HR: 0830h
AN: SA51A-0503    [PDF]
TI: Atmospheric Effects of Solar Maximum to Minimum UV Variation: In the Light of New Developments in Atmospheric Chemistry
AU: * Prasad, S S
EM: ssp@CreativeResearch.org
AB: Because they are entwined, considerable attention has been given to the understanding of the atmospheric effects of solar activities so that we may more clearly understand and more reliably predict the effects of human activities on the atmosphere. The talk, therefore, will present a new modeling study of the effects of solar maximum to minimum UV variability on the Earth's mesosphere and stratosphere. Several striking developments have taken place in atmospheric chemistry, since the previous modeling studies of the effects of solar UV variability. For example, a new source of odd nitrogen (NO$_X$ = NO + NO$_2$) directly from the O$_2$ and N$_2$ principals rather than their O($^1$D) and N$_2$O derivatives have been found. This source is driven by solar UV with $\lambda$ $<$ 205 nm. As another example, it has been found that photodissociation of O$_3$ at $\lambda$193 nm (or less) produces O($^1$S) and that this production significantly modifies the middle atmospheric source strength of the OH radicals. These new molecular processes directly amount to new mechanism to link the variable solar UV to the middle atmospheric trace species concentration, O$_3$, heating rates, dynamics etceteras. Without the extra OH production via the O($^1$S), the new sources of NO$_X$ tend to widen the gap between the model predictions and observations of middle atmospheric O$_3$ changes in response to solar maximum to minimum UV variation. The effect of the additional OH production is currently being modeled. The presentation will include discussions of both. Furthermore, what needs to be done in the laboratory, modeling, and observational data analysis will also be discussed.
DE: 0340 Middle atmosphere--composition and chemistry
DE: 0341 Middle atmosphere--constituent transport and chemistry (3334)
DE: 1650 Solar variability
SC: SPA - Aeronomy [SA]
MN: 2003 Fall Meeting