Seasonal MLT-region nightglow intensities, temperatures, and emission heights at a Southern Hemisphere midlatitude site

Spargo, Andrew J.; Woithe, J. M.; Klekociuk, Andrew; Younger, J. P.; Sivjee, G. G.

doi:10.5194/angeo-35-567-2017

Cited by 15 publications

(15 citation statements)

References 56 publications

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“…In contrast, the reversal near 80 km is caused by the neutralization of meteoric plasma in addition to ambipolar diffusion (Lee et al, ; Younger et al, ). The height of the lower inflection point can be used as a tool for measuring the height of a constant density surface (Reid et al, ; Younger et al, ). It should be noted that values of log 10 D derived from the KMMR show excellent agreement with the independent SABER measurements near 90 km.…”

Section: Discussionmentioning

confidence: 99%

“…However, accurate knowledge of neutral atmospheric density in the MLT region is essential for studying the dynamics and climate of the middle atmosphere, including shorter‐term wave motions, such as gravity waves, tides, and planetary waves, as well as long‐term changes, such as interannual variations, seasonal variations, and intraseasonal variations (Stober et al, , ; Younger et al, ). Furthermore, neutral atmospheric density measurements are critical for the correct interpretation of O, O 2 , and OH airglow measurements of atmospheric temperature in the MLT region (Reid et al, ; Takahashi et al, ). Knowledge of the change in neutral atmospheric density over time is crucial information for determining the atmospheric drag on low Earth orbit satellites and directly governs the orbit cycles of satellites; moreover, safe launches and precise landings of spacecraft also require an accurate knowledge of neutral atmospheric density in the MLT region.…”

Section: Introductionmentioning

confidence: 99%

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Estimation of Mesospheric Densities at Low Latitudes Using the Kunming Meteor Radar Together With SABER Temperatures

Xue

Younger

et al. 2018

JGR Space Physics

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Neutral mesospheric densities at a low latitude have been derived during April 2011 to December 2014 using data from the Kunming meteor radar in China (25.6°N, 103.8°E). The daily mean density at 90 km was estimated using the ambipolar diffusion coefficients from the meteor radar and temperatures from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument. The seasonal variations of the meteor radar‐derived density are consistent with the density from the Mass Spectrometer and Incoherent Scatter (MSIS) model, show a dominant annual variation, with a maximum during winter, and a minimum during summer. A simple linear model was used to separate the effects of atmospheric density and the meteor velocity on the meteor radar peak detection height. We find that a 1 km/s difference in the vertical meteor velocity yields a change of approximately 0.42 km in peak height. The strong correlation between the meteor radar density and the velocity‐corrected peak height indicates that the meteor radar density estimates accurately reflect changes in neutral atmospheric density and that meteor peak detection heights, when adjusted for meteoroid velocity, can serve as a convenient tool for measuring density variations around the mesopause. A comparison of the ambipolar diffusion coefficient and peak height observed simultaneously by two co‐located meteor radars indicates that the relative errors of the daily mean ambipolar diffusion coefficient and peak height should be less than 5% and 6%, respectively, and that the absolute error of the peak height is less than 0.2 km.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Estimation of Mesospheric Densities at Low Latitudes Using the Kunming Meteor Radar Together With SABER Temperatures

Xue

Younger

et al. 2018

JGR Space Physics

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“…The temperatures, winds and densities in the mesopause region are essential for studying the dynamics and climate, including both short-term wave motions (e.g., gravity waves, tides and planetary waves) and long-term climate variations (e.g., interannual variations, seasonal variations and intraseasonal variations), of the middle and upper atmosphere. The climatology of the temperature and wind within the mesopause region has been studied for decades using ground-based instruments such as meteor radars, mediumfrequency (MF) radars, lidars (Dowdy et al, 2001;Dou et al, 2009;Li et al, 2008Li et al, , 2012Li et al, , 2018 and satellite instruments (Garcia et al, 1997;Remsberg et al, 2002;Xu et al, 2007). It is well established that the semiannual oscillation (SAO) dominates the seasonal variations in both the wind and the temperature in the low-latitude mesosphere (Li et al, 2012), whereas the annual oscillation (AO) dominates the seasonal variations in the mid-and high-latitude mesosphere (Remsberg et al, 2002;Xu et al, 2007;Dou et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

“…The climatology of the temperature and wind within the mesopause region has been studied for decades using ground-based instruments such as meteor radars, mediumfrequency (MF) radars, lidars (Dowdy et al, 2001;Dou et al, 2009;Li et al, 2008Li et al, , 2012Li et al, , 2018 and satellite instruments (Garcia et al, 1997;Remsberg et al, 2002;Xu et al, 2007). It is well established that the semiannual oscillation (SAO) dominates the seasonal variations in both the wind and the temperature in the low-latitude mesosphere (Li et al, 2012), whereas the annual oscillation (AO) dominates the seasonal variations in the mid-and high-latitude mesosphere (Remsberg et al, 2002;Xu et al, 2007;Dou et al, 2009). However, in contrast to temperature and wind observations, longterm continuous measurements of the atmospheric density in the mesopause region are still quite rare; as a result, the seasonal variations in the mesopause, especially with regard to its global structure, are still unclear.…”

Section: Introductionmentioning

confidence: 99%

Climatology of the mesopause relative density using a global distribution of meteor radars

Xue

Murphy

et al. 2019

Atmos. Chem. Phys.

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Abstract. The existing distribution of meteor radars located from high- to low-latitude regions provides a favorable temporal and spatial coverage for investigating the climatology of the global mesopause density. In this study, we report the climatology of the mesopause relative density estimated using multiyear observations from nine meteor radars, namely, the Davis Station (68.6∘ S, 77.9∘ E), Svalbard (78.3∘ N, 16∘ E) and Tromsø (69.6∘ N, 19.2∘ E) meteor radars located at high latitudes; the Mohe (53.5∘ N, 122.3∘ E), Beijing (40.3∘ N, 116.2∘ E), Mengcheng (33.4∘ N, 116.6∘ E) and Wuhan (30.5∘ N, 114.6∘ E) meteor radars located in the midlatitudes; and the Kunming (25.6∘ N, 103.8∘ E) and Darwin (12.3∘ S, 130.8∘ E) meteor radars located at low latitudes. The daily mean relative density was estimated using ambipolar diffusion coefficients derived from the meteor radars and temperatures from the Microwave Limb Sounder (MLS) on board the Aura satellite. The seasonal variations in the Davis Station meteor radar relative densities in the southern polar mesopause are mainly dominated by an annual oscillation (AO). The mesopause relative densities observed by the Svalbard and Tromsø meteor radars at high latitudes and the Mohe and Beijing meteor radars at high midlatitudes in the Northern Hemisphere show mainly an AO and a relatively weak semiannual oscillation (SAO). The mesopause relative densities observed by the Mengcheng and Wuhan meteor radars at lower midlatitudes and the Kunming and Darwin meteor radars at low latitudes show mainly an AO. The SAO is evident in the Northern Hemisphere, especially at high latitudes, and its largest amplitude, which is detected at the Tromsø meteor radar, is comparable to the AO amplitudes. These observations indicate that the mesopause relative densities over the southern and northern high latitudes exhibit a clear seasonal asymmetry. The maxima of the yearly variations in the mesopause relative densities display a clear latitudinal variation across the spring equinox as the latitude decreases; these latitudinal variation characteristics may be related to latitudinal changes influenced by gravity wave forcing. In addition to an AO, the mesopause relative densities over low latitudes also clearly show an intraseasonal variation with a periodicity of 30–60 d.

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“…In addition, sudden stratospheric warmings alter the OH altitude, producing up to 10 km vertical shifts during the descent phase (Shepherd et al, 2010b). On a medium timescale, the seasonal variation in the emission altitudes exhibits semiannual, annual and quasi-biennial oscillations with up to 1.0, 1.5 and 0.5 km amplitudes, respectively (Winick et al, 2009;Gao et al, 2010;Sheese et al, 2014;von Savigny, 2015;Reid et al, 2017). Ghodpage et al (2016) and Sivakandan et al (2016) reported a year-to-year monthly mean OH altitude variation of 2-3 km and attributed it to the effect of the El Niño-Southern Oscillation (ENSO).…”

Section: Introductionmentioning

confidence: 99%

Mesospheric OH layer altitude at midlatitudes: variability over the Sierra Nevada Observatory in Granada, Spain (37° N, 3° W)

García‐Comas¹,

López-González²,

González‐Galindo³

et al. 2017

Ann. Geophys.

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Abstract. The mesospheric OH layer varies on several timescales, primarily driven by variations in atomic oxygen, temperature, density and transport (advection). Vibrationally excited OH airglow intensity, rotational temperature and altitude are closely interrelated and thus accompany each other through these changes. A correct interpretation of the OH layer variability from airglow measurements requires the study of the three variables simultaneously. Ground-based instruments measure excited OH intensities and temperatures with high temporal resolution, but they do not generally observe altitude directly. Information on the layer height is crucial in order to identify the sources of its variability and the causes of discrepancies in measurements and models. We have used SABER space-based 2002-2015 data to infer an empirical function for predicting the altitude of the layer at midlatitudes from ground-based measurements of OH intensity and rotational temperature. In the course of the analysis, we found that the SABER altitude (weighted by the OH volume emission rate) at midlatitudes decreases at a rate of 40 m decade −1 , accompanying an increase of 0.7 % decade −1 in OH intensity and a decrease of 0.6 K decade −1 in OH equivalent temperature. SABER OH altitude barely changes with the solar cycle, whereas OH intensity and temperature vary by 7.8 % per 100 s.f.u. and 3.9 K per 100 s.f.u., respectively. For application of the empirical function to Sierra Nevada Observatory SATI data, we have calculated OH intensity and temperature SATI-to-SABER transfer functions, which point to relative instrumental drifts of −1.3 % yr −1 and 0.8 K yr −1 , respectively, and a temperature bias of 5.6 K. The SATI predicted altitude using the empirical function shows significant short-term variability caused by overlapping waves, which often produce changes of more than 3-4 km in a few hours, going along with 100 % and 40 K changes in intensity and temperature, respectively. SATI OH layer wave effects are smallest in summer and largest around New Year's Day. Moreover, those waves vary significantly from day to day. Our estimations suggest that peak-to-peak OH nocturnal variability, mainly due to wave variability, changes within 60 days at least 0.8 km for altitude in autumn, 45 % for intensity in early winter and 6 K for temperature in midwinter. Plausible upper limit ranges of those variabilities are 0.3-0.9 km, 40-55 % and 4-7 K, with the exact values depending on the season.

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Seasonal MLT-region nightglow intensities, temperatures, and emission heights at a Southern Hemisphere midlatitude site

Cited by 15 publications

References 56 publications

Estimation of Mesospheric Densities at Low Latitudes Using the Kunming Meteor Radar Together With SABER Temperatures

Estimation of Mesospheric Densities at Low Latitudes Using the Kunming Meteor Radar Together With SABER Temperatures

Climatology of the mesopause relative density using a global distribution of meteor radars

Mesospheric OH layer altitude at midlatitudes: variability over the Sierra Nevada Observatory in Granada, Spain (37° N, 3° W)

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Seasonal MLT-region nightglow intensities, temperatures, and emission heights at a Southern Hemisphere midlatitude site

Cited by 15 publications

References 56 publications

Estimation of Mesospheric Densities at Low Latitudes Using the Kunming Meteor Radar Together With SABER Temperatures

Estimation of Mesospheric Densities at Low Latitudes Using the Kunming Meteor Radar Together With SABER Temperatures

Climatology of the mesopause relative density using a global distribution of meteor radars

Mesospheric OH layer altitude at midlatitudes: variability over the Sierra Nevada Observatory in Granada, Spain (37° N, 3° W)

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Mesospheric OH layer altitude at midlatitudes: variability over the Sierra Nevada Observatory in Granada, Spain (37° N, 3° W)