MOPITT Mission Description Document Index

1 Introduction 1.1 Science 1.2 Measurement Concepts 1.3 Verification 1.4 Calibration and Validation 1.5 Data Processing 1.6 Instrumentation 2 Science 2.1 Objectives of Project 2.2 Science Background 2.2.1 Introduction 2.2.2 OH 2.2.3 Sources of CO 2.2.4 CO Sinks 2.2.5 CO Distribution 2.2.6 Transport of CO 2.2.7 Modelling 2.2.7.1 General 2.2.7.2 3-D Photochemical Modelling 2.2.7.3 Dynamical Modelling 2.2.8 3-D Modelling Effort 2.2.9 Integrating Measurements into Models 2.2.10 Significance of Studies of Carbon Monoxide 2.2.11 Atmospheric Methane 2.2.12 Methane Sources 2.2.13 Methane loss and mixing ratios 2.2.14 Satellite Observations of Methane 2.2.15 Summary of CH4 Measurement Potential 3 Instrument Concept 3.1 Principles of Operation 3.1.1 The Pressure Modulator Radiometer 3.1.2 The Length Modulated Radiometer 3.1.3 PMR vs. LMR 3.1.4 Pressure Control and Stabilisation 3.2 Requirements and Performance Calculations 3.2.1 Science Requirements 3.2.2 Instrument Performance Evaluation 3.3 Carbon Monoxide (CO) Instrumentation 3.3.1 Correlation Spectroscopy of Carbon Monoxide 3.3.2 Carbon Monoxide in the Atmosphere 3.3.3 Carbon Monoxide Signal Functions 3.3.4 CO Profile Measurements - Performance Requirements 3.3.5 Total Column Measurements 3.3.6 CO Column Measurements - Performance Requirements 3.4 Methane (CH4) Instrumentation 3.4.1 Correlation Spectroscopy of Methane 3.4.2 Methane in the Atmosphere 3.4.3 CH4 Measurements - Performance Requirements 3.5 Instrument Field-of-View Considerations 3.6 Input Signal Range 3.7 Correlation Cell Pressures 3.7.1 Correlation Cell Pressure Stability 3.7.2 Correlation Cell Pressure Knowledge 3.8 Instrument Performance Summary 4 Verification 4.1 Purpose 4.2 Instrument Performance Verification 4.3 Science Performance Verification 5 Calibration and Validation 5.1 Calibration 5.1.1 Thermal (Emission) Channels 5.1.2 Solar (Reflection) Channels 5.1.3 Other Calibration Considerations 5.2 Validation 5.2.1 Level 0 Data (Raw Instrument Output) 5.2.2 Level 1 Data (Calibrated Radiances) 5.2.3 Level 2 Data (Retrieved profiles and column amounts) 6 Data Analysis 6.1 Overall Plan 6.2 Data Products 6.2.1 Level 0 6.2.2 Level 1 6.2.3 Level 2 6.2.4 Level 3 6.2.5 Special Products 6.3 Ancillary Data Required 6.3.1 Global Temperature Data 6.3.2 Global Water Vapour Data 6.3.3 Global Cloud Data 6.3.4 Wind and Geopotential Height Data 6.4 Algorithm Development 6.4.1 Level 0-1 6.4.2 Level 1-2 6.4.3 Level 2-3 6.5 Data Processing Requirement and Volume 7 MOPITT Instrument Science Requirements 7.1 Introduction 7.1.1 General 7.1.2 Spacecraft Resource Allocations 7.1.3 Lifetime Requirement 7.1.4 Channel Configuration 7.2 Subsystem Configuration 7.2.1 Optical Subsystem 7.2.1.1 Instrument Field-of-View 7.2.1.2 Field of View Alignment 7.2.1.3 Scanning Mirrors 7.2.1.4 Pressure Modulator Cells 7.2.1.5 Length Modulator Cells 7.2.1.6 Choppers 7.2.1.7 Beamsplitters 7.2.1.8 Detector Elements 7.2.1.9 Focussing Requirements 7.2.1.10 Stray Light. 7.2.1.11 Polarisation 7.2.2 Signal Channels 7.2.2.1 Length Modulator Cell Output 7.2.2.2 Pressure Modulator Cell Output 7.2.3 Science Data Output 7.2.4 Internal Calibration 7.2.4.1 Targets for Longwave Channels 7.2.4.2 Targets for Shortwave Channels 7.2.4.3 Temperature Monitoring 7.2.4.4 Pressure 7.2.4.5 Positions and Rates 7.2.4.6 Space View 7.2.5 Stirling Cycle Coolers (SCCs) 7.2.6 Instrument Computer 7.2.7 Instrument Port Covers 7.2.8 Heaters and Thermostats 7.2.8.1 Molecular sieve 7.2.8.2 Survival Heaters 7.2.8.3 Other Heating/Thermostatting Requirements 7.3 Instrument Performance Requirements 7.3.1 Introduction 7.3.2 Filter Profiles 7.3.3 Signal Channel Performance 7.4 Operating Modes 7.4.1 Off 7.4.2 Survival 7.4.3 Launch 7.4.4 Safe 7.4.5 Science 7.4.5.1 Normal Scan 7.4.5.2 Short Calibration 7.4.5.3 Long Calibration 7.4.5.4 Commandable Scan 7.4.6 Other Modes 7.5 Data Output 7.5.1 Data Streams 7.5.2 Radiometric Data 7.5.3 Housekeeping 7.5.3.1 Temperatures 7.5.3.2 Rates and Positions 7.5.3.3 Voltages 7.5.3.4 Currents 7.6 Commands 7.6.1 Packetised Commands 7.6.1.1 Memory loads 7.6.1.2 Parameter loads 7.6.1.3 Operational Commands 7.6.2 Discrete Commands and Telemetry 7.7 Ground Support Equipment (GSE) 7.7.1 Electrical - Bench Checkout Unit (BCU) 7.7.1.1 Power supply 7.7.1.2 Command Capability 7.7.1.3 Data Capability 7.7.1.4 Data Storage 7.7.1.5 Interface 7.7.1.6 Ancillary Equipment 7.7.2 Mechanical 7.7.3 Thermal 7.8 Software Requirements 7.8.1 Instrument Software 7.8.2 Ground Support (pre-launch) Software A An Introduction to Correlation Spectroscopy A.1 An Introduction to Correlation Spectroscopy A.1.1 Introduction A.1.2 Correlation Spectroscopy Techniques A.1.3 MOPITT CR Design A.1.4 Application of Double-Chopping CR to Nadir Sounding A.2 Historical Reference List for Correlation Radiometers B CO and CH4 Chemistry B.1 Detailed Equations of OH Chemistry B.2 Detailed Chemistry of Methane C Pressure Modulator Cells C.1 Summary C.2 History C.3 Operational Theory C.4 Optical Realisation C.5 Mechanical Realisation C.6 Electronic Drive Subsystem C.7 Resonant Frequency C.8 Molecular Sieve Operation C.9 Customisation and Accommodation Data C.10 Performance Verification of GFE C.11 Physical Data D Length Modulator Cells D.1 Summary D.2 History D.3 Operational Theory D.4 Optical Realisation D.5 Mechanical Realisation D.6 Electronic Drive Subsystem D.7 Molecular Sieve Operation D.8 Double-Pass Optical System D.9 Customisation and Accommodation Data D.10 Physical Data E Stirling Cycle Coolers F Instrument Calibration F.1 In-flight Calibration F.2 Pre-Launch Calibration and Characterisation F.2.1 Radiometric Targets F.2.2 Gaseous Targets F.2.3 Space Simulation F.2.4 Spectral Sources F.2.5 Correlation Cell Amounts F.2.6 Field-of-View F.2.6.1 General F.2.6.2 Pixels F.2.6.3 Scanning F.2.6.4 Pixel Co-location F.2.6.5 Polarisation G Instrument Calibration Facility (ICF) G.1 Simulated Coldplate G.2 Radiometric Targets G.3 Gaseous Targets G.4 Space Simulation G.5 Spectral Sources G.6 Correlation Cell Amounts G.7 Field-of-View G.7.1 General G.7.2 Pixels G.7.3 Scanning G.7.4 Pixel Co-location G.8 Polarisation H Reliability Issues and Mission Success H.1 Introduction H.2 Possible Failure Modes H.2.1 Fatal H.2.2 Severe H.2.3 Minor H.3 Science Recovery for Various Failures H.3.1 Fatal H.3.2 Severe H.3.2.1 Single cooler failure H.3.2.2 Correlation Cell Failure H.3.2.3 Chopper Failure H.3.2.4 Scan mirror Failure H.3.2.5 Blackbody Failure H.3.2.6 Detector Array Failure H.3.3 Minor H.3.3.1 Single pixel detector failure H.3.3.2 Increased Radiometric Noise H.4 Conclusions I References


MOPITT Mission Description Document - 30 October 1993