Opinion: Coordinated development of emission inventories for climate forcers and air pollutants Atmospheric Chemistry and Physics DOI 10.5194/acp-22-13201-2022 2 January 2023 Emissions into the atmosphere of greenhouse gases (GHGs) and air pollutants, quantified in emission inventories, impact human health, ecosystems, and the climate. We review how air pollutant and GHG inventory activities have historically been structured and their different uses and requirements. We discuss the benefits of increasing coordination between air pollutant and GHG inventory development efforts, but also caution that there are differences in appropriate methodologies and applications. Read more
Cloud adjustments from large-scale smoke–circulation interactions strongly modulate the southeastern Atlantic stratocumulus-to-cumulus transition Atmospheric Chemistry and Physics DOI 10.5194/acp-22-12113-2022 14 December 2022 Smoke from southern Africa blankets the southeast Atlantic from June-October, overlying a major transition region between overcast and scattered clouds. The smoke affects Earth’s radiation budget by absorbing sunlight and changing cloud properties. We investigate these effects in regional climate and large eddy simulation models based on international field campaigns. We find that large-scale circulation changes more strongly affect cloud transitions than smoke microphysical effects in our case. Read more
Bayesian assessment of chlorofluorocarbon (CFC), hydrochlorofluorocarbon (HCFC) and halon banks suggest large reservoirs still present in old equipment Atmospheric Chemistry and Physics DOI 10.5194/acp-22-11125-2022 16 November 2022 Halocarbons contained in equipment continue to be emitted after production has ceased. These “banks” must be carefully accounted for in evaluating compliance with the Montreal Protocol. We extend a Bayesian model to the suite of regulated chemicals subject to banking. We find that banks are substantially larger than previous estimates, and we identify banks by chemical and equipment type whose future emissions will contribute to global warming and delay ozone-hole recovery if left unrecovered. CFC), hydrochlorofluorocarbon (HCFC) and halon banks suggest large reservoirs still present in old equipment">Read more
Quantifying methane emissions from the global scale down to point sources using satellite observations of atmospheric methane Atmospheric Chemistry and Physics DOI 10.5194/acp-22-9617-2022 2 November 2022 We review the capability of satellite observations of atmospheric methane to quantify methane emissions on all scales. We cover retrieval methods, precision requirements, inverse methods for inferring emissions, source detection thresholds, and observations of system completeness. We show that current instruments already enable quantification of regional and national emissions including contributions from large point sources. Coverage and resolution will increase significantly in coming years. Read more
Stable water isotope signals in tropical ice clouds in the West African monsoon simulated with a regional convection-permitting model Atmospheric Chemistry and Physics DOI 10.5194/acp-22-8863-2022 14 October 2022 The Earth’s water cycle contains the common H2O molecule but also the less abundant, heavier HDO. We use their different physical properties to study tropical ice clouds in model simulations of the West African monsoon. Isotope signals reveal different processes through which ice clouds form and decay in deep-convective and widespread cirrus. Previously observed variations in upper-tropospheric vapour isotopes are explained by microphysical processes in convective updraughts and downdraughts. Read more
Black carbon aerosol reductions during COVID-19 confinement quantified by aircraft measurements over Europe Atmospheric Chemistry and Physics DOI 10.5194/acp-22-8683-2022 28 September 2022 The abrupt reduction in human activities during the first COVID-19 lockdown created unprecedented atmospheric conditions. We took the opportunity to quantify changes in black carbon (BC) as a major anthropogenic air pollutant. Therefore, we measured BC on board a research aircraft over Europe during the lockdown and compared the results to measurements from 2017. With model simulations we account for different weather conditions and find a lockdown-related decrease in BC of 41 %. COVID-19 confinement quantified by aircraft measurements over Europe">Read more
The Sun’s role in decadal climate predictability in the North Atlantic Atmospheric Chemistry and Physics DOI 10.5194/acp-22-7893-2022 14 September 2022 Solar irradiance varies with a period of approximately 11 years. Using a unique large chemistry-climate model dataset, we investigate the solar surface signal in the North Atlantic and European region and find that it changes over time, depending on the strength of the solar cycle. For the first time, we estimate the potential predictability associated with including realistic solar forcing in a model. These results may improve seasonal to decadal predictions of European climate. Read more
Australian wildfire smoke in the stratosphere: the decay phase in 2020/2021 and impact on ozone depletion Atmospheric Chemistry and Physics DOI 10.5194/acp-22-7417-2022 24 August 2022 We present and discuss 2 years of long-term lidar observations of the largest stratospheric perturbation by wildfire smoke ever observed. The smoke originated from the record-breaking Australian fires in 2019–2020 and affects climate conditions and even the ozone layer in the Southern Hemisphere. The obvious link between dense smoke occurrence in the stratosphere and strong ozone depletion found in the Arctic and in the Antarctic in 2020 can be regarded as a new aspect of climate change. Read more
New insights on the prevalence of drizzle in marine stratocumulus clouds based on a machine learning algorithm applied to radar Doppler spectra Atmospheric Chemistry and Physics DOI 10.5194/acp-22-7405-2022 22 August 2022 Drizzle (small rain droplets) is an important component of warm clouds; however, its existence is poorly understood. In this study, we capitalized on a machine-learning algorithm to develop a drizzle detection method. We applied this algorithm to investigate drizzle occurrence and found out that drizzle is far more ubiquitous than previously thought. This study demonstrates the ubiquitous nature of drizzle in clouds and will improve understanding of the associated microphysical process. Read more
Assessing the consequences of including aerosol absorption in potential stratospheric aerosol injection climate intervention strategies Atmospheric Chemistry and Physics DOI 10.5194/acp-22-6135-2022 3 August 2022 Simulations are presented investigating the influence of moderately absorbing aerosol in the stratosphere to combat the impacts of climate change. A number of detrimental impacts are noted compared to sulfate aerosol, including (i) reduced cooling efficiency, (ii) increased deficits in global precipitation, (iii) delays in the recovery of the stratospheric ozone hole, and (iv) disruption of the stratospheric circulation and the wintertime storm tracks that impact European precipitation. Read more
