SA32B-01 INVITED 11:20h
Solar Ultraviolet Irradiance Variability During the TIMED Mission
The TIMED satellite was launched in December 2001 near solar cycle maximum. The solar activity remained at solar maximum conditions during 2002 and has declined to low-moderate activity in 2003 and 2004, but this later period included several large solar storm periods in June 2003, October 2003, and July 2004. As part of the TIMED mission objective to study the energetics of the upper atmosphere, the Solar EUV Experiment (SEE) aboard TIMED measures the solar extreme ultraviolet (EUV) energy input. The SEE instrument is measuring the solar UV irradiance with a 3% duty cycle (3 minutes each orbit) and with a spectral resolution of 0.4 nm between 27 and 194 nm and with 7-10 nm resolution shortward of 27 nm. The solar UV irradiance varies on all time scales, seconds to years, and this variation is very dependent on wavelength. During the TIMED mission, the SEE instrument has observed over 200 flares which last from minutes to hours, over 35 solar rotations which have a period of about 27 days, and maximum to low-moderate conditions during the current 11-year solar cycle. The coronal emissions, such as the Fe XVI 33.5 nm emission and X-rays, vary the most, with variations of a factor of 30 for the large flares, a factor of 2 for solar rotation, and a factor of 5 during the TIMED mission (2 years). The transition region emissions, such as the H I 121.6 nm and He II 30.4 nm emissions, vary less, with variations of a factor of 1.5 for the large flares, a factor of 1.2 for solar rotation and a factor of 1.6 during the TIMED mission. The chromospheric and photospheric emissions vary even less. The variations of the solar UV irradiance shortward of 194 nm will be discussed in the context of the TIMED mission.
http://lasp.colorado.edu/see/
SA32B-02 INVITED 11:40h
GUVI Observations of the Ionosphere and Thermosphere
The TIMED mission is the first of the Solar Terrestrial Probes line and was much delayed, low cost, and highly productive. The Global Ultraviolet Imager, as one of the four components of TIMED, has been an important contributor to the TIMED mission and to our understanding of the interaction of the Earth with geospace. GUVI, which operates in the far ultraviolet (115 to 180 nm), measures the emissions from O, N2 and H and observes the absorption of the N2 Lyman Birge Hopfield bands by O2. From these emissions we are able to infer dayside neutral composition, nightside ionosphere electron density profiles, and auroral energy deposition. In this talk we review the range of contributions that GUVI has made to the TIMED mission objectives, how GUVI supports SEC objectives, how GUVI fits into the new NASA Science directorate and future TIMED and GUVI activities.
http://guvi.jhuapl.edu
SA32B-03 INVITED 12:00h
First Three Years of TIMED: New Results in Sun-Earth Connections
TIMED is flying in an atmospheric region where signatures of forcing from below and forcing from geospace intermingle in complex ways, where questions remain regarding the influence of feedbacks from the upper atmosphere on global geospace system behavior, and where as yet poorly understood processes couple solar variability to lower altitudes in the neutral atmosphere but coupling pathways are masked by large inherent atmospheric variability. TIMED has been unique among geospace missions; it is the first to combine space observations with dedicated systematic ground-based observations. TIMED investigations, over the first 3 years, have been enriched by collaborations with a suite of operating SEC satellite missions, sampling the state of the heliosphere and geospace and providing valuable context for TIMED results. In return, TIMED has provided new information about the geoeffectiveness of disturbances and the effects of the atmosphere on connected regions. Finally, the close coupling between TIMED data and large-scale models of the MLTI region provided a fundamental means of interpreting observations, separating drivers and looking for signals related to solar variability. We report, here, a few of the key new findings from these collaborations, including: (1) the identification of new coupling pathways linking geomagnetic disturbances to the lower atmosphere, (2) the first comprehensive observations of the NO thermostat and its drivers in action, (3) new sources of periodicity in the MLTI region (4) discovery of oxygen aurora at low latitudes, (5) new views of stormtime neutral composition changes & their feedbacks, and (6) MLTI response to solar wind pressure hits. Further details of these topics will be given in other talks within this session.