Forbush Effects on the Martian Surface and Earth’s Poles

Friday, 18 December 2015
Poster Hall (Moscone South)
Arik Posner1, Jingnan Guo2, Bernd Heber2, R F Wimmer-Schweingruber2, Cary Zeitlin3,4, Yihua Zheng5, Peter J MacNeice5, Dusan Odstrcil5, Lutz Rastaetter5, Christian T Steigies6, John P Andrews3, Jan Kristoffer Appel2, Rudolf Beaujean6, Lars Berger2, Stephan I Böttcher2, David E Brinza7, Mark Bullock3, Soenke Burmeister2, Francis Cucinotta8, Nina Dresing2, Christian Drews2, Bent Ehresmann3, Michael E Epperly9, Don Hassler3, Konstantin Herbst2, Myung-Hee Y Kim10, Jan Kohler2, Patrick Kühl2, Henning Lohf2, Cesar Martin-Garcia2, Reinhold Müller-Mellin2, Kerry Neal3, Scot CR Rafkin3, Gunther Reitz11, Kelly D Smith9, Yvette Tyler9 and Gerald weigle II12, (1)NASA Headquarters, Washington, DC, United States, (2)University of Kiel, Kiel, Germany, (3)Southwest Research Institute Boulder, Boulder, CO, United States, (4)NASA Johnson Space Center, Houston, TX, United States, (5)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (6)Christian-Albrechts-Universität zu Kiel, Kiel, Germany, (7)Jet Propulsion Laboratory, Pasadena, CA, United States, (8)University of Nevada Las Vegas, Las Vegas, NV, United States, (9)Southwest Research Institute, San Antonio, TX, United States, (10)Organization Not Listed, Washington, DC, United States, (11)DLR, Cologne, Germany, (12)Big Head Endian, San Antonio, TX, United States
We analyzed MSL/RAD observation of Forbush effects on the surface of Mars over a full Mars year from landing through the Mars opposition period in 2014. For the extended Mars opposition phase we compared the observed Forbush effects with those identified at Earth’s south pole utilizing observations of the South Pole neutron monitor. Identification of the drivers of Forbush effects, recurrent and transient solar wind structures in the inner heliosphere, is aided by WSA-ENLIL simulations. We show that a remarkable correlations of count rates of (secondary) cosmic rays at Mars’ surface and at the Earth’s south pole is established for a minimum duration of 6 months around the Mars opposition, in particular when time shifted with propagation and/or corotation delays of the drivers of cosmic ray decreases in the solar wind. Moreover, the magnitude of Forbush effects on Mars is larger statistically than the equivalent near Earth’s poles.