Evaluation of three low-order boundary layer parameterizations in a new single column thermodynamic model using SHEBA field data

A new single column climate model (SCM) was created to aid in the development and testing of physical parameterizations pertinent to high latitude climate research. Three first-order planetary boundary layer (PBL) parameterizations were implemented for intercomparison and evaluation, as well as for the purpose of demonstrating the utility of the SCM as a parameterization testing and development tool. Several simulations using the different boundary layer schemes are compared against one another and against data collected during SHEBA. The boundary layer scheme evaluations are somewhat ambiguous due to problems with the advective tendencies used to force the SCM, which are derived from GCM output. However, comparisons indicate that the increasingly sophisticated schemes give generally more realistic profiles, motivating the implementation and further evaluation of higher-order schemes. The results of the experiments also indicate the difficulty of evaluating SCM output against observations using forcing data that contain considerable bias. These results thereby also motivate the need for the creation of a better data set for advective tendencies. Until better lateral forcing is obtained, allowing for meaningful comparisons between SCM simulations and observations, PBL parameterizations can only be evaluated against one another, as was done in this paper, or against output from a large eddy simulation (LES) model driven by the same data set, which will be the focus of future work. The SCM framework is shown to work well as a parameterization testbed in spite of the problems with the advections, and will be a useful tool once appropriate lateral forcing is obtained. At that time, the SCM and the LES model will be used in conjunction for testing and development of higher-order PBL schemes. Preliminary efforts toward that goal are presented.