Accounting for Non-Detects in Satellite Ammonia Observations
Author Information
Author(s): Evan White, Mark W. Shephard, Karen E. Cady-Pereira, Shailesh K. Kharol, Sean Ford, Enrico Dammers, Evan Chow, Nikolai Thiessen, David Tobin, Greg Quinn, Jason O’Brien, Jesse Bash
Primary Institution: Environment and Climate Change Canada
Hypothesis
How can we accurately account for non-detects in satellite measurements of ammonia?
Conclusion
Accounting for non-detects significantly improves the accuracy of satellite-derived ammonia measurements, especially in low concentration areas.
Supporting Evidence
- In regions with low ammonia concentrations, non-detects can exceed 70%, significantly affecting average values.
- Accounting for non-detects can reduce average ammonia values by over 50% in non-source conditions.
- The methodology developed allows for better representation of ammonia concentrations in satellite data.
- Non-detects occur less than 5% of the time in larger emission source regions.
Takeaway
This study shows that when satellites can't detect low levels of ammonia, we can still make educated guesses about those amounts to get better overall data.
Methodology
The study developed a methodology to identify and account for non-detects in satellite ammonia observations using the CrIS Fast Physical Retrieval algorithm.
Potential Biases
Potential biases may arise from the limited number of continuous surface monitoring stations in non-source regions.
Limitations
The study relies on in-situ surface observations which may not be available in all regions.
Digital Object Identifier (DOI)
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