ARM Data as a Source of Validation of GCM Physics
| Stephens, Graeme | Colorado State University |
| Wood, Norm | Colorado State University |
| Gabriel, Philip | Colorado State University |
Data provided by the Atmospheric Radiation Measurement (ARM) program are analyzed in an attempt to evaluate key physical parameterizations of atmospheric general circulation models (GCMs). The research focuses on two key aspects of the physical climate system. The first aspect concerns the radiative processes that are a principal component of the model energetics. The second concerns the parameterization of the hydrological cycle of the model. The connections between these two components of the climate system are considered critical to important but highly uncertain climate system feedbacks. The majority of our effort has been in the evaluation of a radiation scheme and how the interaction of radiation with clouds is treated in a variety of atmospheric models, as the treatment of this interaction in models has long been considered suspect. In this regard, ARM data have been used to study aspects of the parameterization specific to GCMs and to quantify errors of these parameterizations, including errors in the parameterizations of (i) cloud overlap; (ii) in-cloud horizontal inhomogeneity; and (iii) cloud optical properties. The second area of research focuses on tropical convection, as the treatment of tropical convection in models is considered one of the main sources of model error. This aspect of the study characterizes the properties of convection as determined from millimeter cloud radar (MMCR ) observations, including those gathered by the ARM MMCR's at Darwin, Manus, and Nauru. The convective characteristics determined by these radar systems are documented and used to evaluate the character of convection as treated by both GCM parameterizations and cloud resolving models.
This poster will be displayed at the ARM Science Team Meeting.