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Explore the link between cosmic rays and weather variations. Investigate how meteorological and solar factors impact cosmic ray flux. Georgia State University maintains cosmic ray detectors for long-term measurements. Results suggest a correlation between cosmic rays and atmospheric conditions. Understand the solar modulation effects on cosmic ray flux.
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Correlation study of atmospheric weatherand cosmic ray flux variation Kanishka Dayananda Georgia State University SESAPS11
Outline • Introduction • Cosmic ray detectors maintained by Georgia State University • Meteorological and solar modulation effects on the variation of cosmic ray flux • Summary SESAPS11
Introduction • There is at present a great debate about the causes of the changing climate of the Earth. • The studies by Svensmark, show that there is a strong link between cosmic rays and low cloud coverage [1]. Very recently, Lu reported that there is a correlation between cosmic rays and ozone depletion over Antarctica [2]. • At Georgia State University we are working on a long-term measurement of secondary cosmic ray flux distribution and are focusing on studying the correlations among variations of cosmic ray flux and atmospheric/space weather. SESAPS11
Pot detector - liquid scintillator 2paddle detector QNet 2paddle detector Lanzhou -China HLCO-BaF2 scintillator QNet 2paddle detector eMorpho 2paddle detector Our cosmic ray detectors http://phynp6.phy-astr.gsu.edu/~kanishka/OnLineMonitor/index.htm SESAPS11
Factors that influence the variation of cosmic ray flux • Meteorological effects • atmospheric pressure, temperature, cloud cover etc… • Solar modulation effects • interplanetary magnetic field, solar wind speed etc… • The barometric effect is the major influencing factor on the secondary cosmic ray particles[3]. • Therefore it is necessary to eliminate the barometric effect first to unfold the solar modulation of the cosmic ray flux. SESAPS11
Barometric effects on secondary cosmic ray flux Pot – counts 11/3010 – 01/27/10 Correlation coefficient ( r ) = -0.64 SESAPS11
Variation of solar parameters in year 2010 http://omniweb.gsfc.nasa.gov/form/dx1.html Correction of counts for pressure Reference [4] b = barometric coefficient I = counts P = pressure I = corrected counts Io = measured counts P0 = mean pressure SESAPS11
Uncorrected counts 11/30/10 – 01/27/10 Correlation coefficient ( r ) = -0.64 Corrected counts 11/30/10 – 01/27/10 Correlation coefficient ( r ) = -0.02 Correction of counts for pressure cont… SESAPS11
Aug 05 2011 Sep 26 2011 Forbush decrease events SESAPS11
Summary • Results confirm that there is an anti-correlation between secondary cosmic ray flux and atm pressure. • Results also confirm that the anti-correlation between secondary cosmic ray flux and atm temperature is due to expansion of the height of the atm pressure levels. • Since our pot detector is sensitive for both charged particles and neutrons, we are currently working on studying the correlation between variation of neutrons and cloud coverage. • These results can be used to unfold the solar modulation effects on the cosmic ray flux. • Our long-term goal is to build a world wide cosmic ray detector network and predict the variation of atmospheric and space weather using the cosmic ray flux variation. SESAPS11
References • N.D. March and H. Svensmark, Low Cloud Properties Influenced by Cosmic Rays, Phys. Rev. Lett. 85, 23 (2000). • Q.-B. Lu, Correlation between Cosmic Rays and Ozone Depletion, Phys. Rev.Lett. 102, 118501 (2009). • A. Chilingarian, T. Karapetyan, Calculation of the barometric coefficients at the start of the 24th solar activity cycle for particle detectors of Aragats Space Environmental Center, Advances in Space Research 47 (2011) 1140–1146. • L.I. Dorman, Cosmic Rays, Variations and Space Exploration. Amsterdam, North-Holland, 1974. • S. Tilav, P. Desiati, T. Kumwabara, D. Rocco, F. Rothmaier, M. Simmons, and H. Wissing, “Atmospheric Variations as Observed by IceCude”, Proceedings of the 31st ICRC, 2009. • M. Bertaina, L. Briatore, A. Longhetto, G. Navarra, The atmospheric moun flux in correlation with temperature variations in the low stratosphere(50-200mb), Proceedings of the 30th International Cosmic Ray Conferrencs. SESAPS11
Thank you SESAPS11
Backup slides SESAPS11
% Variation of atm heights of different atm pressure levels SESAPS11
% Variation of atm temperatures of different pressure levels SESAPS11
Correlation of temperature and counts in different atm pressure regions SESAPS11
Correlation of temperature and counts in different atm pressure regions cont… SESAPS11