Evidence for Deep Ingression of the Midlatitude MSTID Into As Low as ~3.5° Magnetic Latitude

Sivakandan, M.; Chakrabarty, D.; Ramkumar, T. K.; Guharay, A.; Taori, A.; Parihar, Navin

doi:10.1029/2018ja026103

Cited by 25 publications

(26 citation statements)

References 57 publications

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“…Mendillo et al (1997) were the pioneers in detecting MSTIDs using all-sky imagers to observe the thermospheric OI 630.0-nm airglow emission. Since then, this optical technique has been widely used to obtain two-dimensional images of these events in the upper atmosphere (e.g., Amorim et al, 2011;Duly et al, 2013;Garcia et al, 2000;Martinis et al, 2010;Pimenta et al, 2008;Seker et al, 2011;Sivakandan et al, 2019).…”

Section: The Arecibo Observatory Rofmentioning

confidence: 99%

Geomagnetic and Solar Dependency of MSTIDs Occurrence Rate: A Climatology Based on Airglow Observations From the Arecibo Observatory ROF

et al. 2020

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We employ in this work the first O(1D) 630.0‐nm airglow data set registered at the Remote Optical Facility (ROF) in Culebra, Puerto Rico, during the descending phase of the solar cycle #24. From 4 November 2015 to 26 September 2019, observations were carried out during 633 nights at ROF using a small all‐sky imager, while MSTID events were identified in 225 of 499 nights classified as clear. A quantitative analysis of these MSTIDs and their dependency by geophysical parameters (solar and geomagnetic activities) are the main focus of this study. We introduce an original statistical methodology that examines the unique features of the data set and minimizes the cross contamination of individual modulators onto one another, avoiding bias in the results. Our findings include a primary peak of MSTIDs occurrence in the December solstice and a secondary peak in the June solstice. We observed a remarkable correlation in the occurrence rate of the MSTIDs with the geomagnetic activity. A notable modulation of the MSTIDs occurrence rate with the solar activity is also found, which includes periods of correlation and anticorrelation depending on the season. This modulation has an annual component that is ~33% and ~83% stronger than the semiannual and terannual components, respectively. We discuss these findings based on a previous study of the thermospheric neutral winds derived from 30 years of Fabry‐Perot interferometer observations at Arecibo Observatory. Our results, which are valid for low to moderate solar activity, point out circumstances that might explain differences in previous climatological studies of nighttime MSTIDs.

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Section: The Arecibo Observatory Rofmentioning

confidence: 99%

Geomagnetic and Solar Dependency of MSTIDs Occurrence Rate: A Climatology Based on Airglow Observations From the Arecibo Observatory ROF

et al. 2020

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“…In order to visualize the spatial and temporal evolution of the airglow emission depletion, keograms are constructed using arbitrary and residual airglow emission intensities (residual intensity derived method is discussed in section ) that is shown in Figure . Detailed description about the keogram analysis is available in literature (Sivakandan et al, ). Figures a and b show the geographic EW and NS keograms (hereafter NS means geographic NS) in terms of total intensity (in arbitrary units) and the Figures c and d show the EW and NS keograms in terms of residual intensity.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, even if EPBs can map up to the mid latitudes on few occasions (Otsuka et al, ; Ma & Maruyama, ; Huang et al, ; Li et al, , ; Aa et al, ; Cherniak et al, ), especially during geomagnetically disturbed conditions, the propagation direction can be used to differentiate EPB and MSF. Consecutively, recent works showed that MSTIDs can ingress very deep into low‐latitude ionosphere (Sivakandan et al, ). However, to the best of our knowledge, MSF structures at the equatorial edge of the mid‐latitude have not been reported so far over the Indian sector.…”

Section: Introductionmentioning

confidence: 99%

Mid‐Latitude Spread‐F Structures Over the Geomagnetic Low‐Mid Latitude Transition Region: An Observational Evidence

et al. 2020

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An observational evidence of a unique plasma depletion event was captured by an O( 1 D) 630.0 nm airglow imager on 13 June 2018 over a transition region of geomagnetic low-mid latitude, Hanle, Leh Ladakh, India (32.77°N, 78.97°E; Mlat.~24. 1°N). The observed plasma depletion structures are tilted at an angle of 13°± 2°west of the geomagnetic north and drifted toward west. Collocated Global Navigation Satellite System-Total Electron Content measurements confirm that the structures are indeed associated with TEC depletions. Simultaneous ionosonde measurements from Delhi, India (28.70°N, 77.10°E; Mlat.~20.2°N) shows spread-F signatures confirming that these structures are associated with the ionospheric irregularities. Interestingly, radar observations over the geomagnetic low-latitude station Gadanki, India (13.5°N; 79.2°E; Mlat.~6.5°N) reveal the absence of equatorial plasma bubbles on this night. Therefore, these observations strongly suggest that the observed structures in the airglow images over Hanle are associated with mid-latitude spread-F (MSF). These MSF structures are possibly affected by the shear in the zonal plasma drift that forces the field aligned plasma irregularity structures to tilt toward west. These observations, for the first time, bring out the presence of MSF structures over geomagnetic low-mid latitude transition region. It is suggested that the plasma distribution over low latitudes plays an important role in the occurrence of MSF structures over this transition region. Understanding the source and characteristics of the plasma irregularity structures over this transition region can help in understanding the spatio-temporal evolution of global L-band scintillation in a better way.Plain Language Summary Understanding the spatio-temporal distribution of the ionospheric plasma irregularities is important in the operational forecasting of L-band scintillation and therefore has important ramifications in the satellite-based communication and navigation systems. Traditionally, plasma irregularities in the low and mid-latitudes had received focused attentions in the past with very less attention has been paid over the low to mid-latitude transition region. The present investigation provides an attempt toward that direction and proposes a mechanism on the relationship between the plasma distribution over low latitudes and the occurrence of the mid-latitude plasma irregularities over the geomagnetic low-mid latitude transition region. Comprehensive investigations are further needed in the future to understand and characterize the ionospheric plasma irregularity structures over this region.

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“…Because they constitute the main source of ionospheric variability at midlatitudes, it was long thought that MSTIDs were confined in such regions. However, Sivakandan et al () observed MSTIDs originating from midlatitude that reached the equatorial region during nighttime conditions. In low‐latitude regions, beside MSTIDs whose the origin is due to AGWs, it exists other structures sharing morphological similarities with MSTIDs which are called upwellings.…”

Section: Introductionmentioning

confidence: 99%

The OI‐135.6 nm Nighttime Emission in ICON‐FUV Images: A New Tool for the Observation of Classical Medium‐Scale Traveling Ionospheric Disturbances?

et al. 2019

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The National Aeronautics and Space Administration Ionospheric Connection Explorer (ICON) mission will study the close relationship between the ionosphere, the atmospheric weather, and space weather using in situ and remote sensing instruments proving plasma density, temperature, ion drift velocity, and thermospheric wind velocity over the equatorial region. In particular, the far ultraviolet (FUV) instrument will image the terrestrial limb in two wavelength channels. During nighttime, only the channel characterizing the bright 135.6‐nm emission of atomic oxygen will be used. The purpose of this study is to simulate FUV nightglow measurements under quiet as well as disturbed ionospheric conditions. Classical medium‐scale traveling ionospheric disturbances (MSTIDs), which are understood as the ionospheric signature of atmospheric gravity waves, are one of the main sources of ionospheric variability. Here, we simulate their potential appearance in the FUV instrument data. The simulation model produces FUV images used as input to identify and characterize MSTIDs. MSTID propagation parameters can be retrieved under specific geometrical configurations between the FUV lines of sight and propagation direction of the MSTID, which differs depending on the limb or sublimb observing geometry. The largest MSTID signature is expected during equinoxes under solar maximum periods, for MSTID periods of less than 30 min. The weak brightness of the 135.6‐nm multiplet under solar minimum conditions is the main limitation to the MSTID detection on the nightside. Future MSTID detection algorithms would have to cope with very low signal‐to‐noise ratio, in particular during solstices and under solar minimum conditions.

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Evidence for Deep Ingression of the Midlatitude MSTID Into As Low as ~3.5° Magnetic Latitude

Cited by 25 publications

References 57 publications

Geomagnetic and Solar Dependency of MSTIDs Occurrence Rate: A Climatology Based on Airglow Observations From the Arecibo Observatory ROF

Geomagnetic and Solar Dependency of MSTIDs Occurrence Rate: A Climatology Based on Airglow Observations From the Arecibo Observatory ROF

Mid‐Latitude Spread‐F Structures Over the Geomagnetic Low‐Mid Latitude Transition Region: An Observational Evidence

The OI‐135.6 nm Nighttime Emission in ICON‐FUV Images: A New Tool for the Observation of Classical Medium‐Scale Traveling Ionospheric Disturbances?

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