ObsErrorModelRamp¶
This function parameterizes the observation error as a piece-wise linear function of a ufo Variable.
The output function is specified by the coordinates of the inflection points and includes:
# initial constant value
# linear growth or decay (ramp)
# final constant value
Diagrams:
err1 - - - *---
,'.
,' .
,' .
err0 --*' .
. .
'--+-------+---
' '
x0 x1
~~~~
In case there are x2 and err2 values:
err2 - - - - - - - *---
, ' .
, ' .
, ' .
err1 - - - *--- .
,'. .
,' . .
,' . .
err0 --*' . .
. . .
'--+-------+---------------
' ' '
x0 x1 x2
~~~~
Notes:
for a decaying ramp, set err1 < err0 and/or err2 < err1.
for a step function starting at either the first or second inflection point, set x0 == x1 or x2 == x1, respectively.
Required input parameters:¶
- xvar
The x-variable of the piece-wise function.
- x0
x-coordinate of the lower ramp inflection point.
- x1
x-coordinate of the upper ramp inflection point.
- err0
y-coordinate of the lower ramp inflection point
- err1
y-coordinate of the upper ramp inflection point
Optional input parameters:¶
- channels
Channels for which to calculate the ObsError for radiances. Omit channels for application to a single non-radiance filter variable. When multiple “filter variables” are provided without channels, they will have the same observation error.
- x2
An extra upper ramp.
- err2
An extra error value.
- save
Whether to save xvar values to the ObsSpace.
Example configurations:¶
### example configurations for a FilterBase derived class: ###
- Filter: {Filter Name}
#### AMSUA ####
filter variables:
- name: brightnessTemperature
channels: &errassignchan 1-15
action:
name: assign error
error function:
name: ObsFunction/ObsErrorModelRamp
channels: *errassignchan
options:
channels: *errassignchan
xvar:
name: ObsFunction/CLWRetMean
options:
clwret_ch238: 1
clwret_ch314: 2
clwret_types: [ObsValue, HofX]
bias_application: HofX
x0: [ 0.050, 0.030, 0.030, 0.020, 0.000,
0.100, 0.000, 0.000, 0.000, 0.000,
0.000, 0.000, 0.000, 0.000, 0.030]
x1: [ 0.600, 0.450, 0.400, 0.450, 1.000,
1.500, 0.000, 0.000, 0.000, 0.000,
0.000, 0.000, 0.000, 0.000, 0.200]
err0: [ 2.500, 2.200, 2.000, 0.550, 0.300,
0.230, 0.230, 0.250, 0.250, 0.350,
0.400, 0.550, 0.800, 3.000, 3.500]
err1: [20.000, 18.000, 12.000, 3.000, 0.500,
0.300, 0.230, 0.250, 0.250, 0.350,
0.400, 0.550, 0.800, 3.000, 18.000]
{save: true}
#### ABI/AHI ####
filter variables:
- name: brightnessTemperature
channels: &errassignchan 8-10
action:
name: assign error
error function:
name: ObsFunction/ObsErrorModelRamp
channels: *errassignchan
options:
channels: *errassignchan
xvar:
name: ObsFunction/SymmCldImpactIR
channels: *errassignchan
options:
channels: *errassignchan
x0: [ 0.0, 0.0, 1.0]
x1: [15.0, 20.0, 25.0]
err0: [ 2.5, 3.2, 3.2]
err1: [17.0, 20.5, 21.1]
#### Non-radiance ObsTypes ####
filter variables:
- name: {filter variable name}
action:
name: assign error
error function:
name: ObsFunction/ObsErrorModelRamp
options:
xvar:
name: {[ObsFunction, GeoVaLs, ObsDiag, ObsValue, etc...]/xvar}
options: {xvar options}
x0: [{X0}]
x1: [{X1}]
err0: [{ERR0}]
err1: [{ERR1}]