NASA's Solar Radiation and Climate Experiment (SORCE) successfully launched Saturday, January 25, 2003 aboard a Pegasus XL rocket. Click here for the press release.
GETTING TO THE SORCE OF CLIMATE CHANGE:
The SOlar Radiation & Climate Experiment to Launch
The Earth presents scientists with a curious puzzle: the phenomenal interconnectedness of each aspect of our world leads to misconceptions and incomplete notions regarding climate change. On Jan. 25, 2003 NASA will be launching the SOlar Radiation & Climate Experiment, or SORCE spacecraft to help answer questions like:
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- How much of climate change is due to mans activity versus naturally occurring?
- What role does the Sun play in our climate and how do changes within the Sun affect us?
- How much does the Sun vary on a daily and long-term basis?
Click here for audio text of this animation
An Earth Science Enterprise mission, SORCE will be focusing on the Sun. With four instruments, it will orbit Earth 15 times a day and measure the suns radiative output (also called Total Solar Irradiance, or TSI) and analyze the Suns energy in visible colors, as well as ultraviolet and infrared wavelengths that can be used to determine solar heating of Earths oceans, ice, land and absorbing layers of the atmosphere. Courtesy: NASA
REIGNING ON EARTHS CLIMATE
What happens when solar irradiance reaches Earth? Only about 70% of the energy that reaches Earth is absorbed, while the other 30% is reflected back into space by atmosphere and aerosols, ocean/land and clouds, as seen in this animation. A closer view reveals a delicate balance between absorption and reflection as well as a release of energy by rocks, air and sea warming and emitting increasing amounts of thermal radiation (heat) in the form of long-wave infrared light. This radiation allows Earth to lose heat at the same rate it gains from the Sun.
Earths output energy (thermal energy emitted into space); heat energy radiated from the Earth is shown in varying shades of yellow, red, blue and white. The brightest yellow areas, such as the Sahara Desert, are emitting the most energy out to space, while the dark blue polar regions and bright white clouds are the coldest areas on Earth, and are emitting the least energy. Courtesy: NASA
Only 1% of the TSI is absorbed by the upper atmosphere mostly UV radiation absorbed by stratospheric ozone. About 20 24% heads into the lower atmosphere (troposphere) and is absorbed by waver vapor, trace gases, clouds and darker aerosols. The remaining 46 50% of visible light penetrates the atmosphere and is absorbed by the land and the oceans. Courtesy: NASA
STAR OF THE SHOW
One of SORCEs main goals is to determine how much solar irradiance changes within the Suns 11-year solar cycle when sunspots and the associated olar activity give rise to varying amounts of ultraviolet and visible radiation that would, in turn, impact our environment. Courtesy: NASA/ESA
THE SOLAR CYCLE
The Suns output fluctuates daily, but science concentrates on the 11-year sunspot cycle. Over the cycle the number of sunspots and associated faculae (bright regions on the Sun's surface which usually form before sunspots appear) observed range from a max 200 spots per month to as few as a dozen per month during minimum. Courtesy: NASA
THE SORCE OF RADIATION
Variations in solar output are due to a balance between decreases caused by sunspots (relatively cold bottlenecks of magnetic fields on the hot solar surface) and associated bright areas called faculae (relatively hotter groupings of magnetic fields). However, the effects of the faculae tend to beat out those of the sunspots so that the hot faculae raise the total solar output than the cooler sunspots subtract. Courtesy: NASA / Mauna Loa Solar Observatory
LITTLE ICE AGE
|"Winter Scene with Frozen Canal" (detail)
by Aert van der Neer
Courtesy: Fine Arts Museums of San Francisco, Gift of Mr. & Mrs. Prentis Cobb Hale 1960.35
How much can solar variability affect us? Unusually low solar activity (marked by fewer sunspots observed) between 1645-1715, called the 'Maunder Minimum' likely triggered the 'Little Ice Age' in regions like Europe and North America. Aert van der Neers painting, Sports on a Frozen River, shows a period where global temperatures differed enough to freeze rivers and cause other far-reaching consequences.
Prior to 1979 scientists considered the Suns output a constant. The launch of Nimbus-7 allowed for the study of sunlight without interference from the atmosphere. With data sets from follow-on missions like the Upper Atmosphere Research Satellite (UARS), scientists know that the Sun has fluctuated about 0.1% since the 1970s. Courtesy: NASA
Laboratory for Atmospheric & Space Physics
The SORCE spacecraft and instruments will be operated from the Laboratory for Atmospheric Physics (LASP) at the University of Colorado for NASA. Located in Boulder, Co., LASP will operate SORCE for its lifetime of approximately five years with a unique staff consisting of university professionals, academic researchers, and University of Colorado students.
SORCE carries four instruments that will be tracking the Suns total output over all its wavelengths including ultraviolet rays in our stratosphere, like UV-B, which leads to ozone destruction. Another will provide insight into the Suns corona (atmosphere), solar events that impact satellite communications, and effects on the outermost layers of the Earths atmosphere.
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