Extended Abstract (548K)1.17
Diagnostic Analysis of Solar Variation Impact on the Lower Atmosphere
Alfred M. Powell Jr., NOAA/NESDIS, Camp Springs, MD; and M. Chen
A diagnostic analysis approach was introduced to search for the possible impact of solar variation on lower atmospheric system. The diagnostic approach was based on the normal mode instability analysis of a simple two-level baroclinic model. It was assumed that the solar radiation changes have the highest probability of showing low Earth atmosphere consequences; and given about 0.1% variation over 11-year cycle, the solar variation would highly probably modulate the thermal structures of limited atmospheric layers. The resultant modulation could be propagated into other layers via the intrinsic dynamics of the atmosphere. The diagnostic analyses showed the two-level model is very suitable, at the first-order approximation, for detecting the thermal signature of solar variation in the lower atmosphere. It was found that the thermal changes in both vertical (static instability) and horizontal (baroclinic instability) directions could be fairly precisely reflected in the wave energy shift in the troposphere and the lower stratosphere. A further study showed that there exists fixed pattern in the thermal structure difference between solar maximum year and solar minimum year. This paper summarizes the favorable results of the wave energy analysis that compared solar maximum and minimum years for three solar forcing timescales: the 11-year solar sunspot cycle, the annual cycle (due to astronomical geometry changes causing variations in solar output as received at the Earth), and the 28-day solar rotational cycle. The basic data set used in the analysis was the NCEP/NCAR (National Center for Environmental Prediction/National Center for Atmospheric Research) Reanalysis Data. The solar radio flux (10.7 cm) was employed as the proxy for solar short wave output since observed values were available daily for the entire 50 plus year record of the Reanalysis Data.
Session 1, Aspects of Space Weather that have an element of commonality with terrestrial weather applications.
Tuesday, 11 January 2005, 8:30 AM-5:30 PM
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