scholarly journals Modelling artificial sea salt emission in large eddy simulations

2014 ◽  
Vol 372 (2031) ◽  
pp. 20140051 ◽  
Author(s):  
Z. Maalick ◽  
H. Korhonen ◽  
H. Kokkola ◽  
T. Kühn ◽  
S. Romakkaniemi
Keyword(s):  
Particle Dispersion ◽  
Sea Salt ◽  
Water Evaporation ◽  
Model Resolution ◽  
Maximum Resolution ◽  
Particle Scavenging ◽  
Maximum Particle ◽  
Negative Buoyancy ◽  
Scavenging Efficiency ◽  
First Time

We study the dispersion of sea salt particles from artificially injected sea spray at a cloud-resolving scale. Understanding of how different aerosol processes affect particle dispersion is crucial when designing emission sources for marine cloud brightening. Compared with previous studies, we include for the first time an explicit treatment of aerosol water, which takes into account condensation, evaporation and their effect on ambient temperature. This enables us to capture the negative buoyancy caused by water evaporation from aerosols. Additionally, we use a higher model resolution to capture aerosol loss through coagulation near the source point. We find that, with a seawater flux of 15 kg s −1 , the cooling due to evaporation can be as much as 1.4 K, causing a delay in particle dispersion of 10–20 min. This delay enhances particle scavenging by a factor of 1.14 compared with simulations without aerosol water. We further show that both cooling and particle dispersion depend on the model resolution, with a maximum particle scavenging efficiency of 20% within 5 h after emission at maximum resolution of 50 m. Based on these results, we suggest further regional high-resolution studies which model several injection periods over several weeks.

High-quality ultralong copper sulphide nanowires for promising applications in high efficiency solar water evaporation

2019 ◽  
Vol 3 (3) ◽  
pp. 394-398 ◽  
Author(s):  
Na Li ◽  
Dandan Yin ◽  
Lingling Xu ◽  
Hongyang Zhao ◽  
Zhengqing Liu ◽  
...  
Keyword(s):  
High Efficiency ◽  
Water Evaporation ◽  
Copper Sulphide ◽  
High Quality ◽  
Solar Water ◽  
Highly Efficient ◽  
First Time

High-quality ultralong copper sulphide nanowires for highly efficient solar water evaporation performance have been synthesized for the first time.

scholarly journals XRD and TG-DTA Study of New Phosphate-Based Geopolymers with Coal Ash or Metakaolin as Aluminosilicate Source and Mine Tailings Addition

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 202
Author(s):  
Dumitru Doru Burduhos Nergis ◽  
Petrica Vizureanu ◽  
Andrei Victor Sandu ◽  
Diana Petronela Burduhos Nergis ◽  
Costica Bejinariu
Keyword(s):  
Mine Tailings ◽  
Room Temperature ◽  
Raw Materials ◽  
Coal Ash ◽  
Water Evaporation ◽  
Oxidation Reactions ◽  
X Ray Diffraction ◽  
Xrd Patterns ◽  
First Time ◽  
Alkali Activated

Coal ash-based geopolymers with mine tailings addition activated with phosphate acid were synthesized for the first time at room temperature. In addition, three types of aluminosilicate sources were used as single raw materials or in a 1/1 wt. ratio to obtain five types of geopolymers activated with H3PO4. The thermal behaviour of the obtained geopolymers was studied between room temperature and 600 °C by Thermogravimetry-Differential Thermal Analysis (TG-DTA) and the phase composition after 28 days of curing at room temperature was analysed by X-ray diffraction (XRD). During heating, the acid-activated geopolymers exhibited similar behaviour to alkali-activated geopolymers. All of the samples showed endothermic peaks up to 300 °C due to water evaporation, while the samples with mine tailings showed two significant exothermic peaks above 400 °C due to oxidation reactions. The phase analysis confirmed the dissolution of the aluminosilicate sources in the presence of H3PO4 by significant changes in the XRD patterns of the raw materials and by the broadening of the peaks because of typically amorphous silicophosphate (Si–P), aluminophosphate (Al–P) or silico-alumino-phosphate (Si–Al–P) formation. The phases resulted from geopolymerisation are berlinite (AlPO4), brushite (CaHPO4∙2H2O), anhydrite (CaSO4) or ettringite as AFt and AFm phases.

scholarly journals Continuous isotopic composition measurements of tropospheric CO<sub>2</sub> at Jungfraujoch (3580 m a.s.l.), Switzerland: real-time observation of regional pollution events

2010 ◽  
Vol 10 (10) ◽  
pp. 24563-24593 ◽  
Author(s):  
B. Tuzson ◽  
S. Henne ◽  
D. Brunner ◽  
M. Steinbacher ◽  
J. Mohn ◽  
...  
Keyword(s):  
Particle Dispersion ◽  
Integration Time ◽  
High Temporal Resolution ◽  
Research Station ◽  
Mixing Ratios ◽  
Keeling Plot ◽  
Time Observation ◽  
First Time ◽  
Pollution Events

Abstract. A quantum cascade laser based absorption spectrometer (QCLAS) is applied for the first time to perform in situ, continuous and high precision isotope ratio measurements of CO2 in the free troposphere. Time series of the three main CO2 isotopologue mixing ratios (12C16O2, 12C16O2 and 12C18O16O) have simultaneously been measured at one second time resolution over two years (from August 2008 to present) at the High Altitude Research Station Jungfraujoch (3580 m a.s.l., Switzerland). This work focuses on periods in February 2009 only, when sudden and pronounced enhancements in the tropospheric CO2 were observed. These short-term changes were closely correlated with variations in CO mixing ratios measured at the same site, indicating combustion related emissions as potential source. The analytical precision of 0.046‰ (at 50 s integration time) for both δ13C and δ18O and the high temporal resolution allowed the application of the Keeling plot method for source signature identification. The spatial origin of these CO2 emission sources was then determined by backward Lagrangian particle dispersion simulations.

scholarly journals Effect of sea-salt aerosol on tropospheric bromine chemistry

2018 ◽  
Author(s):  
Lei Zhu ◽  
Daniel J. Jacob ◽  
Sebastian D. Eastham ◽  
Melissa P. Sulprizio ◽  
Xuan Wang ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Marine Boundary Layer ◽  
Elemental Mercury ◽  
Sea Salt ◽  
Heterogeneous Reactions ◽  
Tropospheric Chemistry ◽  
Sulfur Species ◽  
Sea Salt Aerosol ◽  
Volatile Organic ◽  
First Time

Abstract. Bromine radicals influence global tropospheric chemistry by depleting ozone and OH, and by oxidizing elemental mercury, sulfur species, and volatile organic compounds. Observations typically indicate a 50 % depletion of sea salt aerosol (SSA) bromide relative to seawater composition, implying that SSA debromination could be the dominant global source of tropospheric bromine. However, it has been difficult to reconcile this large source with the relatively low BrO concentrations observed in the marine boundary layer (MBL). Here we present a new mechanistic description of SSA debromination in the GEOS-Chem global atmospheric chemistry model with a detailed representation of halogen (Cl, Br, and I) chemistry. We show, for the first time, observed levels of SSA debromination can be reproduced in a manner consistent with observed BrO concentrations. Bromine radical sinks from the HOBr + S(IV) heterogeneous reactions and from ocean emission of acetaldehyde are found to be critical in moderating tropospheric BrO levels. The resulting HBr is rapidly taken up by SSA and also deposited. We find that the source of bromine radicals is mostly from SSA in the MBL, but from organobromines in the free troposphere. Simulated BrO in the MBL is generally much higher in winter than in summer due to a combination of greater SSA emission and weaker radiation. Outstanding issues are the model underestimate of free tropospheric BrO, driven by the HOBr + S(IV) reactions, and uncertainty regarding HBr uptake by SSA.

Centennial-scale evolution of methane during the penultimate deglaciation

2020 ◽  
Author(s):  
Loïc Schmidely ◽  
Lucas Silva ◽  
Christoph Nehrbass-Ahles ◽  
Juhyeong Han ◽  
Jinhwa Shin ◽  
...  
Keyword(s):  
Temporal Resolution ◽  
Ice Core ◽  
Ice Cores ◽  
Before Present ◽  
Last Deglaciation ◽  
Rates Of Change ◽  
Maximum Resolution ◽  
The Last Deglaciation ◽  
First Time ◽  
Temporal Coverage

&lt;p&gt; Small air inclusions in ice cores represent a direct archive of past atmospheric compositions, allowing us to measure the concentration of the three most potent non-condensable Greenhouse Gases (GHG) CO&lt;sub&gt;2&lt;/sub&gt;, CH&lt;sub&gt;4&lt;/sub&gt; and N&lt;sub&gt;2&lt;/sub&gt;O as far back as 800,000 years before present (kyr BP). These records demonstrate that transitions from glacial to interglacial conditions are accompanied by a substantial net increase of CO&lt;sub&gt;2&lt;/sub&gt;, CH&lt;sub&gt;4&lt;/sub&gt; and N&lt;sub&gt;2&lt;/sub&gt;O in the atmosphere (L&amp;#252;thi et al. 2008, Loulergue et al. 2008, Schilt et al. 2010). A sound understanding of the interplay between the reorganization of the climate system and the perturbation of GHG inventories during glacial terminations is partly limited by the temporal resolution of the records derived from ice cores. In fact, with the exception of the last deglaciation (23-9 kyr BP) centennial-scale GHG variability remained uncaptured for precedings glacial terminations.&lt;/p&gt;&lt;p&gt;In this work, we exploit the exceptionally long temporal coverage of the EPICA Dome C (EDC) ice core to reconstruct, for the first time, centennial-scale fluctuations of CH&lt;sub&gt;4&lt;/sub&gt; mole fractions from 145 to 125 kyr BP, encompassing the entire penultimate deglaciation (138-128 kyr BP). With a temporal resolution of ~100 years, our new record is now unveiling all climate-driven signals enclosed into the EDC ice core, exploiting the maximum resolution possible at Dome C (). This offers us the opportunity to study the timing and rates of change of CH&lt;sub&gt;4&lt;/sub&gt; in unprecedented details.&lt;/p&gt;&lt;p&gt;Preliminary analysis reveals that the deglacial CH&lt;sub&gt;4 &lt;/sub&gt;rise is a superimposition of gradual millennial-scale increases (~0.01-0.02 ppb/year) and abrupt and partly intermittent centennial-scale events (~80-200 ppb in less than a millennium). We will investigate processes modulating the observed changes in the CH&lt;sub&gt;4&lt;/sub&gt; cycle, compare the structure of our record with the CH&lt;sub&gt;4&lt;/sub&gt; profile of the last deglaciation (Marcott, 2014) and contrast it with the EDC CO&lt;sub&gt;2&lt;/sub&gt; and N&lt;sub&gt;2&lt;/sub&gt;O records over the penultimate glacial termination now available in similar resolution.&lt;/p&gt;

scholarly journals From Equilibrium Liquid Crystal Formation and Kinetic Arrest to Photonic Bandgap Films Using Suspensions of Cellulose Nanocrystals

Crystals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 199 ◽  
Author(s):  
Christina Schütz ◽  
Johanna R. Bruckner ◽  
Camila Honorato-Rios ◽  
Zornitza Tosheva ◽  
Manos Anyfantakis ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Cellulose Nanocrystals ◽  
Cholesteric Liquid Crystal ◽  
Water Evaporation ◽  
Isotropic Phase ◽  
Crystal Formation ◽  
Scientists And Engineers ◽  
Coffee Ring Effect ◽  
Kinetic Arrest ◽  
First Time

The lyotropic cholesteric liquid crystal phase developed by suspensions of cellulose nanocrystals (CNCs) has come increasingly into focus from numerous directions over the last few years. In part, this is because CNC suspensions are sustainably produced aqueous suspensions of a fully bio-derived nanomaterial with attractive properties. Equally important is the interesting and useful behavior exhibited by solid CNC films, created by drying a cholesteric-forming suspension. However, the pathway along which these films are realized, starting from a CNC suspension that may have low enough concentration to be fully isotropic, is more complex than often appreciated, leading to reproducibility problems and confusion. Addressing a broad audience of physicists, chemists, materials scientists and engineers, this Review focuses primarily on the physics and physical chemistry of CNC suspensions and the process of drying them. The ambition is to explain rather than to repeat, hence we spend more time than usual on the meanings and relevance of the key colloid and liquid crystal science concepts that must be mastered in order to understand the behavior of CNC suspensions, and we present some interesting analyses, arguments and data for the first time. We go through the development of cholesteric nuclei (tactoids) from the isotropic phase and their potential impact on the final dry films; the spontaneous CNC fractionation that takes place in the phase coexistence window; the kinetic arrest that sets in when the CNC mass fraction reaches ∼10 wt.%, preserving the cholesteric helical order until the film has dried; the ’coffee-ring effect’ active prior to kinetic arrest, often ruining the uniformity in the produced films; and the compression of the helix during the final water evaporation, giving rise to visible structural color in the films.

scholarly journals Triple-wavelength lidar observations of the linear depolarization ratio of dried marine particles

2018 ◽  
Vol 176 ◽  
pp. 05014
Author(s):  
Moritz Haarig ◽  
Albert Ansmann ◽  
Holger Baars ◽  
Ronny Engelmann ◽  
Dietrich Althausen ◽  
...  
Keyword(s):  
Sea Salt ◽  
Aerosol Layer ◽  
Marine Aerosol ◽  
Depolarization Ratio ◽  
Model Simulations ◽  
Marine Particles ◽  
Linear Depolarization Ratio ◽  
First Time ◽  
Lidar Observations

For aerosol typing with lidar, sea salt particles are usually assumed to be spherical with a consequently low depolarization ratio. Evidence of dried marine particles at the top of the humid marine aerosol layer with a depolarization ratio up to 0.1 has been found at predominately maritime locations on Barbados and in the Southern Atlantic. The depolarization ratio for these probably cubic sea salt particles has been measured at three wavelengths (355, 532 and 1064 nm) simultaneously for the first time and compared to model simulations.

scholarly journals Continuous isotopic composition measurements of tropospheric CO<sub>2</sub> at Jungfraujoch (3580 m a.s.l.), Switzerland: real-time observation of regional pollution events

2011 ◽  
Vol 11 (4) ◽  
pp. 1685-1696 ◽  
Author(s):  
B. Tuzson ◽  
S. Henne ◽  
D. Brunner ◽  
M. Steinbacher ◽  
J. Mohn ◽  
...  
Keyword(s):  
Particle Dispersion ◽  
Integration Time ◽  
High Temporal Resolution ◽  
Research Station ◽  
Mixing Ratios ◽  
Keeling Plot ◽  
Time Observation ◽  
First Time ◽  
Pollution Events

Abstract. A quantum cascade laser based absorption spectrometer (QCLAS) is applied for the first time to perform in situ, continuous and high precision isotope ratio measurements of CO2 in the free troposphere. Time series of the three main CO2 isotopologue mixing ratios (12C16CO2, 13C16CO2 and 12C18O16O) have simultaneously been measured at one second time resolution over two years (from August 2008 to present) at the High Altitude Research Station Jungfraujoch (3580 m a.s.l., Switzerland). This work focuses on periods in February 2009 only, when sudden and pronounced enhancements in the tropospheric CO2 were observed. These short-term changes were closely correlated with variations in CO mixing ratios measured at the same site, indicating combustion related emissions as potential source. The analytical precision of 0.046‰ (at 50 s integration time) for both δ13C and δ18O and the high temporal resolution allowed the application of the Keeling plot method for source signature identification. The spatial origin of these CO2 emission sources was then determined by backward Lagrangian particle dispersion simulations.

scholarly journals Natural evaporation from open water, bare soil and grass

1948 ◽  
Vol 193 (1032) ◽  
pp. 120-145 ◽  
Keyword(s):  
Meteorological Data ◽  
Turbulent Transport ◽  
Open Water ◽  
Eddy Diffusion ◽  
Bare Soil ◽  
Water Evaporation ◽  
Theoretical Approaches ◽  
Catchment Areas ◽  
Satisfactory Account ◽  
First Time

Two theoretical approaches to evaporation from saturated surfaces are outlined, the first being on an aerodynamic basis in which evaporation is regarded as due to turbulent transport of vapour by a process of eddy diffusion, and the second being on an energy basis in which evaporation is regarded as one of the ways of degrading incoming radiation. Neither approach is new, but a combination is suggested that eliminates the parameter measured with most difficulty—surface temperature—and provides for the first time an opportunity to make theoretical estimates of evaporation rates from standard meteorological data, estimates that can be retrospective. Experimental work to test these theories shows that the aerodynamic approach is not adequate and an empirical expression, previously obtained in America, is a better description of evaporation from open water. The energy balance is found to be quite successful. Evaporation rates from wet bare soil and from turf with an adequate supply of water are obtained as fractions of that from open water, the fraction for turf showing a seasonal change attributed to the annual cycle of length of daylight. Finally, the experimental results are applied to data published elsewhere and it is shown that a satisfactory account can be given of open water evaporation at four widely spaced sites in America and Europe, the results for bare soil receive a reasonable check in India, and application of the results for turf shows good agreement with estimates of evaporation from catchment areas in the British Isles.

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