RAP for YOPP: The NOAA Rapid Refresh Model and Its Contribution to the Year of Polar Prediction

The NOAA Rapid Refresh (RAP) numerical weather prediction model is an hourly updated model that provides weather forecasts out to 39 hours. The RAP domain covers all of North America including almost the entire Arctic Ocean. Data from a wide range of sources (synoptic radiosondes, aircraft data, surface met, satellite observations, and cloud observations) are all used to provide the best initial state of the atmosphere and clouds over this domain. The model development is continuous, with updates released to operations within the National Weather Service every 2 years. Recent model development has emphasized improved data assimilation, especially of cloud fields, and improved treatment of the physical processes in the land surface model, the boundary layer parameterization, radiation scheme, and microphysics.

This presentation will present a brief overview of the RAP, and will then focus on the model’s ability to accurately simulate the atmosphere, clouds, and radiation in the Arctic for different forecast lengths. Profiles of bias and root mean square error in temperature, humidity and wind from both radiosondes and aircraft data will be shown, as well as comparisons with surface meteorological observations. The unique cloud and radiation observations at the Department of Energy’s Atmospheric Radiation Measurement sites at both Utqiagvik (formerly Barrow) and Oliktok will be compared against RAP forecasts. These comparisons provide a baseline characterization of the model’s ability to simulate the Arctic atmosphere, and both the analyses and forecasts fields will be made available to the YOPP participants.