Sporadic sodium layers(SSLs)were studied with sodium(Na)lidar at Beijing(40.5°N,116.0°E)and Haikou(19.5°N,109.1°E)in China.The altitude distribution,strength factors,and occurrence time of SSL and sporadic E(Es)layer events were statistically analyzed at both observing sites.SSL occurrence had a maximum near22:00 local time,and Eslayer occurrence had a maximum before midnight.The altitude distributions of SSL and Es layer events were better correlated at Haikou than at Beijing.All the average values of height and strength factor for SSL and Eslayer events,as well as the average of the maximum frequency that can be reflected by the Eslayer(foEs),at Beijing were higher than those at Haikou.A better correlation between SSL and Eslayer events was also found at Haikou,and the formation of SSLs was considered to likely depend on the seasonal variability of chemical and dynamical processes.
A double-laser-beam lidar was successfully developed in 2010 to measure the K layer over Yanqing County, Beijing(40.5°N, 116.2°E). Comprehensive statistical analyses of sporadic K(Ks) layer parameters were conducted using two years of lidar data, and the parameters of the Ks layers and their distribution obtained by the analyses are described. The seasonal distribution of Ks occurrence was obtained, with two maxima observed in January and July, respectively. The seasonal distributions of sporadic E(Es) occurrence over Beijing differ from those of Ks occurrence. However, good correlations between Es and Ks in case by case study were found. We also found that four Ks events with peak altitudes lower than 90 km were associated with large and sharp temperature increases in five comparative examples.
JIAO JingYANG Guo TaoWANG Ji HongWANG Ze LongYANG Yong
Based on observations from daytime lidars in eastern China,diurnal cycles of the sodium layer over Wuhan(30.5°N,114.6°E)and Beijing(40.5°N,116°E)are investigated.Diurnal variations of Na density,root mean square(RMS)layer width,and centroid height of the sodium layer are analyzed.Results reveal that the large diurnal cycles of the sodium layer are controlled mainly by 24-hr oscillations at the two observation sites.The diurnal variation of the sodium layer over Wuhan was modulated mainly by tidal perturbations during the lidar observation campaign.Conversely,the diurnal variation over Beijing was controlled principally by photoionization and photochemistry effects during another campaign,and there was little evidence of direct tidal perturbations.These comparisons suggest that the diurnal variation of the sodium layer perhaps has obvious regional characteristics across China.The variation can be either controlled mainly by tidal perturbations or by photoionization and photochemistry effects in different seasons.
GONG ShaoHuaYANG GuoTaoCHENG XueWuGONG Shun ShengXU JiYaoLI FaQuanGONG WeiWANG JiHong
