Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.naic.edu/~astro/talks/abstracts/raizada_16sep05.htm
Дата изменения: Fri Sep 2 23:30:07 2005
Дата индексирования: Sat Dec 22 20:10:59 2007
Кодировка:

Поисковые слова: m 80
Dr. Shikha Raizada, Arecibo Observatory
The Effect of Ice Particles on the Mesospheric Potassium Layer at High Latitudes

Recently, there has been increasing evidence for the removal of mesospheric metal atoms in the presence of ice particles. This talk will focus on the quantitative evaluation of the influence of ice particles on the K layer. Various observational efforts have shown that ice particles manifest in the form of Polar Mesospheric Summer Echoes (PMSE) and Noctilucent Clouds (NLCs). We use simultaneous measurements of radar and lidar for studying the effect of ice particles on the metal layer. The methodology involves determination of the volumetric surface area of the ice particles by using a combination of CARMA (Community Aerosol and Radiation model for Atmospheres) and a charging model that gives an empirical proxy for PMSE based on the microphysical properties of the charged aerosol particles. We develop an empirical relationship between the proxy for the peak summer conditions at the latitude of Spitsbergen and the PMSE/NLC data from the SOUSY radar/lidar respectively. This is used for determining volumetric surface area of ice particles [Aice] corresponding to PMSE and NLC. The loss rate of K atoms during the summer season (June and July) due to uptake on ice is determined by using the early May K density as the background profile in the absence of ice particles. A fairly good agreement in the shape of the profiles showing the loss rate of K atoms and the difference between the K density during the peak summer season and the background profile is observed at altitudes below 88 km. The variability of [Aice] on background perturbations will also be discussed.