FouryearsofNOAA-10 retrieved C02concentrations. - - PowerPoint PPT Presentation

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FouryearsofNOAA-10 retrieved C02concentrations. - - PowerPoint PPT Presentation

Apr 02, 2023 155 likes •339 views

FouryearsofNOAA-10 retrieved C02concentrations. ApplicationtoAIRSsimulations AlainChedin AIRSscienceteammeetingSept.2002 FIRSTGLOBALMEASUREMENTOFMID- TROPOSPHERICCO 2

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FouryearsofNOAA-10 retrieved C02concentrations. ApplicationtoAIRSsimulations

AlainChedin AIRSscienceteammeetingSept.2002

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  • FIRSTGLOBALMEASUREMENTOFMID-

TROPOSPHERICCO2FROMNOAAPOLARSATELLITES THEINTERTROPICALZONE

Aneuralnetworkapproach

  • Multilayerperceptron(Rumelhart,1986)
  • Twohiddenlayers
  • Inputs:satelliteobservations(HIRSandMSU)
  • Outputs:
  • difference between true mixing ratio and a reference

valueforCO2(354ppm)

  • difference between true and reference CO2 brightness

temperaturesforHIRSchannels

  • TrainedontheTIGRdatasetwithvariableqCO2
  • NoisedTB

HIRS and MSU Channels

qtrue-qref

  • (TBtrue-TBref)HIRS

2hiddenlayers

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FIRSTCO2OBSERVATIONFROMSPACE:NOAAPOLARSATELLITES

Timeperiodcovered :07/87-07/91– Monthlymaps 5°x5°- Intertropicalzone Examples ofresults for4months (02/90;04/90;08/90;11/90) IPSL/LMD/ARA* *Paperinpreparation (A.Chédin,S.Serrar,N.A.Scott;2002)

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Themeanseasonalcyclefor10latitudebandsbetween25Nand25S left:asretrievedbyNOAA-10(07/87-07/91) right:asobservedbycommercialaircraft(1994-1998;Matsuedaetal.,2002)

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For each pressure level : 1-Select t he channels t hat best cover t he level (by t he CO2 J acobian). 2-Rej ect t he channels present ing a low ∆TB (< 0.05K). 3-Comput e t he STI rat io : 4-Order t he channels and remove t he channels present ing a t oo low rat io. H2O, N2O, CO, O3,

ε and Ts signals AI RS channels select ion : t he OSP met hod

CO2 signal int erf erence

Application to AI RS

Crevoisier et al., 2002. Submitted to Q. J. R. Meteorol. Soc.

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The 43 channels obt ained wit h t he OSP met hod.

CO2 signal 15µm 4.3µm

Spectral location of the 43 channels

21 channels 22 channels

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The 43 channels obt ained wit h t he OSP met hod. CO2 Jacobians of the 43 channels

St rat osphere Tropopause Troposphere 33 channels 10 channels

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St and-alone approach f or CO2 ret rieval.

Based on a Neural Net work approach. 43 AI RS TB 4 surf ace TB (AMSU-A TB)

∆qCO2

2 hidden layers

  • Trained on t he TI GR dat a set wit h variable qCO2.
  • Noised TB.

43 ∆TB

We have t rained t he NN f or only one scan angle and f or several set s of input s and out put s.

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Noise/3 No Noise 0.77 ppmv 0.28 ppmv First result s… .

Training set : 872 Tropical sit uat ions. I nput s : 43 AI RS TB and 4 surf ace TB. Convergence of t he NN

1.79 ppmv Noise

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1.71 ppmv First result s… .

Training set : 872 Tropical sit uat ions. I nput s : 43 AI RS TB and 4 surf ace TB and 9AMSUA-A TB. Convergence of t he NN

1.79 ppmv Without AMSU With AMSU

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1.98 ppmv First result s… .

Training set : 872 Tropical or 742 Temperat e sit uat ions I nput s : 43 AI RS TB and 4 surf ace TB.. Convergence of t he NN

1.79 ppmv Tropical Temperate