HR: 14:20h
AN: SA42A-03 INVITED     [PDF]
TI: Long-Term Trends Derived from Satellite PMC Data
AU: * DeLand, M T
EM: matthew_deland@ssaihq.com
AF: Science Systems and Applications, Inc. (SSAI), 10210 Greenbelt Rd., Suite 400, Lanham, MD 20706 United States
AB: The recent availability of long-term PMC data sets from satellites provides the opportunity to evaluate possible PMC trends over the past few decades. Satellite PMC data have daily coverage to characterize seasonal variations, sufficient detections for each season to give good statistics, quantitative information for physical analysis, and coverage of both hemispheres to evaluate global behavior. Multiple PMC data sets are available from the SBUV and SBUV/2 instruments on the Nimbus-7 and NOAA TIROS polar orbiting satellites. These overlapping data sets now provide more than 24 years of continuous data from November 1978 to the present, typically with concurrent measurements from multiple instruments during each PMC season. The SAGE II instrument has also accumulated more than 17 years of PMC data since 1985. Analysis of these lengthy data sets shows a clear anti-correlation between seasonally averaged PMC occurrence frequency and solar UV activity over the past two solar cycles, in agreement with model predictions. The SBUV data also show a significant long-term increase in PMC brightness in both hemispheres, approximately +4%/decade in the Northern Hemisphere and +7%/decade in the Southern Hemisphere. These results can be compared with information about trends in plausible source mechanisms such as mesospheric water vapor and temperature. Model results suggest that PMC brightness changes are consistent with observed long-term water vapor changes. Additional factors probably contribute to the overall PMC response for individual seasons. Future satellite instruments (SBUV/2, OMPS) will continue the SBUV PMC data record for an additional 10-20 years. Hopefully, further improvements in modeling will allow these data to become useful in characterizing the trends in atmospheric parameters.
DE: 0320 Cloud physics and chemistry
DE: 0340 Middle atmosphere--composition and chemistry
DE: 1610 Atmosphere (0315, 0325)
DE: 1650 Solar variability
SC: SPA - Aeronomy [SA]
MN: 2003 Fall Meeting