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Fang, XK, Park S, Saito T, Tunnicliffe R, Ganesan AL, Rigby M, Li SL, Yokouchi Y, Fraser PJ, Harth CM, Krummel PB, Muhle J, O'Doherty S, Salameh PK, Simmonds PG, Weiss RF, Young D, Lunt MF, Manning AJ, Gressentl A, Prinn RG.  2019.  Rapid increase in ozone-depleting chloroform emissions from China. Nature Geoscience. 12:89-+.   10.1038/s41561-018-0278-2   AbstractWebsite

Chloroform contributes to the depletion of the stratospheric ozone layer. However, due to its short lifetime and predominantly natural sources, it is not included in the Montreal Protocol that regulates the production and uses of ozone-depleting substances. Atmospheric chloroform mole fractions were relatively stable or slowly decreased during 1990-2010. Here we show that global chloroform mole fractions increased after 2010, based on in situ chloroform measurements at seven stations around the world. We estimate that the global chloroform emissions grew at the rate of 3.5% yr(-1) between 2010 and 2015 based on atmospheric model simulations. We used two regional inverse modelling approaches, combined with observations from East Asia, to show that emissions from eastern China grew by 49 (41-59) Gg between 2010 and 2015, a change that could explain the entire increase in global emissions. We suggest that if chloroform emissions continuously grow at the current rate, the recovery of the stratospheric ozone layer above Antarctica could be delayed by several years.

Xiao, X, Prinn RG, Simmonds PG, Steele LP, Novelli PC, Huang J, Langenfelds RL, O'Doherty S, Krummel PB, Fraser PJ, Porter LW, Weiss RF, Salameh P, Wang RHJ.  2007.  Optimal estimation of the soil uptake rate of molecular hydrogen from the Advanced Global Atmospheric Gases Experiment and other measurements. Journal of Geophysical Research-Atmospheres. 112   10.1029/2006jd007241   AbstractWebsite

[1] Hydrogen (H(2)), a proposed clean energy alternative, warrants detailed investigation of its global budget and future environmental impacts. The magnitudes and seasonal cycles of the major ( presumably microbial) soil sink of hydrogen have been estimated from high-frequency in situ AGAGE H(2) observations and also from more geographically extensive but low-frequency flask measurements from CSIRO and NOAA-GMD using the Kalman filter in a two-dimensional (2-D) global transport model. Hydrogen mole fractions exhibit well-defined seasonal cycles in each hemisphere with their phase difference being only about 3 months. The global production rate of H(2) is estimated to be 103 +/- 10 Tg yr(-1) with only a small estimated interannual variation. Soil uptake ( 84 +/- 8 Tg yr(-1)) represents the major loss process for H(2) and accounts for 81% of the total destruction. Strong seasonal cycles are deduced for the soil uptake of H(2). The soil sink is a maximum over the northern extratropics in summer and peaks only 2 to 3 months earlier in the Northern Hemisphere than in the Southern Hemisphere. Oxidation by tropospheric OH (18 +/- 3 Tg yr(-1)) accounts for 17% of the destruction, with the remainder due to destruction in the stratosphere. The calculated global burden is 191 +/- 29 Tg, indicating an overall atmospheric lifetime of 1.8 +/- 0.3 years. Hydrogen in the troposphere ( 149 +/- 23 Tg burden) has a lifetime of 1.4 +/- 0.2 years.

Murphy, PP, Harrison DE, Feely RA, Takahashi T, Weiss RF, Gammon RH.  1998.  Variability of Δ pCO2 in the subarctic North Pacific. A comparison of results from four expeditions. Tellus Series B-Chemical and Physical Meteorology. 50:185-204.   10.1034/j.1600-0889.1998.t01-1-00006.x   AbstractWebsite

Time-space variability of surface seawater pCO(2) is examined over the region (150 degrees W-180 degrees, 46 degrees N-50 degrees N) of the subarctic North Pacific where large meridional gradients of temperature and nutrient concentrations exist. The data were collected during four trans-Pacific expeditions in three different years (1985-1987), but within the same 30-day period of the year (August-September). Systematic measurement differences between the four data sets are estimated as <10 mu atm. The inter-expedition comparison suggests that surface seawater pCO(2) in the study area is quite variable, with mean differences of up to 25 mu atm and local differences up to 60 mu atm. Spatial and interannual variability of surface seawater pCO(2) were found to contribute significant uncertainty to estimates of the mean Delta pCO(2) for the study area. Fluxes were calculated using Delta pCO(2) values from the four expeditions combined with gas exchange coefficients calculated from four different wind fields giving a range of -0.94 to +4.1 mmol CO2 m(-2) d(-1). The range of fluxes from the study area is scaled to a larger area of the North Pacific to address how this variability can translate into uncertainties in basin-wide carbon air-sea exchange fluxes.

Landrum, LL, Gammon RH, Feely RA, Murphy PP, Kelly KC, Cosca CE, Weiss RF.  1996.  North Pacific Ocean CO2 disequilibrium for spring through summer, 1985-1989. Journal of Geophysical Research-Oceans. 101:28539-28555.   10.1029/96jc02100   AbstractWebsite

Extensive measurements of CO2 fugacity in the North Pacific surface ocean and overlying atmosphere during the years 1985-1989 are synthesized and interpreted to yield a basin-wide estimate of Delta fCO(2). The observations, taken from February through early September, suggest that the subtropical and subarctic North Pacific is a small sink for atmospheric CO2 (0.07 to 0.2 Gton C (half year)(-1) for the region north of 15 degrees N). Objective analysis techniques are used to estimate uncertainty fields resulting from constructing basin-wide contours of oceanic fCO(2) on the basis of individual cruise transects. The uncertainties are significant and imply that future sampling programs need to recognize that estimating oceanic uptake of anthropogenic CO2 from ship-transect observations of oceanic fCO(2) alone will require very extensive sampling.