14:15 〜 14:30
[ACC26-03] Methane concentration in Dome Fuji ice core measured with a continuous flow analysis system
キーワード：ドームふじアイスコア 、メタン、連続融解法
We have been measuring CH4 concentration in the Dome Fuji ice core by using a Continuous Flow Analyses (CFA) system. The CFA system can continuously measure multiple components contained in ice cores. It provides high-resolution data more efficiently than traditional discrete measurements, and thus has become a common way to obtain detailed paleoclimatic data from deep ice cores.
Millennial-scale variations of CH4 in the last glacial period have been extensively studied by analyzing ice cores from high-accumulation sites (e.g., Rhodes et al., 2017). To reconstruct the CH4 variabilities in older periods beyond the last glacial period, the high-resolution analysis of low-accumulation ice cores such as Dome Fuji ice core is essential. However, the currently available resolutions of the CH4 data from the low-accumulation ice cores are insufficient for the millennial-scale reconstructions in the older glacial periods, and CH4 data using CFA is still absent.
Here, we present the Dome Fuji CH4 record in selected periods from the last glacial to Holocene using the CFA system. We discuss age distribution and associated smoothing of atmospheric signals for the low-accumulation core, as well as the reconstructed millennial- and centennial-scale CH4 variabilities by comparing our results with the high-accumulation WAIS-Divide ice core data (Rhodes et al., 2017) and low-accumulation (EDC and Vostok) ice-core CFA data (Fourteau et al.,2017; 2020).
Our data includes abrupt changes such as the transitions during the last deglaciation, and the 8.2ka event in the Holocene. We find strong smoothing effect of atmospheric signals due to the broad age distribution of the Dome Fuji ice core. Moreover, we observe fine-scale age reversals along depth probably due to the so-called layered trapping (i.e., firn layers with air bubbles formed at the depths significantly different from the average close-off depth), which have originally been reported from the Vostok ice core (Fourteau et al., 2017; 2020). We will also present the CH4 record around Dansgaard-Oeschger event 17 (about 60 kyr before present).
References
Rhodes et al., 2017: Atmospheric methane variability: Centennial-scale signals in the Last Glacial Period, Global Biogeochem. Cycles, 31, 575–590.
Fourteau et al., 2017: Analytical constraints on layered gas trapping and smoothing of atmospheric variability in ice under low-accumulation conditions. Clim. Past, 13, 1815–1830.
Fourteau et al., 2020: Estimation of gas record alteration in very low-accumulation ice cores. Clim. Past, 16, 503–522.
Millennial-scale variations of CH4 in the last glacial period have been extensively studied by analyzing ice cores from high-accumulation sites (e.g., Rhodes et al., 2017). To reconstruct the CH4 variabilities in older periods beyond the last glacial period, the high-resolution analysis of low-accumulation ice cores such as Dome Fuji ice core is essential. However, the currently available resolutions of the CH4 data from the low-accumulation ice cores are insufficient for the millennial-scale reconstructions in the older glacial periods, and CH4 data using CFA is still absent.
Here, we present the Dome Fuji CH4 record in selected periods from the last glacial to Holocene using the CFA system. We discuss age distribution and associated smoothing of atmospheric signals for the low-accumulation core, as well as the reconstructed millennial- and centennial-scale CH4 variabilities by comparing our results with the high-accumulation WAIS-Divide ice core data (Rhodes et al., 2017) and low-accumulation (EDC and Vostok) ice-core CFA data (Fourteau et al.,2017; 2020).
Our data includes abrupt changes such as the transitions during the last deglaciation, and the 8.2ka event in the Holocene. We find strong smoothing effect of atmospheric signals due to the broad age distribution of the Dome Fuji ice core. Moreover, we observe fine-scale age reversals along depth probably due to the so-called layered trapping (i.e., firn layers with air bubbles formed at the depths significantly different from the average close-off depth), which have originally been reported from the Vostok ice core (Fourteau et al., 2017; 2020). We will also present the CH4 record around Dansgaard-Oeschger event 17 (about 60 kyr before present).
References
Rhodes et al., 2017: Atmospheric methane variability: Centennial-scale signals in the Last Glacial Period, Global Biogeochem. Cycles, 31, 575–590.
Fourteau et al., 2017: Analytical constraints on layered gas trapping and smoothing of atmospheric variability in ice under low-accumulation conditions. Clim. Past, 13, 1815–1830.
Fourteau et al., 2020: Estimation of gas record alteration in very low-accumulation ice cores. Clim. Past, 16, 503–522.