Rotational Raman scattering (Ring effect) in satellite backscatter ultraviolet measurements

Area of Science:

• Atmospheric physics
• Radiative transfer theory
• Remote sensing

Background:

• Satellite measurements of backscattered ultraviolet radiation are crucial for atmospheric studies.
• Solar Fraunhofer lines in spectra are affected by atmospheric scattering processes.
• Rotational Raman scattering (RRS) introduces frequency shifts in scattered light, impacting spectral measurements.

Purpose of the Study:

• To quantify the impact of rotational Raman scattering (RRS) on satellite measurements of backscattered ultraviolet radiation.
• To develop and validate a radiative transfer model for predicting the RRS filling-in effect.
• To understand the factors influencing the magnitude of RRS-induced spectral changes.

Main Methods:

• Detailed radiative transfer calculations were performed.
• A model was developed to simulate the filling-in of solar Fraunhofer lines due to RRS.
• Model predictions were compared with observational data from satellite instruments.

Main Results:

• The study estimates the effects of RRS on satellite UV measurements.
• RRS causes filling in of solar Fraunhofer lines, known as the Ring effect.
• The magnitude of the Ring effect is dependent on wavelength, solar zenith angle, surface reflectance, surface pressure, and instrument spectral resolution.

Conclusions:

• The developed radiative transfer model accurately predicts the Ring effect caused by RRS.
• Model predictions show good agreement with observations from the Shuttle Solar Backscatter Ultraviolet Radiometer and Nimbus-7 Solar Backscatter Ultraviolet Radiometer.
• This work validates the understanding of RRS effects in satellite UV remote sensing.