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CAGEX Version 3: Tightening Shortwave Fluxes and Measurements of Surface Spectral Characteristics

Alberta, T.L., Analytical Services and Materials, Inc.; Charlock, T.P., National Aeronautics and Space Administration-Langley Research Center
Ninth Atmospheric Radiation Measurement (ARM) Science Team Meeting

Version 3 of the CAGEX (Clouds and Earth's Radiant Energy System [CERES]/Atmospheric Radiation Measurement [ARM]/Global Energy and Water Experiment [GEWEX]) is introduced. As with Version 2 (10/95) and Version 1 (4/94), Version 3 provides input data sufficient for broadband radiative transfer calculations; fluxes computed with those inputs and the Fu-Liou code as modified by Hu, Rose and Kratz; and measurements for validation and diagnostics. Along with the usual ARM data sets (Solar and Infrared Radiation Station (SIRS) radiometry, Microwave Radiometer (MWR) precipitable and liquid water, balloon-borne soundings, etc.), Version 3 will include a surface radiometry data set and helicopter measurements of spectral reflectances for six scene types. These measurements, referred to as the CERES/ARM Radiation Experiment (CARE), were collected by a NASA Langley Research Center team led by Cahoon and Rutledge. One of the important aspects of CAGEX Version 3 is the treatment of shortwave diffuse fluxes, as measured by Eppley Shaded Pyranometers. These fluxes are adjusted for the purposes of reducing negative offsets, which are a function of the net longwave flux at the instrument and are typical of these types of radiometers. Our poster will address our method of adjustment, which follows techniques suggested by Dutton. A second important aspect of Version 3 is the unique spectral reflectance measurements collected by NASA Langley Research Center's Airborne Radiometer System (ARS) aboard a helicopter that makes several passes (azimuths) over a specific site at various solar zenith angles, measuring several parameters, including spectral bidirectional reflectance distribution functions (BRDFs), upwelling shortwave (SW) and longwave (LW) fluxes, and LW directional radiances.

Note: This is the poster abstract presented at the meeting; an extended version was not provided by the author(s).