Broadband radiative closure studies in the Atmospheric Radiation Measurement (ARM) program

One of the greatest successes of the Atmospheric Radiation Measurement (ARM) program has been the spectral radiative closure studies that have been performed at the Southern Great Plains (SGP) ARM Climate Research Facility (ACRF). These primarily clear-sky measurement-model comparisons of surface radiation have led to advancements in the three components of radiative closure analyses: model calculations, including spectroscopic parameters; radiometric measurement accuracy; and the specification of the atmospheric state in the radiating column. This presentation will describe an ongoing project in ARM to expand these closure studies in multiple directions: intensive analysis of cloudy cases; broadband measurements and calculations; shortwave and longwave; cases at all ACRFs are to be analyzed; both soda-straw and GCM-sized spatial domains are considered; and, in addition to surface radiation closure analyses, computations and measurements will be compared at TOA . A second major component of this effort is the production of a dataset of computed heating rates profiles for diagnostic purposes and to drive climate models. This effort, named the ARM Broadband Heating Rate Profile (BBHRP) project, is a collaboration of all the working groups in the program.

This presentation will present selected results from this closure study for both clear and cloudy conditions, including an analysis of the relative model-measurement agreement resulting from the use of a number of different cloud property retrieval algorithms. Future development plans will be discussed, including plans for using the BBHRP framework as the foundation for the next version of a international radiation model intercomparison.