Four-Dimensional Weather System (4DWX)

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Over the past decade, the U.S. Army Test and Evaluation Command (ATEC) has sponsored the research and development of the Four-Dimensional Weather (4DWX) system, a cutting-edge weather modeling system based on MM5 and the WRF Model.  4DWX provides high-resolution mesoscale modeling capability, short-term thunderstorm prediction, multi-dimensional integrated displays, and fine-scale climatological analysis tools, enabling the Army to test military hardware under precise conditions across the full spectrum of arctic, tropical, desert, and other natural and controlled environments. 4DWX is accredited for operational use at seven test ranges across the United States.

Accomplishments in FY06

Real-Time Four-Dimensional Data Assimilation (RTFDDA) system is now assimilating all available observations from a number of data feeds and producing a new analysis and forecast every one to three hours, depending on the test range.  3-Dimensional Variational Data Assimilation (3DVAR) techniques at the mesoscale are being evaluated, and a number of non-standard observations that cannot be included in RTFDDA's observation-nudging scheme, such as satellite radiance, GPS, and radar, are being incorporated. 3DVAR is currently being integrated into the RT-FDDA system, yielding a model-based solution that will account for all available observations. Weather Research and Forecasting (WRF) Model: The latest version of 4DWX includes the WRF model as one of its forecast cores. Currently both MM5 and the WRF Model are being run in parallel operationally, but in the near future, 4DWX will be entirely WRF-based.  Ensemble Forecasting:  An Ensemble Transform Kalman Filter perturbation algorithm has been implemented and is being evaluated.  Research into the vital issue of ensemble calibration (including first and second moments of ensemble distributions) is also underway as is work on perturbation scaling, specification of lateral boundary conditions, and comparison with other methods.  Coupled Applications: The 4DWX team is heavily involved in coupling numerical weather prediction output with specialized models to create new coupled applications for operational use. This effort currently focused on the Noise Assessment and Prediction System (NAPS) model to predict sound levels generated during the testing of explosives materiel at ATC; the Second-order Closure Integrated Puff (SCIPUFF) model to predict the plume concentration and dosage fields based on user-specified materiel releases; and the General Electric Missile and Satellite Simulation (GEMASS) model to insure that missiles fired from ATEC ranges stay on the ranges.  Model Verification of High-Resolution Models: RAL is applying innovative object-oriented verification techniques that treat predicted and observed weather as one or more “events,” or “objects”. This form of verification does not inherently handicap higher-resolution models, and it is often more consistent with the mental image that end-users have of forecasts and observations. MetVault Data Repository: In order to manage the large datasets generated by 4DWX, and in order to collect other ancillary datasets that may be useful to the ATEC sponsor, RAL is developing a central data repository called the MetVault.

Plans For FY07:

In addition to continuing the research and development efforts noted above, RAL is developing a Web portal to provide 4DWX users with intuitive and coherent access to the underlying system capabilities. Users will be able to configure the portal so that its content and arrangement best suits their work style.  RAL will also design and implement a quality control system for observations that are being ingested into the 4DWX database that will become part of MetVault. To improve the management of the increasingly powerful computers that are being used in the ATEC program, engineers and scientists will continue development of a Model Manager in FY07.  The Model Manager will also provide RAL staff with more modular and automated control of non-operational RTFDDA simulations.