A closer look at the invisible: Unprecedented levels of ultrafine particles and the hydrological cycle

2021 ◽  
Author(s):  
Wolfgang Junkermann ◽  
Jorg Hacker
Keyword(s):  
Ultrafine Particles ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Global Climate ◽  
Cloud Condensation Nuclei ◽  
Global Climate Model ◽  
Anthropogenic Sources ◽  
Emission Rates ◽  
Weather Patterns ◽  
Sulphur Emissions

<p>Continental as well as maritime ultrafine particles as cloud condensation nuclei (CCN) are likely initially produced by gas to particle conversion starting with nucleation mode aerosol and slowly (within several hours)  growing into CCN sizes. Although these birth and growing processes were well investigated since about 50 years, the source locations, where the anthropogenic fraction of these particles are preferably formed still remain uncertain as well as the strength of individual natural or anthropogenic sources.</p> <p>We present an analysis based on two decades of airborne studies of number and size distribution measurements across Europe, Australia, Mexico and China on nucleation and Aitken mode particles serving as CCN or their precursors. Selected flight patterns allow source apportionment for typical major sources and even a quantitative estimate of their emission rates. </p> <p>Contrary to current global climate model RCP assumptions with decreasing aerosol from 2005 towards the end of the century trends of ultrafine particles and CCN are no longer correlated to sulphur emissions within the last two decades. Nowadays nitrogen and ammonia chemistry is becoming increasingly important for global anthropogenic nanoparticle particle formation and number concentrations. Due to their impact on the hydrological cycle, changes like a slowdown of raindrop production, an increased latent heat flux into the lower free troposphere, an invigoration of torrential rains and a larger water vapour column density might be the consequences. Such recently observed weather patterns are well in agreement with current observations of regional UFP/CCN concentrations and their timely evolution.</p>

The effect of the photomineralization mechanism on ambient organic aerosols' cloud condensation nuclei and ice nucleation abilities

2020 ◽  
Author(s):  
Silvan Müller ◽  
Nadine Borduas-Dedekind
Keyword(s):  
Climate Model ◽  
Global Climate ◽  
Cloud Condensation Nuclei ◽  
Global Climate Model ◽  
Complex Mixture ◽  
Substantial Effect ◽  
Ice Nucleation ◽  
Anthropogenic Sources ◽  
Wood Smoke ◽  
Condensation Nuclei

<p>Organic aerosol (OA) is an important component of the atmospheric submicron particulate mass, consisting of a complex mixture of organic compounds from natural and anthropogenic sources. During its lifetime of approximately one week in the atmosphere, OA is exposed to sunlight and thus undergoes atmospheric processing through photochemistry. This photochemical aging mechanism is thought to have a substantial effect on the propensity of OA to participate in cloud-forming processes by increasing its cloud condensation nuclei (CCN) activity. However, this effect is not well-constrained, and the influence of photochemistry on the ice nucleation (IN) activity of OA is uncertain. In this study, we aim to better understand how the photomineralization mechanism changes the cloud-forming properties of OA by measuring the CCN and IN abilities of photochemically aged OA of different sources: (1) Laboratory-generated ammonium sulfate-methylglyoxal (a proxy for secondary OA), and ambient OA bulk solutions collected from (2) wood smoke and (3) urban particulate matter in Padua (Italy). The solutions are exposed to UV-B radiation in a photoreactor for up to 25 hour and subsequently analyzed for their IN ability and, following aerosolization, for their CCN ability. To correlate changes in cloud-forming properties with changes in chemical composition due to photomineralization, we measure total organic carbon, UV-Vis absorbance, and CO, CO<sub>2</sub>, acetic acid, formic acid, pyruvic acid and oxalic acid production. Indeed, preliminary data of wood smoke OA highlights photomineralization as an important atmospheric aging process that modifies the CCN ability of OA. By characterizing both the CCN and IN abilities of photochemically aged OA, our study may thus provide important insights into the atmospheric evolution and cloud-forming properties of OA, potentially establishing photomineralization of OA as an important mechanism to consider in regional and global climate model predictions.</p>

scholarly journals A Mathematical Framework for Analysis of Water Tracers. Part II: Understanding Large-Scale Perturbations in the Hydrological Cycle due to CO2 Doubling

2016 ◽  
Vol 29 (18) ◽  
pp. 6765-6782 ◽  
Author(s):  
Hansi K. A. Singh ◽  
Cecilia M. Bitz ◽  
Aaron Donohoe ◽  
Jesse Nusbaumer ◽  
David C. Noone
Keyword(s):  
Moisture Transport ◽  
Large Scale ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Global Climate ◽  
Global Climate Model ◽  
Mathematical Framework ◽  
Surface Evaporation ◽  
And Shifts

Abstract The aerial hydrological cycle response to CO2 doubling from a Lagrangian, rather than Eulerian, perspective is evaluated using information from numerical water tracers implemented in a global climate model. While increased surface evaporation (both local and remote) increases precipitation globally, changes in transport are necessary to create a spatial pattern where precipitation decreases in the subtropics and increases substantially at the equator. Overall, changes in the convergence of remotely evaporated moisture are more important to the overall precipitation change than changes in the amount of locally evaporated moisture that precipitates in situ. It is found that CO2 doubling increases the fraction of locally evaporated moisture that is exported, enhances moisture exchange between ocean basins, and shifts moisture convergence within a given basin toward greater distances between moisture source (evaporation) and sink (precipitation) regions. These changes can be understood in terms of the increased residence time of water in the atmosphere with CO2 doubling, which corresponds to an increase in the advective length scale of moisture transport. As a result, the distance between where moisture evaporates and where it precipitates increases. Analyses of several heuristic models further support this finding.

scholarly journals The value of remote marine aerosol measurements for constraining radiative forcing uncertainty

2020 ◽  
Vol 20 (16) ◽  
pp. 10063-10072 ◽  
Author(s):  
Leighton A. Regayre ◽  
Julia Schmale ◽  
Jill S. Johnson ◽  
Christian Tatzelt ◽  
Andrea Baccarini ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Northern Hemisphere ◽  
Radiative Forcing ◽  
Climate Model ◽  
Global Climate ◽  
Cloud Condensation Nuclei ◽  
Global Climate Model ◽  
Model Parameters ◽  
Marine Aerosol ◽  
Aerosol Emissions

Abstract. Aerosol measurements over the Southern Ocean are used to constrain aerosol–cloud interaction radiative forcing (RFaci) uncertainty in a global climate model. Forcing uncertainty is quantified using 1 million climate model variants that sample the uncertainty in nearly 30 model parameters. Measurements of cloud condensation nuclei and other aerosol properties from an Antarctic circumnavigation expedition strongly constrain natural aerosol emissions: default sea spray emissions need to be increased by around a factor of 3 to be consistent with measurements. Forcing uncertainty is reduced by around 7 % using this set of several hundred measurements, which is comparable to the 8 % reduction achieved using a diverse and extensive set of over 9000 predominantly Northern Hemisphere measurements. When Southern Ocean and Northern Hemisphere measurements are combined, uncertainty in RFaci is reduced by 21 %, and the strongest 20 % of forcing values are ruled out as implausible. In this combined constraint, observationally plausible RFaci is around 0.17 W m−2 weaker (less negative) with 95 % credible values ranging from −2.51 to −1.17 W m−2 (standard deviation of −2.18 to −1.46 W m−2). The Southern Ocean and Northern Hemisphere measurement datasets are complementary because they constrain different processes. These results highlight the value of remote marine aerosol measurements.

scholarly journals Global change in flood and drought intensities under climate change in the 21<sup>st</sup> century

2017 ◽  
Author(s):  
Behzad Asadieh ◽  
Nir Y. Krakauer
Keyword(s):  
21St Century ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Global Climate ◽  
Global Climate Model ◽  
The Arctic ◽  
Simultaneous Increase ◽  
Drought Intensity ◽  
Global Land ◽  
Streamflow Extremes

Abstract. Global warming is expected to intensify the Earth’s hydrological cycle and increase flood and drought risks. Changes in global high and low streamflow extremes over the 21st century under two warming scenarios are analyzed as indicators of hydrologic flood and drought intensity, using an ensemble of bias-corrected global climate model (GCM) fields fed into different global hydrological models (GHMs). Based on multi-model mean, approximately 37 % and 43 % of global land areas are exposed to increases in flood and drought intensities, respectively, by the end of the 21st century under RCP8.5 scenario. The average rates of increase in flood and drought intensities in those areas are projected to be 24.5 % and 51.5 %, respectively. Nearly 10 % of the global land areas are under the potential risk of simultaneous increase in both flood and drought intensities, with average rates of 10.1 % and 19.8 %, respectively; further, these regions tend to be highly populated parts of the globe, currently holding around 30 % of the world’s population (over 2.1 billion people). In a world more than 4 degrees warmer by the end of the 21st century compared to the pre-industrial era (RCP8.5 scenario), increases in flood and drought intensities are projected to be nearly twice as large as in a 2 degree warmer world (RCP2.6 scenario). Results also show that GHMs contribute to more uncertainties in streamflow changes than the GCMs. Under both forcing scenarios, there is high model agreement for significant increases in streamflow of the regions near and above the Arctic Circle, and consequent increases in the freshwater inflow to the Arctic Ocean, while subtropical arid areas experience reduction in streamflow.

scholarly journals A predictive algorithm for wetlands in deep time paleoclimate models

2019 ◽  
Vol 12 (4) ◽  
pp. 1351-1364 ◽  
Author(s):  
David J. Wilton ◽  
Marcus P. S. Badger ◽  
Euripides P. Kantzas ◽  
Richard D. Pancost ◽  
Paul J. Valdes ◽  
...  
Keyword(s):  
Methane Emission ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Grid Cell ◽  
Methane Flux ◽  
Early Eocene ◽  
Emission Rates ◽  
Deep Time ◽  
Vegetation Models

Abstract. Methane is a powerful greenhouse gas produced in wetland environments via microbial action in anaerobic conditions. If the location and extent of wetlands are unknown, such as for the Earth many millions of years in the past, a model of wetland fraction is required in order to calculate methane emissions and thus help reduce uncertainty in the understanding of past warm greenhouse climates. Here we present an algorithm for predicting inundated wetland fraction for use in calculating wetland methane emission fluxes in deep-time paleoclimate simulations. For each grid cell in a given paleoclimate simulation, the algorithm determines the wetland fraction predicted by a nearest-neighbour search of modern-day data in a space described by a set of environmental, climate and vegetation variables. To explore this approach, we first test it for a modern-day climate with variables obtained from observations and then for an Eocene climate with variables derived from a fully coupled global climate model (HadCM3BL-M2.2; Valdes et al., 2017). Two independent dynamic vegetation models were used to provide two sets of equivalent vegetation variables which yielded two different wetland predictions. As a first test, the method, using both vegetation models, satisfactorily reproduces modern day wetland fraction at a course grid resolution, similar to those used in paleoclimate simulations. We then applied the method to an early Eocene climate, testing its outputs against the locations of Eocene coal deposits. We predict global mean monthly wetland fraction area for the early Eocene of 8×106 to 10×106 km2 with a corresponding total annual methane flux of 656 to 909 Tg CH4 yr−1, depending on which of the two different dynamic global vegetation models are used to model wetland fraction and methane emission rates. Both values are significantly higher than estimates for the modern day of 4×106 km2 and around 190 Tg CH4 yr−1 (Poulter et al., 2017; Melton et al., 2013).

scholarly journals A Predictive Algorithm For Wetlands In Deep Time Paleoclimate Models

2018 ◽  
Author(s):  
David J. Wilton ◽  
Marcus Badger ◽  
Euripides P. Kantzas ◽  
Richard D. Pancost ◽  
Paul J. Valdes ◽  
...  
Keyword(s):  
Methane Emission ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Grid Cell ◽  
Methane Flux ◽  
Early Eocene ◽  
Emission Rates ◽  
Deep Time ◽  
Vegetation Models

Abstract. Methane is a powerful greenhouse gas produced in wetland environments via microbial action in anaerobic conditions. If the location and extent of wetlands are unknown, such as for the Earth many millions of years in the past, a model of wetland fraction is required in order to calculate methane emissions and thus help reduce uncertainty in the understanding of past warm greenhouse climates. Here we present an algorithm for predicting inundated wetland fraction for use in calculating wetland methane emission fluxes in deep time paleoclimate simulations. The algorithm determines, for each grid cell in a given paleoclimate simulation, the wetland fraction predicted by a nearest neighbours search of modern day data in a space described by a set of environmental, climate and vegetation variables. To explore this approach, we first test it for a modern day climate with variables obtained from observations and then for an Eocene climate with variables derived from a fully coupled global climate model (HadCM3BL-M2.2). Two independent dynamic vegetation models were used to provide two sets of equivalent vegetation variables which yielded two different wetland predictions. As a first test the method, using both vegetation models, satisfactorily reproduces modern data wetland fraction at a course grid resolution, similar to those used in paleoclimate simulations. We then applied the method to an early Eocene climate, testing its outputs against the locations of Eocene coal deposits. We predict global mean monthly wetland fraction area for the early Eocene of 8 to 10 × 106 km2 with corresponding total annual methane flux of 656 to 909 Tg, depending on which of two different dynamic global vegetation models are used to model wetland fraction and methane emission rates. Both values are significantly higher than estimates for the modern-day of 4 × 106 km2 and around 190 Tg (Poulter et. al. 2017, Melton et. al., 2013).

scholarly journals The sensitivity of the energy budget and hydrological cycle to CO<sub>2</sub> and solar forcing

2013 ◽  
Vol 4 (1) ◽  
pp. 393-428
Author(s):  
N. Schaller ◽  
J. Cermak ◽  
M. Wild ◽  
R. Knutti
Keyword(s):  
Water Vapor ◽  
Energy Budget ◽  
Large Scale ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Global Climate ◽  
Global Climate Model ◽  
Strong Increase ◽  
Solar Forcing ◽  
Co2 Forcing

Abstract. The transient responses of the energy budget and the hydrological cycle to CO2 and solar forcings of the same magnitude in a global climate model are quantified in this study. Idealized simulations are designed to test the assumption that the responses to forcings are linearly additive, i.e. whether the response to individual forcings can be added to estimate the response to the combined forcing, and to understand the physical processes occurring as a response to a surface warming caused by CO2 or solar forcing increases of the same magnitude. For the global climate model considered, the responses of most variables of the energy budget and hydrological cycle, including surface temperature, do not add linearly. A separation of the response into a forcing and a feedback term shows that for precipitation, this non-linearity arises from the feedback term, i.e. from the non-linearity of the temperature response and the changes in the water cycle resulting from it. Further, changes in the energy budget show that less energy is available at the surface for global annual mean latent heat flux, and hence global annual mean precipitation, in simulations of transient CO2 concentration increase compared to simulations with an equivalent transient increase in the solar constant. On the other hand, lower tropospheric water vapor increases more in simulations with CO2 compared to solar forcing increase of the same magnitude. The response in precipitation is therefore more muted compared to the response in water vapor in CO2 forcing simulations, leading to a larger increase in residence time of water vapor in the atmosphere compared to solar forcing simulations. Finally, energy budget calculations show that poleward atmospheric energy transport increases more in solar forcing compared to equivalent CO2 forcing simulations, which is in line with the identified strong increase in large-scale precipitation in solar forcing scenarios.

scholarly journals Global precipitation response to changing forcings since 1870

2011 ◽  
Vol 11 (18) ◽  
pp. 9961-9970 ◽  
Author(s):  
A. Bichet ◽  
M. Wild ◽  
D. Folini ◽  
C. Schär
Keyword(s):  
Greenhouse Gas ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Global Climate ◽  
Global Climate Model ◽  
Internal Variability ◽  
Temperature And Precipitation ◽  
Global Land ◽  
Climate Forcings ◽  
Aerosol Emissions

Abstract. Predicting and adapting to changes in the hydrological cycle is one of the major challenges for the 21st century. To better estimate how it will respond to future changes in climate forcings, it is crucial to understand how the hydrological cycle has evolved in the past and why. In our study, we use an atmospheric global climate model with prescribed sea surface temperatures (SSTs) to investigate how, in the period 1870–2005, changing climate forcings have affected the global land temperature and precipitation. We show that between 1870 and 2005, prescribed SSTs (encapsulating other forcings and internal variability) determine the decadal and interannual variabilities of the global land temperature and precipitation, mostly via their influence in the tropics (25° S–25° N). In addition, using simulations with prescribed SSTs and considering the atmospheric response alone, we find that between 1930 and 2005 increasing aerosol emissions have reduced the global land temperature and precipitation by up to 0.4 °C and 30 mm yr−1, respectively, and that between about 1950 and 2005 increasing greenhouse gas concentrations have increased them by up to 0.25 °C and 10 mm yr−1, respectively. Finally, we suggest that between about 1950 and 1970, increasing aerosol emissions had a larger impact on the hydrological cycle than increasing greenhouse gas concentrations.

scholarly journals Hydrological simulations driven by RCM climate scenarios at basin scale in the Po River, Italy

2014 ◽  
Vol 364 ◽  
pp. 128-133 ◽  
Author(s):  
R. Vezzoli ◽  
M. Del Longo ◽  
P. Mercogliano ◽  
M. Montesarchio ◽  
S. Pecora ◽  
...  
Keyword(s):  
Climate Model ◽  
Hydrological Cycle ◽  
Global Climate ◽  
Global Climate Model ◽  
Global Climate Models ◽  
Balance Model ◽  
Climate Change Scenarios ◽  
Po River ◽  
Basin Scale ◽  
The Future

Abstract. River discharges are the main expression of the hydrological cycle and are the results of climate natural variability. The signal of climate changes occurrence raises the question of how it will impact on river flows and on their extreme manifestations: floods and droughts. This question can be addressed through numerical simulations spanning from the past (1971) to future (2100) under different climate change scenarios. This work addresses the capability of a modelling chain to reproduce the observed discharge of the Po River over the period 1971–2000. The modelling chain includes climate and hydrological/hydraulic models and its performance is evaluated through indices based on the flow duration curve. The climate datasets used for the 1971–2000 period are (a) a high resolution observed climate dataset, and COSMO-CLM regional climate model outputs with (b) perfect boundary condition, ERA40 Reanalysis, and (c) suboptimal boundary conditions provided by the global climate model CMCC–CM. The aim of the different simulations is to evaluate how the uncertainties introduced by the choice of the regional and/or global climate models propagate in the simulated discharges. This point is relevant to interpret the results of the simulated discharges when scenarios for the future are considered. The hydrological/hydraulic components are simulated through a physically-based distributed model (TOPKAPI) and a water balance model at the basin scale (RIBASIM). The aim of these first simulations is to quantify the uncertainties introduced by each component of the modelling chain and their propagation. Estimation of the overall uncertainty is relevant to correctly understand the future river flow regimes. The results show how bias correction algorithms can help in reducing the overall uncertainty associated to the different stages of the modelling chain.

scholarly journals Global precipitation response to changing external forcings since 1870

2011 ◽  
Vol 11 (3) ◽  
pp. 9375-9405
Author(s):  
A. Bichet ◽  
M. Wild ◽  
D. Folini ◽  
C. Schär
Keyword(s):  
Climate Model ◽  
Decadal Variability ◽  
Hydrological Cycle ◽  
Global Climate ◽  
Global Climate Model ◽  
Temperature And Precipitation ◽  
Global Land ◽  
Climate Forcings ◽  
Aerosol Emissions ◽  
Global Precipitation

Abstract. Predicting and adapting to changes in the hydrological cycle is one of the major challenges for the twenty-first century. To better estimate how it will respond to future changes in climate forcings, it is crucial to understand how it has evolved in the past and why. In our study, we use an atmospheric global climate model with prescribed sea surface temperatures (SSTs) to investigate how changing external climate forcings have affected global land temperature and precipitation in the period 1870–2005. We show that prescribed SSTs (encapsulating other forcings) are the dominant forcing driving the decadal variability of land temperature and precipitation since 1870. On top of this SSTs forcing, we also find that the atmosphere-only response to increasing aerosol emissions is a reduction in global land temperature and precipitation by up to 0.4 °C and 30 mm year−1, respectively, between about 1930 and 2000. Similarly, the atmosphere-only response to increasing greenhouse gas concentrations is an increase in global land temperature and precipitation by up to 0.25 °C and 10 mm year−1, respectively, between about 1950 and 2000. Finally, our results also suggest that between about 1950 and 1970, increasing aerosol emissions had a larger impact on the hydrological cycle than increasing greenhouse gases concentrations.

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