Project Scientist

Research Interests:

  • AGAGE (Advanced Global Atmospheric Gases Experiment) http://agage.eas.gatech.edu/
  • Greenhouse gases
  • Halogenated trace gases
  • Ozone depleting compounds
  • Trace gas measurements (especially GC-FID/ECD/MSD)
  • Global warming
  • Top-down (measurement based) verification of bottom-up emission estimates
  • Atmospheric chemistry
  • Wildfire emissions
  • Long-range transport of pollutants

Degrees:

  • Diploma in Chemistry, University of Wuppertal
  • Doctor of Natural Sciences, Max Planck Institute for Chemistry, Mainz and Johannes Gutenberg University Mainz

Recent Publications

Deeds, DA, Kulongoski JT, Mühle J, Weiss RF.  2015.  Tectonic activity as a significant source of crustal tetrafluoromethane emissions to the atmosphere: Observations in groundwaters along the San Andreas Fault. Earth and Planetary Science Letters. 412:163-172. AbstractWebsite

Abstract Tetrafluoromethane (CF4) concentrations were measured in 14 groundwater samples from the Cuyama Valley, Mil Potrero and Cuddy Valley aquifers along the Big Bend section of the San Andreas Fault System (SAFS) in California to assess whether tectonic activity in this region is a significant source of crustal CF4 to the atmosphere. Dissolved CF4 concentrations in all groundwater samples but one were elevated with respect to estimated recharge concentrations including entrainment of excess air during recharge ( C r e ; ∼30 fmol kg−1 H2O), indicating subsurface addition of CF4 to these groundwaters. Groundwaters in the Cuyama Valley contain small CF4 excesses (0.1–9 times C r e ), which may be attributed to an in situ release from weathering and a minor addition of deep crustal CF4 introduced to the shallow groundwater through nearby faults. CF4 excesses in groundwaters within 200 m of the SAFS are larger (10–980 times C r e ) and indicate the presence of a deep crustal flux of CF4 that is likely associated with the physical alteration of silicate minerals in the shear zone of the SAFS. Extrapolating CF4 flux rates observed in this study to the full extent of the SAFS (1300 km × 20–100 km) suggests that the SAFS potentially emits ( 0.3 – 1 ) × 10 − 1 kg CF4 yr−1 to the Earth's surface. For comparison, the chemical weathering of ∼ 7.5 × 10 4 km 2 of granitic rock in California is estimated to release ( 0.019 – 3.2 ) × 10 − 1 kg CF4 yr−1. Tectonic activity is likely an important, and potentially the dominant, driver of natural emissions of CF4 to the atmosphere. Variations in preindustrial atmospheric CF4 as observed in paleo-archives such as ice cores may therefore represent changes in both continental weathering and tectonic activity, including changes driven by variations in continental ice cover during glacial–interglacial transitions.

Arnold, T, Ivy DJ, Harth CM, Vollmer MK, Mühle J, Salameh PK, Steele PL, Krummel PB, Wang RHJ, Young D, Lunder CR, Hermansen O, Rhee TS, Kim J, Reimann S, O'Doherty S, Fraser PJ, Simmonds PG, Prinn RG, Weiss RF.  2014.  HFC-43-10mee atmospheric abundances and global emission estimates. Geophysical Research Letters. :2013GL059143. AbstractWebsite

We report in situ atmospheric measurements of HFC-43-10mee (C5H2F10, 1,1,1,2,2,3,4,5,5,5-decafluoropentane) from seven observatories at various latitudes, together with measurements of archived air samples and recent Antarctic flask air samples. The global mean tropospheric abundance was 0.21 ± 0.05 ppt (parts-per-trillion, dry air mole fraction) in 2012, rising from 0.04 ± 0.03 ppt in 2000. We combine the measurements with a model and inverse method to estimate rising global emissions –– from 0.43 ± 0.34 Gg yr-1 in 2000 to 1.13 ± 0.31 Gg yr-1 in 2012 (~1.9 Tg CO2-eq yr-1 based on a 100-yr global warming potential of 1,660). HFC-43-10mee –– a cleaning solvent used in the electronics industry –– is currently a minor contributor to global radiative forcing relative to total HFCs; however, our calculated emissions highlight a significant difference from the available reported figures and projected estimates.

Fraser, PJ, Dunse BL, Manning AJ, Walsh S, Wang RHJ, Krummel PB, Steele LP, Porter LW, Allison C, O'Doherty S, Simmonds PG, Mühle J, Weiss RF, Prinn RG.  2014.  Australian carbon tetrachloride emissions in a global context. Environmental Chemistry. 11:77-88. AbstractWebsite

Global (1978-2012) and Australian (1996-2011) carbon tetrachloride emissions are estimated from atmospheric observations of CCl4 using data from the Advanced Global Atmospheric Gases Experiment (AGAGE) global network, in particular from Cape Grim, Tasmania. Global and Australian emissions are in decline in response to Montreal Protocol restrictions on CCl4 production and consumption for dispersive uses in the developed and developing world. However, atmospheric data-derived emissions are significantly larger than 'bottom-up' estimates from direct and indirect CCl4 production, CCl4 transportation and use. Australian CCl4 emissions are not a result of these sources, and the identification of the origin of Australian emissions may provide a clue to the origin of some of these 'missing' global sources. Journal compilation © CSIRO 2014.

Rigby, M, Prinn RG, O'Doherty S, Miller BR, Ivy D, Mühle J, Harth CM, Salameh PK, Arnold T, Weiss RF, Krummel PB, Steele LP, Fraser PJ, Young D, Simmonds PG.  2014.  Recent and future trends in synthetic greenhouse gas radiative forcing. Geophysical Research Letters. :2013GL059099. AbstractWebsite

Atmospheric measurements show that emissions of hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) are now the primary drivers of the positive growth in synthetic greenhouse gas (SGHG) radiative forcing. We infer recent SGHG emissions and examine the impact of future emissions scenarios, with a particular focus on proposals to reduce HFC use under the Montreal Protocol. If these proposals are implemented, overall SGHG radiative forcing could peak at around 355 mW m-2 in 2020, before declining by approximately 26% by 2050, despite continued growth of fully fluorinated greenhouse gas emissions. Compared to “no HFC policy” projections, this amounts to a reduction in radiative forcing of between 50 and 240 mW m-2 by 2050, or a cumulative emissions saving equivalent to 0.5 to 2.8 years of CO2 emissions at current levels. However, more complete reporting of global HFC emissions is required, as less than half of global emissions are currently accounted for.

Ganesan, AL, Rigby M, Zammit-Mangion A, Manning AJ, Prinn RG, Fraser PJ, Harth CM, Kim KR, Krummel PB, Li S, Mühle J, O'Doherty SJ, Park S, Salameh PK, Steele LP, Weiss RF.  2014.  Characterization of uncertainties in atmospheric trace gas inversions using hierarchical Bayesian methods. Atmospheric Chemistry and Physics. 14:3855-3864.: Copernicus Publications AbstractWebsite
n/a
Fraser, PJ, Krummel PB, Steele LP, Trudinger C, Etheridge DM, Derek N, O’Doherty S, Simmonds PG, Miller BR, Mühle J, Weiss RF, Oram DE, Prinn RG, Wang RHJ.  2014.  Equivalent effective stratospheric chlorine from Cape Grim Air Archive, Antarctic firn and AGAGE global measurements of ozone depleting substances. Baseline atmospheric program 2009-2010. ( Krummel PB, Derek N, Eds.).:17-23.