THE ROLE OF COSMIC RAYS IN ATMOSPHERIC PROCESSES A. Zanini INFN Sez.Torino Via P. Giuria 1, Torino, Italy. The search of a causal link between star activity and Earth climate comes far away in human history….
Tycho Brahe in 1573,De Nova Stella, included an introduction to an almanac for the year in which he states that stars could have some influence on the turbulence of weather and other weather patterns.
He argued that the “astro-metereology” should be able to predict the weather on the basis of the heavenly configurations.
That there is a causal connection between the observed variations in the forces of the Sun, the terrestrial magnetic field and the meteorological elements has been the conclusion of every research into this subject…
“Solar radiation, clouds, ocean currents and the atmospheric circulation act together in a complex and chaotic way to produce our climate..”
John H. Seinfeld, Californian Institute of Technology, 2001
Cosmic ray effects, modulated by solar activity could be relevant to climate change?
Hypothesis: a causal link between GCR-Sun activity-cloud cover produces effects on short and long term climate changes
An High Mountain Observatory Network as a new approach to climate studies
GCR (Galactic cosmic Rays): galactic origin, generated outside the solar system, in supernovae explosions and accelerated by the shockwaves
ACR (Anomalous Cosmic Rays): galactic origin, generated in the interplanetary space.
SCR (Solar Cosmic Rays): events following the 11 year cycles.
87% protons, 12% a particles, 1% HZE (High Z Elements).
Secondary radiation: is produced by interaction of primary cosmic rays with atmospheric nuclei (O e N);
the atmospheric cascade is characterized by:
1. N component (nucleonic component), which includes all the particles that are subjected
to strong interaction;
2. Soft component (electromagnetic component), which consists of electrons, positrons
and electromagnetic quanta;
3. Hardcomponent (muon component).
Calculated hadron fluence rates as a function of altitude for different input conditions ( ) high latitude, solar minimum activity; () high laditude solar maximum activity, ( ) low latitude solar minimun activity.
A.Ferrari, M.Pelliccioni, T.Rancati, “Calculation of the Radiation Environment Caused by Galactic Cosmic Rays for Determing Air Crew Exposure”, Rad. Prot. Dos. 93, 2, 101-114 Nucl. Tech. Pub. (2001).
Cosmic ray intensity on Earth depends on
The sun is a G2V star
Sun mass 1.99 x 1030 kg
Mass density 1.4 g/cm3
g: 2.74 m s2
T: 5780 K
Revolution period around the galactic center :200 Myrs
Position at 2/3 from the galctic center
Solar surface is periodically characterized by outstanding events (solar flares, Coronal Mass Ejections, Filament Disruptions).
The solar activity is described by sunspot numbers, characterized by an 11-year cycle.
The sunspot number unit is the Wolf number:
Group of spots
The solar magnetic field changes its polarity each sunspot maximum.
The total duration of the magnetic cycle is 22 years.
Increase of the cromospheric activity, with emission of very energetic particles
The solar wind is a shielding for GCR.
Higher solar activity corresponds to lower cosmic ray flux on Earth.
The Sun is the driving factor for the climate on the Earth
Evidences both from recent observation and from climate proxies suggest that solar variability is an important contribution to climate change
Variation of solar irradiance are too small to account the climate variability
The Earth has a high sensitivity to irradiance changes
other mechanisms exist to amplify the solar variations
Maunder Minimum: 1600-1720
(Louis XIV, Le roi Soleil, 1643-1715)
River Tames in London regulary frozen
11 years-cycle mean sea surface temperature (1860-1985)
Global mean surface temperature of the Earth
North Hemisphere temperature relative increase from 1610 to 1995
What causes global warming: this is a very strong debate…
Solar irradiance [W/m2]
Vulcanic dust index
DT [K]=l DF [W/m2]
lEvaluated from past climate changes and climate models
l [KW-1m2] = 0.3 - 0.7
The Sun-Earth link
Physical paths connecting variation of the Sun to the Earth climate:
Both historical and recent observations
suggest that cosmic rays may play
a significant role in the climate processes
Proxies from C14 in Ice cover
Coldest region of atm
High ionization thermal conduction
Historical data: 140 years of instrumental records
1 historical documents
2 Corals : oxigen and isotopes trace metals to reconstruct water temperature
3 fossil pollen
4-Tree rings: tree growth is influenced by climatic conditions
5-Ice cores : high mountains and in polar ice caps O18/O16 ratio
6-Vulcanic eruption :D/H ratio
7-Ocean and lake sediments
Old period of warmth are not similar to 20th century warming
No global in extent
Climatic forcing conditions are different in the past
The cosmic ray produce cosmogenic nuclides
C14 forms CO2 and exchange with the main reservoirs of the carbon cycle
Be10 and Cl36 are attached to aereosol and after 1-2 years are removed from atmosphere by precipitations
Interaction of cosmic rays with atmosphere
The yearly average values of atmospheric electric current J and cosmic ray flux at h=8 km in polar region
The decrease of the daily precipitation level during a Forbush decrease (D%=-17.4%)
The increase of the daily precipitation level during a SPE (D%=+13.3%)
Solar protons :
in correspondence with the solar activity mainly occur during ascending and descending phases.
mainly occur during descending phases (Forbush decrease)
Explained the enhanced grow rate of sub-nanometer clusters related to ion concentrations
1 free electrons and simple positive ions N+ O+
2 electrons +O2 negative ions
Plasma of ± ions - fast ions molecule reactions- stable ions H3O+ NH4+ NO3- HSO4- recombination -aereosol -massive charged clusters
Fig 1 pag 102
Sprites are massive but weak luminous flashes that appear directly above an active thunderstorm system and are coincident with cloud-to-ground or intra-cloud lightning strokes. The brightest region lies in the altitude range 65-75 km, above which there is often a faint red glow or wispy structure that extends to about 90 km. Below the bright red region, blue tendril-like filamentary structures often extend downward to as low as 40 km. Sprites rarely appear singly, usually occurring in clusters of two, three or more. Other events are more loosely packed and may extend across horizontal distances of 50 km or more and occupy atmospheric volumes in excess of 10,000 cubic km.
Blue jets are a optical ejections from the top of the electrically active core regions of thunderstorms. They typically propagate upward in narrow cones at vertical speeds of roughly 100 km/s (Mach 300), fanning out and disappearing at heights of about 40-50 km. Blue jets are not aligned with the local magnetic field.
Elves are diffuse regions of luminosity which occur high above energetic CG discharges of positive or negative polarity. Elves most likely result when an energetic electromagnetic pulse (EMP) propagates into the ionosphere in the form of intense radio waves emitted from powerful lightning flashes. The radiating pulse excites the electrons in the nitrogen gas which then emits light by fluorescence. Though they can be accompanied by sprites, the causative mechanism is of an entirely different nature. Incidentally, elves got their unusual name as an acronym for Emission of Light and VLF perturbations due to EMP Sources.
The Aurora Borealis is a good example of atmospheric conditions being in the correct alignment to see radiation in the visible from the high-energy electrons following diaellel lines and causing atmospheric molecules to move to an excited energy state after which they emit in the visible, which we see.
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