim2d_weight file must contain as many records as the control parameter time series itself (approximately the run length divided by xx_gentim2d_period).
The parameter mult_gen* sets the multiplier for the corresponding cost function penalty [
in (8.1);
by default). The preconditioner,
, does not directly appear in the estimation problem, but only serves to push the optimization process in a certain direction in control space; this operator is specified by gen*Precond (
by default).
Next: 8.4 SMOOTH: Smoothing And
Up: 8. Ocean State Estimation
Previous: 8.2 PROFILES: modeldata comparisons
Contents
mitgcmsupport@mitgcm.org
Copyright © 2006
Massachusetts Institute of Technology 
Last update 20180123 

