Many recent satellites have mission periods longer than 10 years; thus, satellite-based local space weather monitoring is becoming more important than ever. This article describes the instruments and data applications of the Korea Space wEather Monitor (KSEM), which is a space weather payload of the GeoKompsat-2A (GK-2A) geostationary satellite. The KSEM payload consists of energetic particle detectors, magnetometers, and a satellite charging monitor. KSEM will provide accurate measurements of the energetic particle flux and three-axis magnetic field, which are the most essential elements of space weather events, and use sensors and external data such as GOES and DSCOVR to provide five essential space weather products. The longitude of GK-2A is 128.2° E, while those of the GOES satellite series are 75° W and 135° W. Multi-satellite measurements of a wide distribution of geostationary equatorial orbits by KSEM/GK-2A and other satellites will enable the development, improvement, and verification of new space weather forecasting models. KSEM employs a service-oriented magnetometer designed by ESA to reduce magnetic noise from the satellite in real time with a very short boom (1 m), which demonstrates that a satellite-based magnetometer can be made simpler and more convenient without losing any performance.

1. INTRODUCTION
 2. KSEM OVERVIEW
  2.1 Particle Detector
  2.2 Magnetometer
  2.3 Charging Monitor
 3. APPLICATION OF KSEM DATA
  3.1 Space Weather Products
  3.2 KSEM Contribution to Improving Science and SpaceWeather Services
 4. CONCLUSION
 REFERENCES

• Daehyeon Oh(National Meteorological Satellite Center, Korea Meteorological Administration)
• Jiyoung Kim(National Meteorological Satellite Center, Korea Meteorological Administration) Corresponding Author
• Hyesook Lee(National Meteorological Satellite Center, Korea Meteorological Administration)
• Kun-Il Jang(National Meteorological Satellite Center, Korea Meteorological Administration)