Vertical Profile of Cloud Optical Parameters Derived from Airborne Measurements Above, Inside and Below Clouds.
Level 4 - case-series / case-control
Non-clinical remote sensing and methodology study evaluated on two observational airborne cases (graded by design analogy).
PubMed 30467442 · doi:10.1016/j.jqsrt.2018.04.005
What was done
The authors developed a retrieval method based on asymptotic radiative transfer theory for thick atmospheres and diffusion domains within clouds to simultaneously estimate two to three optical parameters (optical thickness, single scattering albedo, and phase function asymmetry parameter) independently for every wavelength. The method was applied to airborne angular solar radiation data collected by NASA's Cloud Absorption Radiometer (CAR) flown above, inside, and below marine stratocumulus clouds in two geographic locations: offshore Namibia and offshore California. Observational and retrieval errors were handled using numerical regularization.
What was found
The abstract reports no specific numerical results, error bounds, or statistical metrics. It reports qualitatively that the method achieved stable and smooth solutions without traditional constraints such as semi-infinite optical thickness or purely non-absorbing scattering, and demonstrated potential for parameterizing shortwave radiative properties including reflection, transmission, radiative divergence, and heating rates.
Why it matters
Traditional cloud remote sensing retrievals frequently depend on simplifying assumptions that limit retrievals to a single optical parameter. This approach provides a framework to simultaneously and independently determine multiple optical parameters per wavelength from multi-angle airborne radiometric observations.
Limits
The abstract reports zero numerical validation metrics, accuracy comparisons, or quantitative uncertainty estimates. The evaluation is restricted to two specific marine stratocumulus cases, providing no data on performance in other cloud regimes or heterogeneous cloud conditions.
Cited by
- supports Long-wavelength light is absorbed and scattered by water, resulting in slight attenuation and diffuse multi-angle arrival on cloudy winter days.