کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1766103 1020134 2010 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
The hydroxyl radical as an indicator of SEP fluxes in the high-latitude terrestrial atmosphere
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات علوم فضا و نجوم
پیش نمایش صفحه اول مقاله
The hydroxyl radical as an indicator of SEP fluxes in the high-latitude terrestrial atmosphere
چکیده انگلیسی

The low background values at nighttime of the mesospheric hydroxyl (OH) radical make it easier to single out the atmospheric response to the external solar forcing in Polar Regions. Because of the short lifetime of HOx, it is possible to follow the trails of Solar Energetic Particle (SEP) events in the terrestrial atmosphere, as shown by Storini and Damiani (2008). The sensitivity of this indicator makes discernible not only extreme particle events with a flux peak of several thousand pfu [1 pfu = 1 particle/(cm2 s sr)] at energies >10 MeV, but also those with lower flux up to about 300 pfu. Using data from the Microwave Limb Sounder (MLS) on board the EOS AURA satellite, we examined the correlation of OH abundance vs. solar proton flux for almost all the identified SEP events spanning from November 2004 to December 2006 (later on no more SEP events occurred during Solar Cycle no. 23). The channels at energies greater than 5 MeV and 10 MeV showed the best correlation values (r ∼ 0.90–0.95) at altitudes around 65–75 km whereas, as expected, the most energetic channels were most highly correlated at lower altitudes. Therefore, it is reasonably possible to estimate the solar proton flux from values of mesospheric OH (and viceversa) and it could be useful in studying periods with gaps in the records of solar particles.In addition, the SEP events of September 2005, characterized by an evident hemispheric asymmetry of the SEP-induced OH formation, have been examined separately. The impact of the SEPs on the hydroxyl radical was appreciably stronger in the Northern Hemisphere than in the Southern at altitudes above roughly 60 km and also the nighttime OH layer was involved. Preliminary analyses performed with other MLS data (i.e., O3, H2O, T) suggest that atmospheric in situ conditions could play a relevant role in explaining the hemispheric asymmetry of OH.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Advances in Space Research - Volume 46, Issue 9, 1 November 2010, Pages 1225–1235
نویسندگان
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