On the estimation of particle energies and fluxes incident over Boston during a daytime auroral event

The earth's upper atmosphere gets affected by the influence of particles of solar wind origin, especially during space weather events. Estimating the energy inputs into the upper atmosphere is very essential to be able to eventually quantify the energy budget into the upper atmosphere and also to understand the coupling between atmospheric regions. During space weather events the incidence of energy flux shows significant spatial and temporal variation. Particle energies have predominantly been measured from instruments onboard satellites. Estimation of energies using radar-based inversion techniques are quiet involved and even when possible, particle energies at only higher energy range (around keV and beyond) can be inferred. In the present paper, we present the results on particle fluxes and energies that we obtained from combined investigations of optical, radar and modeling techniques. The storm of October 30, 2003 was considered for analysis. On that day we had carried out one of the first daytime auroral observations of the OI red emission line from Boston using the BU-built High Resolution Echelle spectrograph. We had measured the peak brightness of aurora to be 38 kR, which is not predicted by the GLOW model. However, the match between the measured brightness and the model prediction during non-storm period of that day is very good. Therefore, assuming the discrepancy in the measured and the model emissions during the storm time to be only due to the particle inputs, we inferred the particle energy fluxes for given characteristic energies as obtained from the peak ionospheric heights observed by the Millstone Hill Incoherent Scatter radar. The energy fluxes vary between 2 to 12 mWm-2. Results such as these add to the credence of the capability of the daytime measurement technique in understanding the upper atmospheric dynamics.