Mesopause Temperature Research Articles

Correlation between Peak Height of Polar Mesospheric Clouds and Mesopause Temperature

Polar mesospheric clouds (PMCs) are ice crystal clouds formed in the mesosphere of high-latitude regions in both the northern (NH) and southern hemispheres (SH). Peak height is an important physical characteristic of PMCs. Satellite observation data from solar occultation for ice experiments (SOFIE) during seven PMC seasons from 2007 to 2014 show that the difference between the height of the mesopause and the peak height of the PMCs (Zmes-Zmax) were inversely correlated with the atmospheric mesopause temperature. The Zmes-Zmax averages for all seasons for the NH and SH were 3.54 km and 2.66 km, respectively. They were smaller at the starting and ending stages of each PMC season and larger in the middle stages. Analysis of the individual cases and statistical results simulated by the PMCs 0-D model also revealed the inverse correlations between the Zmes-Zmax and mesopause temperature, with correlation coefficients of −0.71 and −0.62 for the NH and SH, respectively. The corresponding rates of change of Zmes-Zmax with respect to mesopause temperature were found to be −0.21 km/K and −0.14 km/K, respectively. The formation mechanism of PMCs suggests that a lower temperature around the mesopause can lead to a greater distance and longer time for ice crystals to condense and grow in clouds. Thus, ice crystals sediment to a lower height, making the peak height of the PMCs further away from the mesopause. In addition, disturbances in small-scale dynamic processes tend to weaken the impact of temperature on the peak height of PMCs.

WACCM6 Projections of Polar Mesospheric Cloud Abundance Over the 21st Century

AbstractPolar mesospheric clouds (PMC), or noctilucent clouds, can be observed over high latitudes with the naked eye from the ground or from space near the summer solstice. PMC are considered a direct and sensitive indicator of climate change and have been reported to appear more frequently in recent decades. How PMC will change in the future under the influence of natural variability and anthropogenic forcing is uncertain. In this study, we utilize model output from the Whole Atmosphere Community Climate Model under several shared socioeconomic pathway (SSP) scenarios and input the water vapor, temperature, and pressure information into a 0‐d PMC model to project the trend and variation of PMC over the 21st century, and their relationship to future changes of temperature, water vapor, and the solar cycle. The 0‐d model calculations indicate that PMC ice water content (IWC) will increase and PMC will extend to lower latitudes under high SSP scenarios. Under these scenarios, more mesospheric water vapor leads to an increased IWC of PMC over the polar region, and colder mesopause temperature leads to more PMC over the mid‐latitudes. There is a significant anti‐correlation between the solar cycle and PMC IWC over the 21st century, but the anti‐correlation is not always significant on the decadal scale. Finally, methane oxidation in the stratosphere and water vapor entering from the troposphere are both responsible for future changes in mesospheric water vapor and thus PMC.

Multi-Year Variations in Temperature in Mesopause Region and F2-Region Peak Electron Density over Eastern Siberia

We performed an analysis of year-to-year variations in the characteristics of the upper neutral atmosphere and the ionosphere over Eastern Siberia. The mesopause temperature (Tm) obtained from the spectrometric observations of the OH(6-2) emission and the peak electron density (NmF2) from the ionosonde measurements were used as atmospheric and ionospheric characteristics. We considered the annual mean Tm and yearly average values of NmF2, as well as yearly average values of day-to-day and intradiurnal variability in Tm and NmF2. To interpret the year-to-year variations, we use multiple regressions of the ionospheric and atmospheric characteristics on the F10.7-index (as a proxy of solar activity) and Ap-index (as a proxy of geomagnetic activity). For the atmospheric characteristics, we also used regressions on the SOI index (as a proxy of circulation in the lower atmosphere). The yearly average values of NmF2 are dominantly controlled by changes in the solar flux. The year-to-year variations in the NmF2 variability are mainly driven by changes in both solar and geomagnetic activity. The year-to-year variations in the mesopause temperature weakly correlate with changes in the indices of solar and geomagnetic activity. The yearly average values of Tm variability correlate with changes in the SOI-index: the day-to-day variability demonstrates a positive correlation with the SOI-index, while the intradiurnal variability shows a negative correlation with the SOI-index. The study did not reveal a significant relationship between the year-to-year variations in the NmF2 variability and Tm variability.

Mesopause temperatures and relative densities at midlatitudes observed by the Mengcheng meteor radar

Mesopause temperatures and relative densities at midlatitudes observed by the Mengcheng meteor radar

Волновая активность мезосферы в диапазоне планетарных волн по наблюдениям эмиссии ОН (3-1) на станциях Маймага и Тикси за период 2015–2020 гг.

The article compares the interannual variability of the atmosphere at the OH glow height, which can be associated with planetary wave propagation, at stations spaced in latitude. As a characteristic reflecting planetary wave activity we consider standard deviations of the average overnight temperature σpw from its monthly average after taking into account the seasonal variation. Joint mesopause temperature measurements at high latitudes at two optical stations Maimaga (63.04° N, 129.51° E) and Tiksi (71.58° N, 128.77° E) began in 2015. The stations are equipped with identical Shamrock (Andor) high image quality infrared spectrographs for registration of OH (3-1) in the near infrared region (~1.5 μm). The main result of studying the planetary wave activity during the 5-year period of simultaneous observations is that at Tiksi station it slightly (by about 1–2 K) exceeds that at Maimaga station. In average annual activity fluctuations, the presence of quasi-biennial oscillations is traced.

Wave activity of the mesosphere in the planetary wave range according to OH (3-1) emission observations at Maimaga and Tiksi stations for 2015–2020

The article compares the interannual variability of the atmosphere at the OH glow height, which can be associated with planetary wave propagation, at stations spaced in latitude. As a characteristic reflecting planetary wave activity we consider standard deviations of the average overnight temperature σpw from its monthly average after taking into account the seasonal variation. Joint mesopause temperature measurements at high latitudes at two optical stations Maimaga (63.04° N, 129.51° E) and Tiksi (71.58° N, 128.77° E) began in 2015. The stations are equipped with identical Shamrock (Andor) high image quality infrared spectrographs for registration of OH (3-1) in the near infrared region (~1.5 μm). The main result of studying the planetary wave activity during the 5-year period of simultaneous observations is that at Tiksi station it slightly (by about 1–2 K) exceeds that at Maimaga station. In average annual activity fluctuations, the presence of quasi-biennial oscillations is traced.

The strong activity of noctilucent clouds at middle latitudes in 2020

The 2020 summer season had more frequent than usual occurrences of noctilucent clouds (NLCs) in the Northern Hemisphere at middle latitudes (45–50°N), with the lowest latitude at which NLCs were seen being 34.1°N. In order to investigate a reason for this extraordinary NLC season, we have analyzed long-term Aura/MLS satellite data for all available summer periods from 2005 to 2021. Both Aura/MLS summer temperature and water vapor in the mesopause region, between about 79 and 89 km altitude, have been considered. There has been a decrease in the summer mesopause temperature between 2016 and 2020. At the same time, water vapor mixing ratio has significantly increased (by about 12–17%) in the zonal mean H2O value in the 2020 summer compared to 2017. There exists a positive linear trend in the H2O amount by about 5% between 2005 and 2021 at middle latitudes 45–50°N at 0.0046 hPa. A combination of lower mesopause temperature and water vapor mixing ratio maximum at middle latitudes is the main reason for frequent and widespread occurrences of NLCs seen around the globe at middle latitudes in the summer of 2020. The 24th solar cycle minimum can explain neither the H2O maximum nor NLC maximum in 2020.

Studies for Mesopause Temperature Distribution Characteristics Based on the Sodium Lidar Data

Studies for Mesopause Temperature Distribution Characteristics Based on the Sodium Lidar Data

On the relationship of energetic particle precipitation and mesopause temperature

Abstract. Energetic particle precipitation (EPP) has the potential to change the neutral atmospheric temperature in the mesopause region. However, recent results are inconsistent, leaving the mechanism and the actual effect still unresolved. In this study we have searched for electron precipitation events and investigated a possible correlation between D-region electron density enhancements and simultaneous neutral temperature changes. The rotational temperature of the excited hydroxyl (OH) molecules is retrieved from the infrared spectrum of the OH airglow. The electron density is monitored by the European Incoherent Scatter Scientific Association (EISCAT) Svalbard Radar. We use all available experiments from the International Polar Year (IPY) in 2007–2008 until February 2019. Particle precipitation events are characterized by rapid increases in electron density by a factor of 4 at an altitude range of 80–95 km, which overlaps with the nominal altitude of the infrared OH airglow layer. The OH airglow measurements and the electron density measurements are co-located. Six of the 10 analysed electron precipitation events are associated with a temperature decrease of 10–20 K. Four events were related to a temperature change of less than 10 K. We interpret the results in terms of the change in the chemical composition in the mesosphere. Due to EPP ionization the population of excited OH at the top of the airglow layer may decrease. As a consequence, the airglow peak height changes and the temperatures are probed at lower altitudes. The observed change in temperature thus depends on the behaviour of the vertical temperature profile within the airglow layer. This is in agreement with conclusions of earlier studies but is, for the first time, constructed from electron precipitation measurements as opposed to proxies. The EPP-related temperature change recovers very fast, typically within less than 60 min. We therefore further conclude that this type of EPP event reaching the mesopause region would only have a significant impact on the longer-term heat balance in the mesosphere if the lifetime of the precipitation was much longer than that of an EPP event (30–60 min) found in this study.

GRIPS-HI, a novel spectral imager for ground based measurements of mesopause temperatures

Abstract The NDMC (Network for the Detection of Mesospheric Change) is a global network of measurement sites dedicated to the surveillance of the mesopause region. One main objective of the network is the early identification of climate signals. A key parameter is the mesopause temperature which can be derived from the emission spectrum of a layer of vibrationally excited hydroxyl (OH) at an altitude of approximately 87 km 87\hspace{0.1667em}\text{km} . Foremost, emission lines in the SWIR regime between 1520 nm 1520\hspace{0.1667em}\text{nm} and 1550 nm 1550\hspace{0.1667em}\text{nm} are of interest for remote temperature sensing. This report deals with the development of a new generation of GRIPS instruments, which are commonly employed for the observation of mesopause temperatures. The new prototype demonstrates how the application of so called Spatial Heterodyne Interferometers (SHI) can overcome the limitations of currently used grating spectrometers, in terms of spectral resolution and optical throughput. The presented prototype proposes improvements in optical throughput and spectral resolution of about one order of magnitude, significantly reducing the uncertainties of the measured mesopause temperatures. Furthermore, an SHI can be built in monolithic configurations which are aligned and characterized once during assembly without the need of realignment at the measurement site. This makes SHI based instruments ideal for mobile applications.

Spatial variability in long-term temperature trends in the middle atmosphere from SABER/TIMED observations

Temperatures obtained from Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on board the Thermosphere Ionosphere Mesosphere Energetics Dynamics (TIMED) satellite during the period from 2003 to 2019 are analysed to obtain trends in the region from 50°S to 50°N using the method of Empirical Mode Decomposition (EMD). This method is used to remove long-term oscillations from the data to accurately estimate the linear trends. The novelty of the current study is in dividing the entire study region into sub-regions of 5° latitude and 10° longitude to investigate the associated longitudinal variability. The study shows that the global middle atmosphere, including the global mesopause and stratopause, is cooling as a whole. In the stratosphere and lower mesosphere the observed trends are −0.5 K/decade and in the upper mesosphere, the trends increase to −1.0 K/decade. Mesopause temperatures in Southern Hemisphere and stratopause temperatures in Northern Hemisphere are showing stronger cooling trends in comparison to the other hemisphere. Over tropical and subtropical regions, Southern Hemisphere mesopause is showing a stronger cooling trend over Indian Ocean and Asian region while the cooling trends are symmetric around the equator over Pacific and Atlantic Oceans. Two important results obtained in the present study are as follows: (1) A warming trend, reaching 2.5 K/decade, is observed around 77 km over the Equator and adjoining tropical latitudes, which is attributed to processes leading to the mesospheric semi-annual oscillation (MSAO). (2) Anomalous cooling is observed in the stratopause region over the Southern Indian Ocean (SIO) longitudes. Temperature trends are large and negative ranging from −1 to −2 K/decade over SIO while the trends over the Southern Pacific Ocean (SPO) and the Southern Atlantic Ocean (SAO) lying in the same latitudinal band are small and positive, reaching values of 1 K/decade. It is envisaged that the recent accelerated warming of the SIO is probably responsible for the cooling of the stratopause region above.

Climatology of Interhemispheric Mesopause Temperatures Using the High‐Latitude and Middle‐Latitude Meteor Radars

AbstractWe present the climatology of mesopause temperatures using high‐latitude and middle‐latitude meteor radars. The daily mesopause temperatures are estimated using ambipolar diffusion coefficient data from the meteor radars at Davis Station (68.6°S, 77.9°E), in Antarctica, Svalbard (78.3°N, 16°E), Tromsø (69.6°N, 19.2°E) in the Arctic, and Mohe (53.5°N, 122.3°E) and Beijing (40.3°N, 116.2°E) in the northern middle latitudes. The seasonal variations in the meteor radar‐derived temperatures are in good agreement with the temperatures from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument onboard the TIMED satellite. Interhemispheric observations indicate that the mesopause temperatures over the southern and northern polar regions show a clear seasonal asymmetry. The seasonal variations in the Davis Station meteor radar temperatures in the southern polar mesopause are dominated by an annual oscillation (AO) with a relatively weak semiannual oscillation (SAO), which show a clear minimum during summer and a maximum during winter. The mesopause temperatures in the northern high and middle latitudes observed by the Svalbard, Tromsø, Mohe, and Beijing meteor radars mainly show an AO, with a maximum during winter and a minimum during summer. The AO in the northern polar regions is stronger than that in the southern polar regions, while the SAO in the southern polar regions is relatively strong compared to that in the northern polar regions.

Temporal evolutions of text {N}_2^+ Meinel (1,2) band near 1.5.,upmu text {m} associated with aurora breakup and their effects on mesopause temperature estimations from OH Meinel (3,1) band

We have carried out ground-based NIRAS (Near-InfraRed Aurora and airglow Spectrograph) observations at Syowa station, Antarctic (69.0^{circ }text {S}, 39.6^{circ }text {E}) and Kiruna (67.8^{circ }text {N}, 20.4^{circ }text {E}), Sweden for continuous measurements of hydroxyl (OH) rotational temperatures and a precise evaluation of auroral contaminations to OH Meinel (3,1) band. A total of 368-nights observations succeeded for 2 winter seasons, and 3 cases in which text {N}_2^+ Meinel (1,2) band around 1.5,mu text {m} was significant were identified. Focusing on two specific cases, detailed spectral characteristics with high temporal resolutions of 30 s are presented. Intensities of text {N}_2^+ band were estimated to be 228 kR and 217 kR just at the moment of the aurora breakup and arc intensification during pseudo breakup, respectively. At a wavelength of text {P}_1(2) line (sim 1523 ,text {nm}), text {N}_2^+ emissions were almost equal to or greater than the OH line intensity. On the other hand, at a wavelength of text {P}_1(4) line (sim 1542 ,text {nm}), the OH line was not seriously contaminated and still dominant to text {N}_2^+ emissions. Furthermore, we evaluated text {N}_2^+ (1,2) band effects on OH rotational temperature estimations quantitatively for the first time. Auroral contaminations from text {N}_2^+ (1,2) band basically lead negative bias in OH rotational temperature estimated by line-pair-ratio method with text {P}_1(2) and text {P}_1(4) lines in OH (3,1) band. They possibly cause underestimations of OH rotational temperatures up to 40 K. In addition, text {N}_2^+ (1,2) band contaminations were temporally limited to a moment around the aurora breakup. This is consistent with proceeding studies reporting that enhancements of text {N}_2^+ (1,2) band were observed associated with International Brightness Coefficient 2–3 auroras. It is also suggested that the contaminations would be neglected in the polar cap and the sub-auroral zone, where strong aurora intensification is less observed. Further spectroscopic investigations at these wavelengths are needed especially for more precise evaluations of text {N}_2^+ (1,2) band contaminations. For example, simultaneous 2-D imaging observation and spectroscopic measurement with high spectral resolutions for airglow in OH (3,1) band will make great advances in more robust temperature estimations in the auroral zone.

Long‐Term Trends and Solar Responses of the Mesopause Temperatures Observed by SABER During the 2002–2019 Period

AbstractThe global distribution and variations of the monthly mesopause temperature are presented during 2002–2019 covering the latitudes of 83°S to 83°N based on Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) observations. To investigate the long‐term trend and solar response of the mesopause temperature, a three‐component harmonic fit is first applied to remove the seasonal variation from the monthly temperature data series. Then a multiple linear regression model is performed to residual temperatures versus constant, linear trend, solar activity, and geomagnetic activity terms. In this study, the mesopause temperature shows a cooling trend through all latitudes ranging from ~0 to −0.14 K/year with a mean of −0.075 ± 0.043 K/year. The cooling trends in the Southern Hemisphere are stronger than those in the Northern Hemisphere. For high latitudes (60–80°), significant negative trends can be observed during nonsummertime, while no significant trends are found for summertime. The mesopause temperature shows apparent positive responses to solar activity through all latitudes ranging from 3.03 to 4.80 K per 100 solar flux units (sfu) with a mean of 3.99 ± 0.49 K per 100 sfu, which is more significant and stable in the Northern Hemisphere. There is a pronounced drop for mesopause height at polar latitudes, which reflects the shrinking effect at lower altitudes mainly caused by greenhouse gas cooling. We show that the length of the time interval analyzed strongly influences the results. Our results, obtained from 18‐year SABER observations, are expected to be a robust measure of the mesopause temperature variability.

Updated Long‐Term Trends in Mesopause Temperature, Airglow Emissions, and Noctilucent Clouds

AbstractWe have updated long‐term trends in mesopause temperature, airglow emission intensities, and noctilucent clouds (NLCs) based on ground‐based observations conducted in the Moscow region (Russia). Trends in mesopause temperature and airglow emissions have been derived for the period 2000–2018 (19 years), and long‐term trends in NLC characteristics have been obtained for 1968–2018 (51 years). Trends in airglow emissions have been estimated separately for winter and summer seasons. There are statistically significant negative trends in molecular oxygen O2 A(0‐1) and hydroxyl OH(6‐2) emission intensities in both winter and summer. Responses of the airglow intensities to solar activity have been found to be significantly positive, with winter ones being 1.5–2 times greater than summer ones. There is a rather strong and statistically significant cooling of the summer mesopause at a rate of −2.4±2.3 K/decade, whereas the winter mesopause demonstrates a small and statistically insignificant cooling of −0.4±2.2 K/decade. The response of the mesopause temperature to solar activity is positive and about 2 times greater in winter than in summer. We consider long‐term trends in the summer mesopause temperature and NLC for the same time period and same geographical region. Secular trends in NLC parameters have been found to be small and statistically insignificant as observed from midlatitudes. NLCs demonstrate statistically significant negative response to solar activity. Ozone forcing produces minor effects on both airglow and NLC characteristics. The observed small secular NLC trends contradict large modeled NLC trends recently obtained by Lübken et al. (2018, https://doi.org/10.1029/2018GL077719).

The Long‐Term Trends of Nocturnal Mesopause Temperature and Altitude Revealed by Na Lidar Observations Between 1990 and 2018 at Midlatitude

AbstractThe mesopause, a boundary between mesosphere and thermosphere with the coldest atmospheric temperature, is formed mainly by the combining effects of radiative cooling of CO2, and the vertical adiabatic flow in the upper atmosphere. A continuous multidecade (1990‐2018) nocturnal temperature data base of an advanced Na lidar, obtained at Fort Collins, CO (41°N, 105°W), and at Logan, UT (42°N, 112°W), provides an unprecedented opportunity to study the long‐term variations of this important atmospheric boundary. In this study, we categorize the lidar‐observed mesopause into two categories: the “high mesopause” (HM) above 97 km during nonsummer months, mainly formed through the radiative cooling, and the “low mesopause” (LM) below 92 km during nonwinter months, generated mostly by the adiabatic cooling. These lidar observations reveal a cooling trend of more than 2 K/decade in absolute mesopause temperature since 1990, along with a decreasing trend in mesopause height: The HM is moving downward at a speed of ~ 450 ± 90 m/decade, while the LM has a slower downward trend of ~ 130 ± 160 m/decade. However, since 2000, while the height trend (‐ 470 ± 160 m/decade for the HM and 150 ± 290 m/decade for the LM) is consistent, the temperature trend becomes statistically insignificant (‐ 0.2 ± 0.7 K/decade and ‐1 ± 0.9 K/decade for the HM and the LM, respectively). A long‐term study by Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM‐X) also indicated the similar mesopause changes, mostly caused by stratosphere‐lower mesosphere cooling and contraction.

Variability of the mesopause temperature and concentrations of reactive components of the mid-latitude atmosphere during sudden stratospheric warmings

We investigated the variations in the temperature regime, atomic oxygen, and ozone concentrations during the 2013 January major sudden stratospheric warming (SSW) and the 2017 February minor SSW. Data from the spectrometric observations of the hydroxyl emission at the longitudinally spaced mid-latitude sites Tory (51.8° N, 103.1° E) and Zvenigorod (55.7º N, 36.8º E), SABER TIMED satellite measurements and MERRA reanalysis were analysed. Concentrations of the atomic oxygen and ozone at the OH emission layer were calculated by using experimental data on the emission intensity and rotational temperature of the OH molecule, photochemical model of OH radiation, and MSISE-E-90 model. Significant changes in the OH temperature and emission intensity, as well as in the concentrations of atomic oxygen and ozone during the SSWs were revealed. These effects may be caused by variations in the height of the hydroxyl emission layer due to the enhancement of vertical motion in the atmosphere during the SSW. We found an increase in the day-to-day variability of the mesopause temperature up to 3 times in comparison with the mean seasonal values. This may indicate the SSW-associated intensification of the manifestation of the traveling planetary waves activity in the upper atmosphere.

Vertical coupling between the mesopause region and sporadic-E layer during equatorial counter electrojet events – A case study

This paper presents a case study exploring the variability of daytime ionospheric sporadic E (Es) during Counter Equatorial Electrojet (CEJ) events over Trivandrum (8.5°N, 77°E, 0.5°N dip lat.), a dip equatorial station in India. It makes use of collocated measurements of (a) daytime mesopause temperature estimated using a Multiwavelength Dayglow Photometer, (b) base height of sporadic E-layer i.e. Esq obtained from a Digital Ionosonde, (c) Equatorial Electrojet (EEJ) induced magnetic field at the surface measured using a Proton Precession Magnetometer and (d) neutral meridional and zonal winds measured using meteor wind radar. The study addresses why, only on certain CEJ days, the Es layer turns into a blanketing Es layer, also referred to as Esb layer, appearing for a brief period and almost simultaneously as the CEJ induced magnetic field on the surface is either zero or very small, and not on all the CEJ days despite the reversal of the zonal winds in the dynamo region (∼98 km). Further, a simulation using the simultaneously measured zonal wind and temperature shows that during CEJ, especially when the zonal wind reverses and the mesopause temperature lowers, the conditions are in fact less favourable for the ionization to converge resulting in Esb. On the other hand, on such occasions, the meridional wind exhibits a tendency to turn equatorward with time with the changeover gradually happening as the altitude decreases. These observations have been discussed to allude to the possible role of the overall wind system and its spatio-temporal changes in the ionospheric altitudes which could influence the gradual transition of Esq to Esb over the dip equator.

Comparison between seasonal variations in tidal and internal gravity wave activity as derived from observations at Maimaga and Tiksi

Since 2015, simultaneous observations of temperature of the high-latitude mesopause (87 km) have been made at Maimaga (63.04° N, 129.51° E) and Tiksi (71.58° N, 128.77° E) stations. These stations record spectra with Shamrock (Andor) photosensitive infrared spectrographs detecting the OH (3, 1) band in the near-infrared region (about 1.5 μm). We analyze temperature data obtained in observation seasons from 2015 to 2017. Standard deviations of temperature σ from its mean values are taken as characteristics of wave activity at night. We have obtained standard temperature deviations corresponding to internal gravity waves (IGW) (σgw) and tidal waves (σtd). Mean night rotational temperatures of hydroxyl emission almost coincide, and seasonal variations of gravity and tidal waves have a similar form during two seasons of simultaneous observations at Tiksi and Maimaga.

Сравнение сезонных вариаций активности приливных и внутренних гравитационных волн по наблюдениям на станциях Маймага и Тикси

Since 2015, simultaneous observations of temperature of the high-latitude mesopause (87 km) have been made at Maimaga (63.04° N, 129.51° E) and Tiksi (71.58° N, 128.77° E) stations. These stations record spectra with Shamrock (Andor) photosensitive infrared spectrographs detecting the OH (3, 1) band in the near-infrared region (about 1.5 μm). We analyze temperature data obtained in observation seasons from 2015 to 2017. Standard deviations of temperature σ from its mean values are taken as characteristics of wave activity at night. We have obtained standard temperature deviations corresponding to internal gravity waves (IGW) (σgw) and tidal waves (σtd). Mean night rotational temperatures of hydroxyl emission almost coincide, and seasonal variations of gravity and tidal waves have a similar form during two seasons of simultaneous observations at Tiksi and Maimaga.