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Delft University of Technology
CHAMP, GRACE, GOCE and Swarm density and wind characterization with improvedgas-surface interactions modelling (PPT)
March, Gunther; Doornbos, Eelco; Visser, Pieter
Publication date2018Document VersionFinal published versionCitation (APA)March, G., Doornbos, E., & Visser, P. (2018). CHAMP, GRACE, GOCE and Swarm density and windcharacterization with improved gas-surface interactions modelling (PPT). 42nd COSPAR Assembly 2018,PAsadena, United States.
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CHAMP, GRACE, GOCE and Swarm density and wind
characterization with improved gas-surface interactions modelling
G. March, E. Doornbos, P.N.A.M. Visser
[email protected] COSPAR Assembly 2018,
Pasadena, California, U.S.A.,
Monday, July 16, 2018.
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Contents
• Introduction;
• Improved SPARTA model;
• Gas-Surface Interactions (GSI);
• Influence on Aerodynamics;
• Influence on Wind;
• Influence on Density;
• Summary and Outlook.
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Introduction
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Improved SPARTA model
Panel model
Pros Cons
Simple approach Low fidelity geometry
No ShadowingLow computational cost
No Multiple reflections
SPARTA (Stochastic PArallel Rarefied-gas Time-accurate Analyzer) model
Pros Cons
High fidelity geometry Complex approach
Shadowing Expensive computational
costMultiple reflections
ESA-EOPG-MOM-MO-15, Siemes (2018)
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New densities turned out to be higher reaching a mean +11% for CHAMP,
+5% for GRACE, +9% for GOCE and +32% for Swarm.
Improved SPARTA model
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Attitude manoeuvre
Comparison
(90° Yaw man.)
13/05/2014
X-Y-Z Accelerations
&
Density comparison with 3
atmospheric models
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OUT IN
Attitude manoeuvre
Comparison
(90° Yaw man.)
13/05/2014
X-Y-Z Accelerations
&
Density comparison with 3
atmospheric models
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Gas-Surface Interactions (GSI)
Specular reflection Diffuse reflection
𝐶𝐷 = (1 − 𝜎) 𝐶𝐷,𝑠𝑝𝑒 + 𝜎 𝐶𝐷,𝑑𝑖𝑓 α𝐸
α𝐸 =𝑇𝑖𝑛𝑐−𝑇𝑟𝑒
𝑇𝑖𝑛𝑐−𝑇𝑤
- Adsorption of gases on satellite surfaces;
- (Solar activity);
- (Altitude);
- …?!
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Influence on Aerodynamics
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Influence on Wind
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Influence on Wind
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Influence on Wind
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Influence on Wind
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Influence on Wind
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Influence on Wind
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Influence on Density: GOCE
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Influence on Density: GOCE
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Influence on Density: GOCE
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Influence on Density: Swarm-A
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Influence on Density: Swarm-A
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Influence on Density: Swarm-A
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Influence on Density (ratios)
HA: High solar Activity; LA: Low solar Activity;
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Influence on Density (ratios)
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Influence on Density (ratios)
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Summary & Outlook
- Optimize coefficients for diffusive & specular reflections (𝛼𝐸, 𝜎);- Improve Solar Radiation Pressure (SRP) accelerations;
- TU Delft works on the improvement of Swarm & GOCE thermospheric products [ESA contract (Starting: Q1-2019)];
- We are interested in revisiting GRACE data and work with GRACE-FO.
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Thank you for your attention!
G. March, E. Doornbos, P.N.A.M. Visser
42nd COSPAR Assembly 2018,
Pasadena, California, U.S.A.,
Monday, July 16, 2018.