"Boston University All-Sky Imaging Network" (BU_ASI)

PIs: Michael Mendillo, Carlos Martinis (Boston U)

Science and measurement objectives
The BU all-sky imager network has been built to study magnetically conjugate processes in the thermosphere-ionosphere from low latitudes to sub-auroral latitudes. In addition, mesospheric dynamics can be studied with each ASI in the network. The processes include Equatorial spread F (ESF), Medium scale travelling ionospheric disturbances (MSTIDs), Stable auroral red (SAR) arcs, and brightness waves (BW) in the thermosphere/ionosphere region. At lower altitudes in the mesosphere the processes include gravity waves, bores, and tidal waves.

Instrument descriptions
The BU ASI Network consists of 14 all-sky imagers. Each imager measures up to 6 different airglow emissions originating at different heights in the upper atmosphere. Each emission is the result of specific chemical reactions involving charged and neutral atoms and molecules.

Instrument performance specifications
Airglow emissions are measured using interference filters that can isolate light coming from a specific wavelength. The system takes images at several wavelengths for the duration of the night on nearly every night in a given month. Thermospheric emissions of neutral oxygen are measured at wavelengths of 630.0 nm and 557.7 nm (emissions due to dissociative recombination of O₂⁺), 777.4 nm (due to radiative recombination of O⁺). Mesospheric processes are studied by measuring emissions at 589.3 nm (neutral Na emissions), 557.7 nm (via the three-body Barth reaction), and lines with λ > 695.0 nm (OH Meinel band emissions). Background filters at 644.4 nm or 605.0 nm, chosen to avoid thermospheric and mesospheric emission lines, are used as control filters. Exposure times are 90÷120 seconds for all the filters except hydroxyl, which has an exposure time of 15÷30 seconds. An entire cycle of observations takes ~10 minutes.

Key/representative publications or references

Mendillo, M., Hickey, D., Martinis, C., Wroten, J., & Baumgardner, J. Space weather nowcasting for area-denied locations: Testing all-sky imaging applications at geomagnetic conjugate points. Space Weather, 16. DOI: 10.1002/2017SW001741, 2018.

Martinis, C., Baumgardner, J., Wroten, J., & Mendillo, M. All-Sky-Imaging Capabilities for Ionospheric Space Weather Research Using Geomagnetic Conjugate Point Observing Sites, Advances in Space Research, DOI: 10.1016/j.asr.2017.07.021, 2017

J. Baumgardner, J. Wroten, J. Semeter, J. Kozyra, M. Buonsanto, P. Erickson, & M. Mendillo, A very bright SAR arc: implications for extreme magnetosphere-ionosphere coupling, Ann. Geophys., 25, 2593-2608, 2007