Airglow Imaging Observations Research Articles

First Observations of Severe Scintillation Over Low‐to‐Mid Latitudes Driven by Quiet‐Time Extreme Equatorial Plasma Bubbles: Conjugate Measurements Enabled by Citizen Science Initiatives

AbstractLow‐cost instrumentation combined with volunteering and citizen science educational initiatives allowed the deployment of L‐band scintillation monitors to remote sense areas that are geomagnetically conjugated and located at low‐to‐mid latitudes in the American sector (Quebradillas in Puerto Rico and Santa Maria in Brazil). On 10 and 11 October, 2023, both monitors detected severe scintillations, some reaching dip latitudes beyond 26°N. The observations show conjugacy in the spatio‐temporal evolution of the scintillation‐causing irregularities. With the aid of collocated all‐sky airglow imager observations, it was shown that the observed scintillation event was caused by extreme equatorial plasma bubbles (EPBs) reaching geomagnetic apex altitudes exceeding 2,200 km. The observations suggest that geomagnetic conjugate large‐scale structures produced conditions for the development of intermediate scale (few 100 s of meters) in both hemispheres, leading to scintillation at conjugate locations. Finally, unlike previous reports, it is shown that the extreme EPBs‐driven scintillation reported here developed under geomagnetically quiet conditions.

A case study on multiple self-interactions of MSTID bands: New insights

In this study, we report a special event of nighttime southwestward propagating medium scale traveling ionospheric disturbances (MSTIDs) observed in O(1D) 630.0 nm airglow images from an all-sky imager at Hanle (32.7°N, 78.9°E; Mlat. ∼ 24.1°N), Leh Ladakh, India on a geomagnetically quiet (Ap = 7) night of 15 September 2018. The time sequence of airglow images unveiled two dynamic interactions between multiple dark bands of MSTID. Following the first interaction, one of the interacting bands decayed possibly due to the entrance of plasma from the ambient higher plasma density region. Shortly after this interaction, the other interacting dark band was involved in the second interaction with a third dark band which resulted in the co-alignment of the two interacting bands. Following this co-alignment, one of the bands started rotating prominently that led to further separation of these two co-aligned bands. These changes in the MSTID phase fronts (bands) are explained based on the development of the polarization electric fields arising out of the interactions. This investigation combines the all-sky 630.0 nm airglow imaging observations with TEC maps constructed, for the first time over the Indian sector, from 67 Global Navigation Satellite System (GNSS) measurements to capture the MSTID over this region. The investigation reveals a few important features of self-interactions of MSTID bands over the geomagnetic low-mid latitude transition region which is important to assess their impact over low latitudes.

Airglow Imaging Observations of Plasma Blobs: Merging and Bifurcation during Solar Minimum over Tropical Region

Plasma blobs are night-time ionospheric irregularities whose generation mechanism is still under investigation. A large number of observations highlighted several aspects of their morphology and dynamics. However, the plasma blobs have not been attributed convincingly to a known mechanism. We analyzed the OI 630.0 nm emission images during March and October of 2019 and 2020 (minimum solar activity) using the ground-based all-sky imager at ZF-2 (2.58° S, 60.22° W) in the Amazon region of Brazil. The novelties of the present study are the rarely reported observation of both plasma blob merging and bifurcation. We studied the evolutional dynamics of plasma blobs and observed that blobs are distinct phenomena with unique properties. We attribute the merging of plasma blobs to the “wind reversion effect” (WRE) mechanism caused by a change in the direction of the zonal thermospheric wind from east to west. In some cases, the slower-drifting plasma blobs may merge with the faster ones. Moreover, blobs were observed initially bifurcating at the topside and later divided into two. The activity of the polarized electric field inside the plasma bubble mapping along the magnetic field lines is possibly responsible for the blob’s bifurcation. Subjecting the two features of ionospheric plasma blobs to simulation may reveal further the physics of blobs’ merging and bifurcation.

A case study of a ducted gravity wave event over northern Germany using simultaneous airglow imaging and wind-field observations

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 northern Germany. The airglow imaging observations at multiple altitudes in the mesosphere and lower thermosphere region reveal that a prominent upward-propagating wave structure appeared in O(1S) and O2 airglow images. However, the same wave structure was observed to be very faint in OH airglow images, despite OH being usually one of the brightest airglow emissions. In order to investigate this rare phenomenon, the altitude profile of the vertical wavenumber was derived based on colocated meteor radar wind-field and SABER temperature profiles close to the event location. The results indicate the presence of a thermal duct layer in the altitude range of 85–91 km in the southwest region of Kühlungsborn, Germany. Utilizing these instrumental data sets, we present evidence to show how a leaky duct layer partially inhibited the wave progression in the OH airglow emission 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.

Gravity wave instability structures and turbulence from more than 1.5 years of OH* airglow imager observations in Slovenia

Abstract. We analysed 286 nights of data from the OH* airglow imager FAIM 3 (Fast Airglow IMager) acquired at Otlica Observatory (45.93∘ N, 13.91∘ E), Slovenia, between 26 October 2017 and 6 June 2019. Measurements have been performed with a spatial resolution of 24 m per pixel and a temporal resolution of 2.8 s. A two-dimensional fast Fourier transform is applied to the image data to derive horizontal wavelengths between 48 m and 4.5 km in the upper mesosphere/lower thermosphere (UMLT) region. In contrast to the statistics of larger-scale gravity waves (horizontal wavelength up to ca. 50 km; Hannawald et al., 2019), we find a more isotropic distribution of directions of propagation, pointing to the presence of wave structures created above the stratospheric wind fields. A weak seasonal tendency of a majority of waves propagating eastward during winter may be due to instability features from breaking secondary gravity waves that were created in the stratosphere. We also observe an increased southward propagation during summer, which we interpret as an enhanced contribution of secondary gravity waves created as a consequence of primary wave filtering by the meridional mesospheric circulation. We present multiple observations of turbulence episodes captured by our high-resolution airglow imager and estimated the energy dissipation rate in the UMLT from image sequences in 25 cases. Values range around 0.08 and 9.03 W kg−1 and are on average higher than those in recent literature. The values found here would lead to an approximated localized maximum heating of 0.03–3.02 K per turbulence event. These are in the same range as the daily chemical heating rates for the entire atmosphere reported by Marsh (2011), which apparently stresses the importance of dynamical energy conversion in the UMLT.

Formation of an additional density peak in the bottom side of the sodium layer associated with the passage of multiple mesospheric frontal systems

Abstract. We present a detailed investigation of the formation of an additional sodium density peak at altitudes of 79–85 km below the main peak of the sodium layer based on sodium lidar and airglow imager measurements made at Ramfjordmoen near Tromsø, Norway, on the night of 19 December 2014. The airglow imager observations of OH emissions revealed four passing frontal systems that resembled mesospheric bores, which typically occur in ducting regions of the upper mesosphere. For about 1.5 h, the lower-altitude sodium peak had densities similar to that of the main peak of the layer around 90 km. The lower-altitude sodium peak weakened and disappeared soon after the fourth front had passed. The fourth front had weakened in intensity by the time it approached the region of lidar beams and disappeared soon afterwards. The column-integrated sodium densities increased gradually during the formation of the lower-altitude sodium peak. Temperatures measured with the lidar indicate that there was a strong thermal duct structure between 87 and 93 km. Furthermore, the temperature was enhanced below 85 km. Horizontal wind magnitudes estimated from the lidar showed strong wind shears above 93 km. We conclude that the combination of an enhanced stability region due to the temperature profile and intense wind shears have provided ideal conditions for evolution of multiple mesospheric bores revealed as frontal systems in the OH images. The downward motion associated with the fronts appeared to have brought air rich in H and O from higher altitudes into the region below 85 km, wherein the temperature was also higher. Both factors would have liberated sodium atoms from the reservoir species and suppressed the reconversion of atomic sodium into reservoir species so that the lower-altitude sodium peak could form and the column abundance could increase. The presented observations also reveal the importance of mesospheric frontal systems in bringing about significant variation of minor species over shorter temporal intervals.

Replication Data for: Formation of an additional density peak in the bottomside of sodium layer associated with the passage of multiple mesospheric frontal systems

The supplementary movie and the data used to generate the figures of the manuscript 'Formation of an additional density peak in the bottomside of sodium layer associated with the passage of multiple mesospheric frontal systems' accepted for publication in Atmospheric Chemistry and Physics are provided herein. The data discussed in the work are sodium lidar and airglow imaging observations from the date 19 December 2014.

Allsky airglow imaging observations from Hanle, Leh Ladakh, India: Image analyses and first results

We have installed a multi-wavelength allsky airglow imager over the Indian Himalayan region at Hanle, Leh Ladakh, (32.7°N, 78.9°E; dip lat. ∼24.1°N). This is the first of its kind that is installed in the Himalayan region at an altitude of around 4200 m above the mean sea level. The high sensitive thermoelectrically cooled CCD based imager is equipped with two interference filters (557.7 nm and 630.0 nm with a bandwidth of 2 nm). The airglow imaging observations have been carried out during moonless nights since June 2018. This paper presents the detailed steps of the image processing techniques to transform the raw images into the geospatially-calibrated images and discusses the process for the estimation of gravity wave parameters (horizontal wavelength, apparent phase velocity and periodicities) from the processed images. In addition, we report a few interesting events like Ripple-type structures, gravity waves and mesospheric bores in the mesopshere and lower thermosphere (MLT) region and the plasma disturbances in the ionospheric F region observed for the first time over Hanle, Leh Ladakh.

Airglow imaging observations of some evolutionary aspects of equatorial plasma bubbles from Indian sector

The ground-based all sky imager (ASI) is an advanced optical technique, capable of measuring the strong F-region nightglow in OI 630.0 nm emission from atomic oxygen. This emission is used to study the large-scale F-region plasma irregularities; called as Equatorial Plasma Bubbles (EPBs) which often disturbs the communication and navigation systems over low latitudes. The observations of OI 630.0 nm nightglow emission have been carried out from low latitude station Kolhapur (16.8°N, 74.2°E, 10.6° dip. lat.) using ASI during moonless nights for the period of 2011 to 2015. We have analyzed images recorded by ASI during this period and found some interesting features of EPBs on few nights (08 cases). This paper reports the analysis and the dynamics of EPBs features such as bifurcation, merging and detachment. The bifurcation in EPBs occurs before mid-night and extends to couple of hours towards dawn. Also, the secondary structures are seen as evolving features on the eastern wall of EPBs. In one of the case, the EPBs are seen to merge with each other due to their opposite tilts. Also, some EPBs detach due to unequal drifts along the meridian indicating the presence of strong latitudinal gradient in zonal neutral winds or altitudinal shear in zonal plasma drift which might be responsible for this detachment. In some cases we note that the EPBs shrink. Some of these features support the previous findings and some are new which needs further detailed investigation.

First OH Airglow Observation of Mesospheric Gravity Waves Over European Russia Region

AbstractFor the first time, we perform a study of mesospheric gravity waves (GWs) for four different seasons of 1 year in the latitudinal band from 45°N to 75°N using an OH all‐sky airglow imager over Kazan (55.8°N, 49.2°E), Russia, during the period of August 2015 to July 2016. Our observational study fills a huge airglow imaging observation gap in Europe and Russia region. In total, 125 GW events and 28 ripple events were determined by OH airglow images in 98 clear nights. The observed GWs showed a strong preference of propagation toward northeast in all seasons, which was significantly different from airglow imager observations at other latitudes that the propagation directions were seasonal dependent. The middle atmosphere wind field is used to explain the lack of low phase speed GWs since these GWs were falling into the blocking region due to the filtering effects. Deep tropospheric convections derived from the European Centre for Medium‐Range Weather Forecasts reanalysis data are determined near Caucasus Mountains region, which suggests that the convections are the dominant source of the GWs in spring, summer, and autumn seasons. This finding extends our knowledge that convection might also be an important source of GWs in the higher latitudes. In winter the generation mechanism of the GWs are considered to be jet stream systems. In addition, the occurrence frequency of ripple is much lower than other stations. This study provides some constraints on the range of GW parameters in GW parameterization in general circulation models in Europe and Russia region.

First Study on the Occurrence Frequency of Equatorial Plasma Bubbles over West Africa Using an All‐Sky Airglow Imager and GNSS Receivers

AbstractThis is the first paper that reports the occurrence frequency of equatorial plasma bubbles and their dependences of local time, season, and geomagnetic activity based on airglow imaging observations at West Africa. The all‐sky imager, situated in Abuja (Geographic: 8.99°N, 7.38°E; Geomagnetic: 1.60°S), has a 180° fisheye view covering almost the entire airspace of Nigeria. Plasma bubbles are observed for 70 nights of the 147 clear‐sky nights from 9 June 2015 to 31 January 2017. Differences between nighttime and daytime ROTIs were also computed as a proxy of plasma bubbles using Global Navigation Satellite Systems (GNSS) receivers within the coverage of the all‐sky imager. Most plasma bubble occurrences are found during equinoxes and least occurrences during solstices. The occurrence rate of plasma bubbles was highest around local midnight and lower for hours farther away. Most of the postmidnight plasma bubbles were observed around the months of December to March, a period that coincides with the harmattan period in Nigeria. The on/off status of plasma bubble in airglow and GNSS observations were in agreement for 67.2% of the total 768 h, while we suggest several reasons responsible for the remaining 32.8% when the airglow and GNSS bubble status are inconsistent. A majority of the plasma bubbles were observed under relatively quiet geomagnetic conditions (Dst ≥ −40 and Kp ≤ 3), but there was no significant pattern observed in the occurrence rate of plasma bubbles as a function of geomagnetic activity. We suggest that geomagnetic activities could have either suppressed or promoted the occurrence of plasma bubbles.

First observation of interhemispheric asymmetry in the EPBs during the St. Patrick's Day geomagnetic storm of 2015

AbstractIn this work, we have studied the characteristics of equatorial plasma bubbles (EPBs), such as their zonal drift and tilt, from the low‐latitude and dip equatorial region in the Indian longitude sector during the main phase of the 17 March 2015 storm. All‐sky airglow imaging observations from Tirunelveli (8.7°N, 77.8°E geographic, 1.7°N dip latitude) and Kolhapur (16.7°N, 74.3°E geographic, 11.5°N dip latitude) are utilized here. On 17 March 2015, EPBs were observed to drift eastward during 14:30–16:30 UT between 3°S and 15°N dip latitudes. A westward drift presumably under the influence of the disturbance dynamo electric field initially appeared at higher dip latitudes almost 10 h after the storm onset, and subsequently, the same was observed at lower dip latitudes. The EPBs attained a peak westward drift at ~17:00 UT followed by a gradual decrease in their speed till ~18:30 UT. After regaining their westward speed, the EPBs continued to drift westward till 22:00 UT. Moreover, a latitudinal gradient in the drift motion of the EPBs was also observed on this night. Another interesting observation made from the images obtained from Tirunelveli was the presence of a large westward tilt of the EPBs. The most intriguing finding of this study, however, was the asymmetry in the tilt of the EPBs at conjugate points during the premidnight hours on 17 March 2015. In this study, the possible mechanisms that can explain these observations are discussed in light of the current understanding of the equatorial electrodynamics and EPBs.

Characteristics of mesospheric gravity waves over the southeastern Tibetan Plateau region

AbstractThe Tibetan Plateau (TP), known as “Third Pole” of the Earth, has important influences on global climates and local weather. An important objective in present study is to investigate how orographic features of the TP affect the geographical distributions of gravity wave (GW) sources. Three‐year OH airglow images (November 2011 to October 2014) from Qujing (25.6°N, 103.7°E) were used to study the characteristics of GWs over the southeastern TP region. Along with the almost concurrent and collocated meteor radar wind measurements and temperature data from SABER/TIMED satellite, the propagation conditions of three types of GWs (freely propagating, ducted, or evanescent) were estimated. Most of GWs exhibited ducted or evanescent characteristics. Almost all GWs propagate southeastward in winter. The GW propagation directions in winter are significantly different from other airglow imager observations at northern middle latitudes. Wind data and convective precipitation fields from the European Centre for Medium‐Range Weather Forecasts reanalysis data are used to study the sources of GWs on the edge of the TP. Using backward ray‐tracing analysis, we find that most of the mesospheric freely propagating GWs are located in or near the large wind shear intensity region (~10 km–~17 km) on the southeastern edge of the TP in spring and winter. The averaged value of momentum flux is 11.6 ± 5.2 m2/s2 in winter and 7.5 ± 3.1 m2/s2 in summer. This work will provide valuable information for the GW parameterization schemes in general circulation models in TP region.

Shrinking equatorial plasma bubbles

AbstractThe formation of equatorial plasma bubbles (EPBs) associated with spread F irregularities are fairly common phenomenon in the postsunset equatorial ionosphere. These bubbles grow as a result of eastward polarization electric field resulting in upward E × B drift over the dip equator. As they grow they are also mapped to low latitudes along magnetic field lines. The EPBs are often observed as airglow depletions in the images of OI 630 nm emission. On occasions the growth of the features over the dip equator is observed as poleward extensions of the depletions in all‐sky images obtained from low latitudes. Herein, we present interesting observations of decrease in the latitudinal extent of the EPBs corresponding to a reduction in their apex altitudes over the dip equator. Such observations indicate that these bubbles not only grow but also shrink on occasions. These are the first observations of shrinking EPBs. The observations discussed in this work are based on all‐sky airglow imaging observations of OI 630.0 nm emission made from Panhala (11.1°N dip latitude). In addition, ionosonde observations made from dip equatorial site Tirunelveli (1.1°N dip latitude) are used to understand the phenomenon better. The analysis indicates that the speed of shrinking occurring in the topside is different from the bottomside vertical drifts. When the EPBs shrink, they might decay before sunrise hours.

Gravity wave characteristics in the mesopause region revealed from OH airglow imager observations over Northern Colorado

AbstractUsing 5 years of all‐sky OH airglow imager data over Yucca Ridge Field Station, CO (40.7°N, 104.9°W), from September 2003 to September 2008, we extract and deduce quasi‐monochromatic gravity wave (GW) characteristics in the mesopause region. The intrinsic periods are clustered between approximately 4 and 10 min, and many of them are unstable and evanescent. GW occurrence frequency exhibits a clear semiannual variation with equinoctial minima, which is likely related to the seasonal variation of background wind. The anomalous propagation direction in January 2006, with strong southward before major warming starting in 21 January and weak southward propagation afterward, was most likely affected by stratospheric sudden warming. The momentum fluxes show strongly anticorrelated with the tides, with ~180° out of phase in the zonal component. While in the meridional component, the easterly maximum occurred approximately 2–6 h after maximum easterly tidal wind. However, the anticorrelations are both weakest during the summer. The dissipating and breaking of small‐scale and high‐frequency GW's components could have a potential impact on the general circulation in the mesopause region.

A study on the night time equatorward movement of ionization anomaly using thermospheric airglow imaging technique

In the night time low latitude ionosphere, the equatorial ionization anomaly (EIA) crest move towards the equator as a result of change in the direction of the zonal electric field from eastward to westward. This is referred to as reverse plasma fountain. On some nights, imaging observations of OI 630.0nm thermospheric nightglow taken from low latitude Indian station Panhala (16.8°N, 74.1°E; 11.1°N dip latitude) during deep solar minimum period revealed southward movement of a broad enhanced airglow intensity region that is aligned along east–west direction. This could be seen in the meridional keograms and is interpreted as the equatorward passage of the EIA crest. The studies that concentrate on the night time evolution of EIA with the help of airglow observations are sparse. In addition to the equatorward motion, the thickness of the crest region decreased as a result of recombination. This reduction in thickness is pronounced in the earlier part of the night and brings about an apparent drift that is added to the true equatorward drift of the EIA crest. In this work, we describe a method to measure the equatorward drift speed of the EIA crest from airglow imaging observations. The method includes the estimation and correction for the apparent drift caused by recombination. The results show that drift speed varies widely between 28m/s and 89m/s (~100km/h to ~315km/h) with an average speed of 52m/s (188km/h). A part of the variability might be due to variations in thermospheric meridional wind. The drifts observed during magnetically disturbed days were found to be relatively smaller than that on quiet days.

Motion of high‐latitude nighttime medium‐scale traveling ionospheric disturbances associated with auroral brightening

We report for the first time the rapid oscillating motion of nighttime medium‐scale traveling ionospheric disturbances (MSTIDs) based on airglow imaging observations at Tromsø (magnetic latitude: 67.1°N), Norway on 8 December, 2009. The MSTIDs appeared in 630‐nm airglow images at 1530 UT as wave‐like structures south of Tromsø with a horizontal wavelength of ∼200 km and a phase surface of north to south. They moved eastward with velocities of 30–60 m/s. The velocity was faster in the poleward‐side of the MSTIDs, forming a northeast–southwest phase surface at later times. This phase surface direction is opposite to that of midlatitude MSTIDs. The MSTIDs show sudden oscillations and phase jump in the east–west direction with a timescale of ∼10 min at 1730 UT. The oscillations were associated with an auroral brightening observed at the poleward edge of the images and small magnetic field perturbations observed by ground magnetometers. The Doppler measurement of the 630‐nm airglow by a Fabry‐Perot interferometer at Tromsø showed a stable southeastward thermospheric wind with a velocity of ∼150 m/s. These observations indicate that the MSTID oscillations were linked to auroral electric field in the ionosphere, implying that the observed MSTIDs are ionospheric plasma structures. We suggest that the observed MSTIDs were created by atmospheric gravity waves at the beginning, left as fossil plasma structures even after the gravity wave packet dissipated in the thermosphere, moved eastward according to the background electric field driven by the F‐region dynamo, and oscillated associated with the auroral electric field.

Mesospheric concentric gravity waves generated by multiple convective storms over the North American Great Plain

We report on six continuous hours of OH airglow imager observations (at z ∼ 87 km) of convectively generated gravity waves (GWs) near Fort Collins, Colorado, on the evening of 08 September 2005. These GWs appeared as nearly concentric rings, and had epicenters near the locations of deep convection in three thunderstorms in Colorado, Nebraska and South Dakota. Using GOES satellite and weather radar observations, we show that the GWs closely follow the thunderstorms. Using the background wind from a nearby radar, the intrinsic wave parameters and vertical wavelengths are calculated. The temperature perturbations are estimated to be ∼ 1–3% for GWs with horizontal wavelengths λh∼ 20–40 km and horizontal phase speeds ∼40–60 m/s. The horizontal wavelengths of GWs from a convective cluster decreased in time from 30 to 15 km. We employ convective plume and ray‐trace models to simulate the GW‐induced OH intensity perturbations from convective plumes, clusters and complexes. We find that the results using the background model wind (radiosonde/TIME‐GCM) agree well with the late‐time observations, when the images are dominated by southwestward, short‐wavelength, high‐frequency GWs. These late‐time GWs propagate against the background wind, and haveλh ∼ 30–40 km and periods of τ ∼ 20–30 min. The OH intensity perturbations are enhanced because the vertical wavelengths λz increased, increased, and the vertical velocity perturbations w′ decreased (because the GWs were near their reflection levels). We also find that these short‐wavelength GWs were created ∼5 h earlier by an extremely energetic, deep convective plume in South Dakota, thereby showing that small‐scale, convective GWs directly link the troposphere and mesopause region.

Short-period gravity waves and ripples in the South Pole mesosphere

[1] In this study, we determined the characteristics of mesospheric wave structures over South Pole Station (90°S) derived from sodium airglow imaging observations. During the winter months of 2003 to 2005 (105 nights), we extracted a total of 768 wave events and separated them into two types (band-type gravity waves and ripples) according to their horizontal wavelengths. The distributions of the observed wave parameters, except for the horizontal propagation directions, were similar to those obtained by imaging observations at other latitudes. The observed gravity waves showed a preference for propagation toward 30°–60°E and 210°–240°E, whereas the ripples showed a preference for motion toward 90°–120°E and 300°–330°E. The gravity waves had a weak tendency of being observed in 0100–0700 UT, although the ripples did not show such a time dependence. We also investigated the characteristics of atmospheric instabilities from the alignment of the phase fronts of the observed ripples.

Airglow imaging observations of small‐scale structures driven by convective instability in the upper mesosphere over Tirunelveli (8.7°N)

Airglow imaging observations of broadband OH Meinel band emissions made on the night of 20 January 2007 from the tropical Indian site Tirunelveli (8.7°N, 77.8°E) reveal large‐ and small‐scale wave features that are aligned perpendicular to each other and that are associated with gravity wave dynamics. The large‐scale waves were the signatures of propagating quasi‐monochromatic (QM) waves, whereas the small‐scale features were identified to be ripples generated by convective instability in the mesosphere‐lower thermosphere (MLT) region. The QM waves showed consistent propagation toward the northwest direction throughout the observation period of ∼4.5 hr, whereas the ripples that manifested as short‐lived patches in the airglow images were transient and did not show any prominent phase propagation. In addition to these well‐resolved structures in images, we infer the presence of waves with relatively longer observed time periods (compared with the observed time period of QM waves) from the spectrum of the time series generated with zenith intensity values derived from the images. From the complementary wind and temperature data obtained with co‐located MF radar and Sounding of Atmosphere with Broad band Emission Radiometry on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics mission, an attempt is made to understand the dynamic processes occurring in the vicinity of the mesopause during the night of 20 January 2007. The uniqueness of the present observations is that there were short‐lived ripple patches seen in various parts of the sky during the entire observation period of 4.5 hr. The precipitation rates obtained by the Tropical Rainfall Measuring Mission satellite mission suggest that the deep convective activity occurring over the equatorial eastern Indian Ocean provided a plausible source mechanism for sustained generation of the waves observed over Tirunelveli during this night.