 | Frank F.I. Atmospheric methane and its isotopic composition in a changing climate: a modelling study: Diss. ... doctoral thesis / Deutsches Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen. - Köln: DRL, 2018. - ix,204 p.: ill. - (Forschungsbericht; 2018-20). - ISSN 1434-8454
Шифр: (Pr 1120/2018-20) 02
|
1 Introduction ............................................... 1
1.1 Motivation ................................................. 1
1.2 Scientific Questions ....................................... 3
1.3 Investigation Strategy ..................................... 3
2 Scientific Background ...................................... 5
2.1 Atmospheric Chemistry ...................................... 5
2.2 Methane as a Greenhouse Gas ................................ 6
2.2.1 Methane Sources ..................................... 8
2.2.2 Metliane Sinks ..................................... 10
2.2.3 Methane Observations ............................... 10
2.3 Introduction to Isotopologues ............................. 11
2.3.1 The δ-Notation ..................................... 12
2.3.2 Isotopologues of Methane ........................... 13
2.4 Isotope Fractionation Effects ............................. 15
2.4.1 Physical Fractionation Effects ..................... 15
2.4.2 The Kinetic Isotope Effect ......................... 17
2.4.3 Fractionation Effects in the Sink Reactions of
Methane ............................................ 18
2.4.4 Further Chemical Fractionation Effects in the
Atmosphere ......................................... 19
2.5 The Hydroxyl Radical ...................................... 20
2.6 Stratospheric Water Vapor ................................. 21
3 The Chemistry Climate Model EMAC .......................... 23
3.1 The Modular Earth Submodel System (MESSy) ................. 23
3.2 Operational Modes of EMAC ................................. 24
3.3 The Submodel CH4 .......................................... 26
3.3.1 The Isotopologue Extension in the CH4 submodel ..... 27
3.3.2 CH4 Submodel with Age and Emission Classes ......... 28
3.4 The Chemical Processes in EMAC ............................ 28
3.5 The Kinetic Chemistry Tagging Technique ................... 29
3.6 The Submodel H2OISO ....................................... 30
3.7 Coupling of Physical and Chemical Water Tracers ........... 31
4 Lifetime of Methane in EMAC ............................... 33
4.1 The Consortial Project ESCiMo ............................. 35
4.1.1 Temperature Profiles and Time Series ............... 35
4.1.2 Simulated Methane in ESCiMo ........................ 39
4.1.3 Profile of OH ...................................... 40
4.2 Simulating Extreme Methane Enhancements with EMAC ......... 41
4.3 Calculation of the Lifetime of Methane .................... 43
4.3.1 Tropospheric Lifetime and Inter-Simulation
Variability ........................................ 44
4.3.2 Sensitivity of the Lifetime of Methane with
respect to OH and Temperature ...................... 47
4.3.3 Lifetime and Airmass Weighted OH in Sub-
Compartments ....................................... 51
4.3.4 Influence of Post-processing, applied Tropopause
Height and Reaction Rates .......................... 55
4.4 Summary .................................................. 60
5 Simulating Methane with Optimized Emission Inventories .... 61
5.1 Inverse Optimization of Emission Inventories .............. 61
5.1.1 Simulating Age and Emission Classes ................ 62
5.1.2 The fixed-lag Kaiman Filter ........................ 63
5.1.3 Observation Stations ............................... 67
5.2 Results of the a Priori Simulation ........................ 67
5.2.1 A Priori Simulation Set-up ......................... 67
5.2.2 Results of the Inverse Optimization ................ 69
5.2.3 A Priori and A Posterior Emission Inventory ........ 70
5.2.4 Dependencies on the Applied Forward Model .......... 72
5.3 Results of the a Posteriori Simulation .................... 76
5.3.1 Configuration of Forward a Posteriori Simulation ... 76
5.3.2 Comparison of a Priori and a Posteriori
Simulation ......................................... 77
5.3.3 Influence of the Applied OH Field .................. 79
5.3.4 Feedback onto the OH Field in the Interactive
Chemistry .......................................... 81
5.4 Evaluation with Observations .............................. 83
5.4.1 Ground based Stationary Data ....................... 83
5.4.2 Airborne Observations .............................. 84
5.5 Summary ................................................... 85
6 Modelling Methane Isotopologues ........................... 87
6.1 Modeling Isotopologues in EMAC ............................ 87
6.1.1 Simulation Set-up .................................. 88
6.1.2 Signatures of Emission Sources ..................... 89
6.2 CH3D and 13CH4 in the Atmosphere ........................... 90
6.2.1 Surface Mean Isotopic Composition .................. 90
6.2.2 Vertical Profile of δ-Composition .................. 91
6.3 Evaluation of Methane Isotopologues with Observations ..... 93
6.3.1 Surface Sampling Sites ............................. 93
6.3.2 Airborne Observations .............................. 95
6.3.3 Balloon Borne Observations ......................... 97
6.4 HDO in the Stratosphere ................................... 99
6.4.1 The Role of Background δD(Н2) for δD(H20) ......... 101
6.4.2 The δD(H2O) Tape Recorder ......................... 101
6.4.3 Evaluation with Satellite Observations ............ 104
6.5 Summary .................................................. 106
7 Feedback of Methane Oxidation onto H2O ................... 109
7.1 Model Set-Up and Methods ................................. 110
7.1.1 Model Set-up ...................................... 110
7.1.2 Calculation of the Chemical H2O Yield from CH4
Oxidation ......................................... 112
7.2 Results of the Different Approaches ...................... 113
7.2.1 Box Model Approach ................................ 114
7.2.2 Global Model Approach ............................. 120
7.2.3 Ratio of H:H2:H2O ................................ 122
7.3 Comparison of the Presented Approaches ................... 123
7.4 Summary .................................................. 127
8 Conclusion and Outlook ................................... 129
8.1 Summary and Conclusions .................................. 129
8.2 Outlook .................................................. 133
A Acronyms, Symbols and Chemical Tracer ..................... 135
В Definitions and Propositions .............................. 141
B.l Reaction Rates of CH4 Depletion ........................... 141
B.2 Fundamental Physical Equations ............................ 141
B.3 Constants ................................................. 142
С Documentation of the CH4 submodel ......................... 143
C.l Introduction .............................................. 143
C.2 MODULE messy_ch4_si: Subroutines in SMIL .................. 144
C.3 MODULE messy_ch4: Subroutines in SMCL ..................... 145
C.4 User interface ............................................ 146
C.5 Private subroutines ....................................... 147
D Documentation of the TRSYNC submodel ...................... 151
D.l Introduction .............................................. 151
D.2 MODULE messy_trsync_si: Subroutines in SMIL ............... 152
D.3 MODULE messy_trsync; Subroutines in SMCL .................. 154
D.4 User interface ............................................ 154
D.5 Private subroutines ....................................... 155
E Chemical Mechanism ........................................ 157
F Additional details ........................................ 161
F.l Correspoding to Chapter: Lifetime of Methane in EMAC ...... 161
F.2 Correspoding to Chapter: Optimized Emission Inventories ... 168
F.3 Correspoding to Chapter: Modelling Methane Isotopologues .. 174
Bibliography .................................................. 175
Data Acknowledgments .......................................... 201
|
|
