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Lucas, DD, Yver Kwok C, Cameron-Smith P, Graven H, Bergmann D, Guilderson TP, Weiss R, Keeling R.  2015.  Designing optimal greenhouse gas observing networks that consider performance and cost. Geosci. Instrum. Method. Data Syst.. 4:121-137.: Copernicus Publications   10.5194/gi-4-121-2015   AbstractWebsite
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Bullister, JL, Weiss RF.  1988.  Determination of CCl3F and CCl2F2 in seawater and air. Deep-Sea Research Part a-Oceanographic Research Papers. 35:839-853.   10.1016/0198-0149(88)90033-7   AbstractWebsite

An improved analytical technique has been developed for the rapid and accurate shipboard measurement of two anthropogenically produced chlorofluorocarbons (CFCs), CCl3F (F-11) and CCl2F2 (F-12) in air and seawater. Gas samples (dry air or standard) are injected into a stream of purified gas and then concentrated in a low temperature trap. Seawater samples collected in oceanographic Niskin bottles are transferred into glass syringes for storage until analysis. An aliquot of approximately 30 cm3 of seawater is introduced into a glass stripping chamber where the dissolved gases are purged with purified gas, and the evolved CFCs are concentrated in the same cold trap. The trap is subsequently isolated and heated, and the CFCs are automatically transferred by a stream of carrier gas into a precolumn and then a chromatographic separating column. The CCl3F and CCl2F2 peaks are detected by an electron capture detector (ECD) and their areas are integrated digitally. CFC amounts are calculated using fitted calibration curves, generated by injection of various multiple aliquots of gas standard containing known concentrations of CFCs. Preliminary concentration values for these compounds are printed at the completion of each analysis. Total analysis time for air and water samples is < 10 min, allowing detailed vertical profiles of the concentrations of these compounds in the water column and concentrations in the overlying atmosphere to be determined within a few hours of the completion of a hydrographic station. Typical relative standard deviations for analyses of CCl3F and CCl2F2 in near-surface seawater containing equilibrium levels of these compounds are approximately 1%. Limits of detection for both compounds in 30 cm3 seawater samples are about 0.005 × 10−12 mol kg−1.

Weiss, RF, Keeling CD, Craig H.  1981.  The determination of tropospheric nitrous oxide. Journal of Geophysical Research-Oceans and Atmospheres. 86:7197-7202.   10.1029/JC086iC08p07197   AbstractWebsite

A two-step technique, in which the N2O/CO2 ratio is measured by ultrasonic phase-shift gas chromatography and the dry air CO2 concentration is measured by nondispersive infrared analysis, has been developed for the determination of the mole fraction of nitrous oxide in dry air. The N2O concentration is given by the product of these two independent measurements and has a precision (±1 standard deviation) ranging between 0.3 and 0.5%. The absence of systematic errors has been verified by extensive standard intercomparisons and by independent cross checks of the sample extraction procedures. The results of extensive measurements by this technique, reported in a companion paper, fix the mean tropospheric dry air mole fraction of nitrous oxide in the northern hemisphere as of January 1, 1978 at 300.2±0.6 parts per billion, including systematic uncertainties.

Weiss, RF.  1981.  Determinations of carbon dioxide and methane by dual catalyst flame ionization chromatography and nitrous oxide by electron capture chromatography. Journal of Chromatographic Science. 19:611-616.   10.1093/chromsci/19.12.611   AbstractWebsite

An automated gas chromatographic (GC) system has been developed for the measurement of carbon dioxide, methane, and nitrous oxide in air and other gases. Carbon dioxide is measured by a flame ionization detector (FID) after conversion to methane in pure hydrogen carrier gas, using palladium and nickel dual catalysts which permit direct on-line injection of oxygen-containing samples. The detector measures methane in the same sample, although the system has not been optimized for this gas. Nitrous oxide is measured in a separate aliquot of the sample using a hot electron capture datector (ECD) and argon-methane carrier gas. Typical relative standard deviations of the calculated results are 0.04% for carbon dioxide, 0.4% for methane, and 0.3% for nitrous oxide.

Weiss, RF.  1969.  Dissolved argon, nitrogen and total carbonate in the Red Sea brines. Hot brines and recent heavy metal deposits in the Red Sea; a geochemical and geophysical account. ( Degens ET, Ross DA, Eds.).:254-260., New York: Springer-Verlag Abstract
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Craig, H, Weiss RF.  1971.  Dissolved gas saturation anomalies and excess helium in the ocean. Earth and Planetary Science Letters. 10:289-296.   10.1016/0012-821x(71)90033-1   AbstractWebsite

New solubility measurements have been made for helium and neon in seawater; the results (published elsewhere) show that neon is actually supersaturated in the ocean, rather than generally undersaturated as indicated by previous data. The pattern of He-Ne-Ar saturation anomalies, based on the new solubility data, shows the presence of an injected “atmospheric component” in Atlantic surface and deep waters and in Pacific deep waters, ranging from 0.5 to 1 ml of air (STP)/kg seawater. Nitrogen-argon relationships in the deep Pacific are also consistent with this effect. In addition to T and P, a third parameter is thus required for the study of saturation anomalies. The magnitude of the injected air fraction accounts for all of the “excess He” in Atlantic Deep Water and about 60% of the excess in the Pacific. The non-atmospheric excess He in the Pacific corresponds to an anomaly of 3%, presumably radiogenic and primordial helium.

Craig, H, Weiss RF, Clarke WB.  1967.  Dissolved gases in Equatorial and South Pacific Ocean. Journal of Geophysical Research. 72:6165-&.   10.1029/JZ072i024p06165   AbstractWebsite

The nitrogen, oxygen, and argon in Pacific samples from two expeditions have been measured by gas chromatography, and the neon and helium by mass spectrometry. Nitrogen is systematically about 2% supersaturated and argon about 1.5% undersaturated, relative to the solubility data of Douglas for a moisture saturated atmosphere at 1013-mb total pressure. N2/Ar ratios are in precise agreement with the solubility ratios of Benson and Parker. The range and covariance of N2 and Ar variations are consistent with atmospheric pressure variations over the sea. Oxygen values are systematically higher than the ‘classical’ Winkler values by 3.7%. No evidence was found for the large supersaturation of argon reported by Bieri, Koide, and Goldberg in 1966 and the Ar-T-S relationships are inconsistent with their vertical mixing model. Small increases in a saturation anomaly are core properties of water types formed by subsurface mixing and are associated with T-S slope changes; these effects were found in Antarctic and North Pacific Intermediate water. An upper limit of 8.7% excess helium was found at a depth of 1000 meters at 33°S latitude.

Mensch, M, Bayer R, Bullister JL, Schlosser P, Weiss RF.  1996.  The Distribution of Tritium and CFCs in the Weddell Sea during the mid-1980s. Progress in Oceanography. 38:377-415.   10.1016/s0079-6611(97)00007-4   AbstractWebsite

Transient tracer data (tritium, CFC11 and CFC12) from the southern, central and northwestern Weddell Sea collected during Polarstern cruises ANT III-3, ANT V-2/3/4 and during Andenes cruise NARE 85 are presented and discussed in the context of hydrographic observations. A kinematic, time-dependent, multi-box model is used to estimate mean residence times and formation rates of several water masses observed in the Weddell Sea. Ice Shelf Water is marked by higher tritium and lower CFC concentrations compared to surface waters. The tracer signature of Ice Shelf Water can only be explained by assuming that its source water mass, Western Shelf Water, has characteristics different from those of surface waters. Using the transient nature of tritium and the CFCs, the mean residence time of Western Shelf Water on the shelf is estimated to be approximately 5 years. Ice Shelf Water is renewed on a time scale of about 14 years from Western Shelf Water by interaction of this water mass with glacial ice underneath the FilchnerRonne Ice shelf. The Ice Shelf Water signature can be traced across the sill of the Filchner Depression and down the continental slope of the southern Weddell Sea. On the continental slope, new Weddell Sea Bottom Water is formed by entrainment of Weddell Deep Water and Weddell Sea Deep Water into the Ice Shelf Water plume. In the northwestern Weddell Sea, new Weddell Sea Bottom Water is observed in two narrow, deep boundary currents flowing along the base of the continental slope. Classically defined Weddeil Sea Bottom Water (theta <= 0.7 degrees C) and Weddell Sea Deep Water (-0.7 degrees C <= theta <= 0 degrees C) are ventilated from the deeper of these boundary currents by lateral spreading and mixing. Model-based estimates yield a total formation rate of 3.5Sv for new Weddell Sea Bottom Water (theta = -1.0 degrees C) and a formation rate of at least 11Sv for Antarctic Bottom Water (theta = -0.5 degrees C). (C) 1997 Elsevier Science Ltd

E
Weiss, RF.  1971.  The effect of salinity on the solubility of argon in seawater. Deep-Sea Research. 18:225-230.   10.1016/0011-7471(71)90111-2   AbstractWebsite

New argon solubility measurements, made by two independent methods, confirm the use of the Setchénow relation in representing the salting-out of argon in seawater. No substantiation was found for the unusual salinity dependence implied by the argon solubility data of Murray and Riley (1970).

Li, S, Kim J, Kim KR, Muhle J, Kim SK, Park MK, Stohl A, Kang DJ, Arnold T, Harth CM, Salameh PK, Weiss RF.  2011.  Emissions of halogenated compounds in East Asia determined from measurements at Jeju Island, Korea. Environmental Science & Technology. 45:5668-5675.   10.1021/es104124k   AbstractWebsite

High-frequency in situ measurements at Gosan (Jeju Island, Korea) during November 2007 to December 2008 have been combined with interspecies correlation analysis to estimate national emissions of halogenated compounds (HCs) in East Asia, including the chlorofluorocarbons (CFCs), halons, hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF(6)), and other chlorinated and brominated compounds. Our results suggest that overall China is the dominant emitter of HCs in East Asia, however significant emissions are also found in South Korea, Japan and Taiwan for HFC-134a, HFC-143a, C(2)F(6), SF(6), CH(3)CCl(3), and HFC-365mfc. The combined emissions of CFCs, halon-1211, HCFCs, HFCs, PFCs, and SF(6) from all four countries in 2008 are 25.3, 1.6, 135, 42.6, 3.6, and 2.0 kt/a, respectively. They account for approximately 15%, 26%, 29%, 16%, 32%, and 26.5% of global emissions, respectively. Our results show signs that Japan has successfully phased out CFCs and HCFCs in compliance with the Montreal Protocol (MP), Korea has started transitioning from HCFCs to HFCs, while China still significantly consumes HCFCs. Taiwan, while not directly regulated under the MP, is shown to have adapted the use of HFCs. Combined analysis of emission rates and the interspecies correlation matrix presented in this study proves to be a powerful tool for monitoring and diagnosing changes in consumption of HCs in East Asia.

Rhew, RC, Miller BR, Bill M, Goldstein AH, Weiss RF.  2002.  Environmental and biological controls on methyl halide emissions from southern California coastal salt marshes. Biogeochemistry. 60:141-161.   10.1023/a:1019812006560   AbstractWebsite

Methyl bromide (CH3Br) and methyl chloride (CH3Cl) emission rates from southern California coastal salt marshes show large spatial and temporal variabilities that are strongly linked to biological and environmental factors. Here we discuss biogeochemical lines of evidence pointing to vegetation as the primary source of CH3Br and CH3Cl emissions from salt marshes. Sediments and macroalgae do not appear to be major producers of these compounds, based on observations that the highest fluxes are not inhibited by soil inundation; their emissions are not correlated with those of certain gases produced in soils; and emissions from mudflat- and macroalgae-dominated sites are relatively small. In contrast, the seasonal and spatial variabilities of methyl halide fluxes in these salt marshes are consistent with the production of these compounds by vascular plants, although the possibility of production by microflora or fungi associated with the salt marsh vegetation is not ruled out. Flux chamber measurements of emission rates are largely correlated to the overall plant biomass enclosed in the chamber, but appear also to be highly dependent on the predominant plant species. Emission rates follow a diurnal trend similar to the trends of ambient air temperature and photosynthetically active radiation, but not surface soil temperature. Diurnal variabilities in the carbon isotope compositions of CH3Cl and CH3Br and their relative ratios of emissions are consistent with simultaneously competing mechanisms of uptake and production.

Jeong, SG, Newman S, Zhang JS, Andrews AE, Bianco L, Bagley J, Cui XG, Graven H, Kim J, Salameh P, LaFranchi BW, Priest C, Campos-Pineda M, Novakovskaia E, Sloop CD, Michelsen HA, Bambha RP, Weiss RF, Keeling R, Fischer ML.  2016.  Estimating methane emissions in California's urban and rural regions using multitower observations. Journal of Geophysical Research-Atmospheres. 121:13031-13049.   10.1002/2016jd025404   AbstractWebsite

We present an analysis of methane (CH4) emissions using atmospheric observations from 13 sites in California during June 2013 to May 2014. A hierarchical Bayesian inversion method is used to estimate CH4 emissions for spatial regions (0.3 degrees pixels for major regions) by comparing measured CH4 mixing ratios with transport model (Weather Research and Forecasting and Stochastic Time-Inverted Lagrangian Transport) predictions based on seasonally varying California-specific CH4 prior emission models. The transport model is assessed using a combination of meteorological and carbon monoxide (CO) measurements coupled with the gridded California Air Resources Board (CARB) CO emission inventory. The hierarchical Bayesian inversion suggests that state annual anthropogenic CH4 emissions are 2.42 +/- 0.49 Tg CH4/yr (at 95% confidence), higher (1.2-1.8 times) than the current CARB inventory (1.64 Tg CH4/yr in 2013). It should be noted that undiagnosed sources of errors or uncaptured errors in the model-measurement mismatch covariance may increase these uncertainty bounds beyond that indicated here. The CH4 emissions from the Central Valley and urban regions (San Francisco Bay and South Coast Air Basins) account for similar to 58% and 26% of the total posterior emissions, respectively. This study suggests that the livestock sector is likely the major contributor to the state total CH4 emissions, in agreement with CARB's inventory. Attribution to source sectors for subregions of California using additional trace gas species would further improve the quantification of California's CH4 emissions and mitigation efforts toward the California Global Warming Solutions Act of 2006 (Assembly Bill 32).

Fraser, A, Palmer PI, Feng L, Boesch H, Cogan A, Parker R, Dlugokencky EJ, Fraser PJ, Krummel PB, Langenfelds RL, O'Doherty S, Prinn RG, Steele LP, van der Schoot M, Weiss RF.  2013.  Estimating regional methane surface fluxes: the relative importance of surface and GOSAT mole fraction measurements. Atmospheric Chemistry and Physics. 13:5697-5713.   10.5194/acp-13-5697-2013   AbstractWebsite

We use an ensemble Kalman filter (EnKF), together with the GEOS-Chem chemistry transport model, to estimate regional monthly methane (CH4) fluxes for the period June 2009-December 2010 using proxy dry-air column-averaged mole fractions of methane (XCH4) from GOSAT (Greenhouse gases Observing SATellite) and/or NOAA ESRL (Earth System Research Laboratory) and CSIRO GASLAB (Global Atmospheric Sampling Laboratory) CH4 surface mole fraction measurements. Global posterior estimates using GOSAT and/or surface measurements are between 510-516 Tg yr(-1), which is less than, though within the uncertainty of, the prior global flux of 529 +/- 25 Tg yr(-1). We find larger differences between regional prior and posterior fluxes, with the largest changes in monthly emissions (75 Tg yr(-1)) occurring in Temperate Eurasia. In non-boreal regions the error reductions for inversions using the GOSAT data are at least three times larger (up to 45 %) than if only surface data are assimilated, a reflection of the greater spatial coverage of GOSAT, with the two exceptions of latitudes >60 degrees associated with a data filter and over Europe where the surface network adequately describes fluxes on our model spatial and temporal grid. We use CarbonTracker and GEOS-Chem XCO2 model output to investigate model error on quantifying proxy GOSAT XCH4 (involving model XCO2) and inferring methane flux estimates from surface mole fraction data and show similar resulting fluxes, with differences reflecting initial differences in the proxy value. Using a series of observing system simulation experiments (OSSEs) we characterize the posterior flux error introduced by non-uniform atmospheric sampling by GOSAT. We show that clear-sky measurements can theoretically reproduce fluxes within 10% of true values, with the exception of tropical regions where, due to a large seasonal cycle in the number of measurements because of clouds and aerosols, fluxes are within 15% of true fluxes. We evaluate our posterior methane fluxes by incorporating them into GEOS-Chem and sampling the model at the location and time of surface CH4 measurements from the AGAGE (Advanced Global Atmospheric Gases Experiment) network and column XCH4 measurements from TCCON (Total Carbon Column Observing Network). The posterior fluxes modestly improve the model agreement with AGAGE and TCCON data relative to prior fluxes, with the correlation coefficients (r(2)) increasing by a mean of 0.04 (range: -0.17 to 0.23) and the biases decreasing by a mean of 0.4 ppb (range: -8.9 to 8.4 ppb).

Huang, J, Golombek A, Prinn R, Weiss R, Fraser P, Simmonds P, Dlugokencky EJ, Hall B, Elkins J, Steele P, Langenfelds R, Krummel P, Dutton G, Porter L.  2008.  Estimation of regional emissions of nitrous oxide from 1997 to 2005 using multinetwork measurements, a chemical transport model, and an inverse method. Journal of Geophysical Research-Atmospheres. 113   10.1029/2007jd009381   AbstractWebsite

Nitrous oxide (N2O) is an important ozone-depleting gas and greenhouse gas with multiple uncertain emission processes. Global nitrous oxide observations, the Model of Atmospheric Transport and Chemistry (MATCH) and an inverse method were used to optimally estimate N2O emissions from twelve source regions around the globe. MATCH was used with forecast center reanalysis winds at T62 resolution (192 longitude by 94 latitude surface grid, and 28 vertical levels) from 1 July 1996 to 30 June 2006. The average concentrations of N2O in the lowest four layers of the model were then compared with the monthly mean observations from four national/international networks measuring at 65 surface sites. A 12-month-running-mean smoother was applied to both the model results and the observations, due to the fact that the model was not able to reproduce the very small observed seasonal cycles. The inverse method was then used to solve for the time-averaged regional emissions of N2O for two time periods (1 January 1997 to 31 December 2001 and 1 January 2002 to 31 December 2005). The best estimate inversions assume that the model stratospheric destruction rates, which lead to a global N2O lifetime of 125 years, are correct. It also assumes normalized emission spatial distributions within each region from Bouwman et al. (1995). We conclude that global N2O emissions with 66% probability errors are 16.3(-1.2)(+1.5) and 15.4(-1.3)(+1.7) TgN (N2O) a(-1), for 1997-2001 and 2001-2005 respectively. Emissions from the equator to 30 degrees N increased significantly from the initial Bouwman et al. (1995) estimates while emissions from southern oceans (30 degrees S-90 degrees S) decreased significantly. The quoted uncertainties include both the measurement errors and modeling uncertainties estimated using a separate flexible 12-box model. We also found that 23 +/- 4% of the N2O global total emissions come from the ocean, which is slightly smaller than the Bouwman et al. (1995) estimate. For the estimation of emissions from the twelve model regions, we conclude that, relative to Bouwman et al. (1995), land emissions from South America, Africa, and China/Japan/South East Asia are larger, while land emissions from Australia/New Zealand are smaller. Our study also shows a shift of the oceanic sources from the extratropical to the tropical oceans relative to Bouwman et al. (1995). Between the periods 1997-2001 and 2002-2005, emissions increased in China/Japan/South East Asia, 0 degrees-30 degrees N oceans, and North West Asia and decreased in Australia/New Zealand, 30 degrees S-90 degrees S oceans, 30 degrees N-90 degrees N oceans, and Africa. The lower tropical ocean emissions in 1997-2001 relative to 2002-2005 could result from the effects of the 1997-1998 El Nino in the earlier period.

Yver, CE, Graven HD, Lucas DD, Cameron-Smith PJ, Keeling RF, Weiss RF.  2013.  Evaluating transport in the WRF model along the California coast. Atmospheric Chemistry and Physics. 13:1837-1852.   10.5194/acp-13-1837-2013   AbstractWebsite

This paper presents a step in the development of a top-down method to complement the bottom-up inventories of halocarbon emissions in California using high frequency observations, forward simulations and inverse methods. The Scripps Institution of Oceanography high-frequency atmospheric halocarbons measurement sites are located along the California coast and therefore the evaluation of transport in the chosen Weather Research Forecast (WRF) model at these sites is crucial for inverse modeling. The performance of the transport model has been investigated by comparing the wind direction and speed and temperature at four locations using aircraft weather reports as well at all METAR weather stations in our domain for hourly variations. Different planetary boundary layer (PBL) schemes, horizontal resolutions (achieved through nesting) and two meteorological datasets have been tested. Finally, simulated concentration of an inert tracer has been briefly investigated. All the PBL schemes present similar results that generally agree with observations, except in summer when the model sea breeze is too strong. At the coarse 12 km resolution, using ERA-interim (ECMWF Re-Analysis) as initial and boundary conditions leads to improvements compared to using the North American Model (NAM) dataset. Adding higher resolution nests also improves the match with the observations. However, no further improvement is observed from increasing the nest resolution from 4 km to 0.8 km. Once optimized, the model is able to reproduce tracer measurements during typical winter California large-scale events (Santa Ana). Furthermore, with the WRF/CHEM chemistry module and the European Database for Global Atmospheric Research (EDGAR) version 4.1 emissions for HFC-134a, we find that using a simple emission scaling factor is not sufficient to infer emissions, which highlights the need for more complex inversions.

Elvidge, EL, Bonisch H, Brenninkmeijer CAM, Engel A, Fraser PJ, Gallacher E, Langenfelds R, Muhle J, Oram DE, Ray EA, Ridley AR, Rockmann T, Sturges WT, Weiss RF, Laube JC.  2018.  Evaluation of stratospheric age of air from CF4, C2F6, C3F8, CHF3, HFC-125, HFC-227ea and SF6; implications for the calculations of halocarbon lifetimes, fractional release factors and ozone depletion potentials. Atmospheric Chemistry and Physics. 18:3369-3385.   10.5194/acp-18-3369-2018   AbstractWebsite

In a changing climate, potential stratospheric circulation changes require long-term monitoring. Stratospheric trace gas measurements are often used as a proxy for stratospheric circulation changes via the "mean age of air" values derived from them. In this study, we investigated five potential age of air tracers - the perfluorocarbons CF4, C2F6 and C3F8 and the hydrofluorocarbons CHF3 (HFC-23) and HFC-125 - and compare them to the traditional tracer SF6 and a (relatively) shorter-lived species, HFC-227ea. A detailed uncertainty analysis was performed on mean ages derived from these "new" tracers to allow us to confidently compare their efficacy as age tracers to the existing tracer, SF6. Our results showed that uncertainties associated with the mean age derived from these new age tracers are similar to those derived from SF6, suggesting that these alternative compounds are suitable in this respect for use as age tracers. Independent verification of the suitability of these age tracers is provided by a comparison between samples analysed at the University of East Anglia and the Scripps Institution of Oceanography. All five tracers give younger mean ages than SF6, a discrepancy that increases with increasing mean age. Our findings qualitatively support recent work that suggests that the stratospheric lifetime of SF6 is significantly less than the previous estimate of 3200 years. The impact of these younger mean ages on three policy-relevant parameters - stratospheric lifetimes, fractional release factors (FRFs) and ozone depletion potentials - is investigated in combination with a recently improved methodology to calculate FRFs. Updates to previous estimations for these parameters are provided.

Deeds, DA, Vollmer MK, Kulongoski JT, Miller BR, Muhle J, Harth CM, Izbicki JA, Hilton DR, Weiss RF.  2008.  Evidence for crustal degassing of CF4 and SF6 in Mojave Desert groundwaters. Geochimica Et Cosmochimica Acta. 72:999-1013.   10.1016/j.gca.2007.11.027   AbstractWebsite

Dissolved tetrafluoromethane (CF(4)) and sulfur hexafluoride (SF(6)) concentrations were measured in groundwater samples from the Eastern Morongo Basin (EMB) and Mojave River Basin (MRB) located in the southern Mojave Desert, California. Both CF(4) and SF(6) are supersaturated with respect to equilibrium with the preindustrial atmosphere at the recharge temperatures and elevations of the Mojave Desert. These observations provide the first in situ evidence for a flux of CF(4) from the lithosphere. A gradual basin-wide enhancement in dissolved CF(4) and SF(6) concentrations with groundwater age is consistent with release of these gases during weathering of the surrounding granitic alluvium. Dissolved CF(4) and SF(6) concentrations in these groundwaters also contain a deeper crustal component associated with a lithospheric flux entering the EMB and MRB through the underlying basement. The crustal flux of CF(4), but not of SF(6), is enhanced in the vicinity of local active fault systems due to release of crustal fluids during episodic fracture events driven by local tectonic activity. When fluxes of CF(4) and SF(6) into Mojave Desert groundwaters are extrapolated to the global scale they are consistent, within large uncertainties, with the fluxes required to sustain the preindustrial atmospheric abundances of CF(4) and SF(6). (c) 2007 Elsevier Ltd. All rights reserved.

Prinn, RG, Huang J, Weiss RF, Cunnold DM, Fraser PJ, Simmonds PG, McCulloch A, Harth C, Salameh P, O'Doherty S, Wang RHJ, Porter L, Miller BR.  2001.  Evidence for substantial variations of atmospheric hydroxyl radicals in the past two decades. Science. 292:1882-1888.   10.1126/science.1058673   AbstractWebsite

The hydroxyl radical (OH) is the dominant oxidizing chemical in the atmosphere. It destroys most air pollutants and many gases involved in ozone depletion and the greenhouse effect. Global measurements of 1,1,1-trichloroethane (CH3CCl3, methyl chloroform) provide an accurate method for determining the global and hemispheric behavior of OH. Measurements show that CH3CCl3 Levels rose steadily from 1978 to reach a maximum in 1992 and then decreased rapidly to levels in 2000 that were Lower than the levels when measurements began in 1978. Analysis of these observations shows that global OH Levels were growing between 1978 and 1988, but the growth rate was decreasing at a rate of 0.23 +/- 0.18% year(-2), so that OH Levels began declining after 1988. Overall, the global average OH trend between 1978 and 2000 was -0.64 +/- 0.60% year(-1). These variations imply important and unexpected gaps in current understanding of the capability of the atmosphere to cleanse itself.

Prinn, RG, Huang J, Weiss RF, Cunnold DM, Fraser PJ, Simmonds PG, McCulloch A, Harth C, Reimann S, Salameh P, O'Doherty S, Wang RHJ, Porter LW, Miller BR, Krummel PB.  2005.  Evidence for variability of atmospheric hydroxyl radicals over the past quarter century. Geophysical Research Letters. 32   10.1029/2004gl022228   AbstractWebsite

The hydroxyl free radical (OH) is the major oxidizing chemical in the atmosphere, destroying about 3.7 petagrams (Pg) of trace gases each year, including many gases involved in ozone depletion, the greenhouse effect and urban air pollution. Measurements of 1,1,1-trichloroethane (methyl chloroform, CH3CCl3), which reacts with OH, provide the most accurate method currently utilized for determining the global behavior of OH. We report that CH3CCl3 levels rose steadily from 1978 to reach a maximum in 1992 and have since decreased rapidly to levels in 2004 about 30% of the levels when measurements began in 1978. Analysis of these observations shows that global average OH levels had a small maximum around 1989 and a larger minimum around 1998, with OH concentrations in 2003 being comparable to those in 1979. This post-1998 recovery of OH reported here contrasts with the situation 4 years ago when reported OH was decreasing. The 1997-1999 OH minimum coincides with, and is likely caused by, major global wildfires and an intense El Nino event at this time.

Papadimitriou, VC, Portmann RW, Fahey DW, Muhle J, Weiss RF, Burkholder JB.  2008.  Experimental and theoretical study of the atmospheric chemistry and global warming potential of SO2F2. Journal of Physical Chemistry A. 112:12657-12666.   10.1021/jp806368u   AbstractWebsite

In this work, potential atmospheric loss processes for SO(2)F(2), a commercially used biocide (fumigant), have been studied and its global warming potential calculated. Rate coefficients for the gas-phase reactions OH + SO(2)F(2) -> products, k(1), and Cl + SO(2)F(2) -> products, k(4), were determined using a relative rate technique to be k(1) < 1 x 10(-16) cm(3) molecule(-1) s(-1) at 296 and 333 K and k(4)(296 K) < 5 x 10(-17) cm(3) molecule(-1) s(-1). UV absorption cross sections of SO(2)F(2) were measured at 184.9, 193, and 213.9 nm, and its photolysis quantum yield at 193 urn was determined to be <0.02. The atmospheric lifetime of SO(2)F(2) with respect to loss by OH, Cl, and O((1)D) reaction and UV photodissociation is estimated to be >300, >10 000, 700, and >4700 years, respectively. The stratospheric lifetime of SO(2)F(2) is calculated using a two-dimensional model to be 630 years. The global warming potential (GWP) for SO(2)F(2) was calculated to be 4780 for the 100 year time horizon using infrared absorption cross sections measured in this work and a SO(2)F(2) globally averaged atmospheric lifetime of 36 years, which is determined primarily by ocean uptake, reported by Muhle et al. (Muhle, J.; Huang, J.; Weiss, R. F.; Prinn, R. G.; Miller, B. R.; Salameh, P. K.; Harth, C. M.; Fraser, P. J.; Porter, L. W.; Greally, B. R.; O'Doherty, S.; Simonds, P. G. J. Geophys. Res., submitted for publication, 2008). Reaction channels and the possible formation of stable adducts in reactions 1 and 4 were evaluated using ab initio, CCSD(T), and density functional theory, B3P86, quantum mechanical electronic Structure calculations. The most likely reaction product channels were found to be highly endothermic, consistent with the upper limits of the rate coefficients measured in this work.

Nevison, CD, Dlugokencky E, Dutton G, Elkins JW, Fraser P, Hall B, Krummel PB, Langenfelds RL, O'Doherty S, Prinn RG, Steele LP, Weiss RF.  2011.  Exploring causes of interannual variability in the seasonal cycles of tropospheric nitrous oxide. Atmospheric Chemistry and Physics. 11:3713-3730.   10.5194/acp-11-3713-2011   AbstractWebsite

Seasonal cycles in the mixing ratios of tropospheric nitrous oxide (N(2)O) are derived by detrending long-term measurements made at sites across four global surface monitoring networks. The detrended monthly data display large interannual variability, which at some sites challenges the concept of a "mean" seasonal cycle. In the Northern Hemisphere, correlations between polar winter lower stratospheric temperature and detrended N(2)O data, around the month of the seasonal minimum, provide empirical evidence for a stratospheric influence, which varies in strength from year to year and can explain much of the interannual variability in the surface seasonal cycle. Even at sites where a strong, competing, regional N(2)O source exists, such as from coastal upwelling at Trinidad Head, California, the stratospheric influence must be understood to interpret the biogeochemical signal in monthly mean data. In the Southern Hemisphere, detrended surface N(2)O monthly means are correlated with polar spring lower stratospheric temperature in months preceding the N(2)O minimum, providing empirical evidence for a coherent stratospheric influence in that hemisphere as well, in contrast to some recent atmospheric chemical transport model (ACTM) results. Correlations between the phasing of the surface N(2)O seasonal cycle in both hemispheres and both polar lower stratospheric temperature and polar vortex break-up date provide additional support for a stratospheric influence. The correlations discussed above are generally more evident in high-frequency in situ data than in data from weekly flask samples. Furthermore, the interannual variability in the N(2)O seasonal cycle is not always correlated among in situ and flask networks that share common sites, nor do the mean seasonal amplitudes always agree. The importance of abiotic influences such as the stratospheric influx and tropospheric transport on N(2)O seasonal cycles suggests that, at sites remote from local sources, surface N(2)O mixing ratio data by themselves are unlikely to provide information about seasonality in surface sources, e. g., for atmospheric inversions, unless the ACTMs employed in the inversions accurately account for these influences. An additional abioitc influence is the seasonal ingassing and outgassing of cooling and warming surface waters, which creates a thermal signal in tropospheric N(2)O that is of particular importance in the extratropical Southern Hemisphere, where it competes with the biological ocean source signal.

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Severinghaus, JP, Keeling RF, Miller BR, Weiss RF, Deck B, Broecker WS.  1997.  Feasibility of using sand dunes as archives of old air. Journal of Geophysical Research-Atmospheres. 102:16783-16792.   10.1029/97jd00525   AbstractWebsite

Large unaltered samples of the atmosphere covering the past century would complement the history of atmospheric gases obtained from bubbles in ice cores, enabling measurement of geochemically important species such as O-2, (CH4)-C-14, and (CO)-C-14. Sand dunes are a porous media with interstitial air in diffusive contact with the atmosphere, somewhat analogous to the unconsolidated layer of firn atop glaciers. Recent studies have demonstrated the value of firn as an archive of old air [Battle et al., 1996; Bender et al., 1994a]. Unlike firn, sand dunes are incompressible and so remain permeable to greater depths and may extend the firn record into the past century. To evaluate the feasibility of using sand dunes as archives of old air, we drilled 60 m deep test holes in the Algodones Dunes, Imperial Valley, California. The main objective was to see if the air in a sand dune is as old as predicted by a diffusion model, or if the dune is rapidly flushed by advective pumping during windstorms and barometric pressure changes. We dated the air with chlorofluorocarbons and krypton-85, anthropogenic tracers whose atmospheric concentrations are known and have been increasing rapidly in the past half century. These tracer data match the pure diffusion model well, showing that advection in this dune is negligible compared to diffusion as a transport mechanism and that the mean age of the air at 61 m depth is similar to 10 years. Dunes therefore do contain old air. However, dunes appear to suffer from two serious drawbacks as archives. Microbial metabolism is evident in elevated CO2 and N2O and depressed CH4 and O-2 concentrations in this dune, corrupting the signals of interest in this and probably most dunes. Second, isotopic analyses of N-2 and O-2 from the dune show that fractionation of the gases occurs due to diffusion of water vapor, complicating the interpretation of the O-2 signal beyond the point of viability for an air archive. Sand dunes may be useful for relatively inert gases with large atmospheric concentration changes such as chlorofluorocarbons.

Weiss, RF.  1971.  Flushing characteristics of oceanographic sampling bottles. Deep-Sea Research. 18:653-656.   10.1016/0011-7471(71)90132-x   AbstractWebsite

The flushing characteristics of several types of oceanographic sampling bottles have been measured in a series of shipboard experiments using fluorescein dye. The results are consistent with a first-order model which may be used to calculate the flushing rate of a sampling bottle directly from its dimensions.

LeBel, DA, Smethie WM, Rhein M, Kieke D, Fine RA, Bullister JL, Min DH, Roether W, Weiss RF, Andrie C, Smythe-Wright D, Jones EP.  2008.  The formation rate of North Atlantic Deep Water and Eighteen Degree Water calculated from CFC-11 inventories observed during WOCE. Deep-Sea Research Part I-Oceanographic Research Papers. 55:891-910.   10.1016/j.dsr.2008.03.009   AbstractWebsite

The accumulation of man-made chlorofluorocarbons (CFCs) in subsurface water masses is directly related to their formation rate, and the water mass formation rate can be calculated from its CFC inventory. CFC-11 inventories between 65 degrees N and 10 degrees S in the Atlantic Ocean have been calculated for Eighteen Degree Water (EDW) and the components of North Atlantic Deep Water (NADW) from data collected primarily between 1996 and 1998 as part of the World Ocean Circulation Experiment (WOCE). CFC-11 inventories for individual water masses are 5.4 million moles for EDW, 10.5 million moles for Upper Labrador Sea Water (ULSW) (4.6 million moles south of 42 degrees N), 23.4 million moles for Classical Labrador Sea Water (CLSW), 10.4 million moles for Iceland-Scotland Overflow Water (ISOW), and 8.3 million moles for Denmark Strait Overflow Water (DSOW). The estimated error for these inventories is about +/- 10%. The sum of the NADW components (ULSW, CLSW, ISOW, DSOW) is 53.2 million moles which is about half of the total CFC-11 inventory, 103.8 million moles, in the North Atlantic Ocean. Maps of water column inventories illustrate the formation mechanisms and spreading pathways within these water masses. The inventories directly reflect the input of newly formed water in the North Atlantic over the time scale of the CFC transient, about 3 decades. The interior regions of the North Atlantic contain most (75-80%) of the CFC-11 inventory in NADW indicating strong recirculation and mixing of newly formed NADW from the DWBC into the interior with a time scale of 2-3 decades. Average water mass formation rates between 1970 and 1997 are: 3.3Sv for EDW, 3.5Sv for ULSW (2.0Sv from the central Labrador Sea and 1.5 Sv from the southern Labrador Sea), 8.2 Sv for CLSW, 5.7 Sv for ISOW, and 2.2 Sv for DSOW. Estimated errors are +/- 20% for CLSW and +/- 16% for the other water masses. The total for NADW, which forms the deep limb of the North Atlantic Meridional Overturning Circulation, is 19.6 Sv. An extensive test of the effects of temporal variability on the average formation rate calculated from the CFC inventory indicates that the error introduced by the assumption of a constant water mass formation rate is no greater than 15% for CLSW and 10% for the other water masses. (c) 2008 Elsevier Ltd. All rights reserved.

Weiss, RF, Kirsten OH, Ackermann R, Ramo S.  1977.  Free vehicle instrumentation for the in-situ measurement of processes controlling the formation of deep-sea ferromanganese nodules. OCEANS '77 Conference Record. , New York, N.Y., United States (USA): Inst. Electric. and Electron. Eng., New York, N.Y.   10.1109/OCEANS.1977.1154352   Abstract

This paper describes the free vehicle instrumentation under development for the Manganese Nodule Program (MANOP) of the International Decade for Ocean Exploration (IDOE). Principal emphasis is being placed on the MANOP Bottom Lander, a device designed to carry out in situ chemical flux experiments at the seawater-sediment interface at depths up to 6 km. This device will collect time-series water samples from three separate bottom chamber experiments, each of which can be spiked with various chemical and radioisotopic tracers. The device will also make oxygen and pH measurements in each chamber and will take box core samples under each chamber before returning to the surface. All operations will be microprocessor-controlled with data storage capability and with an acoustic data-link to the surface. Deployments will be for periods of up to 1 year.