DOI: 10.5194/tc-10-2099-2016
Scopus记录号: 2-s2.0-84987845576
论文题名: Dispersion in deep polar firn driven by synoptic-scale surface pressure variability
作者: Buizert C ; , Severinghaus J ; P
刊名: Cryosphere
ISSN: 19940416
出版年: 2016
卷: 10, 期: 5 起始页码: 2099
结束页码: 2111
语种: 英语
英文关键词: atmospheric pressure
; boundary layer
; concentration (composition)
; dispersion
; firn
; mixing
; surface pressure
; synoptic meteorology
; trace gas
; vertical mixing
; Antarctica
; East Antarctica
; Law Dome
英文摘要: Commonly, three mechanisms of firn air transport are distinguished: molecular diffusion, advection, and near-surface convective mixing. Here we identify and describe a fourth mechanism, namely dispersion driven by synoptic-scale surface pressure variability (or barometric pumping). We use published gas chromatography experiments on firn samples to derive the along-flow dispersivity of firn, and combine this dispersivity with a dynamical air pressure propagation model forced by surface air pressure time series to estimate the magnitude of dispersive mixing in the firn. We show that dispersion dominates mixing within the firn lock-in zone. Trace gas concentrations measured in firn air samples from various polar sites confirm that dispersive mixing occurs. Including dispersive mixing in a firn air transport model suggests that our theoretical estimates have the correct order of magnitude, yet may overestimate the true dispersion. We further show that strong barometric pumping, such as at the Law Dome site, may reduce the gravitational enrichment of δ 15N-N2 and other tracers below gravitational equilibrium, questioning the traditional definition of the lock-in depth as the depth where δ 15N enrichment ceases. Last, we propose that 86Kr excess may act as a proxy for past synoptic activity (or paleo-storminess) at the site. © Author(s) 2016. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/75077
Appears in Collections: 影响、适应和脆弱性 气候变化与战略
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作者单位: College of Earth, Ocean and Atmospheric Sciences, Oregon State University, Corvallis, OR, United States; Scripps Institution of Oceanography, University of California San Diego, San Diego, CA, United States
Recommended Citation:
Buizert C,, Severinghaus J,P. Dispersion in deep polar firn driven by synoptic-scale surface pressure variability[J]. Cryosphere,2016-01-01,10(5)