Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions : (RECONCILE) ; activities and results

The international research project RECONCILE has addressed central questions regarding polar ozone depletion, with the objective to quantify some of the most relevant yet still uncertain physical and chemical processes and thereby improve prognostic modelling capabilities to realistically predict the response of the ozone layer to climate change. This overview paper outlines the scope and the general approach of RECONCILE, and it provides a summary of observations and modelling in 2010 and 2011 that have generated an in many respects unprecedented dataset to study processes in the Arctic winter stratosphere. Principally, it summarises important outcomes of RECONCILE including (i) better constraints and enhanced consistency on the set of parameters governing catalytic ozone destruction cycles, (ii) a better understanding of the role of cold binary aerosols in heterogeneous chlorine activation, (iii) an improved scheme of polar stratospheric cloud (PSC) processes that includes heterogeneous nucleation of nitric acid trihydrate (NAT) and ice on non-volatile background aerosol leading to better model parameterisations with respect to denitrification, and (iv) long transient simulations with a chemistry-climate model (CCM) updated based on the results of RECONCILE that better reproduce past ozone trends in Antarctica and are deemed to produce more reliable predictions of future ozone trends. The process studies and the global simulations conducted in RECONCILE show that in the Arctic, ozone depletion uncertainties in the chemical and microphysical processes are now clearly smaller than the sensitivity to dynamic variability

The state of the Martian climate

60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes

Schmidt-hammer exposure ages from periglacial patterned ground (sorted circles) in Jotunheimen, Norway, and their interpretative problems

© 2016 Swedish Society for Anthropology and Geography Periglacial patterned ground (sorted circles and polygons) along an altitudinal profile at Juvflya in central Jotunheimen, southern Norway, is investigated using Schmidt-hammer exposure-age dating (SHD). The patterned ground surfaces exhibit R-value distributions with platycurtic modes, broad plateaus, narrow tails, and a negative skew. Sample sites located between 1500 and 1925 m a.s.l. indicate a distinct altitudinal gradient of increasing mean R-values towards higher altitudes interpreted as a chronological function. An established regional SHD calibration curve for Jotunheimen yielded mean boulder exposure ages in the range 6910 ± 510 to 8240 ± 495 years ago. These SHD ages are indicative of the timing of patterned ground formation, representing minimum ages for active boulder upfreezing and maximum ages for the stabilization of boulders in the encircling gutters. Despite uncertainties associated with the calibration curve and the age distribution of the boulders, the early-Holocene age of the patterned ground surfaces, the apparent cessation of major activity during the Holocene Thermal Maximum (HTM) and continuing lack of late-Holocene activity clarify existing understanding of the process dynamics and palaeoclimatic significance of large-scale sorted patterned ground as an indicator of a permafrost environment. The interpretation of SHD ages from patterned ground surfaces remains challenging, however, owing to their diachronous nature, the potential for a complex history of formation, and the influence of local, non-climatic factors

Aircraft emission mitigation by changing route altitude: A multi-model estimate of aircraft NOx emission impact on O3 photochemistry

The atmospheric impact of aircraft NOx emissions are studied using updated aircraft inventories for the year 2006, in order to estimate the photochemistry-related mitigation potential of shifting cruise altitudes higher or lower by 2000 ft. Applying three chemistry-transport models (CTM) and two climatechemistry models (CCM) in CTM mode, all including detailed tropospheric and stratospheric chemistry, we estimate the short-lived radiative forcing (RF) from O3 to range between 16.4 and 23.5 mW m 2, with a mean value of 19.5 mW m 2. Including the long-lived RF caused by changes in CH4, the total NOxrelated RF is estimated to about 5 mW m 2, ranging 1e8 mW m 2. Cruising at 2000 ft higher altitude increases the total RF due to aircraft NOx emissions by 2 ± 1 mW m 2, while cruising at 2000 ft lower altitude reduces RF by 2 ± 1 mWm 2. This change is mainly controlled by short-lived O3 and show that chemical NOx impact of contrail avoiding measures is likely small

The (Dis)Pleasures of Creativity: Spontaneous Eye Blink Rate during Divergent and Convergent Thinking Depends on Individual Differences in Positive and Negative Affect

Previous research has demonstrated that individual differences in affect and motivation predict divergent and convergent thinking performance, two thinking processes involved in creative idea generation. Individual differences in affect and motivation also predict spontaneous eye blink rate (sEBR) during divergent and convergent thinking; and sEBR predicts divergent and convergent thinking performance. The present study investigates experimentally whether the relationship between sEBR and divergent and convergent thinking depends on individual differences in affect and motivation. Eighty-two participants completed the Emotion/motivation-related Divergent and Convergent thinking styles Scale (EDICOS; Soroa et al., 2015), performed the alternative uses task (AUT; divergent thinking) or the remote associates task (RAT; convergent thinking), while their sEBR was captured with an eye-tracker. The results showed that individual differences in positive affect positively correlated with sEBR for the AUT, whereas individual differences in negative affect positively correlated with sEBR for the RAT. Furthermore, the interaction between individual differences in positive and negative affect predict divergent and convergent thinking performance. The contribution of our study is therefore that individual differences in positive and negative affect can both positively correlate with sEBR during divergent and convergent thinking; and that this predicts divergent and convergent thinking performance

Chemistry and radiation changes in the ozone layer

Centro de Informacion y Documentacion Cientifica (CINDOC). C/Joaquin Costa, 22. 28002 Madrid. SPAIN / CINDOC - Centro de Informaciòn y Documentaciòn CientìficaSIGLEESSpai

European surface ozone in the extreme summer 2003

Measurements of ozone and other trace species in the European EMEP network in 2003 are presented. The European summer of 2003 was exceptionally warm and the surface ozone data for central Europe show the highest values since the end of the 1980s. The 99 percentiles of daily maximum hourly ozone concentrations in 2003 was higher than the corresponding parameter measured in any previous year at many sites in France, Germany, Switzerland and Austria. In this paper we argue that a number of positive feedback effects between the weather conditions and ozone contributed to the elevated surface ozone. Firstly we calculated an extended residence time of air parcels in the atmospheric boundary layer for several sites in central Europe. Secondly we show that it is likely that extensive forest fires on the Iberian Peninsula, resulting from the drought and heat, contributed to the peak ozone values in North Europe in August. Thirdly, regional scale model calculations indicate that biogenic isoprene could have contributed with 20% of the peak ozone concentrations. Measurements indicate elevated concentrations of isoprene compared to previous years. Sensitivity runs with a global chemical transport model showed that a reduction in the surface dry deposition due to drought and the elevated air temperature both could have contributed significantly to the enhanced ozone concentrations. Due to climate change, situations like this may occur at a higher frequency in the future and may gradually overshadow the effect of reduced emissions from anthropogenic sources of VOC and NOx

Anthropogenic influence on SOA and the resulting radiative forcing

The effect of chemical changes in the atmosphere since the pre-industrial period on the distributions and burdens of Secondary Organic Aerosol (SOA) has been calculated using the off-line aerosol chemistry transport model Oslo CTM2. The production of SOA was found to have increased from about 35 Tg yr−1 to 53 Tg yr−1 since pre-industrial times, leading to an increase in the global annual mean SOA burden from 0.33 Tg to 0.50 Tg, or about 51%. The effect of allowing semi-volatile species to partition to sulphate aerosol was also tested, leading to an increase in SOA production from about 43 Tg yr−1 to 69 Tg yr−1 since pre-industrial times, while the annual mean SOA burden increased from 0.44 Tg to 0.70 Tg, or about 59%. The increases were greatest over industrialised areas, especially when partitioning to sulphate aerosol was allowed, as well as over regions with high biogenic precursor emissions. The contribution of emissions from different sources to the larger SOA burdens has been calculated. The results suggest that the majority of the increase was caused by emissions of primary organic aerosols (POA), from fossil fuel and bio fuel combustion. As yet, very few radiative forcing estimates of SOA exist, and no such estimates were provided in the latest IPCC report. In this study, we found that the change in SOA burden caused a radiative forcing (defined here as the difference between the pre-industrial and the present day run) of −0.09 W m−2, when SOA was allowed to partition to both organic and sulphate aerosols, and −0.06 W m−2 when only partitioning to organic aerosols was assumed. Therefore, the radiative forcing of SOA was found to be stronger than the best estimate for POA in the latest IPCC assessment.ISSN:1680-7375ISSN:1680-736

New directions : watching over tropospheric hydroxyl (OH)

Mean tropospheric hydroxyl radical (OH) abundance is often used as a measure of the oxidation capacity (or “self-cleansing”) of the atmosphere. The primary mechanism by which atmospheric pollutant gases are removed from the atmosphere is initiated by the reaction with OH. As a result, large interannual or decadal variations in OH concentrations, as suggested in recent reports, are of great concern. In addition, an important method for discerning tropospheric OH burdens and variability, the analysis of methyl chloroform (MCF) observations, will soon become less useful as the concentration of this industrial gas approaches zero. With these concerns in mind, a workshop focusing on global OH trends and variability was convened in Boulder, Colorado, on 28–30 November 2005. Although the concept of tropospheric mean OH does not do justice to regional OH differences, and ignores the less significant contributions by other oxidants, global OH changes integrate the response to large-scale atmospheric chemistry forcings. The latter include the tendencies of atmospheric water vapour, solar radiation and notably the human-induced emissions of NOx, CO, CH4 and other hydrocarbons. Analogously, the global mean surface temperature change is an integral climate response to natural and anthropogenic forcings by greenhouse gases, aerosols, etc. Furthermore, the variability of mean OH is an indicator of the sensitivity of atmospheric chemistry to global air pollution and natural events (e.g., large volcano eruptions, El Niño). A large response to a small forcing is typical for a system that is not well buffered and vice versa. The analysis of relatively long-lived gases for which emission magnitudes are well characterized can provide insight into the interannual and decadal variability of tropospheric OH. Analysis of MCF measurements, a tracer with a lifetime of about 5 yr owing to its removal by OH, points to a substantial OH growth in the 1980s, a decline in the 1990s and a recovery after 1998, indicating decadal OH changes of 10–15% (R.G. Prinn et al., 2005, Geophysical Research Letters 32, L07809, doi:10.1029/2004GL022228). MCF analysis furthermore suggests a large interannual OH variability of 8.5±1.0%; however, this may reflect uncertainties in the MCF emission inventory (P. Bousquet et al., 2005, Atmospheric Chemistry and Physics 5, 2635–2656). Using radiocarbon 14CO as a diagnostic for OH gives additional evidence of 10% variability in OH over timescales of less than a year, although the 14CO measurements are only representative of the extratropical southern hemisphere (M.R. Manning et al., 2005, Nature 436, 1001–1004). Even though chemistry–transport models fail to reproduce the large OH variability, many studies point to relatively large OH changes after the 1991 Mt. Pinatubo eruption and during the 1997/8 El Niño event. The likelihood of large OH variability is challenged by CH4 mass balance calculations based on the NOAA network measurements. Emissions of CH4 (E) can be derived from the measured global burden [CH4] and rate of CH4 increase, and an estimate of the CH4 lifetime: E=d[CH4]/dt+[CH4]/τ, where d[CH4]/dt is the observed rate of increase and τ the CH4 lifetime. Since τ is not constant in the real atmosphere, fixing it in the equation means that E includes variability of the sink, i.e. changes in OH. Calculation of E based on yields a mean source of 556±10 Tg CH4 yr−1 for 1984 to 2004, with a trend of 0.1±0.4 Tg yr−1. Maximum deviations from E are 18.4 Tg in 1991 and 27.0 Tg in 1998 (see Fig. 1). Assuming that emissions are uncorrelated with OH, these anomalies provide upper limits of the interannual variability of OH, e.g., 3–5% in 1991 and 1998. In other years the OH variability is typically less than 2%, in agreement with chemistry–transport models. Yet, there is little doubt that global OH decreased immediately after the Mt. Pinatubo eruption, as this is evident in both the CH4 and 14CO measurements. The large anomaly in CH4 in 1998 had contributions by increased emissions from wetlands and biomass burning (S. Morimoto et al., 2006, Geophysical Research Letters 33, L01807, doi:10.1029/2005GL024648), and decreased OH resulting from the Indonesian biomass burning emissions (T.M. Butler et al., 2005, Journal of Geophysical Research 110, D21310, doi:10.1029/2005JD006071)