Observations of Nitric Oxide by the Remote Atmospheric Ionospheric Detection System (RAIDS)

Nitric oxide (NO) is a minor constituent of the lower thermosphere which plays numerous key roles there. Its production is very sensitive to those energy sources able to break the strong molecular nitrogen bond; thus NO concentrations are indicative of energy deposition. Cooling through infrared NO emission is a crucial part of the thermospheric energy balance. NO is also the terminal ion in the E-region of the ionosphere. If NO is transported to lower altitudes, it is a catalytic destroyer of ozone. The Remote Atmospheric and Ionospheric Detection System (RAIDS) is a suite of limb viewing radiance monitors observing the lower thermosphere at wavelengths from the EUV through the NIR. An inverse technique is applied to radiance profiles near 237 nm measurements so that the vertical profile of NO density can be determined. One of the key advantages of RAIDS NO observations compared to previous experiments is that RAIDS is attached to the International Space Station and thus not in a sun-synchronous orbit. RAIDS thus will be able to observe NO concentrations at all sunlit local times. To validate the RAIDS NO observations, we present comparisons with previous NO measurements from SNOE. We will also show our first results regarding local time variation of NO and observe the longer-term variation from the data of the past few months.