Mesospheric Temperature Inversion Research Articles

Observation of Gravity Wave Vertical Propagation through a Mesospheric Inversion Layer

The impact of a mesospheric temperature inversion on the vertical propagation of gravity waves has been investigated using OH airglow images and ground-based Rayleigh lidar measurements carried out in December 2017 at the Haute-Provence Observatory (OHP, France, 44N). These measurements provide complementary information that allows the vertical propagation of gravity waves to be followed. An intense mesospheric inversion layer (MIL) observed near 60 km of altitude with the lidar disappeared in the middle of the night, offering a unique opportunity to evaluate its impact on gravity wave (GW) propagation observed above the inversion with airglow cameras. With these two instruments, a wave with a 150 min period was observed and was also identified in meteorological analyses. The gravity waves’ potential energy vertical profile clearly shows the GW energy lost below the inversion altitude and a large increase of gravity wave energy above the inversion in OH airglow images with waves exhibiting higher frequency. MILs are known to cause instabilities at its top part, and this is probably the reason for the enhanced gravity waves observed above.

Characteristics of a mesospheric front observed in Polar Mesospheric Cloud fields

We report on a Polar Mesospheric Cloud (PMC) front structure observed on July 2, 2007 over Greenland. This structure appears to be localized solitary wave, with a sharp boundary that separates a cloud and cloud-free region. Near-coincident temperature measurements indicate a 20 K temperature difference between these two regions that likely contributed to the sharp PMC front boundary. Gravity wave (GW) temperature amplitude and buoyancy frequency show that large amplitude GWs and the formation of a stable atmospheric layer between two unstable regions supported the formation of a pronounced mesospheric temperature inversion that destroyed PMCs. Given the absence of an inversion layer close to the location of PMC front, it is not clear if a similar thermal duct but with colder temperatures supported the formation of a single wave resulting in the formation of the observed PMC front. The buoyancy frequency structure with stable and unstable regions also indicates mesospheric wave propagation, and is present in both the cloud and cloud-free regions. We identify a tropospheric low-pressure area and a frontal system as potential sources of these mesospheric GWs. Ray-tracing simulations indicate that GWs from these sources propagated to the mesosphere and may have contributed to the observed PMC variability.

Mesospheric Temperature Inversions Observed in OH and O2 Rotational Temperatures From Mount Abu (24.6°N, 72.8°E), India

AbstractWe present a detailed investigation of upper mesospheric temperature inversions (MTIs) based on around 4.5 years of data of O2 and OH nightglow emission intensities (I(O2) and I (OH)) and temperature (T(O2) and T (OH)) corresponding to 94 and 87‐km altitudes. These measurements were carried out using Near‐Infrared Imaging Spectrograph from a low‐latitude location, Mount Abu (24.6°N, 72.8°E), in India. A total of 745 nights of Near‐Infrared Imaging Spectrograph observations is used, which showed the mean of T(O2) and T (OH) to be 199.6 and 203.0 K. However, there are nights that showed T(O2) greater than T (OH), which is considered as an indicator of upper MTIs. Among these nights, around 28% (209 out of 745) showed MTIs. It is found that 75% and 25% of MTIs occurred during premidnight and postmidnight hours. It was noted that maximum number of nights showed MTIs for a duration of around 4 hr followed by 3, 2, 5, and 6 hr. Investigation of causative mechanism for the upper MTIs revealed that although both wave dynamics and chemical heating by the exothermic reactions do work together, the in situ chemical heating process seems to be a more probable cause as compared to the vertical transport of energy from lower below. So far, such detailed statistics on MTIs does not exist in the published literature, and thus, the information presented in this work provides the necessary input for a greater understanding of the atmospheric temperature structure through modeling and simulation studies.

"Stratosphere-mesosphere Coupling Through Vertically Propagating Gravity Waves During Mesospheric Temperature Inversion (MTI): An Evidence"

"Stratosphere-mesosphere Coupling Through Vertically Propagating Gravity Waves During Mesospheric Temperature Inversion (MTI): An Evidence"

Near InfraRed Imaging Spectrograph (NIRIS) for ground-based mesospheric OH(6-2) and $$\hbox {O}_{2}$$ O 2 (0-1) intensity and temperature measurements

This paper describes the development of a new Near InfraRed Imaging Spectrograph (NIRIS) which is capable of simultaneous measurements of OH(6-2) Meinel and $$\hbox {O}_{2}$$ (0-1) atmospheric band nightglow emission intensities. In this spectrographic technique, rotational line ratios are obtained to derive temperatures corresponding to the emission altitudes of 87 and 94 km. NIRIS has been commissioned for continuous operation from optical aeronomy observatory, Gurushikhar, Mount Abu ( $$24.6^{\circ }\hbox {N}$$ , $$72.8^{\circ }\hbox {E}$$ ) since January 2013. NIRIS uses a diffraction grating of 1200 lines $$\hbox {mm}^{-1}$$ and 1024 $$\times $$ 1024 pixels thermoelectrically cooled CCD camera and has a large field-of-view (FOV) of $$80^{\circ }$$ along the slit orientation. The data analysis methodology adopted for the derivation of mesospheric temperatures is also described in detail. The observed NIRIS temperatures show good correspondence with satellite (SABER) derived temperatures and exhibit both tidal and gravity waves (GW) like features. From the time taken for phase propagation in the emission intensities between these two altitudes, vertical phase speed of gravity waves, $$c_{z}$$ , is calculated and along with the coherent GW time period ‘ $$\tau $$ ’, the vertical wavelength, $$\lambda _{z}$$ , is obtained. Using large FOV observations from NIRIS, the meridional wavelengths, $$\lambda _{y}$$ , are also calculated. We have used one year of data to study the possible cause(s) for the occurrences of mesospheric temperature inversions (MTIs). From the statistics obtained for 234 nights, it appears that in situ chemical heating is mainly responsible for the observed MTIs than the vertical propagation of the waves. Thus, this paper describes a novel near infrared imaging spectrograph, its working principle, data analysis method for deriving OH and $$\hbox {O}_{2}$$ emission intensities and the corresponding rotational temperatures at these altitudes, derivation of gravity wave parameters ( $$\tau $$ , $$c_{z}$$ , $$\lambda _{z}$$ , and $$\lambda _{y})$$ , and results on the statistical study of MTIs that exist in the earth’s mesospheric altitudes.

Investigations of mesospheric temperature inversions over sub-tropical location using lidar and satellites measurements

Characteristics of Mesospheric Temperature Inversions (MTIs) are studied using ~290 nights of Rayleigh Lidar data collected over Mt. Abu (24.5°N, 72.7°E) during the period of 1997 to 2004 for the first time from an Indian sub-tropical location. Three MTI events have been investigated and statistical analysis has also been performed. A strong MTI event, with amplitude of about 30K, at altitudes between 60 and 70km was observed on 30 December 2003. It was accompanied by strongly perturbed mesospheric zonal winds as observed by TIMED Doppler Interferometer (TIDI) onboard Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED). Two MTI episodes during March and December 2000 have been investigated, which showed that MTI can persist for few days and its amplitude varies gradually. Ozone observed by Halogen Occultation Experiment (HALOE) onboard Upper Atmospheric Research Satellite (UARS) also showed significantly higher variability during strong MTI events. A statistical analysis of MTI occurrence and their characteristics have been done using Lidar data (1997–2004), HALOE on board UARS (1997–2004) and SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) on board TIMED (2002–2004). The frequency of occurrence of MTIs is maximum during winter and minimum during summer and average magnitude of MTIs is ~20K with prominent seasonal variability. SABER and Lidar observed occurrence statistics is showing very similar pattern and SABER is able to capture stronger MTIs (~50K). The average bottom height of MTIs from Lidar is having strong seasonality (lower height during winter) in contrast to satellites observed heights of MTIs.

Lidar observations of the middle atmospheric thermal structure over north China and comparisons with TIMED/SABER

According to the observational data for over 120 nights of the Rayleigh lidar located in Beijing, China (40.5°N, 116.2°E), the middle atmospheric thermal structure (35–85km) over North China was obtained. Lidar observation results show good agreements with SABER temperature data sets, which justify that both the two instruments are reliable. Lidar results show significant difference with the NRLMSISE-00 empirical model and lidar temperatures are usually colder than the model data during the observational time, which may be due to the associations of high level of solar activity, greenhouse gases and the frequent haze weather in North China. To characterize the seasonal variations of the atmospheric temperature structure over Beijing, the amplitude and phase profiles of the annual, semi-annual and 3-month sinusoidal oscillations were extracted by multi-parameter sinusoidal regression. A stratospheric temperature enhancement (STE) event and a long-term mesospheric temperature inversion layer (MIL) are observed in the early winter of 2012/2013. The observed STE event could be due to the enhancement of planetary wave (k=1) activity while the long-term MIL could be due to gravity wave-planetary wave interactions in the masopause region.

Coordinated investigation of midlatitude upper mesospheric temperature inversion layers and the associated gravity wave forcing by Na lidar and Advanced Mesospheric Temperature Mapper in Logan, Utah

AbstractMesospheric inversion layers (MIL) are well studied in the literature but their relationship to the dynamic feature associated with the breaking of atmospheric waves in the mesosphere/lower thermosphere (MLT) region are not well understood. Two strong MIL events (ΔT ~30 K) were observed above 90 km during a 6 day full diurnal cycle Na lidar campaign conducted from 6 August to 13 August Logan, Utah (42°N, 112°W). Colocated Advanced Mesospheric Temperature Mapper observations provided key information on concurrent gravity wave (GW) events and their characteristics during the nighttime observations. The study found both MILs were well correlated with the development and presence of an unstable region ~2 km above the MIL peak altitudes and a highly stable region below, implicating the strengthening of MIL is likely due to the increase of downward heat flux by the enhanced saturation of gravity wave, when it propagates through a highly stable layer. Each MIL event also exhibited distinct features: one showed a downward progression most likely due to tidal‐GW interaction, while the peak height of the other event remained constant. During further investigation of atmospheric stability surrounding the MIL structure, lidar measurements indicate a sharp enhancement of the convective stability below the peak altitude of each MIL. We postulate that the sources of these stable layers were different; one was potentially triggered by concurrent large tidal wave activity and the other during the passage of a strong mesospheric bore.

Modes of zonal mean temperature variability 20–100 km from the TIMED/SABER observations

Abstract. In this study we investigate the spatial variabilities of the zonal mean temperature (20–100 km) from the TIMED (Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics)/SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) satellite using the empirical orthogonal functions (EOFs). After removing the climatological annual mean, the first three EOFs are able to explain 87.0% of temperature variabilities. The primary EOF represents 74.1% of total anomalies and is dominated by the north–south contrast. Patterns in the second and third EOFs are related to the semiannual oscillations (SAO) and mesospheric temperature inversions (MTI), respectively. The quasi-biennial oscillation (QBO) component is also decomposed into the seventh EOF with contributions of 1.2%. Last, we use the first three modes and annual mean temperature to reconstruct the data. The result shows small differences are in low latitude, which increase with latitude in the middle stratosphere and upper mesosphere.

Planetary wave‐gravity wave interactions during mesospheric inversion layer events

AbstractRayleigh lidar temperature observations over Gadanki (13.5°N, 79.2°E) show a few mesospheric inversion layer (MIL) events during 20–25 January 2007. The zonal mean removed SABER temperature shows warm anomalies around 50°E and 275°E indicating the presence of planetary wave of zonal wave number 2. The MIL amplitudes in SABER temperature averaged for 10°N–15°N and 70°E–90°E show a clear 2 day wave modulation during 20–28 January 2007. Prior to 20 January 2007, a strong 2day wave (zonal wave number 2) is observed in the height region of 80–90 km and it gets largely suppressed during 20–26 January 2007 as the condition for vertical propagation is not favorable, though it prevails at lower heights. The 10 day mean zonal wind over Tirunelveli (8.7°N, 77.8°E) shows deceleration of eastward winds indicating the westward drag due to wave dissipation. The nightly mean MF radar observed zonal winds show the presence of alternating eastward and westward winds during the period of 20–26 January 2007. The two dimensional spectrum of Rayleigh lidar temperature observations available for the nights of 20, 22, and 24 January 2007 shows the presence of gravity wave activity with periods 18 min, 38 min, 38 min, and vertical wavelengths 6.4 km, 4.0 km, 6.4 km respectively. From the dispersion relation of gravity waves, it is inferred that these waves are internal gravity waves rather than inertia gravity waves with the horizontal phase speeds of ~40 m/s, ~37 m/s, and ~50 m/s respectively. Assuming the gravity waves are eastward propagating waves, they get absorbed only in the eastward local wind fields of the planetary wave thereby causing turbulence and eddy diffusion which can be inferred from the estimation of large drag force due to the breaking of gravity wave leading to the formation of large amplitude inversion events in alternate nights. The present study shows that, the mesospheric temperature inversion is caused mainly due to the gravity wave breaking and the inversion amplitude may get modulated by the interaction between gravity waves and planetary waves. The eddy diffusion associated with gravity wave drag may also cause suppression in the planetary wave activity.

The temperature structure of the mesosphere over Taiwan and comparison with other latitudes

[1] We present here a detailed investigation of the mesospheric temperature structure over Taiwan, a subtropical location, using 9 years of observations (March 2002 to October 2010) by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument onboard the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite. The mesopause (MP) is always found to be located at a higher level with a mean altitude of 98.2 ± 1.8 km and mean temperature of 165.0 ± 5.8 K. The climatological study shows that MP is lower and warmer during summer and higher and cooler during winter, which is different from the midlatitudes and high latitudes as well as from low latitudes. The temperatures of the mesospheric temperature inversions (MTI) and secondary minimum (SM), on the other hand, are lower during summer and higher during winter, and their altitudes do not show any annual variation. It is found that the thermal structure over Taiwan undergoes a phase shift between 89 and 95 km, and above this region it is in phase with the solar flux. Since MP is always above these altitudes, it shows a seasonal variation that is in phase with the solar energy inputs, and the temperatures below (that of MTI and SM) show the opposite seasonal variation caused by mesospheric adiabatic cooling and warming processes.

Study of Atmospheric Forcing and Responses (SAFAR) campaign: overview

Abstract. Study of Atmospheric Forcing and Responses (SAFAR) is a five year (2009–2014) research programme specifically to address the responses of the earth's atmosphere to both natural and anthropogenic forcings using a host of collocated instruments operational at the National Atmospheric Research Laboratory, Gadanki (13.5° N, 79.2° E), India from a unified viewpoint of studying the vertical coupling between the forcings and responses from surface layer to the ionosphere. As a prelude to the main program a pilot campaign was conducted at Gadanki during May–November 2008 using collocated observations from the MST radar, Rayleigh lidar, GPS balloonsonde, and instruments measuring aerosol, radiation and precipitation, and supporting satellite data. We show the importance of the large radiative heating caused by absorption of solar radiation by soot particles in the lower atmosphere, the observed high vertical winds in the convective updrafts extending up to tropopause, and the difficulty in simulating the same with existing models, the upward traveling waves in the middle atmosphere coupling the lower atmosphere with the upper atmosphere, their manifestation in the mesospheric temperature structure and inversion layers, the mesopause height extending up to 100 km, and the electro-dynamical coupling between mesosphere and the ionosphere which causes irregularities in the ionospheric F-region. The purpose of this communication is not only to share the knowledge that we gained from the SAFAR pilot campaign, but also to inform the international atmospheric science community about the SAFAR program as well as to extend our invitation to join in our journey.

Influence of gravity waves and tides on mesospheric temperature inversion layers: simultaneous Rayleigh lidar and MF radar observations

Abstract. Three nights of simultaneous Rayleigh lidar temperature measurements over Gadanki (13.5° N, 79.2° E) and medium frequency (MF) radar wind measurements over Tirunelveli (8.7° N, 77.8° E) have been analyzed to illustrate the possible effects due to tidal-gravity wave interactions on upper mesospheric inversion layers. The occurrence of tidal gravity wave interaction is investigated using MF radar wind measurements in the altitude region 86–90 km. Of the three nights, it is found that tidal gravity wave interaction occurred in two nights. In the third night, diurnal tidal amplitude is found to be significantly larger. As suggested in Sica et al. (2007), mesospheric temperature inversion seems to be a signature of wave saturation in the mesosphere, since the temperature inversion occurs at heights, when the lapse rate is less than half the dry adiabatic lapse rate.

Model‐measurement comparison of mesospheric temperature inversions, and a simple theory for their occurrence

Mesospheric temperature inversions are well established observed phenomena, yet their properties remain the subject of ongoing research. Comparisons between Rayleigh‐scatter lidar temperature measurements obtained by the University of Western Ontario's Purple Crow Lidar (42.9°N, 81.4°W) and the Canadian Middle Atmosphere Model are used to quantify the statistics of inversions. In both model and measurements, inversions occur most frequently in the winter and exhibit an average amplitude of ∼10 K. The model exhibits virtually no inversions in the summer, while the measurements show a strongly reduced frequency of occurrence with an amplitude about half that in the winter. A simple theory of mesospheric inversions based on wave saturation is developed, with no adjustable parameters. It predicts that the environmental lapse rate must be less than half the adiabatic lapse rate for an inversion to form, and it predicts the ratio of the inversion amplitude and thickness as a function of environmental lapse rate. Comparison of this prediction to the actual amplitude/thickness ratio using the lidar measurements shows good agreement between theory and measurements.

Nocturnal temperature structure in the mesopause region over the Arecibo Observatory (18.35°N, 66.75°W): Seasonal variations

We present the mean seasonal climatology of the nocturnal temperature structure in the mesopause region (80–105 km) above the Arecibo Observatory, Puerto Rico (18.35°N, 66.75°W) from 106 nights of potassium Doppler lidar observations between December 2003 and September 2006. This first complete range‐resolved mesopause climatology for a tropical latitude exhibits several unique features. Compared to higher latitude sites, mesospheric temperature inversion layers in the nocturnal means are much weaker at Arecibo. Seasonally large inversions occur in summer but are almost non‐existent during the rest of the year. The Arecibo climatology shows a three‐level mesopause: a high altitude in summer (∼100 km), a medium altitude in late autumn and winter (∼96 km), and a low altitude in early spring (∼91 km). The mesopause is cold in the solstices (∼171 K in summer, ∼176 K in winter) and warm around equinoxes, particularly late autumn when it is near 195 K, while the spring mesopause temperature is close to 185 K. The lower thermosphere around 100 km at Arecibo shows a decreasing temperature from spring to summer when it reaches its coldest temperature, which is contrary to the increasing temperature observed at all midlatitude locations. Semiannual variations in the seasonal temperature have amplitudes as large as the annual variations through most of the MLT altitude range at Arecibo. These observed seasonal variations appear to be associated with the semi‐annual oscillation, a predominantly tropical phenomenon. This report provides one of the very few observations of the semi‐annual oscillation in lower thermosphere temperature.

Climatology of low‐latitude mesospheric echo characteristics observed by Indian mesosphere, stratosphere, and troposphere radar

Low‐latitude mesospheric echo characteristics are investigated using data collected during June 1994 to July 2005 (11 years) by the Indian mesosphere, stratosphere, and troposphere radar located at Gadanki (13.5°N, 79.2°E). Mesospheric echoes are frequently observed during 1000–1530 hrs (local time) in the height range of 68–78 km and are found to be highly intermittent in both space and time, consistent with those reported elsewhere. Although echoes are observed throughout the year, strong seasonal dependence has been observed in both echo occurrence and signal‐to‐noise ratio (SNR). Percentage occurrence (PO) of mesospheric echoes shows two maxima, one during late March equinox and early summer, and another during September. However, corresponding SNR suggests that strong echoes occur in both equinoxes with a minimum during winter. A clear semiannual variation is observed in PO of echoes with a peak occurring during the months of May and October. Similar variation is observed in SNR with peaks in March and September–November. These features are quite different from those observed at midlatitudes and high latitudes. Annual oscillation seems to fit well above 78 km and below 68 km, although on many occasions, occurrence of echo is poor at these heights. The ratio of vertical to off‐vertical beam SNR (which could be taken as a measure of aspect sensitivity) was close to unity at these heights, indicating that scattering is due to turbulence‐generated refractive index fluctuations. A positive correlation (R = 0.37) between PO and solar activity is observed, whereas a negative correlation (R = −0.55) is found between SNR and solar activity. The echo characteristics observed have been compared in detail with those reported from midlatitudes and high latitudes. The mechanisms behind the observed features are discussed in the light of mesospheric temperature inversions (MTIs), which are often noticed at this location, and wave breaking at these altitudes.

Global variability of mesospheric temperature: Planetary‐scale perturbations at equatorial and tropical latitudes

The study examines the source of a cold temperature perturbation observed in the Wind Imaging Interferometer (WINDII) daytime daily zonal mean temperatures at 87 km height during March/April 1993, also seen to some extent in 1995 and 1997 over the latitude range 25°S to 25°N. The perturbation appears centered at 10°S as a departure of 10K to 35K below the semiannual climatological mean, which peaks at equinox. After accounting for tidal contributions to the observations, by adopting tidal parameters determined from the Microwave Limb Sounder (MLS) temperature observations the cold temperature signature still remained in the residual data. The perturbation is a global phenomenon immediately following March equinox and lasts over a period of 2 weeks. The period is marked by the presence of mesospheric temperature inversions over the altitude range of 70–90 km. Harmonic analysis reveals the presence of planetary waves of wave number 1 with periods of 3 days, 4–5 days and 7 days. A cross section of the temperature monthly zonal mean data and month of the year over the period from January 1992 to December 1995 revealed a distinct MSAO, modulated by a QBO with strong cold anomalies in March/April 1993, 1995 and 1997 in excellent agreement with the MSAO easterly phase of correlative MF radar wind observations at Tirunelveli (8.7°N, 77.8°E). It is shown that the observed temperature anomalies can be produced by the residual circulation associated with the wave driving of the MSAO itself.

A comprehensive study on middle atmospheric thermal structure over a tropic and sub-tropic stations

The general characteristics of middle atmospheric thermal structure have been studied by making use of the Rayleigh lidar data collected over the period of about four years (1998–2001). Here, the data has been used from two different stations in the Indian sub-continent in tropics (Gadanki; 13.5°N, 79.2°E) and in sub-tropics (Mt. Abu; 24.5°N, 72.7°E). The observed monthly mean temperature profiles are compared with different model atmospheres (CIRA-86 and MSISE-90). We observed, the mean temperature profiles have closer agreement with MSISE-90 than CIRA-86. The temperature profiles measured by lidar and HALOE satellite overpass nearby lidar site are generally in agreement with each other. The systematic and statistical errors in deriving temperature are found to be uniform for both the stations, as ∼1 K at 50 km, ∼3 K at 60 km and ∼10 K at 70 km. The special features of mesospheric temperature inversion (MTI) and double stratopause structure (DBS) are also addressed for both the stations.

Nocturnal thermal structure of the mesosphere and lower thermosphere region at Maui, Hawaii (20.7°N), and Starfire Optical Range, New Mexico (35°N)

The nighttime thermal structure of the mesosphere and lower thermosphere (MLT) region at the Starfire Optical Range (SOR), New Mexico (35.0°N, 106.5°W), and at Maui, Hawaii (20.7°N, 156.3°W), are characterized using Na lidar observations. Both locations exhibit mesospheric temperature inversion layers (MILs) between 85 and 100 km that are not predicted by the MSIS‐00 model. The amplitudes of the Maui MILs (∼5.8 K) are about half of those at SOR (∼9.8 K), and the Maui MILs have a smaller width (∼11.1 km) compared to the SOR MILs (∼14.5 km). The Maui lidar temperatures are generally warmer than the MSIS‐00 predictions, while the SOR lidar data are comparable to the MSIS‐00, except in the MIL altitude range. Both SOR and Maui mesopause temperatures are coldest in midsummer and are warmest during the mesopause transition periods. However, the Maui mesopause is warmer than the SOR, and the amplitude of the mesopause temperature variations at Maui (∼9 K) is much smaller than at SOR (∼19 K). Two distinct levels of mesopause altitudes are clearly shown in the SOR seasonal data with a low altitude around 86.5 km in summer (May through August) and a high altitude around 101 km during the rest of the year. Abrupt transitions between the two stable levels occur in early May and early September. The lidar measurements indicate a low mesopause altitude near 87.5 km in July at Maui when averaging over a 10‐hour period centered at local midnight.

Global variability of mesospheric temperature: Mean temperature field

Daytime zonally (longitudinally) averaged temperatures from the Wind Imaging Interferometer (WINDII) on the Upper Atmosphere Research Satellite (UARS) and nightly temperatures from various ground‐based hydroxyl airglow observations are employed in the study of the global and seasonal variability of the upper mesospheric temperature field. The study examines the latitudinal variability of the annual cycle of mesospheric temperature at 75, 82, and 87 km employing 7 years (1991–1997) of WINDII mesospheric temperature data at latitudes from 20°S to 65°N at 75 km, 35°S to 65°N at 82 km, and from 45°S to 65°N at 87 km height. Particular attention is given to the latitude region of ±40° around the equator. Harmonic analysis of the 7‐year temperature time series reveals the presence of a dominant annual, ∼90‐ and 60‐day oscillations at high northern latitudes and a strong semiannual oscillation (SAO) at equatorial and tropical latitudes. A quasi‐biennial oscillation (QBO) is also identified extending from 45°S to 65°N. At 75 km the SAO is manifested as minima in the temperature composites at spring and fall equinox and maxima at winter and summer solstice; at 87 km the SAO is out of phase with respect to the 75‐km SAO, with maxima at equinox and minima around the solstice periods. The phase reversal takes place around 82 km and is associated with a mesospheric temperature inversion between 77 and 86 km height. Accounting for tidal contribution by adopting tidal predictions by the Extended Canadian Middle Atmosphere Model (CMAM) shows that a strong temperature decrease (∼35 K) seen during the 1993 March equinox at equatorial and tropical latitudes is not associated with solar migrating tides. WINDII global climatology derived at 75, 82, and 87 km revealed mesospheric SAO asymmetry with a stronger September equinox and interhemispheric asymmetry with a quieter and colder southern hemisphere. Comparisons with independent ground‐based observations and the Solar Mesospheric Explorer (SME) satellite data are also presented showing good to excellent agreement in the derived annual and SAO parameters. The results presented provide the first high‐vertical‐and‐temporal resolution global daytime temperature climatology in the upper mesosphere and in the vicinity of the mesopause.