scholarly journals Global sensitivity of aviation NO<sub>x</sub> effects to the HNO<sub>3</sub>-forming channel of the HO<sub>2</sub> + NO reaction

2013 ◽  
Vol 13 (6) ◽  
pp. 3003-3025 ◽  
Author(s):  
K. Gottschaldt ◽  
C. Voigt ◽  
P. Jöckel ◽  
M. Righi ◽  
R. Deckert ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Rate Coefficient ◽  
Global Climate ◽  
Climate Impact ◽  
Mitigation Strategies ◽  
Climate Simulation ◽  
Nox Emissions ◽  
Global Sensitivity ◽  
Cooling Effects ◽  
The Impact

Abstract. The impact of a recently proposed HNO3-forming channel of the HO2 + NO reaction on atmospheric ozone, methane and their precursors is assessed with the aim to investigate its effects on aviation NOx induced radiative forcing. The first part of the study addresses the differences in stratospheric and tropospheric HOx-NOx chemistry in general, by comparing a global climate simulation without the above reaction to two simulations with different rate coefficient parameterizations for HO2 + NO → HNO3. A possible enhancement of the reaction by humidity, as found by a laboratory study, particularly reduces the oxidation capacity of the atmosphere, increasing methane lifetime significantly. Since methane lifetime is an important parameter for determining global methane budgets, this might affect estimates of the anthropogenic greenhouse effect. In the second part aviation NOx effects are isolated independently for each of the three above simulations. Warming and cooling effects of aircraft NOx emissions are both enhanced when considering the HNO3-forming channel, but the sum is shifted towards negative radiative forcing. Uncertainties associated with the inclusion of the HO2 + NO → HNO3 reaction and with its corresponding rate coefficient propagate a considerable additional uncertainty on estimates of the climate impact of aviation and on NOx-related mitigation strategies.

scholarly journals Global sensitivity of aviation NO<sub>x</sub> effects to the HNO<sub>3</sub>-forming channel of the HO<sub>2</sub>+NO reaction

2012 ◽  
Vol 12 (9) ◽  
pp. 24287-24349
Author(s):  
K. Gottschaldt ◽  
C. Voigt ◽  
P. Jöckel ◽  
M. Righi ◽  
R. Deckert ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Radiative Forcing ◽  
Climate Model ◽  
Rate Coefficient ◽  
Climate Impact ◽  
Mitigation Strategies ◽  
Global Sensitivity ◽  
Mixing Ratios ◽  
Modelling Studies ◽  
The Impact

Abstract. The impact of a recently proposed HNO3-forming channel of the HO2+NO reaction (Butkovskaya et al., 2005, 2007) on atmospheric mixing ratios of ozone, methane and their precursors is assessed with a global stratosphere-troposphere chemistry-climate model. Previous modelling studies applied a rate coefficient that depends only on pressure and temperature. We additionally considered a possible enhancement of the reaction by humidity, as found by a laboratory study (Butkovskaya et al., 2009). This particularly reduces the oxidation capacity of the atmosphere, increasing methane lifetime significantly. The effects of aircraft NOx emissions on atmospheric chemistry are altered when considering the above reaction, resulting in a negative net radiative forcing relative to an atmosphere without aviation NOx. Uncertainties associated with the inclusion of the HO2+NO → HNO3 reaction and with its corresponding rate coefficient propagate a considerable additional uncertainty on estimates of the climate impact of aviation and on NOx-related mitigation strategies.

scholarly journals The global impact of the transport sectors on atmospheric aerosol in 2030 – Part 1: Land transport and shipping

2014 ◽  
Vol 14 (16) ◽  
pp. 22985-23025
Author(s):  
M. Righi ◽  
J. Hendricks ◽  
R. Sausen
Keyword(s):  
Atmospheric Aerosol ◽  
Radiative Forcing ◽  
Global Climate ◽  
Climate Impact ◽  
Radiation Budget ◽  
Intergovernmental Panel ◽  
Surface Level ◽  
Aerosol Module ◽  
Year 2000 ◽  
The Impact

Abstract. Using the EMAC global climate-chemistry model coupled to the aerosol module MADE, we simulate the impact of land transport and shipping emissions on global atmospheric aerosol and climate in 2030. Future emissions of short-lived gas and aerosol species follow the four Representative Concentration Pathways (RCPs) designed in support of the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. We compare the resulting 2030 land-transport- and shipping-induced aerosol concentrations to the ones obtained for the year 2000 in a previous study with the same model configuration. The simulations suggest that black carbon and aerosol nitrate are the most relevant pollutants from land transport in 2000 and 2030, but their impacts are characterized by very strong regional variations during this time period. Europe and North America experience a decrease in the land-transport-induced particle pollution, although in these regions this sector remains the dominant source of surface-level pollution in 2030 under all RCPs. In Southeast Asia, on the other hand, a significant increase is simulated, but in this region the surface-level pollution is still controlled by other sources than land transport. Shipping-induced air pollution is mostly due to aerosol sulfate and nitrate, which show opposite trends towards 2030. Sulfate is strongly reduced as a consequence of sulfur reduction policies in ship-fuels in force since 2010, while nitrate tends to increase due to the excess of ammonia following the reduction in ammonium-sulfate. The aerosol-induced climate impact of both sectors is dominated by aerosol-cloud effects and is projected to decrease between 2000 and 2030, nevertheless still contributing a significant radiative forcing to the Earth's radiation budget.

scholarly journals Regional emission metrics for short-lived climate forcers from multiple models

2016 ◽  
Vol 16 (11) ◽  
pp. 7451-7468 ◽  
Author(s):  
Borgar Aamaas ◽  
Terje K. Berntsen ◽  
Jan S. Fuglestvedt ◽  
Keith P. Shine ◽  
Nicolas Bellouin
Keyword(s):  
East Asia ◽  
Radiative Forcing ◽  
Climate Models ◽  
Global Climate ◽  
Climate Impact ◽  
Ozone Precursors ◽  
Direct Forcing ◽  
Rf Values ◽  
Global Temperature Change ◽  
The Impact

Abstract. For short-lived climate forcers (SLCFs), the impact of emissions depends on where and when the emissions take place. Comprehensive new calculations of various emission metrics for SLCFs are presented based on radiative forcing (RF) values calculated in four different (chemical-transport or coupled chemistry–climate) models. We distinguish between emissions during summer (May–October) and winter (November–April) for emissions in Europe and East Asia, as well as from the global shipping sector and global emissions. The species included in this study are aerosols and aerosol precursors (BC, OC, SO2, NH3), as well as ozone precursors (NOx, CO, VOCs), which also influence aerosols to a lesser degree. Emission metrics for global climate responses of these emissions, as well as for CH4, have been calculated using global warming potential (GWP) and global temperature change potential (GTP), based on dedicated RF simulations by four global models. The emission metrics include indirect cloud effects of aerosols and the semi-direct forcing for BC. In addition to the standard emission metrics for pulse and sustained emissions, we have also calculated a new emission metric designed for an emission profile consisting of a ramping period of 15 years followed by sustained emissions, which is more appropriate for a gradual implementation of mitigation policies.For the aerosols, the emission metric values are larger in magnitude for emissions in Europe than East Asia and for summer than winter. A variation is also observed for the ozone precursors, with largest values for emissions in East Asia and winter for CO and in Europe and summer for VOCs. In general, the variations between the emission metrics derived from different models are larger than the variations between regions and seasons, but the regional and seasonal variations for the best estimate also hold for most of the models individually. Further, the estimated climate impact of an illustrative mitigation policy package is robust even when accounting for the fact that the magnitude of emission metrics for different species in a given model is correlated. For the ramping emission metrics, the values are generally larger than for pulse or sustained emissions, which holds for all SLCFs. For SLCFs mitigation policies, the dependency of metric values on the region and season of emission should be considered.

scholarly journals Process-oriented analysis of aircraft soot-cirrus interactions constrains the climate impact of aviation

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Bernd Kärcher ◽  
Fabian Mahrt ◽  
Claudia Marcolli
Keyword(s):  
Radiative Forcing ◽  
Large Scale ◽  
Climate Models ◽  
Climate Model ◽  
Global Climate ◽  
Climate Impact ◽  
Global Climate Models ◽  
Soot Particles ◽  
Cloud Ice ◽  
The Impact

AbstractFully accounting for the climate impact of aviation requires a process-level understanding of the impact of aircraft soot particle emissions on the formation of ice clouds. Assessing this impact with the help of global climate models remains elusive and direct observations are lacking. Here we use a high-resolution cirrus column model to investigate how aircraft-emitted soot particles, released after ice crystals sublimate at the end of the lifetime of contrails and contrail cirrus, perturb the formation of cirrus. By allying cloud simulations with a measurement-based description of soot-induced ice formation, we find that only a small fraction (<1%) of the soot particles succeeds in forming cloud ice alongside homogeneous freezing of liquid aerosol droplets. Thus, soot-perturbed and homogeneously-formed cirrus fundamentally do not differ in optical depth. Our results imply that climate model estimates of global radiative forcing from interactions between aircraft soot and large-scale cirrus may be overestimates. The improved scientific understanding reported here provides a process-based underpinning for improved climate model parametrizations and targeted field observations.

scholarly journals Multimodel emission metrics for regional emissions of short lived climate forcers

2015 ◽  
Vol 15 (18) ◽  
pp. 26089-26130 ◽  
Author(s):  
B. Aamaas ◽  
T. K. Berntsen ◽  
J. S. Fuglestvedt ◽  
K. P. Shine ◽  
N. Bellouin
Keyword(s):  
East Asia ◽  
Radiative Forcing ◽  
Climate Models ◽  
Global Climate ◽  
Winter Season ◽  
Climate Impact ◽  
Mitigation Policy ◽  
Ozone Precursors ◽  
Rf Values ◽  
The Impact

Abstract. For short lived climate forcers (SLCFs), the impact of emissions depends on where and when the emissions take place. Comprehensive new calculations of various emission metrics for SLCFs are presented based on radiative forcing (RF) values calculated in four different (chemistry-transport or coupled-chemistry climate) models. We distinguish between emissions during summer (May–October) and winter season (November–April) for emissions from Europe, East Asia, as well as the global shipping sector. The species included in this study are aerosols and aerosols precursors (BC, OC, SO2, NH3), and ozone precursors (NOx, CO, VOC), which also influence aerosols, to a lesser degree. Emission metrics for global climate responses of these emissions, as well as for CH4, have been calculated relative to CO2, using Global Warming Potential (GWP) and Global Temperature change Potential (GTP), based on dedicated RF simulations by four global models. The emission metrics include indirect cloud effects of aerosols and the semi-direct forcing for BC. In addition to the standard emission metrics for pulse and sustained emissions, we have also calculated a new emission metric designed for an emission profile consisting of a ramp up period of 15 years followed by sustained emissions, which is more appropriate for a gradual implementation of mitigation policies. For the aerosols, the emission metric values are larger in magnitude for Europe than East Asia and for summer than winter. A variation is also observed for the ozone precursors, with largest values in East Asia and winter for CO and in Europe and summer for VOC. In general, the variations between the emission metrics derived from different models are larger than the variations between regions and seasons, but the regional and seasonal variations for the best estimate also hold for most of the models individually. Further, the estimated climate impact of a mitigation policy package is robust even when accounting for correlations. For the ramp up emission metrics, the values are generally larger than for pulse or sustained emissions, which holds for all SLCFs. For a potential SLCFs mitigation policy, the dependency of metric values on the region and season of emission should be considered.

scholarly journals A strategy for climate evaluation of aircraft technology: an efficient climate impact assessment tool – AirClim

2007 ◽  
Vol 7 (4) ◽  
pp. 12185-12229 ◽  
Author(s):  
V. Grewe ◽  
A. Stenke
Keyword(s):  
Climate Change ◽  
Radiative Forcing ◽  
Climate Impact ◽  
Climate Impacts ◽  
Assessment Tools ◽  
Nox Emissions ◽  
Near Surface ◽  
Temperature Changes ◽  
Concentration Changes ◽  
The Impact

Abstract. Climate change is a challenge to society and to cope with requires assessment tools which are suitable to evaluate new technology options with respect to their impact on climate. Here we present AirClim, a model which comprises a linearisation of the processes occurring from the emission to an estimate in near surface temperature change, which is presumed to be a reasonable indicator for climate change. The model is designed to be applicable to aircraft technology, i.e.~the climate agents CO2, H2O, CH4 and O3 (latter two resulting from NOx-emissions) and contrails are taken into account. It employs a number of precalculated atmospheric data and combines them with aircraft emission data to obtain the temporal evolution of atmospheric concentration changes, radiative forcing and temperature changes. The linearisation is based on precalculated data derived from 25 steady-state simulations of the state-of-the-art climate-chemistry model E39/C, which include sustained normalised emissions at various atmospheric regions. The results show that strongest climate impacts from ozone changes occur for emissions in the tropical upper troposphere (60 mW/m²; 80 mK for 1 TgN emitted), whereas from methane in the middle tropical troposphere (–2.7% change in methane lifetime; –30 mK per TgN). The estimate of the temperature changes caused by the individual climate agents takes into account a perturbation lifetime, related to the region of emission. A comparison of this approach with results from the TRADEOFF and SCENIC projects shows reasonable agreement with respect to concentration changes, radiative forcing, and temperature changes. The total impact of a supersonic fleet on radiative forcing (mainly water vapour) is reproduced within 5%. For subsonic air traffic (sustained emissions after 2050) results show that although ozone-radiative forcing is much less important than that from CO2 for the year 2100. However the impact on temperature is of comparable size even when taking into account temperature decreases from CH4. That implies that all future measures for climate stabilisation should concentrate on both CO2 and NOx emissions. A direct comparison of super- with subsonic aircraft (250 passengers, 5400 nm) reveals a 5 times higher climate impact of supersonics.

scholarly journals The global impact of the transport sectors on atmospheric aerosol in 2030 – Part 1: Land transport and shipping

2015 ◽  
Vol 15 (2) ◽  
pp. 633-651 ◽  
Author(s):  
M. Righi ◽  
J. Hendricks ◽  
R. Sausen
Keyword(s):  
Atmospheric Chemistry ◽  
Atmospheric Aerosol ◽  
Radiative Forcing ◽  
Global Climate ◽  
Climate Impact ◽  
Radiation Budget ◽  
Intergovernmental Panel ◽  
Surface Level ◽  
Aerosol Dynamics ◽  
The Impact

Abstract. Using the EMAC (ECHAM/MESSy Atmospheric Chemistry) global climate-chemistry model coupled to the aerosol module MADE (Modal Aerosol Dynamics model for Europe, adapted for global applications), we simulate the impact of land transport and shipping emissions on global atmospheric aerosol and climate in 2030. Future emissions of short-lived gas and aerosol species follow the four Representative Concentration Pathways (RCPs) designed in support of the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. We compare the resulting 2030 land-transport- and shipping-induced aerosol concentrations to the ones obtained for the year 2000 in a previous study with the same model configuration. The simulations suggest that black carbon and aerosol nitrate are the most relevant pollutants from land transport in 2000 and 2030 and their impacts are characterized by very strong regional variations during this time period. Europe and North America experience a decrease in the land-transport-induced particle pollution, although in these regions this sector remains a major source of surface-level pollution in 2030 under all RCPs. In Southeast Asia, however, a significant increase is simulated, but in this region the surface-level pollution is still controlled by other sources than land transport. Shipping-induced air pollution is mostly due to aerosol sulfate and nitrate, which show opposite trends towards 2030. Sulfate is strongly reduced as a consequence of sulfur reduction policies in ship fuels in force since 2010, while nitrate tends to increase due to the excess of ammonia following the reduction in ammonium sulfate. The aerosol-induced climate impact of both sectors is dominated by aerosol-cloud effects and is projected to decrease between 2000 and 2030, nevertheless still contributing a significant radiative forcing to Earth's radiation budget.

Revisiting the Krakatau 1883 Volcanic Aerosol Dispersal 

2021 ◽  
Author(s):  
Rafael Castro ◽  
Tushar Mittal ◽  
Stephen Self
Keyword(s):  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Volcanic Eruptions ◽  
Climate Impact ◽  
Volcanic Plume ◽  
Quasi Biennial Oscillation ◽  
Aerosol Cloud ◽  
Pinatubo Eruption ◽  
The Impact

&lt;p&gt;The 1883 Krakatau eruption is one of the most well-known historical volcanic eruptions due to its significant global climate impact as well as first recorded observations of various aerosol associated optical and physical phenomena. Although much work has been done on the former by comparison of global climate model predictions/ simulations with instrumental and proxy climate records, the latter has surprisingly not been studied in similar detail. In particular, there is a wealth of observations of vivid red sunsets, blue suns, and other similar features, that can be used to analyze the spatio-temporal dispersal of volcanic aerosols in summer to winter 1883. Thus, aerosol cloud dispersal after the Krakatau eruption can be estimated, bolstered by aerosol cloud behavior as monitored by satellite-based instrument observations after the 1991 Pinatubo eruption. This is one of a handful of large historic eruptions where this analysis can be done (using non-climate proxy methods). In this study, we model particle trajectories of the Krakatau eruption cloud using the Hysplit trajectory model and compare our results with our compiled observational dataset (principally using Verbeek 1884, the Royal Society report, and Kiessling 1884).&lt;/p&gt;&lt;p&gt;In particular, we explore the effect of different atmospheric states - the quasi-biennial oscillation (QBO) which impacts zonal movement of the stratospheric volcanic plume - to estimate the phase of the QBO in 1883 required for a fast-moving westward cloud. Since this alone is unable to match the observed latitudinal spread of the aerosols, we then explore the impact of an&amp;#160; umbrella cloud (2000 km diameter) that almost certainly formed during such a large eruption. A large umbrella cloud, spreading over ~18 degrees within the duration of the climax of the eruption (6-8 hours), can lead to much quicker latitudinal spread than a point source (vent). We will discuss the results of the combined model (umbrella cloud and correct QBO phase) with historical accounts and observations, as well as previous work on the 1991 Pinatubo eruption. We also consider the likely impacts of water on aerosol concentrations and the relevance of this process for eruptions with possible significant seawater interactions, like Krakatau. We posit that the role of umbrella clouds is an under-appreciated, but significant, process for beginning to model the climatic impacts of large volcanic eruptions.&lt;/p&gt;

scholarly journals Sensitivity of black carbon concentrations and climate impact to aging and scavenging

2016 ◽  
Author(s):  
Marianne T. Lund ◽  
Terje K. Berntsen ◽  
Bjørn H. Samset
Keyword(s):  
Nitric Acid ◽  
Black Carbon ◽  
Radiative Forcing ◽  
Mitigation Strategies ◽  
The Arctic ◽  
Climate Mitigation ◽  
Vertical Profiles ◽  
The Impact ◽  
Model Measurement ◽  
Global Mean

Abstract. Despite recent improvements, significant uncertainties in global modeling of black carbon (BC) aerosols persist, posing important challenges for the design and evaluation of effective climate mitigation strategies targeted at BC emission reductions. Here we investigate the sensitivity of BC concentrations in the chemistry-transport model OsloCTM2 with the microphysical aerosol parameterization M7 (OsloCTM2-M7) to parameters controlling aerosol aging and scavenging. We focus on Arctic surface concentrations and remote region BC vertical profiles, and introduce a novel treatment of condensation of nitric acid on BC. The OsloCTM2-M7 underestimates annual averaged BC surface concentrations, with a mean normalized bias of −0.55. The seasonal cycle and magnitude of Arctic BC surface concentrations is improved compared to previous OsloCTM2 studies, but model-measurement discrepancies during spring remain. High-altitude BC over the Pacific is overestimated compared with measurements from the HIPPO campaigns. We find that a shorter global BC lifetime improves the agreement with HIPPO, in line with other recent studies. Several processes can achieve this, including allowing for convective scavenging of hydrophobic BC and reducing the amount of soluble material required for aging. Simultaneously, the concentrations in the Arctic are reduced, resulting in poorer agreement with measurements in part of the region. A first step towards inclusion of aging by nitrate in OsloCTM2-M7 is made by allowing for condensation of nitric acid on BC. This results in a faster aging and reduced lifetime, and in turn to a better agreement with the HIPPO measurements. On the other hand, model-measurement discrepancies in the Arctic are exacerbated. Work to further improve this parameterization is needed. The impact on global mean radiative forcing (RF) and surface temperature response (TS) in our experiments is estimated. Compared to the baseline, decreases in global mean direct RF on the order of 10–30 % of the total pre-industrial to present BC direct RF is estimated for the experiments that result in the largest changes in BC concentrations. We show that globally tuning parameters related to BC aging and scavenging can improve the representation of BC vertical profiles in the OsloCTM2-M7 compared with observations. Our results also show that such improvements can result from changes in several processes and often depend on assumptions about uncertain parameters such as the BC ice nucleating efficiency and the change in hygroscopicity with aging. It is also important to be aware of potential tradeoffs in model performance between different regions. Other important sources of uncertainty, particularly for Arctic BC, such as model resolution has not been investigated here. Our results underline the importance of more observations and experimental data to improve process understanding and thus further constrain models.

scholarly journals Hindcasting and forecasting of regional methane from coal mine emissions in the Upper Silesian Coal Basin using the online nested global regional chemistry–climate model MECO(n) (MESSy v2.53)

2020 ◽  
Vol 13 (4) ◽  
pp. 1925-1943 ◽  
Author(s):  
Anna-Leah Nickl ◽  
Mariano Mertens ◽  
Anke Roiger ◽  
Andreas Fix ◽  
Axel Amediek ◽  
...  
Keyword(s):  
Coal Mining ◽  
Spatial Resolution ◽  
Radiative Forcing ◽  
Climate Model ◽  
Mitigation Strategies ◽  
Climate Mitigation ◽  
Coal Basin ◽  
Airborne Measurements ◽  
Upper Silesian Coal Basin ◽  
The Impact

Abstract. Methane is the second most important greenhouse gas in terms of anthropogenic radiative forcing. Since pre-industrial times, the globally averaged dry mole fraction of methane in the atmosphere has increased considerably. Emissions from coal mining are one of the primary anthropogenic methane sources. However, our knowledge about different sources and sinks of methane is still subject to great uncertainties. Comprehensive measurement campaigns and reliable chemistry–climate models, are required to fully understand the global methane budget and to further develop future climate mitigation strategies. The CoMet 1.0 campaign (May to June 2018) combined airborne in situ, as well as passive and active remote sensing measurements to quantify the emissions from coal mining in the Upper Silesian Coal Basin (USCB, Poland). Roughly 502 kt of methane is emitted from the ventilation shafts per year. In order to help with the flight planning during the campaigns, we performed 6 d forecasts using the online coupled, three-time nested global and regional chemistry–climate model MECO(n). We applied three-nested COSMO/MESSy instances going down to a spatial resolution of 2.8 km over the USCB. The nested global–regional model system allows for the separation of local emission contributions from fluctuations in the background methane. Here, we introduce the forecast set-up and assess the impact of the model's spatial resolution on the simulation of methane plumes from the ventilation shafts. Uncertainties in simulated methane mixing ratios are estimated by comparing different airborne measurements to the simulations. Results show that MECO(3) is able to simulate the observed methane plumes and the large-scale patterns (including vertically integrated values) reasonably well. Furthermore, we obtain reasonable forecast results up to forecast day four.

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