Table of Contents
Table of Contents i
1 Introduction 1
2 Forward model 7
2.1 The radiative transfer equation . . . 7
2.2 Parametrisation of the atmosphere . . . 8
2.3 Atmospheric line shape . . . 11
2.4 Spectroscopic database . . . 11
2.5 Fine frequency grid . . . 12
2.6 The scattering source function . . . 14
2.7 Instrument modelling . . . 14
2.8 Forward models validation . . . 15
3 Retrieval code 19 3.1 Mathematics of the retrieval . . . 20
3.2 Wide-band retrieval accounting for FM errors . . . 22
3.3 Multi-target retrieval . . . 26
3.3.1 Volume Mixing Ratio and gradient retrieval . . . 26
3.3.2 Temperature retrieval . . . 27
3.3.3 Continuum absorption retrieval . . . 27
3.3.4 Pointing bias retrieval . . . 27
3.3.5 Instrumental gain and offset retrieval . . . 28
3.4 The retrieval vector and the use of optimal estimation . . . 28
3.5 The averaging kernel . . . 32
3.6 Assessment of retrievals quality: qualifiers . . . 33
3.6.1 The reduced χ2 test . . . 33
3.6.2 Integral of the averaging kernel . . . 33 i
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3.6.3 Full width at half maximum of the averaging kernel . . . . 33
3.6.4 Ratio between the constrained and un-constrained error . . 34
3.6.5 Trace of the averaging kernel matrix . . . 34
3.6.6 Information content . . . 34
3.7 Retrieval code for REFIR-PAD measurements . . . 35
4 Instruments and measurement campaigns 37 4.1 The MARSCHALS instrument . . . 37
4.2 The REFIR-PAD instrument . . . 38
4.3 The measurement campaigns . . . 41
4.3.1 The MARSCHALS measurement campaign . . . 41
4.3.2 The REFIR-PAD measurement campaign . . . 44
5 Theoretical retrieval study of MARSCHALS measurements 45 5.1 Set-up of the simulations . . . 45
5.2 Preliminary results . . . 47
5.3 Tuning of the vertical retrieval grid . . . 47
5.3.1 Temperature . . . 48 5.3.2 H2O . . . 48 5.3.3 O3 . . . 48 5.3.4 HNO3 . . . 48 5.3.5 N2O . . . 49 5.3.6 CO . . . 49
5.3.7 Continuum absorption retrieval . . . 49
5.3.8 Multi-target retrieval . . . 49
5.4 Robustness of the retrieval . . . 50
5.5 Gradient retrievals . . . 51
5.5.1 O3 gradient . . . 51
5.5.2 H2O gradient . . . 52
5.6 Test retrievals on scalar parameters . . . 53
5.7 Information content of individual bands . . . 54
5.8 Tuning of the number of up- and down-looking geometries to be measured . . . 57
5.9 Retrieval in cloudy scenes . . . 57
6 Analysis of MARSCHALS data 69 6.1 Flight overview . . . 69
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6.3 Initial guess atmosphere . . . 71
6.4 Retrieval of band C . . . 72
6.4.1 Use GPS altitude . . . 72
6.4.2 Use averaged noise level . . . 72
6.4.3 Set-up of the retrieval . . . 72
6.4.4 Results of the retrieval . . . 73
6.4.5 Quality of the spectroscopic database . . . 83
6.5 Retrieval of band B . . . 83
6.6 Sequential fit: band C + band B . . . 87
6.7 Band C retrieval including systematic errors . . . 87
6.8 Clouds analysis . . . 88
6.8.1 Cloud characterisation by means of external data . . . 91
6.8.2 Use of cloud model in the retrieval . . . 92
7 Analysis of REFIR-PAD data 101 7.1 Instrument performances and Level-1B analysis . . . 101
7.1.1 Absorption inside the instrument . . . 102
7.2 Retrieval set-up for REFIR-PAD data . . . 104
7.3 Results . . . 105
7.4 Comparison with ECMWF data . . . 111
7.5 Analysis of the fitting residuals . . . 115
7.6 REFIR-PAD measurements, greenhouse effect and outgoing far infrared flux . . . 123 8 Conclusion 127 Acknowledgements 131 Bibliography 133 Acronyms 141 List of Tables 145 List of Figures 147
