Impact of E-Region Ion-Neutral Chemistry on SABER Measurements of 4.3 um Emission and the Retrieval of Kinetic Temperature and Carbon Dioxide

The TIMED/SABER experiment is based on broadband limb emission measurements. Measurements from the 4.3 um channel, in particular, are strongly enhanced during nighttime aurora. Auroral particle precipitation increases the ionization of the neutral atmosphere, followed by fast ion-neutral exothermic reactions that produce vibrationally excited NO+ (i.e., NO+(v)), which promptly emits at 4.3 um. Therefore, SABER 4.3 um measurements provide a unique tool for observing and analyzing the E-region response to auroral particle energy deposition, as NO+ is the terminal E-region ion. We use SABER data products and 4.3 um measurements, the field-line interhemispheric plasma (FLIP) model, measurements of auroral particle energy characteristics from the NOAA/POES satellites, and radiation transfer algorithms to analyze the ion-neutral energy transfer mechanisms that produce NO+(v) and emission at 4.3 um during the April 2002 and October-November 2003 solar storms. Furthermore, since SABER kinetic temperature (Tk) and CO2 are simultaneously retrieved from the 15 um and 4.3 um channel measurements, respectively, NO+(v) 4.3 um emission can introduce biases in the SABER Tk/CO2 retrievals at polar latitudes even during quiescent conditions, with maximum biases occurring at summer solstice. Moreover, sensitivity studies are conducted to assess potential biases in SABER Tk/CO2 due to contamination by NO+(v) 4.3 um emission.