Optical radiometry and spectroradiometry in the atmospheric radiation measurement (ARM) program

The ARM program has provided much of the impetus for significant improvements in measurement accuracy of both shortwave (solar) and longwave (terrestrial infrared) radiation and in the measurement of inputs needed for model calculations. Largely this has been prompted by measurement and model comparisons that force the modelers and experimentalists to more closely examine their respective products. This paper outlines the ARM measurements of radiation and improvements made in measuring broadband and spectral shortwave and broadband longwave radiation