A history of chemically and radiatively important gases in air deduced from ALE/GAGE/AGAGE

Abstract

Abstract. We describe in detail the instrumentation and calibrations used in the Atmospheric Lifetime Experiment (ALE), the Global Atmospheric Gases Experiment (GAGE), and the Advanced Global Atmospheric Gases Experiment (AGAGE) and present a history of the majority of the anthropogenic ozone-depleting and climate-forcing gases in air based on these experiments. Beginning in 1978, these three successive automated high-frequency in situ experiments have documented the long-term behavior of the measured concentrations of these gases over the past 20 years, and show both the evolution of latitudinal gradients and the high-frequency variability due to sources and circulation. We provide estimates of the long-term trends in total chlorine contained in long-lived halocarbons involved in ozone depletion. We summarize interpretations of these measurements using inverse methods to determine trace gas lifetimes and emissions. Finally, we provide a combined observational and modeled reconstruction of the evolution of chlorocarbons by latitude in the atmosphere over the past 60 years which can be used as boundary conditions for interpreting trapped air in glaciers and oceanic measurements of chlorocarbon tracers of the deep oceanic circulation. Some specific conclusions are as follows: (1 are not yet at levels sufficient to contribute significantly to atmospheric chlorine loading. These replacement species could in the future provide independent estimates of the global weighted-average OH concentration provided their industrial emissions are accurately documented; (6) in the future, analysis of pollution events measured using high-frequency in situ measurements of chlorofluorocarbons and their replacements may enable emission estimates at the regional level, which, together with industrial end-use data, are of sufficient accuracy to be capable of identifying regional noncompliance with the Montreal Protocol. IntroductionCurrent concerns about the atmospheric levels of chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), A third phase, the Advanced Global Atmospheric Gases Experiment (AGAGE), began over the 1993-1996 time period. AGAGE, which continues to the present, has two instrumental components. First, a highly improved gas chromatographic system measures five biogenic/anthropogenic gases [CH4, N20 , CHC13, CO, and hydrogen ( 2. The second objective is to accurately document the global distributions and temporal behavior of the biogenic/ anthropogenic gases N20 , CH4, CO, H2, CH3C1, CH3Br , and CHC13 over the globe. N20 and CH 4 are important in both the chemistry and radiative budget of the atmosphere, and changes in N20 and CH 4 may also be regarded as sensitive signals of current change in the global biosphere. CO is the major sink for OH, and both CO and CH3C1 are important indicators for regional biomass burning. Together CH3C1 and CHC13 contribute about 20% of the stratospheric chlorine content, and CH3Br contributes about 50% of bromine content [Solomon et al., 1995].3. The third objective is to optimall...

Uncertainties of fluxes and <sup>13</sup>C ∕ <sup>12</sup>C ratios of atmospheric reactive-gas emissions

“…Since methane is largely abundant and long lived, its signature shows a low variability on top of a weak longterm trend (about +0.3 ‰ per decade around the year 2000, Lassey et al, 2000) due to the input of the industrial fossil carbon, and little spatial and temporal variability. Quay et al (1999) estimated the hemispheric gradient (averages of −47.2 ‰ vs. −47.4 ‰ for the SH and NH, respectively) and the monthly variation of δ 13 C(CH 4 ) to be both of the order of ±0.2 ‰. That is negligible in view of ±3 ‰ variations in tropospheric δ 13 C of CO and its large surface sources.…”

“…CH 4 , CO 2 , N 2 O, etc.). The nudging fields are based on the observed mixing ratios from the AGAGE database (Prinn et al, 2000). Amongst the tracers undergoing nudging, CH 4 , CH 3 CCl 3 , CCl 4 , CH 3 Cl, and CO 2 are isotopically separated.…”

Anthropogenic changes of CO2, CH4, N2O, CFCl3, CF2Cl2, CCl2FCClF2, CHCl3, CH3CCl3, CCl4, SF6 and SF5CF3 mixing ratios in the atmosphere over southern Poland

“…They were cal cu lated as arithme tic av er ages of in di vid ual mea sure ments. Shown also are trend curves (red) de rived from daily means of these compounds mea sured at the Mace Head sta tion rep re sent ing the re gional ma rine back ground (http://agage.eas.gatech.edu; Fraser et al, 1996;Cunnold et al, 1997;Prinn et al, 2000;O'Doherty et al, 2001;Reimann et al, 2005), cal cu lated us ing the CCGvu 4.40 rou tine (Thoning et al, 1989). Fig ure 5H shows the at mo spheric con cen tra tions of SF 5 CF 3 mea sured in flask sam ples col lected in Kraków and at Kasprowy Wierch.…”

“…It is clear from Fig ure 7 that the larger vari abil ity and en hanced SF 6 lev els re corded in Kraków have their or i gin in lo cal sources of this gas as so ci ated ei ther with the Kraków ag glom er a tion or with the in dus tri al ized re gion of Up per Silesia. Cunnold et al, 1997;Prinn et al, 2000;O'Doherty et al, 2001;Reimann et al, 2005); H -SF 5 CF 3 mix ing ra tios mea sured at Kasprowy Wierch (green points) and in Kraków (blue points); the trend curve (red line) repre sents a poly no mial fit of the data shown in Fig ure 5H, in clud ing also all other at mo spheric SF 5 CF 3 data pub lished up to now (Sturges et al, 2000(Sturges et al, , 2012Rosiek et al, 2007;Busenberg and Plummer, 2008;Erboy and Smethie, 2012) CONCLUSIONS Long-term, sys tem atic ob ser va tions of three ma jor greenhouse gases (CO 2 , CH 4 , N 2 O) and se lected halogenated compounds CHCl 3 , CH 3 CCl 3 , CCl 4 and SF 6 ) in the at mo sphere over south ern Po land al lowed a deeper in sight into the pro cesses con trol ling the lev els of these gases in the con ti nen tal at mo sphere at dif fer ent time scales. Com par i son of the trace gas com po si tion of ma rine air masses en ter ing the Eu ro pean con ti nent, rep re sented by the Mace Head data, with the at mo spheric mix ing ra tios of these gases mea sured in the cen tre of the con ti nent, some 1600 km from the At lan tic coast, helps to quan tify the im pact of con ti nen tal sources of these gases on the com po si tion of the near-ground at mo sphere in Cen tral and East ern Eu rope.…”

“…Sec ondly, they help to as sess the ef fec tive ness of in ter na tional agree ments, such as the Kyoto Pro to col or Mon treal Pro to col, aimed at re duc ing at mospheric con cen tra tions of key trace sub stances in flu enc ing the ra di a tive bal ance of Earth such as CO 2 , CH 4 , N 2 O and SF 6 , or de plet ing the strato spheric ozone layer (Freons, halogenated com pounds). Fi nally, they pro vide valu able data for cur rent research on the global car bon cy cle (Global Car bon Pro ject, 2012) and the be hav ior of var i ous trace sub stances in the atmo sphere (e.g., Prinn et al, 2000;Fang et al, 2012;Maione et al, 2013). In ad di tion to large-scale moni tor ing ac tiv i ties, many lo cal net works are also in op er a tion, provid ing ground-truth data for man ag ers and pol i ti cians re spon sible for air qual ity is sues in ur ban cen ters.…”