First meteor radar observations of tidal oscillations over Jicamarca (11.95° S, 76.87° W)

Abstract. Tidal oscillations in the equatorial mesosphere and lower thermosphere (MLT) region over Jicamarca (11.95° S, 76.87° W) are studied using the observations from the newly installed Jicamarca All-sky Specular MEteor Radar (JASMET). The vertical structure and seasonal variability of diurnal and semidiurnal tides from 80–100 km are presented. The analyses show a strong diurnal tide over Jicamarca for both zonal and meridional components with the meridional amplitudes being larger than the zonal ones. Maximal diurnal amplitudes, 45 m/s for zonal and 55 m/s for meridional, are observed around equinox. The zonal diurnal amplitudes reach maxima at 90–96 km, while the meridional diurnal amplitudes grow with altitude for most months. Semidiurnal amplitudes vary not as strong as diurnal amplitudes. The vertical structures of the tidal components are compared with Global Scale Wave Model (GSWM02) prediction and the tidal wind analysis results from TIDI measurements onboard of the TIMED satellite. The data from JASMET and TIDI show similar amplitudes for both diurnal and semidiurnal tides. GSWM02 overestimates diurnal amplitudes, but underestimates semidiurnal amplitudes for both zonal and meridional components.

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Diurnal tidal variability in the upper mesosphere and lower thermosphere

Annales Geophysicae ◽

10.1007/s00585-997-1176-x ◽

1997 ◽

Vol 15 (9) ◽

pp. 1176-1186 ◽

Cited By ~ 50

Author(s):

M. E. Hagan ◽

C. McLandress ◽

J. M. Forbes

Keyword(s):

Heat Source ◽

Latent Heat ◽

Seasonal Variability ◽

Lower Thermosphere ◽

Wave Model ◽

Global Scale ◽

Horizontal Wind ◽

Boreal Winter ◽

Tidal Effects ◽

Mesosphere And Lower Thermosphere

Abstract. We explore tropospheric latent heat release as a source of variability of the diurnal tide in the mesosphere and lower thermosphere (MLT) in two ways. First, we present analyses of the UARS WINDII horizontal wind data, which reveal signatures of nonmigrating tidal effects as large as 25 m/s during both vernal equinox and boreal winter. These effects are of greater relative importance during the latter season. Complementary global-scale wave model (GSWM) results which account for a tropospheric latent heat source generally underestimate the observed nonmigrating tidal effects but capture the seasonal variability that is observed. Second, we pursue a new parameterization scheme to investigate seasonal variability of the migrating diurnal tidal component of the latent heat source with GSWM. These results confirm previously reported seasonal trends, but suggest that the MLT effects may be as much as an order of magnitude larger than earlier predictions.

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Special Structures of Sodium Layer Observed in the Daytime Over Beijing, China

EPJ Web of Conferences ◽

10.1051/epjconf/202023704005 ◽

2020 ◽

Vol 237 ◽

pp. 04005

Author(s):

Yuan Xia ◽

Guotao Yang ◽

Jihong Wang ◽

Xuewu Cheng ◽

Faquan Li

Keyword(s):

Signal To Noise Ratio ◽

Lower Thermosphere ◽

Meteor Radar ◽

Diurnal Cycles ◽

Dual Channel ◽

Sodium Layer ◽

Mesosphere And Lower Thermosphere ◽

Beijing China ◽

Observation Results ◽

Mlt Region

In this paper the observation of sodium (Na) layer in mesosphere and lower thermosphere (MLT) region over complete diurnal cycles based on broadband Na lidar at Yanqing Station, Beijing, China (40.5°N,116°E ) was reported. Faraday filters with dual-channel design were used in the lidar receiving unit to suppress the strong background light in the daytime, which allow observation of Na layer with an acceptable signal-to-noise ratio (SNR) under sunlit condition. Several special structures of Na layer observed in the daytime was discussed. The simultaneous continuous observation of zonal wind by meteor radar was presented for comparison. These observation results can provide direct and reliable supports for the study of mesopause dynamics and solar effect on Na layer.

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Seasonal variability of atmospheric tides in the mesosphere and lower thermosphere and lower thermosphere: meteor radar data and simulations

10.5194/angeo-2018-17-rc1 ◽

2018 ◽

Author(s):

Anonymous

Keyword(s):

Seasonal Variability ◽

Lower Thermosphere ◽

Radar Data ◽

Atmospheric Tides ◽

Meteor Radar ◽

Mesosphere And Lower Thermosphere

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The ultra-fast Kelvin waves in the equatorial ionosphere: observations and modeling

Annales Geophysicae ◽

10.5194/angeo-31-209-2013 ◽

2013 ◽

Vol 31 (2) ◽

pp. 209-215 ◽

Cited By ~ 15

Author(s):

A. N. Onohara ◽

I. S. Batista ◽

H. Takahashi

Keyword(s):

Lower Thermosphere ◽

Equatorial Ionosphere ◽

Equatorial Region ◽

South American ◽

Meteor Radar ◽

Vertical Coupling ◽

Wave Characteristics ◽

E Region ◽

Mesosphere And Lower Thermosphere ◽

Mlt Region

Abstract. The main purpose of this study is to investigate the vertical coupling between the mesosphere and lower thermosphere (MLT) region and the ionosphere through ultra-fast Kelvin (UFK) waves in the equatorial atmosphere. The effect of UFK waves on the ionospheric parameters was estimated using an ionospheric model which calculates electrostatic potential in the E-region and solves coupled electrodynamics of the equatorial ionosphere in the E- and F-regions. The UFK wave was observed in the South American equatorial region during February–March 2005. The MLT wind data obtained by meteor radar at São João do Cariri (7.5° S, 37.5° W) and ionospheric F-layer bottom height (h'F) observed by ionosonde at Fortaleza (3.9° S; 38.4° W) were used in order to calculate the wave characteristics and amplitude of oscillation. The simulation results showed that the combined electrodynamical effect of tides and UFK waves in the MLT region could explain the oscillations observed in the ionospheric parameters.

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Monthly mean climatology of the prevailing winds and tides in the Arctic mesosphere/lower thermosphere

Annales Geophysicae ◽

10.5194/angeo-22-3395-2004 ◽

2004 ◽

Vol 22 (10) ◽

pp. 3395-3410 ◽

Cited By ~ 39

Author(s):

Y. I. Portnyagin ◽

T. V. Solovjova ◽

N. A. Makarov ◽

E. G. Merzlyakov ◽

A. H. Manson ◽

...

Keyword(s):

Vertical Structure ◽

Lower Thermosphere ◽

Meridional Wind ◽

The Arctic ◽

Different Types ◽

Mlt Dynamics ◽

Mesosphere And Lower Thermosphere ◽

Resolute Bay ◽

Mlt Region

Abstract. The Arctic MLT wind regime parameters measured at the ground-based network of MF and meteor radar stations (Andenes 69° N, Tromsø 70° N, Esrange 68° N, Dixon 73.5° N, Poker Flat 65° N and Resolute Bay 75° N) are discussed and compared with those observed in the mid-latitudes. The network of the ground-based MF and meteor radars for measuring winds in the Arctic upper mesosphere and lower thermosphere provides an excellent opportunity for study of the main global dynamical structures in this height region and their dependence from longitude. Preliminary estimates of the differences between the measured winds and tides from the different radar types, situated 125-273km apart (Tromsø, Andenes and Esrange), are provided. Despite some differences arising from using different types of radars it is possible to study the dynamical wind structures. It is revealed that most of the observed dynamical structures are persistent from year to year, thus permitting the analysis of the Arctic MLT dynamics in a climatological sense. The seasonal behaviour of the zonally averaged wind parameters is, to some extent, similar to that observed at the moderate latitudes. However, the strength of the winds (except the prevailing meridional wind and the diurnal tide amplitudes) in the Arctic MLT region is, in general, less than that detected at the moderate latitudes, decreasing toward the pole. There are also some features in the vertical structure and seasonal variations of the Arctic MLT winds which are different from the expectations of the well-known empirical wind models CIRA-86 and HWM-93. The tidal phases show a very definite longitudinal dependence that permits the determination of the corresponding zonal wave numbers. It is shown that the migrating tides play an important role in the dynamics of the Arctic MLT region. However, there are clear indications with the presence in some months of non-migrating tidal modes of significant appreciable amplitude.

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