DYCOMS-II

Description

The second  Dynamics and Chemistry of Marine Stratocumulus Experiment (DYCOMS-II)  took place in July 2001 over an area of roughly 300 km X 300 km shown in Fig. 1.  Missions were conducted using the NSF/NCAR C-130 Hercules aircraft.  Nine flight missions were performed, seven of which dropsondes were deployed near 0800 UTC and 1400 UTC.  

Profiles of the modified index of refraction were computed from the dropsondes data in order to validate COAMPS® forecasts of modified refractivity and to investigate the impact of model vertical resolution on refractivity forecasts. 

Results

Shown in Fig. 2 are profiles of modified refractivity and potential temperature from COAMPS® (dashed) and from the verifying dropsonde sounding (solid) from the first DYCOMS-II research flight (10 July 2001).  Note that the duct base height (DBH) is well forecast but that the strength of the duct (DS) is under-forecast.   The structure of the boundary layer is captured well by the model.  

Statistical analysis of the model performance during the DYCOMS-II field campaign revealed a bias in DBH of –46 m (the model is 46 m too low in the mean) and an average DBH of 746 m; a bias in DS of –7.3 and an average DS of 26.2.