Interhemispheric transit time distributions and path-dependent lifetimes constrained by measurements of SF 6 , CFCs, and CFC replacements
We constrain tropospheric transport from Northern Hemisphere midlatitudes to the Southern Hemisphere (SH) surface using measurements of SF6, CFCs, and CFC replacement gases and a novel maximum-entropy-based inversion approach. We provide the first estimate of the width Δ of the tropospheric interhem...
| Published in: | Geophysical Research Letters |
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| Main Authors: | , |
| Format: | Article in Journal/Newspaper |
| Language: | unknown |
| Published: |
American Geophysical Union (AGU)
2015
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| Subjects: | |
| Online Access: | http://hdl.handle.net/1959.4/unsworks_37741 https://unsworks.unsw.edu.au/bitstreams/3b996eaa-b4c9-47fe-91b0-93bcee5400f6/download https://doi.org/10.1002/2015GL064172 |
| Summary: | We constrain tropospheric transport from Northern Hemisphere midlatitudes to the Southern Hemisphere (SH) surface using measurements of SF6, CFCs, and CFC replacement gases and a novel maximum-entropy-based inversion approach. We provide the first estimate of the width Δ of the tropospheric interhemispheric transit time distribution (TTD). We find that Δ has a value of ∼1.3 years that varies little with SH latitude, compared to the mean transit time Γ that increases from ∼1.1 years in the SH tropics to ∼1.4 years at the South Pole. The TTD shape parameter Δ/Γ is thus larger in the SH tropics than at middle and high SH latitudes. Our analysis introduces a simple path-dependent lifetime that parameterizes chemical losses. The path-dependent lifetimes are estimated for CFC replacements, and systematic differences between path-dependent and global lifetimes are interpreted. The path-dependent lifetimes have the potential to provide new observational constraints on tropospheric and stratospheric loss processes. |
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