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efc &-1 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Space Weather Impact on Climate?
Alpbach Summer School on Space Weather: Physics,
Impacts and Predictions
Eigil Friis-Christensen
efc &-2 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Solar Activity and Monsoon Precipitation in Oman
Stalagmites in caves in Oman show that changes in monsoon precipitation during 3000 years is strongly correlated with changes in solar activity.
Past northwardshifts of the intertropicalconvergence zone
U. Neff et al., Nature 411, 290-293, 2001
efc &-3 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
What Are the Causes of Climate Variations?
Internal oscillations in atmosphere-ocean systemVariation in energy received from the Sun: • Solar irradiance variations - various spectral bands.• Cloudiness.• Volcanic dust and aerosols.• Other aerosols, natural and human induced.
Variation in energy radiated away from Earth: • Atmospheric properties, in particular greenhouse gasses like
– CO2, Methane, CFCs, Ozone.– Cloudiness and water vapor (important part of feed-back mechanisms).
• Surface properties like– Ice cover, land and ocean.– Vegetation.– Land erosion.
efc &-4 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
How Do We Define Solar Variability in This Context?
Total solar irradiance• Relatively small during a solar cycle (0.1%)• Long-term variations (0.25%?)
UV-radiation changes• Small power compared to the visible part of the spectrum.• Relatively large variation during a solar cycle (> 1% at
stratospheric heights, even more at higher altitudes)
Changes in the solar wind (heliosphere)• Extremely small power.• Very large relative variations during a solar cycles - and on
longer terms.• Earth’s surface modulation of cosmic ray flux ~ 20%• Middle atmosphere formation of odd Nitrogen
efc &-5 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Irradiance measurements are made by several instruments on SOHO:
VIRGO - Total solar irradianceSEM (Celias): EUV disk integrated flux from 1-770Å and in He II 304 ÅCDS: EUV 307-380 Å and 515-632 Å Spectral irradiance and 69 full disk images taken each month
efc &-6 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Sunspots – an “indicator” of Solar Energy Output
efc &-7 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Magnetic fields on the Solar surface
efc &-8 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Sunspot Number R
1750 1800 1850 1900 1950 2000Year
50
100
150
200
250
300
R
Sunspot number R, monthly values
Period between 9 and 13 y
Longer periods exist, 60-100 y
efc &-9 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Earth’s Magnetic Field and the Heliosphere
Earth’s magnetic field and production rate of Carbon-14 caused by cosmic rays
Solar wind variations affect the production rate of C-14
efc &-10 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Production rate C-14 and Be-10
efc &-11 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Maunder Minimum
Reconstructions of Solar irradiation indicate very small variations at a very low level
Beryllium-10 isotope indicate a significant modulation caused by changes in the cosmic ray flux – likely caused by changes in solar magnetic fields.
Reconstructed temperatures follow Be-10
efc &-12 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Solar Variability Seen in the Atmosphere
efc &-13 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Solar and Geomagnetic Activity
Yearly average Geomagnetic activity index (aa)Sunspot number (R)
Solar activity ~ 11-y period. The rhythm, not the form, is reproduced in geomagnetic activity. Long-term variation is differentConclusion: R and aa are different manifestations of solar energy output
efc &-14 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Global temperature and sunspots
efc &-15 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Global Temperature and Cycle Length: An Update
During the latest about 20 years, temperature has increased more than expected - based on the length of the solar cycle
The effect of enhanced greenhouse effect is finally seen
The climatic effect of solar activity is not fully described by the length of the solar cycle
Surface temperature are not representative (Satellite MSU measurements)
IPCC 1990: Increase by 0.3 to 0.6°C over last century broadly consistent with climate model predictions.FCL 1991: Major part of temperature changes during last century well correlated with solar activity.IPCC 2001: Temperature increase during the last 50 years mainly caused by human activity.
efc &-16 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Sun-climate relationship – in a longer perspective
Correlation between SCL og GR-LA temperature for 1590-1970 gives thefollowing Correlation Coefficient:
Temp. ref. 1881-1975:
-0.79
Temp. ref. 1950-81:
-0.83
Groveman og Landsberg (GR-LA) 1979 reconstruction
efc &-17 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Spring in Middle and Lower Yangtze River Valley
Phenological data -personal diaries and other documents• Time of blossoming of
specific plants• Last day of snow events
Spring time - “days before and after an average date” • (Hamed and Gong,
1993).• 10 years average
Solar cycle length, L
1600 1700 1800 1900 2000Year
-15
-10
-5
0
5
10
15
20
Day
s
8
9
10
11
12
13
14
Years
dageL
9 10 11 12 13Cycle Length (years)
-15
-10
-5
0
5
10
15
20
Day
s
efc &-18 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Temperature variations during 1000 years
11-year mean values,Jones et al. (1998)
and
Reconstruction of thetemperature at Dye-3 based on directtemperature measurements in bore hole
efc &-19 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Past Temperature
Jones et al.No assumptions
Traditional averaging
Mann et al. Assumptions:
Relationships between temperature variations at different sites are unchanged in time
11-Year Mean Values of Reconstructed Temperatures
efc &-20 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Past Temperatures - Greenland Ice Sheet
Reconstruction of past temperatures based on bore hole data from two sites:
Dye-3 and Gripon the Greenland Ice Sheet.
Dahl-Jensen et al.Science 1998
efc &-21 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Reconstruction of temperature
efc &-22 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Temperature observations –at surface and measured with balloon
efc &-23 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Cosmic Rays and Clouds
efc &-24 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Atmospheric Ionisation Density Profile
Viggiano and Arnold, 1995
efc &-25 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Ion pair production over Thule
SolarMinimum
SolarMaximum
“The meteorological variable subject to the largest solar-cycle modulation in the dense layers of the atmosphere is the atmospheric ionisation produced by cosmic rays.”
E.P. Ney, Nature, 1959.
efc &-26 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Cloud Types and Cosmic Rays
High (< 440 hPa)
Middle (440-680 hPa)
Low (>680 hPa)
Cosmic Ray Intensity -Huancayo
efc &-27 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Long term drifts in cloud data
ISCCP Low IR (blue)SSMI (green)
Average based on areas of high correlation
Average land and oceansblue: ISCCP Low IRgreen: adjusted according to linear trend from above
efc &-28 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Radiation Properties of Clouds
High Clouds MiddleClouds
LowClouds
Thin Thick Thin Thick AllTotal
GlobalFraction % 10.1 8.6 10.7 7.3 26.6 63.3Net CloudForcingWm-2
2.4 -7.0 1.1 -7.5 -16.7 -27.7
efc &-29 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Possible Causes of Cloud Variability
Volcano's
El-Nino
Clouds and Cosmic Rays
efc &-30 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Low cloud cover – cosmic rays – and ENSO
efc &-31 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Low cloud top temperature – cosmic rays – and ENSO
efc &-32 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Aerosols and Cloud MicrophysicsSatellite Observations of Ship Tracks
Visible: 0.9 µm NIR-IR: 3.9 - 10.7 µm
efc &-33 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Formation of Ultra Fine Aerosols ( ~ 3 nm)
Homogeneous Nucleation
Ion Mediated Nucleation
Nuc
leat
ion
rate
(P
artic
les p
r se
c pr
cc)
Hom
ogen
eous
Ion Mediated Nucleation
H2SO4 molecules pr cc
1
+
+
_
_107 108
0.1
10
100
0.01
Range based on observation over the Pacific Ocean (Clarke et al. 1998)
efc &-34 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Physical mechanisms - formation of clouds
Low clouds are affected• Implies an effect on water vapour clouds - not ice clouds• Aerosols - via production of cloud condensation nuclei (CCN) - are
important for the cloud formation • How are CCNs formed?
– Insufficient understanding• Do electric charges play a role?
– Yes, according to new research results, computer simulations• What is missing?
– Experimental proof
efc &-35 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Physical processes and their implementation in climate models
Changes in total irradiance• Easy to include in models, but effect is small.
Changes in UV-radiation• Modulation of ozone concentrations modify vertical transport• Decadal variations in observed parameters can be modeled.• Significant regional effects on surface temperature - small global effects
Changes in energetic particle flux• Cosmic ray flux
– Direct change in cloud nucleation processes.– Via changes in atmospheric electricity and electro freezing.
• Energetic electron precipitation– formation of middle atmosphere Noy - transport to stratosphere– contribute to the destruction of Ozone
efc &-36 /July 2002Alpbach Summer School 2002 on Space Weather: Physics, Impacts and Predictions
Conclusion
Changes in total irradiance• Some effect is probable
Changes in UV-radiation• Decadal variations in observed parameters can be modeled• Systematic effects observed at high altitudes - less at the surface
Changes in energetic particle flux• Cosmic ray flux
– Effect on cloud nucleation seems a promising mechanism - potentially large effect
• Energetic electron precipitation– effect on ozone may be similarly effective as UV effect
All components may work together– and do not exclude an effect of the increased amount of greenhouse gases
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