James Hansen, Makiko Sato, Paul Hearty, Reto Ruedy, Maxwell Kelley, Valerie Masson-Delmotte, Gary Russell, George Tselioudis, Junji Cao, Eric Rignot, Isabella Velicogna, Blair Tormey, Bailey Donovan, Evgeniya Kandiano, Karina von Schuckmann, Pushker Kharecha, Allegra N. Legrande, Michael Bauer, and Kwok-Wai Lo
Final revised paper published in ACP(110 comments)
We use climate simulations, paleoclimate data and modern observations to infer that continued high fossil fuel emissions will yield cooling of Southern Ocean and North Atlantic surfaces, slowdown and shutdown of SMOC & AMOC, increasingly powerful storms and nonlinear sea level rise reaching several meters in 50–150 years, effects missed in IPCC reports because of omission of ice sheet melt and an insensitivity of most climate models, likely due to excessive ocean mixing.
Clarification is needed in the terminology used to discuss ice nucleation in the literature. Conflicting interpretations coupled with uncertainties about the details of the processes have led to difficulties in the clear communication of results and ideas. This paper contains a proposal for future usage. This proposed terminology was arrived at as a result of a year-long exchange of suggestions by a number of scientists.
A. Baklanov, K. Schlünzen, P. Suppan, J. Baldasano, D. Brunner, S. Aksoyoglu, G. Carmichael, J. Douros, J. Flemming, R. Forkel, S. Galmarini, M. Gauss, G. Grell, M. Hirtl, S. Joffre, O. Jorba, E. Kaas, M. Kaasik, G. Kallos, X. Kong, U. Korsholm, A. Kurganskiy, J. Kushta, U. Lohmann, A. Mahura, A. Manders-Groot, A. Maurizi, N. Moussiopoulos, S. T. Rao, N. Savage, C. Seigneur, R. S. Sokhi, E. Solazzo, S. Solomos, B. Sørensen, G. Tsegas, E. Vignati, B. Vogel, and Y. Zhang
PM2.5 filter samples have been collected in three megacities at the middle and lower reaches of the Yangtze River: Wuhan, Nanjing, and Shanghai. The samples were analyzed using ultra-high-performance liquid chromatography coupled with Orbitrap mass spectrometry, which allowed for detection of about 200 formulas of particulate organosulfates, including dozens of formulas of nitrooxy-organosulfates, with various numbers of isomers for each tentatively determined formula at each location.
The climatology of the Brewer–Dobson circulation and the potential contribution of gravity waves (GWs) are examined using four modern reanalysis datasets for the annual mean and each season. In this study, unresolved waves are designated as GWs. GWs are essential to determine the high-latitude extension and the turn-around latitude except in summer, although their contribution to the upward mass flux is relatively small. Plausible deficiencies of the current GW parameterizations are discussed.
This article presents a comparison between the two surface-UV dose series, measured with Brewer spectrophotometers working simultaneously at two different sites in Poland: in a large city agglomeration and in the suburbs. We consider whether the city of Warsaw acts as a shield from ultraviolet overexposure. Our study proves that the UV level in Warsaw is slightly lower than that found in cleaner suburbs of the city.
J. Mühle, A. L. Ganesan, B. R. Miller, P. K. Salameh, C. M. Harth, B. R. Greally, M. Rigby, L. W. Porter, L. P. Steele, C. M. Trudinger, P. B. Krummel, S. O'Doherty, P. J. Fraser, P. G. Simmonds, R. G. Prinn, and R. F. Weiss
Our work suggests that a large corona discharge system is an efficient and possibly economically sustainable way to increase the ion density in the open air and control the precipitation of atmospheric aerosols. Once the system is installed on a mountaintop, it will generate lots of charged nuclei, which may trigger water precipitation or fog elimination within a certain region in the downwind directions.
This paper reports a systematic assessment of the information content of remote sensing measurements with regard to the chemical composition of aerosols. The focus is on ground-based, airborne, or space-borne lidar observations. The results are exploited in an air-quality forecasting model by incorporating measurements into the model in such a way that one maximises the use of available information. The goal of this work is to improve air-quality forecasting for suspended particulate matter.
Because of an increase in population UV exposure due to depletion of ozone, solar UV data were collected at Chilton, south England, from 1991 to 2015 and compared with ozone (O), cloudiness (C) and aerosols (A). Using multiple regression analysis, the results showed O exhibited a small increasing tendency over the same period; C played a more important role in the increasing trend in UV for 1991–2004 than O, while for 2004–2015 the decreasing trend in UV was less associated with C and A than O.
One of the most important parameters in climate science is the equilibrium climate sensitivity (ECS). Estimates of this quantity based on 20th-century observations suggest low values of ECS (below 2 °C). We show that these calculations may be significantly in error. Together with other recent work on this problem, it seems probable that the ECS is larger than suggested by the 20th-century observations.
To our knowledge, this is the first simultaneous field measurement of bioaerosols in dust events at four sites along the transport pathway of Asian dust. The samples were analyzed by means of fluorescence microscopy, scanning electron microscopy, and MiSeq sequencing analysis. The results indicate that dust clouds can carry many bacteria of various types into downwind regions, the alpha and beta diversity of which were investigated.
Gerrit de Leeuw, Larisa Sogacheva, Edith Rodriguez, Konstantinos Kourtidis, Aristeidis K. Georgoulias, Georgia Alexandri, Vassilis Amiridis, Emmanouil Proestakis, Eleni Marinou, Yong Xue, and Ronald van der A
The complementary use of two sensors, ATSR and MODIS, to provide aerosol information over two decades (1995–2015) is described. To this end, the AOD retrieved from both instruments had to be compared, showing that ATSR slightly underestimates and MODIS overestimates by a similar amount. Results show the increase of aerosols over the years, with an indication of the onset of a decrease in recent years. The AOD spatial distribution shows seasonal variations across China.
In this work we evaluate the contribution of the major anthropogenic emission sources to global air quality and human health, focusing on particulate matter (PM) concentrations because of their importance in populated areas and the proven cumulative negative effects on human health. We show that in order to improve air quality, regional policies should be implemented due to the transboundary features of PM pollution.
The 2015/16 Arctic winter stratosphere was the coldest on record through late February, raising the possibility of extensive chemical ozone loss. However, a major final sudden stratospheric warming in early March curtailed ozone destruction. We used Aura MLS satellite trace gas data and MERRA-2 meteorological data to show the details of transport, mixing, and dispersal of chemically processed air during the major final warming, and how these processes limited Arctic chemical ozone loss.
Mineral dust aerosol affects climate through interaction with radiation and clouds, human health through contribution to particulate matter, and ecosystem health through nutrient transport and deposition. In this study, we use satellite and in situ retrievals to derive an observational estimate of the global dust AOD with which evaluate modeled dust AOD. Differences in the seasonality and regional distribution of dust AOD between observations and models are highlighted.
C. Senten, M. De Mazière, B. Dils, C. Hermans, M. Kruglanski, E. Neefs, F. Scolas, A. C. Vandaele, G. Vanhaelewyn, C. Vigouroux, M. Carleer, P. F. Coheur, S. Fally, B. Barret, J. L. Baray, R. Delmas, J. Leveau, J. M. Metzger, E. Mahieu, C. Boone, K. A. Walker, P. F. Bernath, and K. Strong
C. Marcolli, M. R. Canagaratna, D. R. Worsnop, R. Bahreini, J. A. de Gouw, C. Warneke, P. D. Goldan, W. C. Kuster, E. J. Williams, B. M. Lerner, J. M. Roberts, J. F. Meagher, F. C. Fehsenfeld, M. Marchewka, S. B. Bertman, and A. M. Middlebrook
M. Kanakidou, J. H. Seinfeld, S. N. Pandis, I. Barnes, F. J. Dentener, M. C. Facchini, R. Van Dingenen, B. Ervens, A. Nenes, C. J. Nielsen, E. Swietlicki, J. P. Putaud, Y. Balkanski, S. Fuzzi, J. Horth, G. K. Moortgat, R. Winterhalter, C. E. L. Myhre, K. Tsigaridis, E. Vignati, E. G. Stephanou, and J. Wilson
Preprint under review for ACP(discussion: final response, 11 comments)
This paper explores the dynamics of gravity waves and turbulence present in the mesosphere and lower thermosphere (MLT) region. We utilized two different techniques on meteor radar observations and simulations to obtain power spectra at different horizontal scales. The techniques are applied to a special campaign conducted in northern Germany in November 2018. The study revealed the dominance of large-scale structures with horizontal scales larger than 500 km during the campaign period.
The objective of this study was to conduct observational evaluations of the daily cycle of the height of the planetary boundary layer from data that were measured and/or estimated using instruments such as a radiosonde, sodar, ceilometer, wind profiler, lidar and microwave radiometer installed in the central Amazon during 2014 (considered a typical year) and 2015 during which an intense El Niño–Southern Oscillation (ENSO) event predominated during the GoAmazon experiment.
This paper presents temporal evolution of stratospheric chlorine and minor species related to Antarctic ozone depletion, based on FTIR measurements at Syowa Station, and satellite measurements by MLS and MIPAS in 2007 and 2011. After chlorine reservoir species were processed on PSCs and active ClO was formed, different chlorine deactivation pathways into reservoir species were identified, depending on the relative location of Syowa Station to the polar vortex boundary.
Background climate can affect the aerosol concentration (AC). It is found that when negative NAO overlaps El Niño, the anomalous circulations are not favorable for the transportation of aerosol, resulting in enhanced AC over eastern China. By contrast, a sole negative NAO event is linked with increased AC over central China. The results suggest that both the extratropical and tropical climate systems play an important role in impacting the AC over China.
Several studies using thermodynamic models estimated pH and sulfate formation rate during pollution periods in China are highly conflicting. Here we show distinct sulfate formation for organic seed particles from that of (NH4)2SO4 seeds, when the particles are exposed to SO2, NO2, and NH3 at high RH. Our results reveal that the pH value of ambient organics-dominated aerosols is sufficiently high to promote efficient SO2 oxidation by NO2 with NH3 neutralization under polluted conditions in China.
A coupled atmospheric dispersion modelling system has been developed, comprising a regional chemical transport model and a street-scale urban dispersion model. It was applied in London for 2012 and for all common regulated air quality pollutants, with evaluation against measurements. The modelling demonstrates the interaction between local and regional scales, which differs between pollutants. Real-world estimates of emissions have been used to adjust standard factors and improve model results.
We developed an integrated approach based on the Automatic Identification System (AIS) to promote the estimation of sectoral ship emissions in China. Based upon this approach, the sector-based contributions, decadal evolution from 2004 to 2013, emission projection to 2040, and impact of different sizes of Emission Control Areas (ECAs) on emission reductions were investigated, aiming to provide solid scientific support for ship emissions control policy making in China.
Methane is a potent greenhouse gas, and leaks from natural gas infrastructure are thought to be a significant emission source. We used a mobile survey method to measure GHGs near Canadian infrastructure. Our results show that ~ 47 % of active wells were emitting. Abandoned and aging wells were also associated with emissions. We estimate methane emissions from this development are just over 111 Mt year−1, which is more than previous government estimates, but less than similar studies in the US.
This paper compares the representation of the monthly-mean zonal wind in the equatorial stratosphere among major global atmospheric reanalysis data sets. Differences among reanalysis display a prominent equatorial maximum, indicating the particularly challenging nature of the reanalysis problem in the low-latitude stratosphere. Our study confirms that the high accuracy in situ wind measurements have provided important constraints to reanalyses of circulation in the tropical stratosphere.
In this study, on-board tests of three offshore vessels in China have been carried out for the first time. Emission factors for gaseous species, PM, and relevant chemical components (OC, EC, metal elements, and water soluble ions) in different operating modes are given, which means a lot for estimating contributions of ships to atmosphere and calculating emission inventories of ships. Additionally, impacts of engine speed on NOx emission factors are discussed for the first time.
The CMAM30 data set takes a chemistry-climate model and relaxes the dynamics to reanalysis, which can then provide chemistry fields not available from the reanalysis data set. This paper addresses this gap by comparing temperature, water vapour, ozone and methane to satellite data to determine and document any biases in the model fields. The lack of ozone destruction and dehydration in the SH polar vortex is shown to be due to the treatment of polar stratosphere clouds in the model.
Record low ozone values were observed in March 2020. Dynamical and chemical circumstances leading to low ozone values in spring 2020 are discussed and are compared to similar dynamical conditions in the Northern Hemisphere in 1996/1997 and 2010/2011. 2019/2020 showed an unusual persistent polar vortex with low stratospheric temperatures, which were permanently below 195 K at 50 hPa. This enabled enhanced formation of polar stratospheric clouds and a subsequent clear reduction of total ozone.
It has been recognized in earlier research that particle size distribution of dust at emission (dust PSD) is dependent on friction velocity. This recognition has been challenged in some recent papers. Based on the analysis of experimental data, we confirm that dust PSD is dependent on friction velocity and atmospheric boundary-layer stability. By theoretical and numerical analysis, we reveal the reasons for this dependency.
Revised manuscript accepted for ACP(discussion: closed, 10 comments)
Impacts of anthropogenic aerosols on deep convective clouds (DCCs) and precipitation are investigated using both the Morrison bulk and spectral-bin microphysics (SBM) schemes. With the SBM scheme, anthropogenic aerosols notably invigorate convective intensity and precipitation, making the simulated DCCs agreeing better with observations whereas such effect is absent with Morrison, mainly due to limitations of the saturation adjustment approach for droplet condensation and evaporation.
We utilized a novel online mass spectrometry method to measure the total concentration of higher alkanes at each carbon number at two different sites in China, allowing us to take into account SOA contributions from all isomers for higher alkanes. We found that higher alkanes account for significant fractions of SOA formation at the two sites. The contributions are comparable to or even higher than single-ring aromatics, the most-recognized SOA precursors in urban air.
The aim of this work was to identify criteria to obtain the minimum amount of data with the maximum meaning and representativeness in order to delimit risk areas, both in a spatial and temporal respect. We have constructed a model of vertical mercury movements which could be used to predict the location and timing of mercury inhalation risk. Also, we have designed a monitoring strategy to identify the relevant criteria, which involved the measurement of gaseous mercury in a vertical section.
Air pollution affects health for millions of people worldwide. This is particularly worrisome for citizens in emerging economies where air quality is often heavily deteriorated. We show how, every year, agricultural burns and forest fires in the grasslands of northern South America increase the concentration of harmful particles in the environment, further worsening air quality for nearly 60 million in this region, even when the fires occur hundreds of kilometers away from urban areas.
This report describes a simple, safe and effective method to prepare nitrate esters of terpenes (carene, limonene, perillic alcohol, beta-pinene and alpha-pinene) which are key oxidation products in the atmosphere. These compounds are implicated in the formation of secondary organic aerosols. A compilation of the relevant spectroscopic data has been presented. The availability of these compounds and their characterization data will enable further study of the structure–reactivity relationships.
NO2 tropospheric vertical columns (TVCDs) and surface concentrations are widely used proxies for NOx emission variations. Through model and observation analyses, we find that satellite NO2 TVCDs provide much better information on anthropogenic NOx emission variations over urban than rural regions. NO2 surface observations, satellite column datasets, and EPA anthropogenic NOx emissions show consistent annual variations over urban regions of the United States with a continuous decrease after 2011.
Biomass burning is one of the largest sources of atmospheric pollutants worldwide. This paper presents an up-to-date compilation of emission factors for over 120 trace gas and aerosol species from the different forms of open vegetation fires and domestic biofuel use, based on an analysis of over 370 published studies. Using these emission factors and current global burning activity data, the annual emissions of important species released by the various types of biomass burning are estimated.
We quantitatively evaluated the relationship between photolysis frequencies and AOD based on 4 years of observational data in Beijing. This study concludes that the influence of aerosol on photolysis frequencies and thus on the rate of oxidation of VOCs and NOx to ozone is important for determining the atmospheric effects of controlling the precursor emissions of these two important air pollutants (aerosols and ozone).
The tornado-scale vortex in the tropical cyclone boundary layer has been speculated in intense hurricanes. A numerical experiment is conducted using the Advanced Weather Research and Forecast model by incorporating the large-eddy simulation technique. The simulated tornado-scale vortex shows the similar features as revealed with the limited observational data. The presence of the tornado-scale vortex also leads to significant gradients in the near surface wind speed and wind gusts.