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Clear Sky Forward Model

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User friendly 'wrap-around' code complete. Fast Model Production Flowchart: Lineshapes ... Steer research direction based on user feedback. Future Goals: ... – PowerPoint PPT presentation

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Title: Clear Sky Forward Model


1
Clear Sky Forward Model Its Adjoint Model
  • MURI Review April 27, 2004
  • leslie moy, dave tobin, paul van delst, hal woolf

2
Accomplishments
Reproduce and Upgrade existing GIFTS/IOMI Fast
Model Coefficients promulgated 2003. Greatly
improved the dependent set statistics (esp. water
vapor). SVD regression and optical depth
weighting incorporated. Written in flexible
code with visualization capabilities. Under CVS
control.
Write the Corresponding Tangent Linear and
Adjoint Code Tested to machine precision
accuracy. User friendly wrap-around code
complete.
3
Fast Model Production Flowchart
keff -ln (teff ) Si1N ci Qi
4
------- GIFTS NeDT_at_296K ------- OSS RMS upper
limit
Dependent Set Statistics RMS(LBL-FM)
current model
MURI version
MURI model w/ OD weighted SVD
AIRS model c/o L. Strow, UMBC
OSS model c/o Xu Liu, AER, Inc.
OPTRAN, AIRS 281 channel set c/o PVD
5
User Input
User Output
Profile of temperature, ozone, water vapor at
101 levels
Profile perturbation of temperature, ozone,
water vapor at 101 levels
Use to adjust initial profile
Forward Model
Adjoint Model
Layer.m - convert 101 level values to 100 layer
values Predictor.m - convert layer values to
predictor values Calc_Trans.m - using predictors
and coefficients calculate level to space
transmittance Trans_to_Rad.m - calculate radiance
Layer_AD.m - layer to level sensitivities Predicto
r_AD.m - level to predictor sensitivities Calc_T
rans_AD.m - predictor to transmittance
sensitivities Trans_to_Rad_AD.m - transmittance
to radiance sensitivities
User Output
User Input
Compare to observations
Radiance Spectrum
Radiance Spectrum perturbation
6
Simple Example One Line Forward Model
  • Forward (FWD) model. The FWD operator maps the
    input state vector, X, to the model prediction,
    Y, e.g. for predictor 11
  • Tangent-linear (TL) model. Linearisation of the
    forward model about Xb, the TL operator maps
    changes in the input state vector, ?X, to changes
    in the model prediction, ?Y,

Or, in matrix form
7
Using the same procedure as in the Simple Model,
build up the Tangent Linear Model.
Forward Model
TL Model
Layer.m - input 101 level values of T,w,oz
output 100 layer values Predictor.m - input
layer values output predictor
values Calc_Trans.m - input predictors, and
coefficients output transmittances Trans_to_Ra
d.m - input transmittances output TOA radiance
Layer_TL.m - input d(level value) output
d(layer value) Predictor_TL.m - input d(layer
value), output d(predictor),
Calc_Trans_TL.m - input d(predictor) output
d(transmittance) Trans_to_Rad_TL.m - input
d(transmittance) output d(radiance)
Testing subroutines A range of Perturbations are
added to a baseline input value. PlusMinus 25
The Forward output (less the baseline value) is
compared to the TL output.
8
TL testing for Dry Predictor 6 (T2) vs Temp at
layer 44. TL results must be linear. TL must
equal (FWD-To) at dT0.
TL results blue, FWD-T0 results red
Difference between TL and FWD
Input Temperature at Layer 44 were varied ?25.
9
TL testing for Dry Predictor 6 vs Temp at all
layers.Similar plots made for each subroutines
variables.
D(dry.pred6)
Layer no.
D(temp),
10
  • Adjoint (AD) model. The AD operator maps in the
    reverse direction where for a given perturbation
    in the model prediction, ?Y, the change in the
    state vector, ?X, can be determined. The AD
    operator is the transpose of the TL operator.
    Using the example for predictor 11 in matrix
    form,

Expanding this into separate equations
11
Adjoint code testing for Dry Predictor 6 vs
Temperature layer.AD - TLt residual must be
zero.Similar plots are produced for every
subroutines variables.
AD - TLt residual
Output variable layer
Input variable layer
12
Adjoint for US Standard Profile,
d(radiance)/d(ozone)
Pressure, -mbar
Wavenumber, cm-1
13
Adjoint for US Standard Profile,
d(radiance)/d(water vapor)
Pressure, -mbar
Wavenumber, cm-1
14
Future Goals
Reproduce and Upgrade existing GIFTS Fast Model
Increase the number and quality of training
profiles (48) extend satellite zenith angle
range further improve the dependent and
independent set statistics. Breakout other
gases. Steer research direction based on user
feedback.
Corresponding Tangent Linear and Adjoint Code
Improve code for speed and ease of use. Convert
to a more efficient programming language.
Investigator testing of code.
15
Adjoint code can be used for sensitivity
analysis.d(Dry Predictor 6) / d(layer
Temperature).
Sensitivity, d(P6)/d(T)
Output variable layer
Input variable layer
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