More Like this

1. Trends in the Airglow Temperatures in the MLT Region—Part 1: Model Simulations

   https://doi.org/10.3390/atmos11050468  

   Huang, Tai-Yin; Vanyo, Michael (May 2020, Atmosphere)

   Airglow intensity-weighted temperature variations induced by the CO2 increase, solar cycle variation (F10.7 as a proxy) and geomagnetic activity (Ap index as a proxy) in the Mesosphere and Lower Thermosphere (MLT) region were simulated to quantitatively assess their influences on airglow temperatures. Two airglow models, MACD-00 and OHCD-00, were used to simulate the O(1S) greenline, O2(0,1) atmospheric band, and OH(8,3) airglow temperature variations induced by these influences to deduce the trends. Our results show that all three airglow temperatures display a linear trend of ~−0.5 K/decade, in response to the increase of CO2 gas concentration. The airglow temperatures were found to be highly correlated with Ap index, and moderately correlated with F10.7, with the OH temperature showing an anti-correlation. The F10.7 and Ap index trends were found to be ~−0.7 ± 0.28 K/100SFU and ~−0.1 ± 0.02 K/nT in the OH temperature, 4.1 ± 0.7 K/100SFU and ~0.6 ± 0.03 K/nT in the O2 temperature and ~2.0 ± 0.6 K/100SFU and ~0.4 ± 0.03 K/nT in the O1S temperature. These results indicate that geomagnetic activity can have a rather significant effect on the temperatures that had not been looked at previously. 

   more » « less
2. A case study of a ducted gravity wave event over northern Germany using simultaneous airglow imaging and wind-field observations

   https://doi.org/10.5194/angeo-40-179-2022  

   Sarkhel, Sumanta; Stober, Gunter; Chau, Jorge L.; Smith, Steven M.; Jacobi, Christoph; Mondal, Subarna; Mlynczak, Martin G.; Russell III, James M. (January 2022, Annales Geophysicae)

   Abstract. An intriguing and rare gravity wave event was recorded on the night of 25 April 2017 using a multiwavelength all-sky airglow imager over northernGermany. The airglow imaging observations at multiple altitudes in themesosphere and lower thermosphere region reveal that a prominent upward-propagating wave structure appeared in O(1S) and O2 airglowimages. However, the same wave structure was observed to be very faint in OH airglow images, despite OH being usually one of the brightest airglowemissions. In order to investigate this rare phenomenon, the altitudeprofile of the vertical wavenumber was derived based on colocated meteorradar wind-field and SABER temperature profiles close to the event location.The results indicate the presence of a thermal duct layer in the altituderange of 85–91 km in the southwest region of Kühlungsborn, Germany.Utilizing these instrumental data sets, we present evidence to show how aleaky duct layer partially inhibited the wave progression in the OH airglowemission layer. The coincidental appearance of this duct layer is responsible for the observed faint wave front in the OH airglow images compared O(1S) and O2 airglow images during the course of the night over northern Germany. 

   more » « less
3. All-Sky Imager Observations of the Latitudinal Extent and Zonal Motion of Magnetically Conjugate 630.0 nm Airglow Depletions

   https://doi.org/10.3390/atmos11060642  

   Martinis, Carlos; Hickey, Dustin; Wroten, Joei; Baumgardner, Jeffrey; Macinnis, Rebecca; Sullivan, Caity; Padilla, Santiago (June 2020, Atmosphere)

   null (Ed.)

   630.0 nm all-sky imaging data are used to detect airglow depletions associated with equatorial spread F. Pairs of imagers located at geomagnetically conjugate locations in the American sector at low and mid-latitudes provide information on the occurrence rate and zonal motion of airglow depletions. Airglow depletions are seen extending to magnetic latitudes as high as 25°. An asymmetric extension is observed with structures in the northern hemisphere reaching higher latitudes. By tracking the zonal motion of airglow depletions, zonal plasma drifts in the thermosphere can be inferred and their simultaneous behavior in both hemispheres investigated. Case studies using El Leoncito and Mercedes imagers in the southern hemisphere, and the respective magnetically conjugate imagers at Villa de Leyva and Arecibo, provide consistent evidence of the influence of the South Atlantic Magnetic Anomaly on the dynamics and characteristics of the thermosphere–ionosphere system at low and mid-latitudes. 

   more » « less
4. Unusual Intensity Patterns of OH(6,2) and O( ¹ S) Airglow Driven by Long‐Period Waves Observed Over the Andes Lidar Observatory

   https://doi.org/10.1029/2020JA028091  

   Amaro‐Rivera, Yolián; Vargas, Fabio; Huang, Tai‐Yin; Urbina, Julio (January 2021, Journal of Geophysical Research: Space Physics)

   Abstract Simultaneous OH(6,2) and O(¹S) nightglow measurements obtained at the Andes Lidar Observatory (ALO) (30.3°S, 70.7°W) from September 2011 to April 2018 have been analyzed to investigate an unusual intensity pattern, that is, O(¹S) nightglow intensity enhancement concurrent with OH(6,2) nightglow intensity weakening. We identified 142 nights showing that behavior during the ∼6.5‐year period. The data set comprised of these 142 nights displayed a semiannual occurrence rate with maxima during the equinoxes. A semidiurnal tide fitting applied to the 30‐min bin size monthly averaged data shows that the largest amplitudes of the tide occur in April–May and August–September in both OH(6,2) and O(¹S). SABER atomic oxygen (O) climatology near ALO shows higher O densities near the equinoxes, with maximum O densities in March and September at ∼96 km. Lidar temperature analysis suggests that the O(¹S) enhancement concurrent with the OH(6,2) weakening is often accompanied by a temperature increase at 96 km and a decrease at 87 km. Simulations using airglow models have also been carried out to investigate the effect of a long‐period oscillation on the OH(6,2) and O(¹S) airglow intensities. A sensitivity study has also been conducted to illustrate the effect of the characteristics of a long‐period wave on the airglow intensity patterns. 

   more » « less
5. All‐Sky Imaging Observations and Modeling of Bright 630‐nm Airglow Structures Associated With MSTIDs

   https://doi.org/10.1029/2019JA026935  

   Martinis, C.; Yokoyama, T.; Nishioka, M. (August 2019, Journal of Geophysical Research: Space Physics)

   Abstract An all‐sky imager at El Leoncito Observatory (−31.8°, 69.3°W, 18.2° magnetic latitude) is used to study 630.0‐nm airglow emissions related to medium‐scale traveling ionospheric disturbances (MSTIDs). On the night of 6 December 2007 an unusual event consisting of bright bands propagating northwestward was observed. Enhancements in total electron content from ground‐based Global Positioning System receivers were observed collocated with the bright airglow bands. A regional Global Positioning System‐derived total electron content map matches the direction of motion, scale size, and location of these bright bands. Model results includingFregion coupling withEregion structures reproduce the characteristics of the bright bands. Specific conditions in theEregion must exist in order to observe these unusual MSTIDs consisting of propagating bright bands only. 

   more » « less