Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 10 2 2010 10.5194/acpd-10-3605-2010 http://www.atmos-chem-phys-discuss.net/10/3605/2010/ http://www.atmos-chem-phys-discuss.net/10/3605/2010/acpd-10-3605-2010.html http://www.atmos-chem-phys-discuss.net/10/3605/2010/acpd-10-3605-2010.pdf 3605 3625 2010-02-09 On microphysical processes of noctilucent clouds (NLC): observations and modeling of mean and width of the particle size-distribution G. Baumgarten baumgarten@iap-kborn.de J. Fiedler M. Rapp Leibniz-Institut für Atmosphärenphysik e.V., 18225 Kühlungsborn, Germany Noctilucent clouds (NLC) in the polar summer mesopause region have been observed in Norway (69&deg; N, 16&deg; E) between 1998 and 2009 by 3-color lidar technique. Assuming a mono-modal Gaussian size distribution we deduce mean and width of the particle sizes throughout the clouds. We observe a quasi linear relationship between distribution width and mean of the particle size at the top of the clouds and a deviation from this behavior for particle sizes larger than 40 nm, most often in the lower part of the layer. The vertically integrated particle properties show that 65% of the data follows the linear relationship with a slope of 0.42&plusmn;0.02. For the vertically resolved particle properties (&Delta;<i>z</i>=0.15 km) the slope is smaller and only 0.39&plusmn;0.03. We compare our observations to microphysical modeling of noctilucent clouds and find that the distribution width depends on turbulence, the time that turbulence can act (cloud age), and the sampling volume/time (atmospheric variability). The model results nicely reproduce the measurements and show that the observed slope can be explained by eddy diffusion profiles as observed from rocket measurements. Bailey,~S M., Thomas,~G E., Rusch,~D W., Merkel,~A W., Jeppesen,~C D., Carstens,~J N., Randall,~C E., McClintock,~W E., and Russell,~J M.: Phase functions of polar mesospheric cloud ice as observed by the CIPS instrument on the AIM satellite, J Atmos. Sol.-Terr. Phy., 71, 373–380, \doi10.1016/j.jastp.2008.09.039, 2009. Baumgarten,~G. and Fiedler,~J.: Vertical structure of particle properties and water content in noctilucent clouds, Geophys. Res. Lett., 35, L10811, \doi10.1029/2007GL033084, 2008. Baumgarten,~G., Lübken,~F.-J., and Fricke,~K H.: First observation of one noctilucent cloud by a~twin lidar in two different directions, Ann. Geophys., 20, 1863–1868, 2002. Baumgarten,~G., von Cossart,~G., and Fiedler,~J.: The size of noctilucent cloud particles above ALOMAR (69N,16E): optical modeling and method description, Adv. Space Res., 40(6), 772–784, \doi10.1016/j.asr.2007.01.018, 2007. Baumgarten,~G., Fiedler,~J., Lübken,~F.-J., and von Cossart,~G.: Particle properties and water content of noctilucent clouds and their interannual variation, J Geophys. Res., 113, D06 203, \doi10.1029/2007JD008884, 2008. Berger,~U. and von Zahn,~U.: Icy particles in the summer mesopause region: three-dimensional modeling of their environment and two-dimensional modeling of their transport, J Geophys. Res., 107, 1366, \doi10.1029/2001JA000316, 2002. Fiedler,~J., von Cossart,~G., and Baumgarten,~G.: Noctilucent clouds above ALOMAR between~1997 and~2001: occurrence and properties, J Geophys. Res., 108, 8453, \doi10.1029/2002JD002419, 2003. Fiedler,~J., Baumgarten,~G., and Lübken,~F.-J.: NLC observations during one solar cycle above ALOMAR, J Atmos. Sol.-Terr. Phy., 71, 424–433, \doi10.1016/j.jastp.2008.11.010, 2009. Fritts,~D C., Isler,~J R., Thomas,~G E., and Andreassen, Ø.: Wave breaking signatures in noctilucent clouds, Geophys. Res. Lett., 20, 2039–2042, 1993. Gadsden,~M. and Schröder,~W.: Noctilucent Clouds, Springer-Verlag, New York, 1989. Hervig,~M., Thompson,~R E., McHugh,~M., Gordley,~L L., Russel~III,~J M., and Summers,~M E.: First confirmation that water ice is the primary component of polar mesospheric clouds, Geophys. Res. Lett., 28, 971–974, \doi10.1029/2000GL012104, 2001. Hervig,~M E., Gordley,~L L., Stevens,~M H., Russell,~J M., Bailey,~S M., and Baumgarten,~G.: Interpretation of SOFIE PMC measurements: cloud identification and derivation of mass density, particle shape, and particle size, J Atmos. Sol.-Terr. Phy., 71, 316–330, \doi10.1016/j.jastp.2008.07.009, 2009. Jensen,~E J. and Thomas,~G E.: Numerical simulations of the effects of gravity waves on noctilucent clouds, J Geophys. Res., 99, 3421–3430, \doi10.1029/93JD01736, 1994. Li,~Q., Rapp,~M., Röttger,~J., Latteck,~R., Zecha,~M., Strelnikova,~I., Baumgarten,~G., Hervig,~M., Hall,~C., and Tsutsumi,~M.: Microphysical parameters of mesospheric ice clouds derived from calibrated observations of polar mesosphere summer echoes at Bragg wavelengths of 2.8 m and 30 cm, J Geophys. Res., \doi10.1029/2009JD012271, in press, 2009. Lübken,~F.: Seasonal variation of turbulent energy dissipation rates at high latitudes as determined by in situ measurements of neutral density fluctuations, J Geophys. Res., 102, 13441–13456, \doi10.1029/97JD00853, 1997. Lübken,~F.-J.: Thermal structure of the arctic summer mesosphere, J Geophys. Res., 104, 9135–9149, \doi10.1029/1999JD900076, 1999. Rapp,~M. and Thomas,~G E.: Modeling the microphysics of mesospheric ice particles: assessment of current capabilities and basic sensitivities, J Atmos. Sol.-Terr. Phy., 68, 715–744, \doi10.1016/j.jastp.2005.10.015, 2006. Rapp,~M., Lübken,~F.-J., Müllemann,~A., Thomas,~G., and Jensen,~E.: Small scale temperature variations in the vicinity of NLC: experimental and model results, J Geophys. Res., 107, 4392, \doi10.1029/2001JD001241, 2002. Rapp,~M., Thomas,~G E., and Baumgarten,~G.: Spectral properties of mesospheric ice clouds: evidence non-spherical particles, J Geophys. Res., 112, 3211, \doi10.1029/2006JD007322, 2007. Robert,~C E., von Savigny,~C., Burrows,~J P., and Baumgarten,~G.: Climatology of noctilucent cloud radii and occurrence frequency using SCIAMACHY, J Atmos. Sol.-Terr. Phy., 71, 408–423, \doi10.1016/j.jastp.2008.10.015, 2009. Seele,~C. and Hartogh,~P.: Water vapor of the polar middle atmosphere: annual variation and summer mesosphere conditions as observed by ground-based microwave spectroscopy, Geophys. Res. Lett., 26, 1517–1520, \doi10.1029/1999GL900315, 1999. Thomas,~G E.: Solar Mesosphere Explorer measurements of polar mesospheric clouds (noctilucent clouds), J Atmos. Terr. Phys., 46, 819–824, 1984. Toon,~O B., Turco,~R P., Hamill,~P., Kiang,~C S., and Whitten,~R C.: A~one-dimensional model describing aerosol formation and evolution in the stratosphere: II Sensitivity studies and comparison with observations., J Atmos. Sci., 36, 718–736, doi:10.1175/1520-0469(1979)036&lt;0718:AODMDA&gt;2.0.CO;2, 1979. Turco,~R P., Hamill,~P., Toon,~O B., Whitten,~R C., and Kiang,~C S.: A~one-dimensional model describing aerosol formation and evolution in the stratosphere: I Physical processes and mathematical analogs, J Atmos. Sci., 36, 699–717, doi:10.1175/1520-0469(1979)036&lt;0699:AODMDA&gt;2.0.CO;2, 1979. Turco,~R P., Toon,~O B., Whitten,~R C., Keesee,~R G., and Hollenbach,~D.: Noctilucent clouds: simulation studies of their genesis, properties and global influences, Planet. Space Sci., 30, 1147–1181, 1982. von Savigny,~C., Petelina,~S V., Karlsson,~B., Llewellyn,~E J., Degenstein,~D A., Lloyd,~N D., and Burrows,~J P.: Vertical variation of NLC particle sizes retrieved from Odin/OSIRIS limb scattering observations, Geophys. Res. Lett., 32, L07806, \doi10.1029/2004GL021982, 2005. Witt,~G.: Height, structure and displacements of noctilucent clouds, Tellus, 14, 1–18, 1962.