First results using TWINS‐derived ion temperature boundary conditions in CRCM

Abstract

AbstractWe have integrated dynamic, spatiotemporally resolved ion temperature boundary conditions into the Comprehensive Ring Current Model (CRCM), which are based on 2‐D equatorial maps derived from the Two Wide‐Angle Imaging Neutral‐Atom Spectrometers (TWINS) energetic neutral atom (ENA) data. The high‐speed stream‐driven event on 22 July 2009 is simulated and compared against an identical simulation using a statistically derived boundary condition model. ENA‐derived temperatures allow users to include event‐specific observations associated with a dynamic plasma sheet. This method also provides temperatures in the important region between geosynchronous orbit and the plasma sheet, a region which existing empirical models exclude. We find that the spatial and energy distributions of ring current flux and pressure have sensitive dependence on boundary conditions during this event. The coupling of boundary conditions to the time history of the convection field strength also plays an important role by throttling the influence of the boundary plasma on the inner magnetosphere. Simulated moments and spectra from our simulations are compared with remotely imaged ion temperatures from TWINS and also in situ energy spectra and temperature moments from Time History of Events and Macroscale Interactions during Substorms‐D. Storm time dusk‐dawn asymmetries consistent with observational data, such as Zhang et al. (2006), are reproduced well when CRCM is provided with the event‐specific boundary model. A hot localized structure observed by TWINS at geosynchronous midnight during a strong northward interplanetary magnetic field interval is also reproduced with this boundary model, whereas the empirical boundary model fails to yield this feature.