Wang‐Sheeley‐Arge–Enlil Cone Model Transitions to Operations

http://www.agu.org/journals/sw/swa/news/article/?id=2011SW000669 The National Weather Service's (NWS) Space Weather Prediction Center (SWPC) is transitioning the first large-scale, physics-based space weather prediction model into operations on the NWS National Centers for Environmental Prediction (NCEP) supercomputing system (see also C. Schultz, Space weather model moves into prime time, Space Weather, 9, S03005, doi:10.1029/2011SW000669, 2011). The model is intended to provide 1- to 4-day advance warning of geomagnetic storms from quasi-recurrent solar wind structures and Earth-directed coronal mass ejections (CMEs). A team has been put together at SWPC to bring an advanced numerical model—developed with broad participation of the research community—into operational status. The modeling system consists of two main parts: (1) a semiempirical near-Sun module (Wang-Sheeley-Arge (WSA)) that approximates the outflow at the base of the solar wind; and (2) a sophisticated three-dimensional magnetohydrodynamic numerical model (Enlil) that simulates the resulting flow evolution out to Earth. The former module is driven by observations of the solar surface magnetic field accumulated over a solar rotation and composited into a synoptic map; this input is used to drive a parameterized model of the near-Sun expansion of the solar corona, which provides input for the interplanetary module to compute the quasi-steady (ambient) solar wind outflow. Finally, when an Earth-directed CME is detected in coronagraph images from NASA spacecraft, these images are used to characterize the basic properties of the CME, including speed, direction, and size. This input “cone” representation is injected into the preexisting ambient flow, and the subsequent transient evolution forms the basis for the prediction of the CME's arrival time at Earth, its intensity, and its duration (Figure 1). The system will be delivered to NCEP in fall 2011, to undergo a year of trial operation. During that time, potential improvements to the modeling system will be evaluated, and early assessments of its performance will be undertaken. This transition draws upon contributions from many agencies and institutions, including the Center for Integrated Space Weather Modeling, Community Coordinated Modeling Center, Naval Research Laboratory, National Center for Atmospheric Research, Laboratory for Atmospheric and Space Physics, Office of Naval Research, Air Force Weather Agency (AFWA), and the Air Force Research Laboratory (AFRL). The long-term success of the system will hinge on training (collective experience), the quality of inputs (better interpretation, new observations), customer interactions, and the establishment of an effective operations-to-research (and the reverse) chain, which is critical to the continued improvement of the system. We thank C. Nick Arge for his essential contribution in the development and implementation of the WSA model. Annette Parsons is the AFWA project administrator at SWPC. Douglas Biesecker is the project verification and validation lead at SWPC. Dusan Odstrcil is the Enlil originator and a researcher at George Mason University, Fairfax, Va. George Millward is the project technical lead at SWPC. Steve Hill is the development and transition section lead at SWPC. Vic Pizzo is project scientist at NOAA SWPC, Boulder, Colo.; E-mail: vic.pizzo@noaa.gov