Testing and Enhancement of the Rapidly Updating Real Time Mesoscale Analysis (RU-RTMA) and Work toward a Three-Dimensional RU-RTMA

Accurate, real-time, rapidly updated analyses of near-surface weather fields are critical for forecasters to generate valuable warnings and short-term forecasts for public safety and to enable efficient weather-sensitive commerce in areas such as aviation, renewable energy, and emergency management. NOAA NWS currently produces a widely used hourly updated operational RTMA, that will soon be updated to an RU-RTMA with a 15-min update cycle. Coordinated work led by EMC is ongoing to improve the RU-RTMA for all variables (including surface temperature, dewpoint, and winds, as well as ceiling and visibility and other fields), as well as extend the RU-RTMA to become a three-dimensional analysis, from which the various 2D fields can be diagnosed. The premise behind the effort to develop a 3D RU-RTMA is that the best strategy for obtaining accurate analyses of certain two-dimensional atmospheric fields is to diagnose them from the most accurate three-dimensional analysis. As an example, 2D fields such as ceiling are likely best diagnosed from a three-dimensional cloud analysis that accounts for the true 3D structure of the atmospheric cloud field. In addition, the 3D RU-RTMA analysis will provide consistent set of 3D fields, which will be useful for a broader set of applications.

In this presentation, the current work to improve the RU-RTMA will be described, including testing and evaluation of variations in the background error covariance and assumed observation errors for surface observations. The testing is being conducting using real-time experimental versions of the RTMA/RUA based on the real-time experimental HRRR, and will include CONUS and Alaska versions. Another key aspect of the work focuses on the impact of the observation data window and cutoff period on the 15-min analysis, given that the background HRRR model is only updated hourly.

Work toward the 3D RU-RTMA will also be described. 2D fields that are intrinsically a function of 3D space (PBL height, precipitable water, ceiling, etc.) are diagnosed from the 3-D RU-RTMA fields, giving full physical consistency through having a very accurate high-resolution model background. Extending the operational RTMA to three dimensions allows for the creation of highly useful nowcasting products, including full-column representation of standard meteorological fields such as temperature, water vapor, and wind, as well as hydrometeors (i.e., clouds, precipitation of all forms), and eventually aerosols. The 3D RU-RTMA also includes land-surface diagnostics (e.g., soil moisture, snow state from multi-level land-surface fields), and convective (e.g., hail size, supercell rotation tracks) fields, developed through collaboration with the National Water Center (NWC) and National Severe Storms Laboratory (NSSL), respectively. The 3D RU-RTMA will potentially improve analysis fields for the NOAA National Blend of Models (NBM) project and add a 3-dimensional perspective including cloud-hydrometeor fields. It could also allow merging in of the NCEP/SPC Hourly Mesoscale Analysis and also provide an initial set of fields for a unified NOAA nowcast system.