Long Duration Daytime Thermospheric Wind Observation Using HIWIND

We propose to fly the balloon-borne Fabry-Perot Interferometer HIWIND (High altitude Interferometer WIND observation) for long duration daytime thermospheric wind observations. The specific scientific questions related to this flight are as follows: 1) how does cusp heating affect the thermospheric winds in the polar region? 2) what are the inter-hemispheric differences in polar cap thermospheric wind patterns? One of the most striking features discovered during the first HIWIND flight in June 2011 is the persistent equatorward wind at all local times just equatorward of the auroral oval [Wu et al, 2012]. The standard NCAR TIEGCM did not reproduce this feature. Instead it showed a strong poleward wind on the dayside. One possible source for the unexpected dayside equatorward winds is strong Joule heating near the cusp region driven by strong east-west IMF conditions [Knipp et al. 2011 and Li et al. 2011]. When the TIEGCM was modified with enhanced cusp heating close to what Knipp et al. [2011] reported, it did reproduce similar equatorward winds. The mystery is that the first HIWIND observation was made during what appears to be modest north, east, and radial IMF conditions. One way to verify the enhanced cusp heating is to make thermospheric wind observations on the poleward side. TIEGCM simulation shows that the enhanced cusp heating can increase the poleward wind on the poleward side of the cusp by ~100 m/s compared to the TIEGCM run with no increased cusp heating. HIWIND is well suited for this kind of observation, because it drifts slowly with the stratospheric winds and scans different geomagnetic latitudes. The proposed HIWIND flight in Antarctica will cover both equatorward and poleward sides of the cusp and provide the necessary data set. Another objective of the HIWIND mission is to understand inter-hemispheric differences in the polar cap thermospheric winds. HIWIND can provide summer time polar cap observations in one hemisphere, while ground based Fabry-Perot interferometers simultaneous measure winds in another. The lack of daytime thermospheric wind observation has left many uncertainties in theories and modeling results on the thermosphere-ionosphere coupling in the summer polar cap. The simultaneous winter and summer polar cap wind comparison can shed more light on this topic. Ion drift observations from SuperDARN and ionosondes in the southern hemisphere and incoherent scatter radars in the northern hemisphere and the NCAR TIEGCM model will all be used to understand the thermospheric wind observations. HIWIND has demonstrated that it can provide accurate localized all local time coverage needed for this kind of study. HIWIND will follow the NASA satellite data-sharing rules for public use. This will be a three-year project. We plan to refurbish HIWIND in 2015 and 2016 and to conduct a long duration (~ 30 days) science flight from McMurdo, Antarctica (78S). The proposed new HIWIND observation will directly address questions related to thermosphere-ionosphere interaction. Such efforts belong to the NASA Heliophysics Research program. The program overview states: 'The program also supports investigations of the physics of magnetospheres, including their formation and fundamental interactions with plasmas, fields, and particles and the physics of the terrestrial mesosphere, thermosphere, ionosphere, and auroras, including the coupling of these phenomena to the lower atmosphere and magnetosphere.' More »