The NOAA real-time solar-wind (RTSW) system using ACE data

The Advanced Composition Explorer (ACE) RTSW system is continuously monitor ing the solar wind and produces warnings of impending major geomagnetic act ivity, up to one hour in advance. Warnings and alerts issued by NOAA allow those with systems sensitive to such activity to take preventative action. The RTSW system gathers solar wind and energetic particle data at high time resolution from four ACE instruments (MAG, SWEPAM, EPAM, and SIS), packs t he data into a low-rare bit stream, and broadcasts the data continuously. N ASA sends real-time data to NOAA each day when downloading science data. Wi th a combination of dedicated ground stations (CRL in Japan and RAL in Grea t Britain), and time on existing ground tracking networks (NASA's DSN and t he USAF's AFSCN), the RTSW system can receive data 24 hours per day through out the year. The raw data are immediately sent from the ground station to the Space Environment Center in Boulder, Colorado, processed, and then deli vered to its Space Weather Operations center where they are used in daily o perations; the data are also delivered to the CRL Regional Warning Center a t Hiraiso, Japan, to the USAF 55th Space Weather Squadron, and placed on th e World Wide Web. The data are downloaded, processed and dispersed within 5 min from the time they leave ACE. The RTSW system also uses the low-energy energetic particles to warn of approaching interplanetary shocks, and to h elp monitor the Bur of high-energy particles that can produce radiation dam age in satellite systems.