Lidar observations of sporadic Na layers over Wuhan (30.5°N, 114.4°E)

Yi, Fan; Zhang, Shaodong; Zeng, Huang; He, Yujin; Yue, Xianchang; Liu, Jingbo; Hong-fang, LV; Xiong, Dongbin

doi:10.1029/2001gl014353

Cited by 35 publications

(32 citation statements)

References 21 publications

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“…This statistical plot excluded those events for which we did not observe the beginning times or ending times. One can find that most of them lasted for about 1-3 h. These results agree with those reported by other sodium lidar groups (Batista et al, 1989;Yi et al, 2002;Gong et al, 2002;Vishnu Prasanth et al, 2007). Figure 3 shows the histogram distribution of the ratio of the falling times versus rising times for the SSL events analyzed in Fig.…”

Section: Instrument Description and Data Analysissupporting

confidence: 82%

“…But subsequent observations showed that the mid-latitude deficit was not thought to be real in recent years. For example, measurements in the Eastern Hemisphere, i.e., Tokyo (35 • N) from November 1991 to October 1993 and Wuhan (31 • N) from February 1996 to August 2001, gave a mean occurrence interval of about 10 h per SSL event (Nagasawa and Abo, 1995;Yi et al, 2002;Gong et al, 2002), and measurements in the Western Hemisphere, i.e., Colorado (40.6 • N) from April to June 2002 and June to August 2003, indicated that 65% of days and 19% of hours had SSLs (Williams et al, 2007). These observations showed much higher occurrence rates than those observed at mid-latitude before the 1990s.…”

Section: Introductionmentioning

confidence: 99%

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A statistical study of sporadic sodium layer observed by Sodium lidar at Hefei (31.8° N, 117.3° E)

et al. 2009

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Abstract. Sodium lidar observations of sporadic sodium layers (SSLs) during the past 3 years at a mid-latitude location (Hefei, China, 31.8 • N, 117.3 • E) are reported in this paper. From 64 SSL events detected in about 900 h of observation, an SSL occurrence rate of 1 event every 14 h at our location was obtained. This result, combined with previous studies, reveals that the SSL occurrence can be relatively frequent at some mid-latitude locations. Statistical analysis of main parameters for the 64 SSL events was performed. By examining the corresponding data from an ionosonde, a considerable correlation was found with a Pearson coefficient of 0.66 between seasonal variations of SSL and those of sporadic E (Es) during nighttime, which was in line with the research by Nagasawa and Abo (1995). From comparison between observations from the University of Science and Technology of China (USTC) lidar and from Wuhan Institute of Physics and Mathematics (WIPM) lidar (Wuhan, China, 31 • N, 114 • E), the minimum horizontal range for some events was estimated to be over 500 km.

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Section: Instrument Description and Data Analysissupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

A statistical study of sporadic sodium layer observed by Sodium lidar at Hefei (31.8° N, 117.3° E)

et al. 2009

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“…For guaranteeing a good data quality, all the 5-min density data used here are required to have the detection thresholds less than 200 cm −3 in the entire altitude range of the metal layers (75-110 km). The sporadic Na and Fe layers are often observed at our lidar site near 30 • N (Yi et al, 2002(Yi et al, , 2007Ma and Yi, 2010). They are characterized by a large density enhancement in a narrow altitude range and have no clear-cut relation with the main metal layers.…”

Section: Observational Resultsmentioning

confidence: 99%

Average properties and small-scale variations of the mesospheric Na and Fe layers as observed simultaneously by two closely colocated lidars at 30° N

Chen

2011

Ann. Geophys.

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Abstract. We report the average properties and small-scale variation features of the mesospheric Na and Fe layers at 30 • N from extensive simultaneous and common-volume Na and Fe lidar measurements at Wuhan, China. The annual mean Na and Fe density profiles are derived in terms of an averaging method taken from an early literature. The mean Na and Fe profiles preserve the sharp gradients present in most individual density profiles near the layer bottom. Near the bottommost of the layers the mean Na and Fe scale heights are respectively −0.42 and −0.30 km. The mean layer parameters coincide well with the previous report. The Na and Fe densities in the lowest several kilometers of the layers consistently exhibit nearly the same time variations. A clearcut distinction between the Na and Fe time variations always appears in an altitude range near 90 km. A relatively weak positive correlation between them persistently occurs also in an altitude range near 100 km. The mean increase and decrease rates for both Na and Fe are altitude dependent and have a single-peak structure. The time constant of the layer variation is ∼0.07-2.0 h for Na and ∼0.02-1.7 h for Fe, suggesting that the variability is dominated by small-scale processes. However, there is also a slow net increase in each of the annual mean column abundances (Na and Fe) during night.

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“…In addition, simultaneous and common volume lidar observations at 30 • N showed that, 62 % of sporadic Na and Fe (Fe s ) layers occurred in overlapping altitude ranges and moved following almost the same track (Yi et al, 2007). Occasionally, Na s layers could appear at extremely high altitude (above 105 km) (Collins et al, 1996;Yi et al, 2002;Gong et al, 2003;Ma and Yi, 2010;Dou et al, 2013). Through a statistics study, Ma and Yi (2010) have found that Na s and Fe s layers above 105 km at 30 • N occurred mostly during summer and possessed long durations and broad layer widths.…”

Section: Introductionmentioning

confidence: 99%

First report of sporadic Na layers at Qingdao (36° N, 120° E), China

Wang

Chen³

et al. 2014

Ann. Geophys.

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Abstract. This paper reports, for the first time, observational results of mesopause sporadic Na (Na s ) layers by a ground-based lidar at Qingdao (36 • N, 120 • E), China. Based on ∼ 430 h of observational data on 95 nights from December 2007 to June 2012, we have selected a total of 53 Na s layer events. It is found that characteristics of Na s layers over Qingdao have general similarity with those over nearby sites, Wuhan (30 • N, 114 • E) and Hefei (32 • N, 117 • E), but not those over the site Hachioji (35 • N, 139 • E) at nearly the same latitude as Qingdao. At the same time, parameters of sporadic E (E s ) layers were recorded by an ionosonde. The fact that E s layer occurrence probabilities of 19, 22, and 18 % in time intervals before, during, and after the Na s layers are very close to the average occurrence ratio of the nocturnal E s layer (21 %), may reveal a general independence between Na s and E s layers over Qingdao. Only those strong Na s layers above the peak altitude of the main Na layer might have a significant correlation with E s layers. In addition, a total of 11 high-altitude (above 105 km) Na s layer events have been surveyed specially. It is found that these high-altitude Na s layers were usually weak. And they possessed long-duration (> 147 min) and broad-layer width (4.0 km) compared with Na s layers below 105 km (> 96 min and 2.4 km). These characteristics are in accord with observational results at Wuhan. It is suggested that there is little correlation between this kind of Na s layers and E s layers. Finally, the summer topside enhancement phenomenon of Na atoms observed at Qingdao is in accord with several earlier observational results at different sites (18, 30, and 54 • N) in the Northern Hemisphere.

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Lidar observations of sporadic Na layers over Wuhan (30.5°N, 114.4°E)

Cited by 35 publications

References 21 publications

A statistical study of sporadic sodium layer observed by Sodium lidar at Hefei (31.8° N, 117.3° E)

A statistical study of sporadic sodium layer observed by Sodium lidar at Hefei (31.8° N, 117.3° E)

Average properties and small-scale variations of the mesospheric Na and Fe layers as observed simultaneously by two closely colocated lidars at 30° N

First report of sporadic Na layers at Qingdao (36° N, 120° E), China

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