[S-EM15] Geomagnetism and paleomagnetism

[SEM15-08] Response of high-altitude clouds to the decadal cycle of galactic cosmic rays in tropical regions

★Invited Papers

*Hiroko Miyahara¹, Kanya Kusano², Ryuho Kataoka³, Emile Touber⁴ (1.Musashino Art Univ., 2.Nagoya Univ., 3.NIPR, 4.OIST)

Keywords:Cosmic ray variation, Climate variation, Cloud activity, Sun-climate connection

Direct and proxy-based observations of solar activity and climate in the past have suggested that the Earth’s climate is responding to solar activity at various time scales; however, the detailed mechanisms behind the connection are not clarified. Galactic cosmic rays are one of the possible mediators of the Sun-climate relation, and it has been suggested that they may impact cloud activity by forming aerosols or by affecting the collisional processes with electrical charges. Originally, it was suggested that low-altitude clouds over oceans are responding to GCR variations. However, cloud chamber experiments have indicated that GCR-induced aerosol formation is more efficient at lower temperatures (i.e., upper troposphere). In this presentation, we show that tropical clouds that are produced associated with deep convections are responding to the decadal cycle of GCRs. Furthermore, following the invigoration of deep convective cloud activity, an intensification of atmospheric circulation and an increase in sea surface temperature gradient over the Pacific were observed. We propose that deep convective cloud activity is mediating the GCR-climate connection.