Support for users and developers of the Hurricane WRF model

Christina Holt (1,2,3), Ligia Bernardet (1,2,3), Vijay Tallapragada (4), Mrinal Biswas (5), Samual Trahan (4,6), Laurie Carson (5)

Abstract
The NOAA operational Hurricane Weather Research and Forecast model (Hurricane WRF, or HWRF) is an important component of the numerical guidance used at the National Hurricane Center, making it critical that the HWRF model be continuously improved. Given the complexity of the HWRF model, which consists of the WRF atmospheric model coupled to the Princeton Ocean Model for Tropical Cyclones (MPIPOM-TC), a sophisticated initialization package including a data assimilation system, and a set of postprocessing and vortex tracking tools, EMC has partnered with the Developmental Testbed Center (DTC) to help accelerate the infusion of the new technologies onto the model. This work describes the support provided to HWRF users and developers through the DTC. The Community HWRF has a yearly release containing all the capabilities of the HWRF operational implementation of that year, plus additional research capabilities, such as alternate physics suites and an idealized simulation package. The Community HWRF code is stable and well tested, and is distributed along with a Users’ Guide, Scientific Documentation, test datasets, and access to an online helpdesk. In person or online tutorials are made available; for example, in 2014 tutorials were presented in College Park, MD, and in Taiwan. In addition to the HWRF release made available to all users, the DTC provides support to those conducting active HWRF development. This support includes access to the HWRF code repository, assistance with creating, updating, and merging branches, training, consistency checks to ascertain that new developments do not break existing capabilities, and integration of codes developed by the HWRF group with those developed by the community at large. The latter activity is particularly important to avoid code divergence for the HWRF components that are extensively developed by non-HWRF groups, such as the WRF atmospheric model. The HWRF developer support provided by the DTC, accessible through http://dtcenter.org/HurrWRF/developers, has been particularly helpful to recipients of grants from the NOAA Hurricane Forecast Improvement Project (HFIP) and the DTC Visitor Program. By making HWRF a well-supported community model through the DTC, the rate of transition of new research and development to HWRF has increased, leading to tangible benefits to tropical cyclone numerical operational forecasting.