Kosmisk stråling, skyer og klima: Observationer og eksperimenter.

Præsentationer af emnet: "Kosmisk stråling, skyer og klima: Observationer og eksperimenter."— Præsentationens transcript:

1 Kosmisk stråling, skyer og klima: Observationer og eksperimenter.
Nigel Marsh Centre for Sun-Climate Research Danish National Space Center Copenhagen.

2 Galaktisk Kosmisk Stråling er accelereret af Supernovaer ind i vores galakse - Mælkevejen.

3 Heliosfære, Kosmisk Stråling og Solaktivitet

4 Solvinden trækker Solens magnetiske felt igennem det inter-planetariske rum.
The Sun is strongly affected by magnetic forces. The red arrows show open magnetic field lines emerging from the poles. The gray arrows represent solar wind particles which carry field lines with it. The bright active regions have closed magnetic field lines (orange).

5 Vores aktive Sol: Solvind observeret fra Soho satellit

6 Solaktivitetens forskel mellem sol-min og sol-max.

7 Solpletter viser Solens aktivitetscyklus
Solen ændrer sig på mange tidskalaer. 11 year cycle (Schwabe cycle) 22 year cycle (magnetic cycle) 80-90 year cycle (Gleissberg) year cycle (Seuss) SOHO, Satellit, 2000 Galileo, Telescope, 1610

8 Variationen i Galaktisk Kosmisk Stråling
~ % Lange tidsskalaer ~10% Korte tidsskalaer Solaktivitet

9 Simulering af en kaskade når en kosmisk partikel (1TeV) rammer atmosfæren ved 20km højde.

10 Kosmisk Stråling ved jordens overflade ind i et “Cloud Chamber”.

11 Kosmisk Stråling flux og Solaktivitet.
Neutron Counter Ion Chamber Sunspot Number

12 Ion-par skabt af Kosmisk Stråling over Thule.
“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.” Solar Minimum Solar Maximum E.P. Ney, Nature, 1959.

13 Havoverflade Temperatur vs Solaktivitet
Sea Surface Temperatures (SST’s) obtained from ships. Reid,Nature, 1987.

14 Ocean Temperatures vs Solar Variability
SST’s over different ocean basins consistent with both 11 and 22 year variability in solar activity. Observed variations in SST larger than expected from changes in Total Solar Irradiance (amplification?). White et al, JGR, 1997.

15 Troposfærisk Temperatur vs Solaktivitet Amplification factor 3-4
DT = l DF = 0.6 KW-1m2 DF = DFs(1-a)/4 DFs = 0.2 Wm-2 DT = 0.1 K but from figure: DT = 0.4 K Amplification factor 3-4 Marsh and Svensmark, SSR, 2003.

16 Cosmogenic 14C • from O, N and Ar (spallation) • 1/2 = 5370 years
• < qG > = 2 atoms cm-2s-1 GALACTIC COSMIC RAYS ATMOSPHERE TREES Bristlecone pine OCEANS BIOMASS

17 Kosmisk Stråling/Solaktivitet varierer med klima over de sidste 1000 år. (Kulstof-14 fra træers år-ringe) Færre GCR Mere GCR London’s River Thames froze in winter during Little Ice Age.

18 Stærk sammenhæng mellem solaktivitet og monsun i Oman mellem 9 og 6 kyr BP.
The formation of stalagmites in northern Oman has recorded past changes in rainfall intensity, the result of either periodic southward shifts of the ITCZ or periods of weaker monsoon. Monsoon rainfall follows GCR. U. Neff et al., Nature 411, (2001)

19 Ice-rafted debris abundance (%) 
8 6 4 2 -2 -4 -6 1000 years 0.2 0.1 -0.1 -0.2 Warmer Ice-rafted debris abundance (%)  14C production rate (atoms cm-2s-1)  k yr BP  (Bond et al., Science, 2001)

20 Kosmisk Stråling og Spiralarmene
Mælkevej L = 50 kpc Spiral arms: Part of density wave Solar System Hz = 2 kpc Shaviv, 2002

21 Kosmisk Stråling og Spiralarm-krydsninger
Shaviv, PRL, 2002. 0.5 Beregnet Kosmisk Flux 1 1.5 600 400 200 Million År

22 Kosmisk Stråling og Spiralarmkrydsninger
0C 8 4 -4 200 1.5 1 0.5 400 600 Shaviv and Veizer, GSA, 2003. Havoverflade-Temperatur Beregnet Kosmisk Flux Million År Shaviv & Veizer, 2003

23 Kosmisk stråling skal FORSTÆRKES før de kan påvirke klimaet.
En grundlæggende mekanisme er nødvendigt til forklare sammenhængen mellem Kosmisk Stråling og Klima Energi ved toppen af Jordens atmosfære: Total Solar Irradiance 1360 W/m2 TSI over Solar Cycle W/m2 Solar Wind ~10-4 W/m2 Galactic Cosmic Rays ~10-5 W/m2 Kosmisk stråling skal FORSTÆRKES før de kan påvirke klimaet.

24 Forstærkning af Kosmisk Stråling: Sammenhæng mellem lave skyer og Galaktisk Kosmisk Stråling?
Low Cloud Cover vs GCR. Marsh and Svensmark, PRL, 2000.

25 Long Wave (IR): Low cloud top temperature
and cosmic rays Correlation map Scatter Plots Liquid water Low altitude Long Wave properties. Cloud Top Temperature - Correlation map. Scatter plots – mean Temperature, Pressure vs correlation coeff. Only low liquid clouds. Correlation only found in low liquid water clouds. Marsh and Svensmark, PRL 2000

26 Hvordan påvirker skyer strålingsbalancer i atmosfæren?
Fange udstråling af jordens varme. Reflektere solens indstråling. Mere CR=Mere lave skyer Færre CR=Færre lave skyer Radiative Properties of Clouds

27 Formation of low stratiform clouds
Condensation Increasing re Constant N Supersaturated air Activated CCN LCL Moist Air Weak updrafts < 1 m/s Parameters influencing cloud droplet distribution: Updraft velocity - changes in solar irradiance force atmospheric large scale circulation? Number of CCN – cosmic ray ionisation influences on aerosol/CCN distribution? Ascending airparcel cools, supersaturates activating CCN and droplets begin to grow. Air ascends through cloud droplets continue to grow, lack of coallescence and supersaturation no new droplets Droplet distribution determined by updraft velocity and background aerosol (CCN). CCN – cosmic rays? Updraft velocity - Solar variability? Today we concentrate on the role of ionisation.

28 Aerosoler og skymikrofysik Satellit-observationer af spor fra skiber
Visible reflection IR absorption emission Visible: 0.9 mm NIR-IR: mm Reflekterer lys fra skyer Opvarmning af skyer

29 Aerosoldannelse og vækst
CN (Condensation Nuclei) Cloud Droplets H2SO4 + Water Organic Vapor UCN (Ultra Fine Condensation Nuclei) CCN (Cloud Condensation Nuclei) Size 0.001 mm 0.01 mm 0.1 mm 10 mm Ioniserings rolle?

30 (Particles pr sec pr cc)
Formation of ultra fine Aerosol ( ~ 3 nm) 100 10 Binary nucleation (Particles pr sec pr cc) Nucleation rate 1 0.1 Ion Mediated Nucleation Binary _ 0.01 + Binary IMN Clarke observations. 107 108 _ H2SO4 molecules pr cc + Observations over the Pacific (Clarke et al. 1998) Ion Mediated Nucleation

31 Ion Induce Nucleation in Ultrafine Aerosol Formation.
Eichkorn et al, GRL, 2002. Lee et al, Science, 2003. Particle diameter (nm) 0.6 0.7 0.8 0.9 1 1.2 1.4 1.6 Large ion growth Normalised count rate CCN sizes Mass (amu) Are aerosol concentrations sensitive to a perturbation in ionisation? Particle diameter (nm)

32 Modelled Ionisation-Nucleation Sensitivity in the lower troposphere.
Lower troposphere sensitive to changes in ionisation rate. Experiment required to test sensitivity to ionisation. Altitude Yu, JGR, 2001.

33 Eksperimentel undersøgelse er igang 
Er der en kosmisk forbindelse til vores klima?