An Intercomparison of Forward Calculated Albedo to Satellite Observed Albedo in Cirrus Clouds
Abstract
Cirrus clouds are one of the least understood components of the global climate system. The Atmospheric Radiation Measurement (ARM) program is attempting to resolve the scientific uncertainties surrounding the effects of clouds on global climatic change. To this end, the ARM program is compiling continuous observations of clouds, including cirrus microphysical properties using a diverse suite of instruments, at several climatically significant locations around the globe. One of the algorithms used by the ARM program to derive the cirrus microphysical properties employs reflectivity measurements from a millimeter wavelength radar, and infrared emission spectra observed by an interferometer. In an effort to validate the results derived from this reflectivity radiance algorithm, the effects of cirrus clouds on the radiation field, calculated using the microphysical properties retrieved by the algorithm, are compared against atmospheric radiative quantities derived from satellite observations and surface radiometers. For 15 cirrus events, the top of the atmosphere albedo calculated from the algorithm's retrievals is compared against the shortwave broadband albedo derived from satellite observations. In an attempt to move toward closure of the column radiation budget, for two case studies, comparisons are made between the calculated and observed surface solar fluxes. Using the results from the two case studies, we attempt to draw conclusions regarding the topic of anomalous absorption of solar radiation in cloudy atmospheres. Problems encountered during this research with the Moderate Resolution Transmittance (MODTRAN) radiative transfer code are also presented.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1999
- Accession Number
- ADA367634
Entities
People
- Donald G. Shannon
Organizations
- University of Utah