Multi-angular polarimetric remote sensing to pinpoint global aerosol absorption and direct radiative forcing

Area of Science:

• Atmospheric Science
• Climate Science
• Remote Sensing

Background:

• Quantitative estimations of atmospheric aerosol absorption are uncertain due to limited global distribution data.
• Satellite sensors often lack sensitivity to aerosol absorption, contributing to large uncertainties in climate forcing assessments (IPCC AR5 and AR6).

Purpose of the Study:

• To utilize multi-angular polarimeters (MAP) for improved constraints on absorbing aerosol emissions.
• To estimate global aerosol absorption optical depth (AAOD) and its climate effect with greater accuracy.

Main Methods:

• Employing multi-angular polarimeters (MAP) to gather aerosol property data.
• Analyzing MAP data to constrain emission of absorbing aerosol species.
• Calculating global AAOD and black carbon direct radiative forcing (BC DRF).

Main Results:

• The estimated modern-era mid-visible AAOD is 0.0070, exceeding IPCC estimates by 1.3-1.8 times.
• The calculated black carbon instantaneous direct radiative forcing (BC DRF) is +0.33 W/m².
• MAP data reduced the 95% confidence interval of BC DRF by a factor of 2, enhancing spatial distribution confidence.

Conclusions:

• MAP instruments provide crucial data for reducing uncertainties in atmospheric aerosol absorption.
• This study offers a more reliable estimate of AAOD and BC DRF, improving climate forcing assessments.
• Enhanced confidence in aerosol radiative forcing is achieved through MAP-based constraints.