Community:Email 27jul11

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This is a generic mailing to the CEDAR community sent 27 July 2011. Meetings and jobs are listed at http://cedarweb.hao.ucar.edu under 'Community' as 'Calendar of Meetings' and 'CEDAR related opportunities'. CEDAR email messages are under 'Community' as 'CEDAR email Newsletters'. All are in 'Quick Links' on the main page.


(1) Skip Reber (

(2) 5-9 December 2011, Fall AGU meeting, San Francisco, CA - abstracts due on-line 4 August. See also http://www.agu.org/meetings/

  • (a)
  • (b) SH18: Solar Spectral Irradiance in the Spacecraft Era.

From jeff.morrill@nrl.navy.mil.






(2) 5-9 December 2011, Fall AGU meeting, San Francisco, CA - abstracts due on-line 4 August. See also http://www.agu.org/meetings/

  • (b) SH18: Solar Spectral Irradiance in the Spacecraft Era.

From jeff.morrill@nrl.navy.mil

This AGU session, SH18: Solar Spectra Irradiance (SSI) in the Spacecraft Era, is intended to review the most recent measurements of SSI and to review and improve our understanding of the changes in SSI as observed from various spacecraft. Presentations are solicited that involve direct SSI measurements, various types of models, and other measured effects of SSI impacts. The focus will be on those wavelengths, UV, vis, and IR, which have the potential to impact terrestrial climate. Please visit the following website for this session.

http://sites.agu.org/fallmeeting/scientific-program/session-search/769

Solar spectral irradiance (SSI) at ultraviolet (UV), visible, and infrared (IR) wavelengths is understood to impact the evolution to Earth's atmosphere and climate. Apart from its importance in understanding the mechanisms that produce the solar spectrum, which originates in the various layers of the solar atmosphere, the SSI affects terrestrial climate because of the absorption of energy at different altitudes as well as inducing changes in constituent densities.

For more than 40 years, SSI spectra have been measured from space using sensitive instruments aboard satellites, rockets, the Space Shuttle, and the Space Station. Although the earlier emphasis has been on UV wavelengths, more recent SI measurements have been performed at visible and infared wavelengths. Variations in SSI are a consequence of changes in solar surface features, such as faculae, plage, sunspots, and network, and may also be the result of global solar changes. The two main periodicities have been identified in SSI time series that of the 11-year solar activity cycle and the apparent 27-day rotation as viewed from the Earth. The relative amplitudes of these periodicities varies with wavelength. For example, the solar cycle variation at the shortest UV wavelengths is in excess of 50% while much less at visible wavelengths.

Currently, discrepancies exist between some data sets and model estimates of SSI. One main difficulty in obtaining accurate SSI measurements is the accurate tracking of responsivity changes in measuring instruments. Several techniques have been used to track these changes. Some instruments are calibrated in flight using onboard light sources while others reply on multiple channels. SSI models are also used to estimate irradiance and can be based on solar activity proxies or on detailed analyses of solar images that reveal surface features.

The focus of this session will be on observations and models of SSI at UV, vis, and IR wavelengths, which are considered to be climate sensitive. Comparisons among data and models through time are encouraged but the primary focus will be on SSI during the space craft era.