Shaohua Gong

Occurrence and characteristics of sporadic sodium layer observed by lidar at a mid-latitude location

Na lidar observations of SSL during the past 5 years at a mid-latitude location (Wuhan, China, 31degreesN, 114degreesE) are reported in this paper. From 26 SSL events detected in about 230 h of observation, an SSL occurrence rate of 1 even/9 h at our location was obtained. This result, combined with that reported by Nagasawa and Abo (Geophys. Res. Lett. 22 (1995) 263) at Tokyo, Japan, reveals that the SSL occurrence can be relatively frequent at some mid-latitude locations. The statistical analyses of main parameters for the 26 SSL events were made, and the results were compared with those previously reported. By examining the corresponding data from a nearby ionosonde, it was found that there was a fairly good correlation between SSL and Es. Of the 18 pairs of SSL and Es events checked, 15 of SSL were accompanied by Es, and 8 pairs of them were correlated within 1 h in time and within 5 km in altitude. From the analyses of observed perturbations during SSL development, the role of dynamic processes of atmosphere in the SSL formations were emphasized

A double sodium layer event observed over Wuhan, China by lidar

[1] A double sodium layer (DSL) structure was observed during the night of June 13, 2000 over Wuhan, China (31degreesN, 114degreesE) by our Na lidar. The unique feature of this DSL is that a normal sodium layer at altitudes of 80 similar to 105 km was accompanied by a secondary sodium layer at altitudes of 105 similar to 125 km for about 2 hours. The lidar observation result together with that obtained from the nearby ionosonde and geomagnetic equipments are presented. While the exact mechanism responsible for this DSL formation is still unclear, some possible explanations and corresponding observation evidences are discussed.

Three-pulse photon echo induced by the optical transition of excitons in core–shell CdSe/ZnS nanocrystal quantum dots

Nicolas Sangouard, Christoph Simon, Jǐŕı Minář, Mikael Afzelius, Thierry Chanelière, Nicolas Gisin, Jean-Louis Le Gouët, Hugues de Riedmatten, and Wolfgang Tittel. Group of Applied Physics, University of Geneva, Switzerland Institute for Quantum Information Science and Department of Physics and Astronomy, University of Calgary, Calgary, Alberta T2N 1N4, Canada Laboratoire Aimé Cotton, CNRS-UPR 3321, Université Paris-Sud, 91405 Orsay cedex, France (Dated: February 26, 2010)

Statistical study of atmospheric gravity waves in the mesopause region observed by a lidar chain in eastern China

Atmospheric gravity wave activities in the mesopause region have been observed and statistically investigated with a sodium lidar chain in eastern China. In total, there were 471 gravity waves identified from over 5400h of observations at Hainan (19.99 degrees N, 110.34 degrees E), Hefei (31.87 degrees N, 117.23 degrees E), and Beijing (40.47 degrees N, 115.97 degrees E). These waves typically had vertical wavelengths of (z)=2-4km, observed periods of T-ob=1-4h, amplitude growth factors of =-0.025 similar to+0.05km(-1), and wave amplitudes of Ae(*90km)=1.5-6%. Strong systematic parameter relationships were found, and they agree with the predictions of diffusive filtering theory. Statistical results show that the seasonal variability of gravity wave activity had a summer-maximum and winter-minimum characteristics in the mesopause region over eastern China. A qualitative interpretation is proposed regarding the seasonal and geographic variability observed by the lidar chain, based on analysis of source properties and influences from background wind, which vary by season.