Ultra-High Resolution Nitrate in Polar Ice as Indicator of Past Solar Activity

Ionization in the polar atmosphere causes the formation of nitrate compounds, which are frozen out and incorporated into the layers of the polar ice sheets. From a 122-m ice core collected in 1992 on the central Greenland ice sheet, it has been possible to examine a solar signal in a ultra-high resolution record of nitrate concentrations. The sequence extends over a period of 415 years at a temporal resolution of no less than one analysis per month (total number of samples 7776 resulting from ∼1.5 cm sampling along the entire core). This type of measurement reveals major nitrate anomalies which are thought to result from the injection of individual solar proton events into the winter polar stratosphere. For this reason, the large nitrate anomalies provide the possibility to delineate a signal of solar activity well beyond the known geophysical records.

[1]  S. Wofsy,et al.  Denitrification in the Antarctic stratosphere , 1989, Nature.

[2]  H. Schlager,et al.  Evidence for stratospheric nitric acid condensation from balloon and rocket measurements in the Arctic , 1989, Nature.

[3]  Mark Z. Jacobson,et al.  A model for studying the composition and chemical effects of stratospheric aerosols , 1994 .

[4]  D. Siskind.  On the radiative coupling between mesospheric and thermospheric nitric oxide , 1994 .

[5]  K. Mccracken.  A correlation between the emission of white light and cosmic radiation by a solar flare , 1959 .

[6]  Charles A. Barth.  Nitric oxide in the lower thermosphere , 1992 .

[7]  Naihui Song.  Freezing temperatures of H2SO4/HNO3/H2O mixtures: Implications for polar stratospheric clouds , 1994 .

[8]  D. Fahey,et al.  Observations of denitrification and dehydration in the winter polar stratospheres , 1990, Nature.

[9]  M. Shea,et al.  A summary of major solar proton events , 1990 .

[10]  J. B. Blake,et al.  Precipitating relativistic electrons: Their long‐term effect on stratospheric odd nitrogen levels , 1991 .

[11]  C. Appenzeller,et al.  Seasonal variation of mass transport across the tropopause , 1996 .

[12]  K. Snetsinger,et al.  Antarctic stratospheric ice crystals , 1989 .

[13]  E. Zeller,et al.  Evidence of individual solar proton events in Antarctic snow , 1990 .

[14]  E. Zeller,et al.  Anomalous nitrate concentrations in polar ice cores—Do they result from solar particle injections into the polar atmosphere? , 1995 .