Assessing the Impact of Non-Conventional Observations on High-Resolution Analyses and Forecasts
A key recommendation of a 2009 report by the National Research Council (NRC) was to integrate existing and new mesoscale observing networks to create a nationwide “network of networks”. This recommendation originated in response to deficiencies in the U.S. mesoscale observing network, particularly the lack of high spatial resolution and temporal frequency moisture, temperature, and wind observations within the lower troposphere. The report further recommended that research testbeds be established to assess the potential forecast impact of such a network. One such testbed has been established in the Dallas-Fort Worth (DFW) metroplex, namely the Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) DFW Urban Demonstration Network.
This research evaluates the impact of non-conventional observing systems in the DFW testbed on high-resolution analyses and forecasts of convection. The non-conventional observing systems include six CASA X-band radars and two Terminal Doppler Weather Radars (TDWRs), along with surface observations from Mobile Platform Environmental Data (MoPED), WeatherBug, Citizen Weather Observer Program (CWOP), and Understory Weather. The Advanced Regional Prediction System (ARPS) model is used to perform observing system experiments (OSEs) that test the impact of these non-conventional observing networks. The ARPS three-dimensional variational (3DVAR) analysis and its associated cloud and hydrometeor analysis are used to produce analysis increments every 10 minutes, which are then applied to the model forecast using incremental analysis updating (IAU) during a 30-minute assimilation window. The experiments are performed in a case study of a prolific hail-producing supercell from 11 April 2016. The analysis includes qualitative comparisons of the forecast reflectivity fields, quantitative comparisons of model-derived hail with radar-observed hail, and surface-level verification of the temperature and dew point fields. The analysis concludes with a brief comparison of the results for single-moment versus double-moment microphysics scheme.