Ground-based observations of noctilucent clouds With the shortest possible wavelength (308 nm)

Updated 2003-03-10

Noctilucent clouds (NLC) remain a fascinating phenomenon of the upper atmosphere to study. The questions about the typical particle density and particle size distribution within a NLC are very prominent ones, to which a number of answers have been given, though some of the answers contradict each other. The parameters of particle size distributions can be derived from groundbased lidar measurements of the spectral dependence of the volume backscatter coefficient of an NLC. Such studies have been performed during a number of NLC events by e.g. the ALOMAR Rayleigh/Mie/Raman (RMR) lidar (von Cossart et al., GRL, 26, 1513, 1999). A drawback of these experiments is the wavelength limitation of the RMR lidar, the shortest wavelength of which is 355 nm. At this wavelength, the sensitivity of the lidar to particles with sizes smaller than, say, 25 nm is minimal. Because a considerable part of the entire particle population may have sizes below that threshold, a lingering question remains whether or not this drawback matters for typical NLC distributions. Using the ALOMAR ozone lidar, a measurement of the NLC volume backscatter coefficient at 308 nm becomes possible. Due to the l-4 -dependence of the backscatter coefficients, the latter are almost a factor of 2 larger at this wavelength than at 355 nm. For this reason and in order to gain a fourth wavelength to the spectral distribution, we aim at using the ozone lidar for the outlined project.

Time frame

Status
Completed
Project time span
2002 - 2002
Data collection
not specified
Data processing
not specified
Data reporting
not specified

Contact information

Contact person
J. Lunde
Address
ALOMAR Observatory And√łya Rocket Range P.O Box 54 8483 Andenes
Phone
+47 76 14 11 00
Fax
+47 76 14 44 01
Email
on.egnartekcor@ramola

Parameters and Media

Not specified

Geography

Regions studied
Norway
Norway

Data availability

Samples/specimens archived in specimen banks?
No

Methods & Procedures

Not specified

Additional Information

Is this a bi- AND multi-lateral project (i.e. a project involving cooperation between different countries)?
No
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