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The Mesospheric Sodium Layer at Calar Alto ,
| Content Provider | Semantic Scholar |
|---|---|
| Author | Spain C. O'Sullivan, M. M. Redfern, R. Michael Ageorgesa H. Holstenberg, C. Hackenberg, Wolfgang K. P. Rabien, Sebastian Ott, Timm Davies, R. National, Eckartba |
| Copyright Year | 2007 |
| Abstract | The short-and long-term characteristics of the sodium layer have important implications for laser guide star systems. Short-timescale variations, in particular, may necessitate frequent refocussing of the beam and wavefront sensor system. In this paper we present results from observations of the mesospheric sodium layer taken at the Max Planck observatory in Calar Alto, Spain in September 1997 and August 1998. We describe our experiment which uses the resonant optical backscatter of 589.2-nm laser light from the upper atmosphere as a measure of sodium abundance. Short-term variations, in which we are most interested, are dominated by the formation of dense sporadic layers in the normal sodium layer. Measurements were made on 3 nights in 1997 and on 2 nights in 1998. Somewhat unexpectedly for a mid-latitude site, sporadic sodium layers were seen on 4 of these 5 nights. One of the sporadic layers was observed for its duration. The 2-km layer reached a maximum intensity of approximately two and a half times that of the background layer and could be distinguished from the background for over ve hours. Centroid-height variations of up to 300m were observed on timescales of 30s. In 1997 we were sensitive to variations of 10% or more in total abundance on timescales of 100ms upwards. We found no evidence for variations of this level on these short timescales. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.eso.org/gen-fac/meetings/eso-osa98/proceedings/osullivan.ps.gz |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
