PhysAtm5_05MokhovLO

• Main Authors: I I Mokhov, V A Bezverkhny, A A Karpenko, Sgmlprep
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Antarctic; Antarc*; ice core
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1060.2883; http://ifaran.ru/old/ltk/Persona/Mokhov_pub/Vostok-FAO05-ACP523.pdf

Abstract -The evolution of radiation-active atmospheric components and climatic characteristics derived from Vostok Antarctic ice-core data is analyzed over 420 000 years with a time resolution of 500 years. These data include the temperature variations ∆ T (determined from the deuterium content δ D i in the ice core) and the contents of carbon dioxide q (ëé 2 ) and methane q (CH 4 ) in the atmosphere. Cross correlation analysis shows that, on the whole, the variations in q (ëé 2 ) and q (CH 4 ) are lagged with respect to the δ D i and temperature variations on time scales from millennia to several hundred thousand years. The characteristic time lag ∆ t of the variations in q (ëé 2 ) and q (CH 4 ) relative to the variations in ∆ T over the entire analyzed period is about 1000 and 500 years, respectively. At the same time, in individual 100 000-yr intervals, the value of ∆ t reaches 1500 years for q (ëé 2 ) and 1000 years for q (CH 4 ) . For the earliest 100 000-yr interval, the temperature variations lag behind the variations in the atmospheric greenhouse gas contents. Crossspectral analysis suggests that the variations in the carbon dioxide and methane contents are generally lagged relative to the temperature variations at periods of approximately 20 000 years or longer except for periods of about 20 000 years for methane. The cross wavelet analysis of the data derived from the Vostok Antarctic ice core over the last 420 000 years reveals that the variations in q (ëé 2 ) and q (CH 4 ) lag behind the temperature variations, including the modes characteristic of variations in the Earth's orbital parameters (Milankovitch cycles), while opposite phase lags are observed in individual time intervals and frequency ranges. The coevolution of ∆ T and q (CH 4 ) is less conclusive than that of ∆ T and q (ëé 2 ) . Over the last 100 000-yr period, the fundamental 100 000-yr mode of the deuterium content and temperature does not lead that of the greenhouse gas contents. An opposite effect is observed, with the temperature ...