Rothman, L. S., Gordon, I. E., Barbe, A., Benner, D. C., Bernath, P. F., Birk, M., Boudon, V., Brown, L. R., Campargue, A., Champion, J. P., Chance, K., Coudert, L. H., Dana, V., Devi, V. M., Fally, S., Flaud, J. M., Gamache, R. R., Goldman, A., Jacquemart, D., Kleiner, I., Lacome, N., Lafferty, W. J., Mandin, J. Y., Massie, S. T., Mikhailenko, S. N., Miller, C. E., Moazzen-Ahmadi, N., Naumenko, O. V., Nikitin, A. V., Orphal, J., Perevalov, V. I., Perrin,
with low levels of NO. However, daytime N2 O 5 + NO 3 concentrations calculated using both steady state (Osthoff et al., 2006) and non-steady state approaches (McLaren et al., 2010) were much lower (by a factor of 1–100) than observations. The daytime concentrations in our study are also much higher than those of previous studies which reported daytime N2 O 5and NO 3 concentrations of only a few to over ten pptv (Geyer
Table 1. Supporting measurements made onboard the BAe 146 aircraft during the RONOCO project and used in the model analysis presented here. a The NO 2measurements used to constrain the model were made by the LIF instrument (Dari-Salisburgo et al., 2009; Di Carlo et al., 2013). 6ANs – sum of alkyl nitrates; 6PNs – sum of peroxy nitrates; PAN – peroxy acetyl nitrate; VOCs – volatile organic compounds. b Aerosol surface area is estimated for ambient relative humidity based on the measured dry size distribution and composition. c The total surface area SMPS + PCASP is within 10 % of the total using the SMPS data alone. Note that the aerosol measurements do not show any evidence for enhanced coarse model aerosol at low altitudes, indicating the aircraft did not enter the marine boundary layer.
similar glass window 13 cm from the center. Vertical slit geometric baffles were used to reduce laser scatter and to exclude ambient light from the cell. The laser power exiting the cell was monitored by a photodiode. The electric field vector of the laser light was aligned parallel to the detection axis in order to minimize the collection of Rayleigh, Raman, and other polarized scattered laser light. NO 3 fluorescence was collected by a
Petelina, S. V., Bourassa, A. E., Wiensz, J. T., Ivanov, E. V., McDade, I. C., Solheim, B. H., McConnell, J. C., Haley, C. S., von Savigny, C., Sioris, C. E., McLinden, C. A., Griffioen, E., Kaminski, J., Evans, W. F. J., Puckrin, E., Strong, K., Wehrle, V., Hum, R. H., Kendall, D. J. W., Matsushita, J., Murtagh, D. P., Brohede, S., Stegman, J., Witt, G., Barnes, G., Payne, W. F., Piche, L., Smith, K., Warshaw, G., Deslauniers, D. L., Marc- hand, P., Richardson, E. H., King, R. A., Wevers, I., McCreath, W., Kyrola, E., Oikarinen, L., Leppelmeier, G. W., Auvinen, H., Megie, G., Hauchecorne, A., Lefevre, F., de La Noe, J., Ricaud, P., Frisk, U., Sjoberg, F., von Scheele, F., and Nordh, L.: The OSIRIS instrument on the Odin spacecraft, Can. J. Phys., 82,
2006 from 0.34±0.08 mg m −2 d −1 in early August to 0.07±0.06 mg m −2 d −1 for four sam- pling dates in September and October. The situation in Lake Lungern was special however, as due to a defect in that year large amounts of water supersaturated with air flowed into the lake. This resulted in air saturations of more than 150% and caused a mixing of the water body down to 40 m, while in normal years the epilimnion is only
which occur in the polar vortex are clearly detectable. Hence, the GOMOS spectrome- ter appears to be a suitable instrument to perform a monitoring of such species in the polar vortex. Furthermore, the temporal study confirms that the halogen activation de- gree and the concomitant denoxification can be effectively monitored by GOMOS. We were able to highlight the correlation between cold temperatures (below T PSC ), weak
The heavy PFCs in this study exhibited the largest growth in the 1980s and 1990s and have since slowed, suggesting that recent emissions may be decreasing as alter- native compounds, with most likely lower GWPs, are used. Based on previous studies, atmospheric observations are crucial in providing measurement-based emission esti- mates to verify bottom-up inventories, which often show large discrepancies (M ¨uhle
Sierra Nevada mountains (altitude = 10 200 ft) for a pump- and-flush procedure that is repeated ten times, in which each canister is pressurized to 40 psig with ambient air and then vented to ambient pressure. Next the canisters are returned to our UC-Irvine laboratory where they are evacuated to 10 −2 Torr and then pressurized to 1000 Torr with ultra-high pu- rity helium before a final evacuation to 10 −2 Torr (E2M12 dual-stage vacuum pumps, Edwards Vacuum, Wilmington, MA). Lastly each canister is humidified by adding ∼17 Torr of purified water (the approximate vapour pressure of wa- ter at room temperature) to minimize surface adsorption and improve the reproducibility of our analytical split ratios dur- ing laboratory analysis (see Sect. 2.1.2). Rigorous sensitivity tests have shown that alkene growth in our passivated canis- ters is limited to a maximum of 0.2 pptv day −1 and all other compounds reported here are stable over the typically short period that the cans are stored before analysis (Sive, 1998). By analyzing the Alberta samples within 7 days of collec- tion, we were able to limit the size of any alkene artefact to 1.4 pptv or less (i.e., to negligible values).
matter in the top soil. Burning of grasslands often results in earlier growth of grass in the growing season, increasing the length of the biomass growth period (Ojima et al., 1994). On the one hand, by maintaining the dominance of grasses over shrubs and trees, fire-based management of grassland increases the detritus in the upper soil centimetres as grasses have a shallower rooting system as compared to shrubs and trees (Ansley et al., 2002). On the other hand, frequent fires (yearly to once every three years) have been reported to lead to a decline in soil C, as a result of fire combustion of above- ground biomass, leaf litter and soil organic matter in the upper few centimetres (Fynn et al., 2003; Knicker, 2007). Furthermore, fire might influence gas diffusivity by chang- ing soil porosity and water balance (Snyman, 2003; Knicker, 2007), which affects soil potential for CH 4 oxidation. Most
Fig. 1. Spatial extent of the region under study including: Albania (ALB), Austria (AUT), Belgium (BEL), Bosnia and Herzegovina (BIH), Bulgaria (BGR), Croatia (HRV), Cyprus (CYP), Czech Republic (CZE), Denmark (DNK), Estonia (EST), Finland (FIN), France (FRA), Germany (DEU), Greece (GRC), Hungary (HUN), Iceland (ISL), Ireland (IRL), Italy (ITA), Kosovo (UNK), Latvia (LVA), Lithuania (LTU), Luxembourg (LUX), Macedonia (MKD), Malta (MLT), the Nether- lands (NLD), Norway (NOR), Poland (POL), Portugal (PRT), Romania (ROU), Serbia and Montenegro (SCG), Slovakia (SVK), Slovenia (SVN), Spain (ESP), Sweden (SWE), Switzer- land (CHE) and United Kingdom (GBR)
vided computer programming and data analysis, B. Paplawski, engineering and chemical ex- pertise, A. Cox, gas cylinder preparation and handling, J. Cooper, data processing, and A. Hartounian, PC and instrument fabrication and software support. N2 O data were provided by the AGAGE program at S.I.O. headed by R. Weiss. P. Salameh and C. Harth provided AGAGE data support. Trinidad Station support was provided by W. Snible and R. Dickau. Shipboard
Number concentrations and size distribution of aerosol particles in the size range between 4 nm and 20 µm were measured with a combination of condensation particle coun- ters and a differential mobility particle sizer mounted in the cabin, as well as two wing-mounted optical aerosol spec- trometer probes in a similar setup described by Weinzierl et al. (2009). The instruments deployed on the DLR Falcon during AMMA are listed in more detail in the supplement of Reeves et al. (2010). The cabin instruments sampled air through the forward facing DLR Falcon aerosol inlet, which is operated close to isokinetic sampling conditions and has no significant sampling losses for particles up to 1.5 µm par- ticle diameter. The size range of particles in the accumula- tion and coarse mode above approximately 0.15 µm particle size is covered by measurementsof the PCASP-100X and the FSSP-300 wing probes, two instruments which in princi- ple detect the amount of light scattered by single particles. In order to infer the particle size distribution, knowledge on the complex refractive index of the aerosol particles is required (Schumann et al., 2010). In this study, we used for simplic- ity an refractive index of 1.54 + 0.0i, commonly used to rep- resent an aged ammonium sulfate type aerosol, for all size distribution data discussed. In particular for particles falling into the PCASP-100X size range (0.15–1.0 µm) the possible error introduced by this simplification is estimated to be be- low natural variability due to the instrument being relatively insensitive to variations in the actual refractive index. Parti- cle concentrations in this manuscript are reported as ambient concentrations.
tion in the temperature-insensitive basal respiration rate, with no discernible effect on the temperature sensitivity. However, a notable finding for our site is that maximum soil respiration occurred under wet and warm environmental conditions. This was specifi- cally remarkable if monthly soil temperatures increased to values > 8 ◦ C, which explains why more than a half of the annual soil CO 2 emission occurred from June to Septem-
Nitric oxide emissions measured at low moisture condi- tions (M25) and 20 to 30 ◦ C soil temperature were 6.4 ± 2.4 and 9.1±4.8 µg N m −2 h −1 , respectively, and therefore higher than the fluxes reported for African sites during the dry sea- son (1.6–2.2 µg m −2 h −1 ; Meixner et al., 1997; Serça et al., 1998) but comparable to dry season conditions observed in Venezuela (Cárdenas et al., 1993). A link between the mag- nitude of NO emissions from savanna soil and soil water content and nutrient availability has been postulated by vari- ous authors (Cárdenas et al., 1993; Feig et al., 2008; Parsons et al., 1996; Poth et al., 1995; Rondón et al., 1993). It was reported that soil moisture is the dominant factor whenever it is not limiting the NO flux, but emission strength is mod- ulated by daily variation of soil temperature (Meixner et al., 1997). A significant correlation of NO emissions with soil pH was also reported (Poth et al., 1995), and it is in agree- ment with the outcome of our relative importance analysis where pH scored second after soil temperature in explaining observed NO emissions post pulse (Fig. 6). The low score of soil moisture in this analysis can be explained by the nonlin- ear response of NO to changing soil moisture levels and is also reflected in the low total explanatory power of 19.4 %. High soil temperatures (40 ◦ C) in combination with medium
Aerosol Physical State Model (APSM) developed here is based on Lagrangian trajecto- ries computed from ECMWF (European Centre for Medium Range Weather Forecasts) analyses, taking full account of the deliquescence/efflorescence hysteresis. As input APSM requires three data sets: (i) deliquescence and efflorescence relative humidities from laboratory measurements, (ii) ammonia-to-sulfate ratios (ASR) calculated by a
CO 2 than unburned plots during the 1st campaign (one month after burning, dry sea- son) but this difference was not detectable any longer in the 2nd campaign (growing season). The clearest effect of fire was the immediate disappearance of the above- ground vegetation, which despite being partially dry due to the strong water limitation, had still about 20% of green biomass. This was most probably supporting the main-
into the actinic region, and the reaction with OH is not likely to contribute significantly to their degradation. In contrast, the mono-substituted alkyl-iodides have considerably longer photolytic lifetimes, and reaction with OH may compete with photolysis. The greatest potential for reaction with OH will be associated with those alkyl- iodides that possess a large number of relatively weak C-H bonds. Given the trend in OH rate con-
The second experiment to characterize the instrument re- sponse involved sampling different volumes from a single air sample (Miller et al., 2008). The range of relative volumes sampled was from 6 % to 200 % of the standard 2-l sample. The volume method has the advantage of characterizing in- strument responses at mole fractions above present day back- ground levels, which could not be easily achieved through the dilution subsamples unless more concentrated samples were prepared. However, as the atmospheric samples mea- sured in the air archives were all below current atmospheric background mole fractions, the volume method served only to complement the dilution method’s instrument response ex- periment. Generally, the systems exhibited a linear response over much of the required range of mole fractions, with de- partures from linearity at mole fractions corresponding to those of the oldest archive samples, which have the lowest mole fractions. Based on these dilution experiment measure- ments, a nonlinearity parameter, ǫ, was estimated for each PFC on each instrument and was used to correct the obser- vations. These nonlinearity parameters were relatively small and ranged from 0 to 0.047, with the largest nonlinearity cor- rection required for C 8 F 18 .
Drevet, J., Eskes, H. J., Fiore, A. M., Gauss, M., Hauglustaine, D. A., Horowitz, L. W., Isak- sen, I. S. A., Lawrence, M. G., Montanaro, V., M ¨uller, J. F., Pitari, G., Prather, M. J., Pyle, J. A., Rast, S., Rodriguez, J. M., Sanderson, M. G., Savage, N. H., Strahan, S. E., Sudo, K., Szopa, S., Unger, N., van Noije, T. P. C., and Zeng, G.: Multimodel simulations of carbon monoxide: comparison with observations and projected near-future changes, J. Geophys.