28 July 2014

Comparing 16 Years of Cloud Fraction and Cloud Albedo from Surface-Based Shortwave Radiation Measurements

Summary

Researchers have conducted ground-based radiation measurements to gain information on clouds and the surface radiation budget. Representing sub-grid processes and properties (e.g. cloud formation and dissipation) within a large-scale model grid box is a challenge in general circulation models (GCMs). A team of scientists, including a Department of Energy researcher at Pacific Northwest National Laboratory, examined a newly-developed approach that allows for simultaneous retrievals of cloud fraction and cloud albedo from ground-based shortwave broadband radiation measurements. They developed the approach, called XL2013, to derive cloud fraction and cloud albedo from ground-based shortwave broadband radiation measurements at the Department of Energy Atmospheric Radiation Measurement (ARM) Southern Great Plains site. The team compared results from the approach with separate retrievals of cloud fraction and cloud albedo also developed using ARM data. Overall they found good agreement between the retrievals of both cloud fraction and cloud albedo, though with a few noted differences attributable to mutual contamination of errors in the techniques that determine these properties separately. The researchers also note that using total radiation partitioned into direct and diffuse radiation in retrievals holds great promise by providing a consistent way to compare the cloud fraction and cloud albedo simulated by GCMs and observations.

Contact
Yu Xie
Funding
Publications
Xie, Y., Liu, Y., Long, C., & Min, Q. "Retrievals of Cloud Fraction and Cloud Albedo from Surface-based Shortwave Radiation Measurements: A Comparison of 16 Year Measurements." Journal of Geophysical Research - Atmospheres (2014). [10.1002/2014JD021705].