3D Simulator for Wind Interferometer Data-Model Comparison
Huda, Md Nurul
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The connection between earth and space weather has numerous impacts on spacecraft, radio communications and GPS signals. Thus, predicted & modeling this region is important, yet models (both empirical and first principles) do a poor job of characterizing the variability of this region. One of the main objectives of the NASA ICON mission is to measure the variability of the ionosphere and thermosphere at low-mid latitudes. The MIGHTI instrument on ICON is a Doppler Interferometer that measures the horizontal wind speed and direction with 2 discrete MIGHTI units, separated by 90˚, mounted on the ICON Payload Interface Plate. This work focuses on building a simulation of wind interferometer data, similar to MIGHTI, using a first-principles model as the input dataset, which will be used for early validation and comparison to the MIGHTI data. Using a ray-tracing approach, parameters like O, O2, O+, O2+, T, wind, solar F10.7 index will be read for every point along every ray from the model and brightness and Line of Sight (LOS) wind will be calculated as functions of altitude and time. These data will be compared to the MIGHTI observations to both to establish the limitation of such models, and to validate the ICON data. ICON will help determine the physics of our space environment and pave the way for mitigating its effects on our technology, communications systems and society. However, ICON is yet to launch and due to the unavailability of MIGHTI data, we have selected another instrument called WINDII (Wind Imaging Interferometer) from a different mission UARS (Upper Atmosphere Research Satellite) to demonstrate the utility of this data-model comparison. Similar to MIGHTI, WINDII measures Doppler shifts from a suite of visible region airglow and measures zonal and meridian winds, temperature, and VER (Volume Emission rate) in the upper mesosphere and lower thermosphere (80 to 300 km) from observations of the Earth's airglow. We will use a similar approach discussed for MIGHTI to calculate vertical profile of Redline airglow, Wind velocity, emission rate and compare them with our simulated results to validate our algorithm. We initially thought asymmetry calculation along the Line of Sight (LOS) would be the limiting factor. We believe there are other things going on such as variability in the winds associated with natural fluctuations in the thermosphere, atmospheric waves, inputs from the sun and the atmosphere below etc., appear to be bigger factor than just asymmetry along the line of sight.
General Audience Abstract
The upper Earth atmosphere host’s most of the valuable spacecraft’s and almost all the communication signals go through this portion of the atmosphere. Yet we do not understand what causes variation in the upper atmosphere. In order to answer what’s causing these changes and to understand this complicated region, NASA has developed the ICON mission. ICON we will mainly study the Ionosphere ranging from 90 to 450 km above the earth surface. In this study have developed a tool able to simulate thermospheric wind profiles, O, O2, O+, O2+ densities, Volume emission rate (VER) of green and red line airglow from measurements on the NASA Ionospheric Connection Explorer (ICON) mission from an instrument on board called MIGHTI. However, ICON is yet to launch so do not have MIGHTI to test our algorithm. We chose an instrument which is similar to MIGHTI called Wind Imaging Interferometer (WINDII), from a different mission called Upper Atmosphere Research Satellite (UARS) to test our algorithm. We initially thought asymmetry calculation along the Line of Sight (LOS) would be the limiting factor. We believe there are other things going on such as variability in the winds associated with natural fluctuations in the thermosphere, atmospheric waves, inputs from the sun and the atmosphere below etc., appear to be bigger factor than just asymmetry along the line of sight.
- Masters Theses