Qingfu Liu

Evaluation of Storm Structure from the Operational HWRF during 2012 Implementation

AbstractIn this work, a high-resolution triple-nested implementation of the National Centers for Environmental Prediction (NCEP) operational Hurricane Weather Research and Forecasting Model (HWRF) for the 2012 hurricane season is evaluated. Statistics of retrospective experiments for the 2010–11 hurricane seasons show that the new configuration demonstrates significant improvement compared to the 2011 operational HWRF in terms of storm track, intensity, size, dynamical constraints between mass and wind field, and initial vortex imbalance. Specifically, the 5-day track and intensify forecast errors are improved by about 19% and 7% for the North Atlantic basin, and by 9% and 30% for the eastern Pacific basin, respectively. Verifications of storm size in terms of wind radii at 34-, 50-, and 64-kt (17.5, 25.7, and 32.9 m s−1) thresholds at different quadrants show dramatic improvement with most of the overestimation of the storm size in previous operational HWRF versions removed at all forecast times. In addi...

Community Support and Transition of Research to Operations for the Hurricane Weather Research and Forecasting Model

AbstractThe Hurricane Weather Research and Forecasting Model (HWRF) is an operational model used to provide numerical guidance in support of tropical cyclone forecasting at the National Hurricane Center. HWRF is a complex multicomponent system, consisting of the Weather Research and Forecasting (WRF) atmospheric model coupled to the Princeton Ocean Model for Tropical Cyclones (POM-TC), a sophisticated initialization package including a data assimilation system and a set of postprocessing and vortex tracking tools. HWRF’s development is centralized at the Environmental Modeling Center of NOAA’s National Weather Service, but it incorporates contributions from a variety of scientists spread out over several governmental laboratories and academic institutions. This distributed development scenario poses significant challenges: a large number of scientists need to learn how to use the model, operational and research codes need to stay synchronized to avoid divergence, and promising new capabilities need to be ...

Representing Multiple Scales in the Hurricane Weather Research and Forecasting Modeling System: Design of Multiple Sets of Movable Multilevel Nesting and the Basin-Scale HWRF Forecast Application

AbstractIn this study, the design of movable multilevel nesting (MMLN) in the Hurricane Weather Research and Forecasting (HWRF) modeling system is documented. The configuration of a new experimental HWRF system with a much larger horizontal outer domain and multiple sets of MMLN, referred to as the “basin scale” HWRF, is also described. The performance of this new system is applied for various difficult forecast scenarios such as 1) simulating multiple storms [i.e., Hurricanes Earl (2010), Danielle (2010), and Frank (2010)] and 2) forecasting tropical cyclone (TC) to extratropical cyclone transitions, specifically Hurricane Sandy (2012). Verification of track forecasts for the 2011–14 Atlantic and eastern Pacific hurricane seasons demonstrates that the basin-scale HWRF produces similar overall results to the 2014 operational HWRF, the best operational HWRF at the same resolution. In the Atlantic, intensity forecasts for the basin-scale HWRF were notably worse than for the 2014 operational HWRF, but this d...

Hurricane Weather Research and Forecasting (HWRF) Model: 2017 Scientific Documentation

1NOAA/NWS/NCEP Environmental Modeling Center, College Park, MD, 2NOAA Earth System Research Laboratory, CIRES / University of Colorado, and Developmental Testbed Center, Boulder, CO, 3National Center for Atmospheric Research and Developmental Testbed Center, Boulder, CO, 4University of Rhode Island, 5IMSG Inc, 6Geophysical Fluid Dynamics Laboratory, Princeton, NJ, 7Hurricane Research Division, AOML, Miami, FL,and RSMAS, CIMAS, University of Miami, Miami, FL

Impact of Assimilating Aircraft Reconnaissance Observations on Tropical Cyclone Initialization and Prediction using Operational HWRF and GSI Ensemble-Variational Hybrid Data Assimilation

AbstractThis study evaluates the impact of assimilating high-resolution inner-core reconnaissance observations on tropical cyclone initialization and prediction in the 2013 version of the operational Hurricane Weather Research and Forecasting (HWRF) model. The 2013 HWRF data assimilation system is a GSI-based hybrid ensemble-variational system that in this study uses the Global Data Assimilation System ensemble to estimate flow-dependent background error covariance. Assimilation of inner-core observations improves track forecasts and reduces intensity error after 18-24 h. The positive impact on the intensity forecast is mainly found in weak storms, where inner-core assimilation produces more accurate tropical cyclone structures and reduces positive intensity bias. Despite such positive benefits, there is degradation in short-term intensity forecasts that is attributable to spin-down of strong storms, which has also been seen in other studies.There are several reasons for the degradation of intense storms....

Increasing vertical resolution in US models to improve track forecasts of Hurricane Joaquin with HWRF as an example

Significance For forecasts of Hurricane Joaquin in 2015, the European Centre for Medium-Range Weather Forecasting model consistently and correctly predicted a track away from the US mainland, while the National Oceanic and Atmospheric Administration National Centers for Environmental Prediction Global Forecast System (GFS) and Hurricane Weather Research and Forecast (HWRF) models made erroneous track forecasts with landfall on the US East Coast. Our investigation found that inadequate vertical resolution in HWRF likely contributed to the track error. A number of HWRF forecasting experiments, carried out at different vertical resolutions, show that the track forecasts of Hurricane Joaquin (2015) were greatly improved by increasing the vertical resolution of the forecast model. These results suggest that hurricane tracks in GFS could also be improved by increasing vertical resolution in that model. The atmosphere−ocean coupled Hurricane Weather Research and Forecast model (HWRF) developed at the National Centers for Environmental Prediction (NCEP) is used as an example to illustrate the impact of model vertical resolution on track forecasts of tropical cyclones. A number of HWRF forecasting experiments were carried out at different vertical resolutions for Hurricane Joaquin, which occurred from September 27 to October 8, 2015, in the Atlantic Basin. The results show that the track prediction for Hurricane Joaquin is much more accurate with higher vertical resolution. The positive impacts of higher vertical resolution on hurricane track forecasts suggest that National Oceanic and Atmospheric Administration/NCEP should upgrade both HWRF and the Global Forecast System to have more vertical levels.