Space weather comes of age: new sensors and models for ionospheric specification and forecast

Traditionally the ionosphere and thermosphere are considered "data-starved" regions of the atmosphere but recent experimental and operational optical satellite instruments and new techniques to exploit GPS and orbiting radio beacons are dramatically improving the situation. Similarly, new classes of assimilating ionospheric models are under development to exploit these data and provide a significantly improved capability to specify and forecast weather of the upper atmosphere and ionosphere. The Advanced Research and Global Observation Satellite (ARGOS), launched by the DoD Space Test Program in 1999 demonstrated ultraviolet remote sensing of the neutral atmosphere and ionosphere from limb sensors in low Earth orbit (LEO). Soon after, the Global Ultraviolet Imager (GUVI) on the NASA TIMED satellite employed a similar capability using cross track ultraviolet remote sensing. The first of five sets of operational versions of both of these instruments, the Special Sensor Ultraviolet Limb Imager (SSULI) and Special Sensor Ultraviolet Spectroscopic Imager (SSUSI), respectively, where launched aboard the first of the DMSP Block 5D3 weather satellites in October of 2003. Radio frequency techniques for ionospheric remote sensing using ground-based dual frequency GPS receivers and GPS occultation receivers on LEO satellites are making a significant contribution to the global ionospheric database. In 2005, the launch of a constellation of six satellites called the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) will provide ionospheric measurements using GPS occultation receivers ultraviolet photometers and dual frequency UHF radio beacons. The latter will allow tomographic ionospheric reconstructions using ground-based receivers. These and other data will be used to drive the Global Assimilations of Ionospheric Measurements (GAIM) model to dramatically improved current modeling and forecast capabilities for the global thermosphere and ionosphere. More innovations are under development in the form of long-dwell, high temporal and spatial resolution measurements of the ionosphere from geosynchronous orbit using the Ionospheric Mapping and Geocoronal Experiment (IMAGER). IMAGER will provide GOES-like monitoring of the ionosphere and neutral atmosphere.