Nitrate in Polar Ice: A New Tracer of Solar Variability

Knowledge of the long-term variability of solar activity is of both astrophysical and geoscientific interest. Reconstructions of solar activity over multiple millennia are traditionally based on cosmogenic isotopes 14C or 10Be measured in natural terrestrial archives, but the two isotopes exhibit si...

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Bibliographic Details
Published in:Solar Physics
Main Authors: Traversi R., Usoskin I. G., Solanki S. K., Becagli S., Frezzotti M., Severi M., Udisti R., STENNI, BARBARA
Other Authors: Traversi, R., Usoskin, I. G., Solanki, S. K., Becagli, S., Frezzotti, M., Severi, M., Stenni, Barbara, Udisti, R.
Format: Article in Journal/Newspaper
Language:English
Published: 2012
Subjects:
Cosmic ray
galactic
Holocene
ice core
nitrate
solar cycle
Antarctic
Talos Dome
Antarc*
Antarctica
Online Access:http://hdl.handle.net/11368/2626918
https://doi.org/10.1007/s11207-012-0060-3
Description
Summary:Knowledge of the long-term variability of solar activity is of both astrophysical and geoscientific interest. Reconstructions of solar activity over multiple millennia are traditionally based on cosmogenic isotopes 14C or 10Be measured in natural terrestrial archives, but the two isotopes exhibit significant differences on millennial time scales, so that our knowledge of solar activity at this time scale remains somewhat uncertain. Here we present a new potential proxy of solar activity on the centennial-millennial time scale, based on a chemical tracer, viz. nitrate content in an ice core drilled at Talos Dome (Antarctica). We argue that this location is optimal for preserving the solar signal in the nitrate content during the Holocene. By using the firn core from the same location we show that the 11-year and Gleissberg cycles are present with the variability of 10 – 25 % in nitrate content in the pre-industrial epoch. This is consistent with the results of independent efforts of modeling HNO3 and NOy in Antarctic near surface air. However, meteorological noise on the interannual scale makes it impossible to resolve individual solar cycles. Based on differentprocesses of formation and transport compared to cosmogenic isotopes, it provides new, independent insight into long-term solar activity and helps resolve the uncertainties related to cosmogenic isotopes as diagnostics of solar activity.

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