Remote measurements of upper atmospheric density and temperature

A suborbital experiment was designed to study the photochemistry of the mesosphere by observing simultaneously the airglow emissions with in-situ minor species number density profiles. The experiment was very successful and some preliminary results have already been reported in various scientific meetings. Two scientific papers are currently in the process of final preparation for submission for publication. In this final project report, we will first give a background description of the experiment and follow by the summaries of the scientific papers currently being prepared

Non-thermal distribution of O(1D) atoms in the night-time thermosphere

The 6300 A O(1D-3P) emission has been used for many years to remotely monitor the thermospheric temperature from the Doppler width of its line profile. The O(1D) atoms in the night-time thermosphere are initially produced by the dissociative recombination of O2+ ions with kinetic energy much greater than the thermal energy of the ambient neutrals. The validity of the technique to monitor neutral ambient temperature by measuring O(1D) 6300 A emission depends on the degree of thermalization of the O(1D) atoms. The object of this study is to calculate the velocity distribution of the O(1D) atoms and to examine the effect of non-thermal distribution on the night-time thermospheric neutral temperature determined.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27473/1/0000514.pd

Observations of O 2 (¹Σ) and OH nightglow during the ALOHA‐90 Campaign

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94977/1/grl5543.pd

Energy transfer of O(1D) atoms in collision with O(3P) atoms

Calculations are carried out of the elastic scattering and excitation exchange cross-sections in collisions of O(1D) and O(3P) atoms, which determine the degree of thermalization of the O(1D) atoms produced by dissociative recombination in the thermosphere. The effective elastic scattering and excitation exchange cross-sections are calculated to be 1.55 x 10-15 and 6.25 x 10-16 cm2, respectively, at a relative collision energy of 1.0 eV. The mutual diffusion coefficient between O(1D) and O(3P) atoms is also presented.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26757/1/0000309.pd

Mesospheric 5577A green line and atmospheric motions--Atmosphere explorer satellite observations

Photometric measurements of the 5577A O(1S) green line mesospheric emission obtained by the Visible Airglow Experiment (VAE) on board the Atmosphere Explorer (AE) satellite have been analyzed. The inverted volume emission rate profiles showed a peak at approximately 96-97 km with a half-width of ~8 km. The diurnal variation of the intensity indicates the presence of a wave component with 10 ~ 12 h period, probably of solar semi-diurnal tide. Shorter time scale variations due to the presence of travelling waves were also observed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26532/1/0000071.pd

The EZIE Way to Measure the Ionospheric Electrojets with a Three-CubeSat Constellation

A recently selected NASA heliophysics mission of opportunity, the Electrojet Zeeman Imaging Explorer (EZIE), will study the electric currents that play a crucial role in the interactions between Earth and the surrounding magnetosphere. The aurora is a spectacular manifestation of these interactions. EZIE consists of three 6U CubeSats flying in a pearls-on-a-string orbit configuration, each carrying a Microwave Electrojet Magnetogram (MEM) instrument. Four beams on each satellite measure polarimetric radiances that contain the magnetic signatures of the intense currents in ionospheric plasmas (electrojets) based on the Zeeman splitting of molecular oxygen thermal emissions. This novel measurement technique allows for the remote sensing of the electrojets at altitudes notoriously difficult to measure in situ. The EZIE constellation will provide, for the first time, measurements with the spatial and temporal resolution required to distinguish between proposed hypotheses for the physical mechanisms behind the auroral and equatorial electrojets. A series of observing system simulation experiments demonstrate how EZIE will explore the impacts of space weather near Earth. Each MEM instrument consists of four compact 118-GHz heterodyne spectropolarimeters, leveraging technologies demonstrated by TEMPEST-D and CubeRRT; the 6U CubeSat bus heritage includes RAVAN, CAT, TEMPEST-D, and CubeRRT. Differential drag maneuvers, akin to those pioneered by CYGNSS and CAT, will be used to manage satellite along-track temporal separation to within 2–10 minutes, eliminating the need for on-board propulsion. EZIE success is possible because of past CubeSat demonstrations and strong commercial partnerships

High Resolution Doppler Imager observations of ozone in the mesosphere and lower thermosphere

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95237/1/jgrd9497.pd

Diagnosis of Middle Atmosphere Climate Sensitivity by the Climate Feedback Response Analysis Method

We present a new method to diagnose the middle atmosphere climate sensitivity by extending the Climate Feedback-Response Analysis Method (CFRAM) for the coupled atmosphere-surface system to the middle atmosphere. The Middle atmosphere CFRAM (MCFRAM) is built on the atmospheric energy equation per unit mass with radiative heating and cooling rates as its major thermal energy sources. MCFRAM preserves the CFRAM unique feature of an additive property for which the sum of all partial temperature changes due to variations in external forcing and feedback processes equals the observed temperature change. In addition, MCFRAM establishes a physical relationship of radiative damping between the energy perturbations associated with various feedback processes and temperature perturbations associated with thermal responses. MCFRAM is applied to both measurements and model output fields to diagnose the middle atmosphere climate sensitivity. It is found that the largest component of the middle atmosphere temperature response to the 11-year solar cycle (solar maximum vs. solar minimum) is directly from the partial temperature change due to the variation of the input solar flux. Increasing CO2 always cools the middle atmosphere with time whereas partial temperature change due to O3 variation could be either positive or negative. The partial temperature changes due to different feedbacks show distinctly different spatial patterns. The thermally driven globally averaged partial temperature change due to all radiative processes is approximately equal to the observed temperature change, ranging from 0.5 K near 70 km from the near solar maximum to the solar minimum

The Electrojet Zeeman Imaging Explorer (EZIE) Mission and the Microwave Electroject Magnetogram (MEM) Radiometer Instrument

The Electrojet Zeeman Imaging Explorer (EZIE) mission is a multi-satellite 6U CubeSat mission designed to temporally and spatially sample the Earth’s current induced magnetic field. The EZIE mission will help discern amongst competing theories of the spatial structures of Auroral Electro Jets (AEJ). The EZIE mission uses a unique payload design relative to traditional magnetometers; a 118.75 GHz mm-wave polarimetric radiometric system with a digital spectrometer backend, called the Microwave Electrojet Magnetogram (MEM) system. MEM measures the Zeeman split in frequency of the Oxygen absorption line that is directly proportional to the strength of the magnetic field of the observation. The polarimetric nature of MEM helps inform about the direction of the magnetic field. The MEM system consists multiple-beams in a push-broom configuration to detect magnetic fields at a approximate altitude of 80km

The visible airglow experiment--a review

Contributions of the Visible Airglow Experiment (VAE) to the understanding of thermospheric aeronomy are summarized and discussed. The importance of instrumental design and operation is considered and particular attention is given to the relationship between observation and inversion for optical measurements of light emissions from a diffuse medium. The specific influence of the VAE investigation on the present understanding of the physical mechanisms which produce and destroy the excited species, O+ (2P), O(1D), O(1S), N(2D), N2+ (B2[Sigma]u+), N2(C3[pi]u) and Mg+ (2P1/2), is discussed in detail.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27442/1/0000482.pd