The project has two main objectives: (1) Improve the International Reference Ionosphere (IRI) model by including the contributions from precipitating electrons to the model; this will result in better specification of the auroral E region in the model; and (2) Develop, implement, test, and validate an auroral boundary and/or Kp driven ability for nowcasting and forecasting of the polar E-region ionosphere. The IRI is an empirical model which is one of the most widely used by the upper atmosphere community to simulate the ionosphere for given conditions. However, its representation of the auroral region has been known to be somewhat compromised due to a lack of information on and observations for the polar region. One of the processes not well parameterized is that due to precipitating electrons, one of the major drivers of space weather in the ionosphere and thermosphere. The precipitation not only creates extra ionization in the high latitude ionosphere which leads to absorption and disturbances in radio communication, but also enhances the Joule heating which alters the thermospheric convection and composition. The altered thermospheric convection brings composition changes induced by Joule heating from high latitudes down to middle and low latitudes, even to the opposite hemisphere, and can cause global ionospheric disturbances. The precipitating electrons will be specified in the new IRI model by using a new Kp-dependent global auroral model that was developed with FUV image data obtained by the GUVI instrument on the TIMED satellite. The auroral model provides the global distribution of mean energy and energy flux of precipitating electrons. With these, one can then determine two key auroral E-layer parameters: the peak E-layer density (NmE) and the E layer height (hmE). The new NmE and hmE values will provide the data base for modifying the IRI E-region model to include the contribution from precipitating electrons. The FUV-based global auroral model will also enable better representation of the real time auroral oval conditions by providing information on the boundaries of the auroral oval and the location of the peak electron energy fluxes in different magnetic local time sectors. These will be represented as a statistical model for inclusion in the IRI. The auroral E-layer representation and the auroral boundaries in the improved IRI will be validated with electron density profile data from incoherent scatter radars such as Sondrestrom, EISCAT, and NSF's new Poker Flat Incoherent Scatter Radar, and with precipitating electron data from the DMSP F13-F17 particle detectors.
Normal 0 false false false EN-US X-NONE X-NONE This award was for a collaborative research project between the Applied Physics Laboratory of Johns Hopkins University and the Space Weather Laboratory of George Mason University. The main objective of this award was the improvement of the International Reference ionosphere (IRI) at high latitudes. IRI is a climatological, data-based model of the ionosphere that is the international standard for the specification of the ionospheric environment. IRI’s importance is highlighted by its many applications including ionospheric corrections for Earth observations from space and Radio astronomy from the ground, background ionosphere for HF radio wave propagation and radio occultation studies, specification of environmental conditions for instrument and satellite design, and orbit determination and navigation in space, to name just a few. Improvements at high latitudes are of special importance because of increased use of transpolar airline routes and the need for continuous ground-to-plane HF communication channels. This is also a region of high scientific interest because it is the coupling region between ionosphere and magnetosphere. The award goals were accomplished by introducing for the first time the specification of auroral boundaries in IRI. The auroral oval is the donut-shaped region around the magnetic poles where precipitating electrons produce the beautiful display of the Northern lights and induce strong changes in the ionospheric plasma. This new model was developed with data from the Global UV Imager (GUVI) instrument that is flying on NASA’s TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics) satellite since 2002. The model was adopted for use in the IRI model and released in the 2012 version of the model. A module for real-time updating with DMSP-SSUSI data was also developed and can be used in conjunction with the IRI-Real-Time (IRI-RT) model. In addition, this award supported research opportunities for graduate students at George Mason University.
