Nasa: Solar activity - Actividad Solar - Annual Comparisons - Comparaciones anuales - 30-06-10
Posted by Ricardo Marcenaro | Posted in Nasa: Solar activity - Actividad Solar - Annual Comparisons - Comparaciones anuales - 30-06-10 | Posted on 7:40
April 29, 1999
April 29, 2000
April 29, 2001
April 29, 2002
April 29, 2003
April 29, 2004
April 29, 2005
April 29, 2006
April 29, 2007
April 29, 2008
April 29, 2009
April 29, 2010
Over the span of 11 years, the Sun’s activity waxes and wanes as magnetic field lines that are wound and tangled inside the Sun periodically break through to the surface. These breakthroughs produce a pair of sunspots of opposite magnetic polarity, one positive and the other negative, that travel together across the face of the Sun. The heightened magnetic activity associated with sunspots can lead to solar flares, coronal mass ejections, and other far-reaching electromagnetic phenomena that endanger astronauts and damage or disrupt satellites.
This series of images from the Solar and Heliospheric Observatory (SOHO) spacecraft shows ultraviolet light (left) and sunspots (right) each spring from 1999 through 2010. Sunspots darken the visible surface of the Sun, while observations of ultraviolet light reveal how the magnetic activity that produced the sunspots excited the overlying solar atmosphere, producing intensely bright areas. As Solar Cycle 23 reached its peak between 2000-2002, numerous sunspots speckled both hemispheres, and then their numbers dramatically dropped off as the cycle went toward its minimum.
If you map the location of the spots on the Sun’s surface over the course of a solar cycle, the pattern they make is shaped like a butterfly. The reason for the butterfly pattern is that the first sunspots of each new solar cycle occur mostly at the Sun’s mid-latitudes, but as the solar cycle progresses, the area of maximum sunspot production shifts toward the (solar) equator.
Solar Cycle 24 began in early 2008, but there was minimal activity through early 2009. The image from April 29, 2009, does show a pair of small sunspots (far right, most visible in large image), but the location of the spots near the equator means that they belong to solar cycle 23. The sunspots visible in the images from May 2, 2010, however, are from the new cycle. The most recent forecast from the Space Weather Prediction Center is that solar cycle 24 will be of below-average intensity, and that it will peak in May 2013.
The small changes in solar irradiance that occur during the solar cycle exert a small influence on Earth’s climate, with periods of intense magnetic activity (the solar maximum) producing slightly higher temperatures, and solar minimum periods such as that seen in 2008 and early 2009 likely to have the opposite effect.
This series of images from the Solar and Heliospheric Observatory (SOHO) spacecraft shows ultraviolet light (left) and sunspots (right) each spring from 1999 through 2010. Sunspots darken the visible surface of the Sun, while observations of ultraviolet light reveal how the magnetic activity that produced the sunspots excited the overlying solar atmosphere, producing intensely bright areas. As Solar Cycle 23 reached its peak between 2000-2002, numerous sunspots speckled both hemispheres, and then their numbers dramatically dropped off as the cycle went toward its minimum.
If you map the location of the spots on the Sun’s surface over the course of a solar cycle, the pattern they make is shaped like a butterfly. The reason for the butterfly pattern is that the first sunspots of each new solar cycle occur mostly at the Sun’s mid-latitudes, but as the solar cycle progresses, the area of maximum sunspot production shifts toward the (solar) equator.
Solar Cycle 24 began in early 2008, but there was minimal activity through early 2009. The image from April 29, 2009, does show a pair of small sunspots (far right, most visible in large image), but the location of the spots near the equator means that they belong to solar cycle 23. The sunspots visible in the images from May 2, 2010, however, are from the new cycle. The most recent forecast from the Space Weather Prediction Center is that solar cycle 24 will be of below-average intensity, and that it will peak in May 2013.
The small changes in solar irradiance that occur during the solar cycle exert a small influence on Earth’s climate, with periods of intense magnetic activity (the solar maximum) producing slightly higher temperatures, and solar minimum periods such as that seen in 2008 and early 2009 likely to have the opposite effect.
World of Change
- Solar Activity
- Recovery at Mt. St. Helens
- Water Level in Lake Powell
- Antarctic Sea Ice
- Arctic Sea Ice
- Larsen-B Ice Shelf
- Amazon Deforestation
- Mesopotamia Marshes
- Severe Storms
- Urbanization of Dubai
- Mountaintop Mining, West Virginia
- Yellow River Delta
- Drought Cycles in Australia
- Antarctic Ozone Hole
- El Niño, La Niña, and Rainfall
- Burn Recovery in Yellowstone
- Global Biosphere
- Shrinking Aral Sea
Recommend this article
Has the Sun been more active in recent decades, and could it be responsible for some global warming?
June 24, 2010
Scientists are still debating whether or not the Sun’s activity increased during the latter half of the 20th century, but even the highest estimates of activity can’t account for the warming observed since about 1950.
Studies do show that solar variability has significantly influenced past climate changes. For example, a decrease in solar activity is thought to have triggered the Northern Hemisphere’s Little Ice Age between approximately 1650 and 1850, when temperatures dipped low enough that rivers that don’t freeze in today’s human-warmed climate froze over.
Scientists use substitutes (proxies) like records of sun spots, which have been kept since Galileo’s time, or carbon in tree rings to estimate the amount of energy the Sun has sent to Earth. Though not perfect, these estimates give a rough approximation of how much the Sun’s activity has varied over time. Scientists are still debating over how reliable proxies are in determining the Sun’s past activity, but current estimates indicate that the Sun is probably now as active as or more active than it has ever been during the past 8,000 years.
A shorter, but more detailed record comes from NASA satellites, which have been recording the Sun’s activity from space since 1978. The measurements, however, come from six different satellites, each with its own bias. It is difficult to combine the measurements from these satellites into a single 25-year-plus record to get a trend of solar activity. Different scientific teams have attempted to create a continuous record from the satellite data. Each long-term record shows the rise and fall of two 11-year sunspot cycles, but they differ from one another in the average trend over the full period. When stitched together one way, the satellites seemed to record a slight increase in solar activity, but in other analyses, solar activity remained constant.
Regardless, even when scientists assume that solar activity is increasing based on proxy data and the satellite record, they can’t account for all of the warming observed at the end of the twentieth century. Climate models can only reproduce the warming observed since 1950 when a rise in greenhouse gases is built into the system.
References
Foucal, P., Frölich, C., Spruit, H., and Wigley, T. (2006). Variations in solar luminosity and their effect on the Earth’s climate. Nature, 443, 161-166.
Fröhlich, C. (2007). Solar Irradiance Variability Since 1978. In Solar Variability and Planetary Climates (pp. 53-65).
Hoyt, D. V., and Schatten K. H. (1997). Group Sunspot Numbers: A New Solar Activity Reconstruction. Solar Physics, 179 (1), 189-219.
Lean, J. L. (2009). Cycles and trends in solar irradiance and climate. Wiley Interdisciplinary Reviews: Climate Change, 1(1), 111-122.
Lindsey, R. (2003). Under a Variable Sun. NASA’s Earth Observatory. Accessed June 20, 2010.
Muscheler, R., Joos, F., Müller, S.A., Snowball, I. (2005). Climate: how unusual is today’s solar activity? Nature, 436, E3-E4.
Rind, D., Shindell, D., Perlwitz, Ju., Lerner, P., Lonergan, P., Lean, J., and McLinden, C. (2004). The relative importance of solar and anthropogenic forcing of climate change between the Maunder Minimum and the present. Journal of Climate, 17, 906-929.
Solanki, S.K., Ususkin, I.G., Kromer, B., Schössler, M., Beer, J. (2004). Unusual activity of the Sun during recent decades compared to the previous 11,000 years. Nature, 431, 1084-1087.
Studies do show that solar variability has significantly influenced past climate changes. For example, a decrease in solar activity is thought to have triggered the Northern Hemisphere’s Little Ice Age between approximately 1650 and 1850, when temperatures dipped low enough that rivers that don’t freeze in today’s human-warmed climate froze over.
Scientists use substitutes (proxies) like records of sun spots, which have been kept since Galileo’s time, or carbon in tree rings to estimate the amount of energy the Sun has sent to Earth. Though not perfect, these estimates give a rough approximation of how much the Sun’s activity has varied over time. Scientists are still debating over how reliable proxies are in determining the Sun’s past activity, but current estimates indicate that the Sun is probably now as active as or more active than it has ever been during the past 8,000 years.
Records of sunspots dating back to 1610 provide an indication of energy output from the Sun. In general, more sunspots (blue peaks) mean more intense solar activity and more energy received by the Earth. On average, there are more sunspots now than during the Maunder Minimum 350 years ago, but the increase in solar activity alone is not sufficient to explain the temperature increases that have occurred since 1950. (Graph by Robert Simmon, based on data from Hoyt and Schatten, 1997.)
Regardless, even when scientists assume that solar activity is increasing based on proxy data and the satellite record, they can’t account for all of the warming observed at the end of the twentieth century. Climate models can only reproduce the warming observed since 1950 when a rise in greenhouse gases is built into the system.
References
Foucal, P., Frölich, C., Spruit, H., and Wigley, T. (2006). Variations in solar luminosity and their effect on the Earth’s climate. Nature, 443, 161-166.
Fröhlich, C. (2007). Solar Irradiance Variability Since 1978. In Solar Variability and Planetary Climates (pp. 53-65).
Hoyt, D. V., and Schatten K. H. (1997). Group Sunspot Numbers: A New Solar Activity Reconstruction. Solar Physics, 179 (1), 189-219.
Lean, J. L. (2009). Cycles and trends in solar irradiance and climate. Wiley Interdisciplinary Reviews: Climate Change, 1(1), 111-122.
Lindsey, R. (2003). Under a Variable Sun. NASA’s Earth Observatory. Accessed June 20, 2010.
Muscheler, R., Joos, F., Müller, S.A., Snowball, I. (2005). Climate: how unusual is today’s solar activity? Nature, 436, E3-E4.
Rind, D., Shindell, D., Perlwitz, Ju., Lerner, P., Lonergan, P., Lean, J., and McLinden, C. (2004). The relative importance of solar and anthropogenic forcing of climate change between the Maunder Minimum and the present. Journal of Climate, 17, 906-929.
Solanki, S.K., Ususkin, I.G., Kromer, B., Schössler, M., Beer, J. (2004). Unusual activity of the Sun during recent decades compared to the previous 11,000 years. Nature, 431, 1084-1087.
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