Emission of trace gases and aerosols from biomass burning – an updated assessment Atmospheric Chemistry and Physics DOI 10.5194/acp-19-8523-2019 4 July 2019 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. Read more
Mid-Holocene climate change over China: model–data discrepancy Climate of the Past DOI 10.5194/cp-15-1223-2019 2 July 2019 The mid-Holocene has been an excellent target for comparing models and data. This work shows that, over China, all the ocean–atmosphere general circulation models involved in PMIP3 show a very large discrepancy with pollen data reconstruction when comparing annual and seasonal temperature. It demonstrates that to reconcile models and data and to capture the signature of seasonal thermal response, it is necessary to integrate non-linear processes, particularly those related to vegetation changes. Read more
Alluvial channel response to environmental perturbations: fill-terrace formation and sediment-signal disruption Earth Surface Dynamics DOI 10.5194/esurf-7-609-2019 1 July 2019 We performed seven physical experiments to explore terrace formation and sediment export from a braided alluvial river system that is perturbed by changes in water discharge, sediment supply, or base level. Each perturbation differently affects (1) the geometry of terraces and channels, (2) the timing of terrace formation, and (3) the transient response of sediment discharge. Our findings provide guidelines for interpreting fill terraces and sediment export from fluvial systems. Read more
Contrail cirrus radiative forcing for future air traffic Atmospheric Chemistry and Physics DOI 10.5194/acp-19-8163-2019 27 June 2019 The climate impact of air traffic is to a large degree caused by changes in cirrus cloudiness resulting from the formation of contrails. We use an atmospheric climate model with a contrail cirrus parameterization to investigate the climate impact of contrail cirrus for the year 2050. The strong increase in contrail cirrus radiative forcing due to the projected increase in air traffic volume cannot be compensated for by the reduction of soot emissions and by improvements in propulsion efficiency. Read more
Evaluating biases in filter-based aerosol absorption measurements using photoacoustic spectroscopy Atmospheric Measurement Techniques DOI 10.5194/amt-12-3417-2019 27 June 2019 This research project assesses biases in traditional, filter-based, aerosol absorption measurements by comparison to state-of-the-art, non-filter-based, or in situ, measurements. We assess biases in traditional absorption measurements for three main aerosol types, including dust and fresh and aged biomass burning aerosols. The main results of this study are that the traditional and state-of-the-art absorption measurements are well correlated and that biases in the former are up to 45 %. Read more
Detecting layer height of smoke aerosols over vegetated land and water surfaces via oxygen absorption bands: hourly results from EPIC/DSCOVR in deep space Atmospheric Measurement Techniques DOI 10.5194/amt-12-3269-2019 20 June 2019 Detecting aerosol layer height from space is challenging. The traditional method relies on active sensors such as lidar that provide the detailed vertical structure of the aerosol profile but is costly with limited spatial coverage (more than 1 year is needed for global coverage). Here we developed a passive remote sensing technique that uses backscattered sunlight to retrieve smoke aerosol layer height over both water and vegetated surfaces from a sensor 1.5 million kilometers from the Earth. Read more
Technical note: A microcontroller-based automatic rain sampler for stable isotope studies Hydrology and Earth System Sciences DOI 10.5194/hess-23-2637-2019 19 June 2019 Most commercial automatic rain samplers are costly and do not prevent evaporation from the collection bottles. Hence, we have developed a microcontroller-based collector enabling timer-actuated integral rain sampling. The simple, low-cost device is robust and effectively minimizes post-sampling evaporation. The excellent performance of the collector during an evaporation experiment in a lab oven suggests that even multi-week field deployments in warm climates are feasible. Read more
Induced seismicity in geologic carbon storage Solid Earth DOI 10.5194/se-10-871-2019 19 June 2019 To meet the goal of the Paris Agreement to limit temperature increase below 2 ºC, geologic carbon storage (GCS) will be necessary at the gigatonne scale. But to successfully deploy GCS, seismicity induced by CO2injection should be controlled and maintained below a threshold that does not generate nuisances to the population. We conclude that felt induced seismicity can be minimized provided that a proper site characterization, monitoring and pressure management are performed. Read more
Aerosol pH and its driving factors in Beijing Atmospheric Chemistry and Physics DOI 10.5194/acp-19-7939-2019 17 June 2019 Aerosol acidity plays a key role in secondary aerosol formation. To provide a more comprehensive reference for aerosol pH and a basis for controlling secondary aerosol generation, this study used the latest data covering four seasons and different particle sizes to obtain the characteristics of aerosol pH and explore the main factors affecting aerosol pH and gas–particle partitioning in the Beijing area. Read more
Including the efficacy of land ice changes in deriving climate sensitivity from paleodata Earth System Dynamics DOI 10.5194/esd-10-333-2019 14 June 2019 Processes causing the same global-average radiative forcing might lead to different global temperature changes. We expand the theoretical framework by which we calculate paleoclimate sensitivity with an efficacy factor. Applying the revised approach to radiative forcing caused by CO2and land ice albedo perturbations, inferred from data of the past 800 000 years, gives a new paleo-based estimate of climate sensitivity. Read more
A sampler for atmospheric volatile organic compounds by copter unmanned aerial vehicles Atmospheric Measurement Techniques DOI 10.5194/amt-12-3123-2019 13 June 2019 Volatile organic compound (VOC) emissions influence air quality and particulate distributions, particularly in major source regions such as the Amazon. A sampler for collecting VOCs from an unmanned aerial vehicle (UAV) is described. Field tests of its performance and an initial example data set collected in the Amazon are also presented. The low cost, ease of use, and maneuverability of UAVs give this method the potential to significantly advance knowledge of the spatial distribution of VOCs. Read more
Analysis of an extreme weather event in a hyper-arid region using WRF-Hydro coupling, station, and satellite data Natural Hazards and Earth System Sciences DOI 10.5194/nhess-19-1129-2019 13 June 2019 The work addresses the need for reliable precipitation forecasts in hyper-arid environments through state-of-the-art hydro-meteorological modeling. Accounting for land–atmosphere interactions in the applied model is shown to improve the accuracy of precipitation output. The chain of events controlling the soil moisture–precipitation feedback are diagnosed and verified by in situ observations and satellite data. Read more
Global distribution of methane emissions, emission trends, and OH concentrations and trends inferred from an inversion of GOSAT satellite data for 2010–2015 Atmospheric Chemistry and Physics DOI 10.5194/acp-19-7859-2019 12 June 2019 We use 2010–2015 satellite observations of atmospheric methane to improve estimates of methane emissions and their trends, as well as the concentration and trend of tropospheric OH (hydroxyl radical, methane’s main sink). We find overestimates of Chinese coal and Middle East oil/gas emissions in the prior estimate. The 2010–2015 growth in methane is attributed to an increase in emissions from India, China, and areas with large tropical wetlands. The contribution from OH is small in comparison. Read more
Responses of an abyssal meiobenthic community to short-term burial with crushed nodule particles in the south-east Pacific Biogeosciences DOI 10.5194/bg-16-2329-2019 6 June 2019 To elucidate the potential effects of crushed nodule particle deposition on abyssal meiobenthos, we covered abyssal soft sediment in the Peru Basin (4200 m depth) with approximately 2 cm of this nodule material for 11 d. About half of the meiobenthos migrated from the sediment into the added material, and nematode feeding type proportions in that added layer were altered. These results considerably contribute to our understanding of the short-term responses of deep-sea meiobenthos to burial. Read more
Aerosol size distributions during the Atmospheric Tomography Mission (ATom): methods, uncertainties, and data products Atmospheric Measurement Techniques DOI 10.5194/amt-12-3081-2019 6 June 2019 From 2016 to 2018 a NASA aircraft profiled the atmosphere from 180 m to ~12 km from the Arctic to the Antarctic over both the Pacific and Atlantic oceans. This program, ATom, sought to sample atmospheric chemical composition to compare with global climate models. We describe the how measurements of particulate matter were made during ATom, and show that the instrument performance was excellent. Data from this project can be used with confidence to evaluate models and compare with satellites. Read more
The Bortoluzzi Mud Volcano (Ionian Sea, Italy) and its potential for tracking the seismic cycle of active faults Solid Earth DOI 10.5194/se-10-741-2019 4 June 2019 The Ionian Sea in southern Italy is at the center of active convergence between the Eurasian and African plates, with many known Mw > 7.0 earthquakes. Here, a recently discovered mud volcano (called the Bortoluzzi Mud Volcano or BMV) was surveyed during the Seismofaults 2017 cruise (May 2017). The BMV is the active emergence of crustal fluids probably squeezed up during the seismic cycle. As such, the BMV may potentially be used to track the seismic cycle of active faults. Read more
Glacial CO2 decrease and deep-water deoxygenation by iron fertilization from glaciogenic dust Climate of the Past DOI 10.5194/cp-15-981-2019 4 June 2019 Proxy records of glacial oxygen change provide constraints on the contribution of the biological pump to glacial CO2 decrease. Here, we report our numerical simulation which successfully reproduces records of glacial oxygen changes and shows the significance of iron supply from glaciogenic dust. Our model simulations clarify that the enhanced efficiency of the biological pump is responsible for glacial CO2 decline of more than 30 ppm and approximately half of deep-ocean deoxygenation. Read more
Telling the boiling frog what he needs to know: why climate change risks should be plotted as probability over time Geoscience Communication DOI 10.5194/gc-2-95-2019 29 May 2019 Humanity’s situation with respect to climate change is sometimes likened to that of a frog in a slow-boiling pot of water. But are we telling the frog what he needs to know? Most climate science is communicated to governments in the form of predictions of what is most likely to happen. I argue it should instead answer the following questions: what is the worst that could happen, and how likely will that become as time goes by? The risks and need to act will then become much clearer to see. Read more
Impacts of Three Gorges Dam’s operation on spatial–temporal patterns of tide–river dynamics in the Yangtze River estuary, China Ocean Science DOI 10.5194/os-15-583-2019 28 May 2019 In this study, we assessed the impacts of the world’s largest dam, the Three Gorges Dam (TGD), on tide–river dynamics and concluded that the strongest impacts occurred during autumn and winter due to the TGD’s operation. The results obtained will hopefully enhance our understanding of the impacts of large-scale human interventions on estuarine hydrodynamics and guide effective and sustainable water management in the Yangtze River estuary and other estuaries with substantial freshwater discharge. Read more
Recrystallization processes, microstructure and crystallographic preferred orientation evolution in polycrystalline ice during high-temperature simple shear The Cryosphere DOI 10.5194/tc-13-1495-2019 27 May 2019 Ice mechanics is an important tool to better predict the response of glaciers or polar ice sheets to climate variations. Nevertheless our current predictive abilities are limited as the microscale mechanisms responsible for ice creep are poorly identified. We show in this study, using state-of-the-art experimental techniques, which recrystallization processes control ice deformation. This will allow realistic simulations, necessary to predict the long-term effects on ice landmasses. Read more