A Fabry-Perot interferometer,funded by the Meridian Project in China,was deployed at the Xinglong station(40.2°N,117.4°E) of the National Astronomical Observatories in Hebei Province,China.The instrument has been operating since April 2010,measuring mesospheric and thermospheric winds.The first observational data of winds at three heights in the mesosphere and thermosphere were analyzed,demonstrating the capacity of this instrument to aid basic scientific research.The wavelengths of three airglow emissions were OH892.0,OI 557.7,and OI 630.0 nm,which corresponded to heights of 87,98,and 250 km,respectively.Three 38-day data sets of horizontal winds,from April 5,2010 to May 12,2010,show clear day-to-day variations at the same height.The minimum and maximum meridional winds at heights of 87,98,and 250 km were-16.5 to 8.7 m/s,-24.4 to 15.9 m/s,and-43.6 to 1.5 m/s.Measurements of zonal winds were-5.4 to 7.6 m/s,2.3 to 23.0 m/s,and-22.6 to 49.3 m/s.The average data from the observations was consistent with the data from HWM93.The wind data at heights of 87 and 98 km suggest a semi-diurnal oscillation,clearly consistent with HWM93 results.Conversely there was a clear discrepancy between the observations and the model at 250 km.In general,this Fabry-Perot interferometer is a useful ground-based instrument for measuring mesospheric and thermospheric winds at middle latitudes.
In order to investigate the global distributions of temporal variations of OH and O2 nightglow emissions,we statistically analyzed their variations with altitude,local time,and season,using the OH and O2 airglow emission rate data observed by the TIMED satellite between 2002 and 2009.The results indicated that the OH nightglow emission was stronger than dayglow emission and the O2 nightglow emission was weaker than dayglow emission.In the tropics,the OH nightglow intensity reached its maximum near midnight;at higher latitudes,the OH nightglow intensities after sunset and before sunrise were much strong.At the equinoxes,the O2 nightglow intensity in the tropics decreased with local time;at the solstices,the local time-latitude distribution of the O2 nightglow intensity had a valley(with weak emission).As for the altitude-latitude distributions of nightglow emission rates,the distribution for OH nightglow at the equinoxes had one peak(with strong emission)at the equator,with a peak height around 85 km;the peak for the March equinox was stronger than that for the September equinox.The distribution for O2 nightglow at the equinoxes had three peaks,lying at 30°in the spring and autumn hemispheres and at the equator,and the peak height at the equator was the lowest.The distributions for both OH and O2 nightglow emissions at the solstices had three peaks.Both nightglow intensities in the tropics had obvious annual and semi-annual variations,the peaks and valleys for semi-annual variations appeared near the equinoxes and solstices,respectively,and the peak at the March equinox was larger than that at the September equinox.The distributions of both OH and O2 nightglow intensities showed a hemispheric asymmetry.
GAO HongXU JiYaoCHEN GuangMingYUAN WeiBELETSKY A. B
In this paper, winds derived from OH Meinel 892.0 nm detection by an FPI （Fabry-Perot Interferometer） are compared with the simultaneous wind measurements from a meteor radar during April-May of 2010. The peak height of OH Meinel 892.0 nm is about 87 km. The variations of FPI wind at 87 km mostly have the similar track to meteor radar wind at 87 km, and the data values of FPI wind mainly fall into the range of meteor radar wind. However, there are still quantitative differences between the observations of the two systems. The best cross-correlation occurs in rneridional winds from two systems in April of 2010. An obvious wave signal with 0.2 cycle/d frequency is found in meridional winds observed by both FPI and meteor radar.
Because of the importance of gravity waves （GWs） in coupling different atmospheric regions, further studies are necessary to investigate the characteristics of GW propagation in a non-isothermal atmosphere. Using a nonlinear numerical model, we simulate the propagation of small amplitude GWs with various wavelengths in different non-isothermal atmospheres. Our re- sults show that the GW vertical wavelength undergoes sharp changes above the stratopause and mesopause region. Specifically for a GW with an initial vertical wavelength of 5 km, the seasonal background temperature structure difference at 50° latitude can cause the vertical wavelength to vary by -2 krn in the mesosphere and by as large as -4.5 km in the lower thermosphere. In addition, the GW paths exhibit great divergence in the height range of -65-110 kin. Our results also show that the variations of GW path, vertical wavelength and horizontal phase velocity are not synchronized in a non-isothermal atmosphere as in an isothermal atmosphere. Despite the fact that all GWs change their characteristics as they propagate upward in a non-isothermal atmosphere, the variations relative to the initial parameters at a reference height are similar for different initial vertical wavelengths. Our results indicate that the changing characteristics of a gravity wave in a non-isothermal atmosphere need to be considered when investigating the relationship of GWs at two different heights.
The global distribution of 1.27 ~tm 02 nightglow brightness observed by the TIMED/SABER satellite has been investigated to find the longitudinal structures for different seasons and latitudes. The results show that the 02 airglow is dominated by wave 4 structure at latitudes between equator and 20°S/N in both hemispheres during most seasons. At mid-latitudes around 40°S/N, the wave 1 structure is observed for most seasons with a small contribution of wave 2 during the June solstice. A comparison of the 02 and OH nightglows shows similarity in their global distributions which can be attributed to their similar photochemical mechanisms.
On June 3,2010,the first meteorological rocket of the Meridian Space Weather Monitoring Project was successfully launched at the Hainan rocket launch site(19.5°N),China.This paper analyzes the vertical profiles of atmospheric temperature and wind recorded by the rocket and its supportive balloons,and investigates wind shear,gravity waves and atmospheric stability.In addition,we compare the vertical profiles of atmospheric temperature and wind with SABER/TIMED temperature measurements and the modeling results of MSIS00 and HWM07.
A SpectroMeter of Atmospheric RadiaTion （SMART） was developed and installed at the Xinglong station of the National Astronomical Observatories in Hebei province, China, which was supported by the Meridian Project [1]. The experimental tests of spectrometric observation of the hydroxyl emission and rotational temperature in China were conducted for the first time on the night of February 23, 2011 and the night of April 27, 2011, respectively. OH 6-2 band and OH 8-3 band spectra were measured and the rotational temperature was retrieved. Hourly average temperatures （186.82±6.40） K of OH 8-3 band and （178.07±6.73） K of OH 6-2 band were derived from the spectra observed on the night of February 23,2011. Intensities and ro- tational temperature against local time were determined by the spectra measured in the whole night of April 27, 2011. The rotational temperature was consistent with the spatial average temperature of NRLMSISE00 empirical model at height 83-91 km and the average temperature of TIMED/SABER from April to May of seven years at height 83-91 kin, with some discrepancies. The results showed that the new instrument and the retrieval method of the rotational temperature can give reasonable results of the airglow emission of OH and the temperature of mesopause.
