An observation-based, reduced-form model for oxidation in the remote marine troposphere

Area of Science:

• Atmospheric Chemistry
• Climate Science
• Remote Sensing

Background:

• Hydroxyl radical (OH) is vital for atmospheric chemistry, controlling methane and air pollutant cycles.
• Direct OH measurements are scarce, hindering detailed atmospheric process understanding.

Purpose of the Study:

• Develop and validate an observation-based proxy for short-term, spatial OH variations.
• Enable better mapping of OH in the remote marine troposphere.

Main Methods:

• Utilized comprehensive data from NASA's ATom airborne campaign.
• Created a reduced OH steady-state equation proxy using dominant production/loss pathways.
• Validated the proxy against in situ OH measurements.

Main Results:

• The proxy accurately reflects spatial OH variations (median r² = 0.90).
• Water vapor (H₂O) and nitric oxide (NO) were identified as key modulators of OH.
• Proxy requires only eight commonly observed variables.

Conclusions:

• The developed proxy offers a feasible method for mapping OH spatial variations across the remote marine troposphere.
• This approach can aid in evaluating climate change and human activity impacts on OH.
• Facilitates intermodel comparison of OH in atmospheric simulations.