Persistent draining of the stratospheric 10Be reservoir after the Samalas volcanic eruption (1257 A.D.)

More than 2,000 analyses of beryllium-10 (Be-10) and sulfate concentrations were performed at a nominal subannual resolution on an ice core covering the last millennium as well as on records from three sites in Antarctica (Dome C, South Pole, and Vostok) to better understand the increase in Be-10 deposition during stratospheric volcanic eruptions. A significant increase in Be-10 concentration is observed in 14 of the 26 volcanic events studied. The slope and intercept of the linear regression between Be-10 and sulfate concentrations provide different and complementary information. Slope is an indicator of the efficiency of the draining of Be-10 atoms by volcanic aerosols depending on the amount of SO2 released and the altitude it reaches in the stratosphere. Intercept gives an image of the Be-10 production in the stratospheric reservoir, ultimately depending on solar modulation. The Samalas event (1257 CE) stands out from the others as the biggest eruption of the last millennium with the lowest positive slope of all the events. We hypothetize that the persistence of volcanic aerosols in the stratosphere after the Samalas eruption has drained the stratospheric Be-10 reservoir for a decade, meaning that solar reconstructions based on Be-10 should be considered with caution during this period. The slope of the linear regression between Be-10 and sulfate concentrations can also be used to correct the Be-10 snow/ice signal of the volcanic disturbance.