scholarly journals Implementation of Aerosol-Cloud Interaction within WRF-CHIMERE Online Coupled Model: Evaluation and Investigation of the Indirect Radiative Effect from Anthropogenic Emission Reduction on the Benelux Union

Atmosphere ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 20 ◽  
Author(s):  
Paolo Tuccella ◽  
Laurent Menut ◽  
Régis Briant ◽  
Adrien Deroubaix ◽  
Dmitry Khvorostyanov ◽  
...  
Keyword(s):  
Indirect Effects ◽  
Coupled Model ◽  
Sensitivity Study ◽  
Cloud Formation ◽  
Radiative Effect ◽  
Satellite Measurements ◽  
Aerosol Cloud ◽  
Order Of Magnitude ◽  
Surface Measurements ◽  
The Impact

The indirect effects of aerosol are particularly important over regions where meteorological conditions and aerosol content are favourable to cloud formation. This was observed during the Intensive Cloud Aerosol Measurement Campaign (IMPACT) (European Integrated project on Aerosol Cloud Climate and Air quality Interaction (EUCAARI) project) in the Benelux Union during May 2008. To better understand this cloud formation variability, the indirect effects of aerosol have been included within the WRF-CHIMERE online model. By comparing model results to the aircraft measurements of IMPACT, to surface measurements from EMEP and AIRBASE and to MODIS satellite measurements, we showed that the model is able to simulate the variability and order of magnitude of the observed number of condensation nuclei (CN), even if some differences are identified for specific aerosol size and location. To quantify the impact of the local anthropogenic emissions on cloud formation, a sensitivity study is performed by halving the surface emissions fluxes. It is shown that the indirect radiative effect (IRE) at the surface is positive for both shortwave and longwave with a net warming of +0.99 W/m2. In addition, important instantaneous changes are modelled at local scale with up to ±6 °C for temperatures and ±50 mm/day for precipitation.

Local Mesh Refinement for Correlation of FEA Estimated Plastic Strain to Tests in Areas of High Plastic Strain

2018 ◽  
Author(s):  
Katharine Liu ◽  
Emma Xiao ◽  
Gregory Westwater ◽  
Christopher R. Johnson ◽  
J. Adin Mann
Keyword(s):  
Plastic Strain ◽  
Mesh Refinement ◽  
Sensitivity Study ◽  
Linear Elastic ◽  
Mesh Sensitivity ◽  
Local Mesh Refinement ◽  
Order Of Magnitude ◽  
High Plastic Strain ◽  
Stabilization Technique ◽  
The Impact

The total strain, elastic plus plastic, was measured with strain gages on valve bodies with internal pressure that caused surface yielding. The correlation of the simulated maximum principal strain was compared to strain gage data. A mesh sensitivity study shows that in regions of large plastic strain, mesh elements are required that are an order of magnitude smaller than what is used for linear elastic stress analysis for the same structure. A local mesh refinement was adequate to resolve the local high strain values. Both the location and magnitude of the maximum strain changed with a local mesh refinement. The local mesh refinement requirement was consistent over several structures that were tested. The test and simulation work will be presented along with the mesh sensitivity study. Some results on using an energy stabilization technique to aid convergence will be presented in terms of the impact on the predicted plastic strain.

scholarly journals Impact of mineral dust on cloud formation in a Saharan outflow region

2011 ◽  
Vol 11 (12) ◽  
pp. 32363-32390 ◽  
Author(s):  
L. Smoydzin ◽  
A. Teller ◽  
H. Tost ◽  
M. Fnais ◽  
J. Lelieveld
Keyword(s):  
Radiative Forcing ◽  
Mineral Dust ◽  
Eastern Mediterranean ◽  
Cloud Condensation Nuclei ◽  
Coupled Model ◽  
Cloud Formation ◽  
Dust Particles ◽  
Ice Nuclei ◽  
Outflow Region ◽  
The Impact

Abstract. We present a numerical modelling study investigating the impact of mineral dust on cloud formation over the Eastern Mediterranean for two case studies: (i) 25 September 2008 and (ii) 28/29 January 2003. On both days dust plumes crossed the Mediterranean and interacted with clouds forming along frontal systems. For our investigation we used the fully online coupled model WRF-chem. The results show that increased aerosol concentrations due to the presence of mineral dust can enhance the formation of ice crystals. This leads to slight shifts of the spatial and temporal precipitation patterns compared to scenarios where dust was not considered to act as ice nuclei. However, the total amount of precipitation did not change significantly. The only exception occurred when dust entered into an area of orographic ascent, causing glaciation of the clouds, leading to a local enhancement of rainfall. The impact of dust particles acting as giant cloud condensation nuclei on precipitation formation was found to be small. Based on our simulations the contribution of dust to the CCN population is potentially significant only for warm phase clouds. Nevertheless, the dust-induced differences in the microphysical structure of the clouds can contribute to a significant radiative forcing.

scholarly journals A six year satellite-based assessment of the regional variations in aerosol indirect effects

2008 ◽  
Vol 8 (6) ◽  
pp. 20349-20397 ◽  
Author(s):  
T. A. Jones ◽  
S. A. Christopher ◽  
J. Quaas
Keyword(s):  
Solar Radiation ◽  
Indirect Effects ◽  
Vertical Motion ◽  
The United States ◽  
Dust Aerosol ◽  
Aerosol Concentration ◽  
Cloud Formation ◽  
Atmospheric Conditions ◽  
Aerosol Cloud ◽  
Cloud Properties

Abstract. Since aerosols act as cloud condensation nuclei (CCN) for cloud water droplets, changes in aerosol concentrations having significant impacts on the corresponding cloud properties. An increase in aerosol concentration leads to an increase in CCN, with an associated decrease in cloud droplet size for a given cloud liquid water content. Smaller droplet sizes may then lead to a reduction in precipitation efficiency and an increase in cloud lifetimes, which induces more reflection of solar radiation back into space, cooling the atmosphere below the cloud layer. In reality, this relationship is much more complex and is interrelated between aerosol, cloud, and atmospheric conditions present at any one time. MODIS aerosol and cloud properties are combined with NCEP Reanalysis data for eight different regions around the globe between March 2000 and December 2005 to study the effects of different aerosol, cloud, and atmospheric conditions on the aerosol indirect effect (AIE). The first AIE for both anthropogenic and dust aerosols is calculated so that the importance of each can be compared. The unique aspect of this research is that it combines multiple satellite data sets over a six year period to provide a comprehensive analysis of indirect effects for different aerosol regimes around the globe. Results show that in most regions, AIE has a distinct seasonal cycle, though the cycle varies in significance and period from region to region. In the Arabian Sea, the six-year mean anthropogenic + dust AIE is −0.4 Wm−2 and is greatest during the summer months (<−2.0 Wm−2) during which dust aerosol concentration is greatest, significant concentrations of anthropogenic aerosols are present, and upward vertical motion is also present providing a favorable environment for cloud formation. In the Bay of Bengal, AIE was negligible owing to less favorable atmospheric conditions and a lower concentration of aerosols. In the eastern North Atlantic, AIE was also small (<0.1 Wm−2) and in this region dust aerosol concentration is much greater than the anthropogenic or sea salt components. However, elevated dust in this region may also absorb solar radiation and warm the atmosphere, stabilizing the atmosphere as evidenced by weak vertical motion during the summer (0.02 Pa s−1) when AOT is greatest. Lower average cloud fraction compared to other regions allows the absorbing effect to offset the cooling effect associated with increasing CCN. The western Atlantic and Pacific oceans have large anthropogenic aerosol concentrations transported from the United States and China respectively and produce modest anthropogenic AIE (0.7, 0.9 Wm−2) in these regions as expected. Anthropogenic AIE was also present off the West African coast corresponding to aerosols produced from seasonal biomass burning. Interestingly, atmospheric conditions were not particularly favorable for cloud formation compared to the other regions during the times where AIE was observed. Overall, we are able to conclude that aerosol type, atmospheric conditions and their relative vertical distributions are a key factors as to whether or not significant AIE occurs and simple correlations between AOT and cloud properties are insufficient to explain the AIE.

scholarly journals The retrieval of snow properties from SLSTR/Sentinel-3 – part 1: method description and sensitivity study

2020 ◽  
Author(s):  
Linlu Mei ◽  
Vladimir Rozanov ◽  
Christine Pohl ◽  
Marco Vountas ◽  
John P. Burrows
Keyword(s):  
Surface Roughness ◽  
Optical Properties ◽  
Particle Shape ◽  
Crystal Surface ◽  
Atmospheric Correction ◽  
Sensitivity Study ◽  
Ice Crystal ◽  
Aerosol Cloud ◽  
Snow Properties ◽  
The Impact

Abstract. The eXtensible Bremen Aerosol/cloud and surfacE parameters Retrieval (XBAER) algorithm has been applied on the Top-Of-Atmosphere reflectance measured by the Sea and Land Surface Temperature Radiometer (SLSTR) instrument onboard Sentinel-3 to derive snow properties: Snow Grain Size (SGS), Snow Particle Shape (SPS) and Specific Surface Area (SSA) under cloud-free conditions. This is the first part of the paper, to describe the retrieval method and the sensitivity study. Nine pre-defined ice crystal particle shapes (aggregate of 8 columns, Drontal, hollow bullet rosettes, hollow column, plate, aggregate of 5 plates, aggregate of 10 plates, solid bullet rosettes, column) are used to describe the snow optical properties. The optimal SGS and SPS are estimated iteratively utilizing a Look-Up-Table (LUT) approach. The SSA is then calculated using another pre-calculated LUT for the retrieved SGS and SPS. The optical properties (e.g., phase function) of the ice crystals can reproduce the wavelength-dependent/angular-dependent snow reflectance features, compared to laboratory measurements. A comprehensive study to understand the impact of aerosol, ice crystal shape, ice crystal surface roughness, and cloud contamination on the retrieval accuracy of snow properties has been performed based on SCIATRAN radiative transfer simulations. The main findings are (1) Snow angular and spectral reflectance feature can be described by the predefined ice crystal properties only when both SGS and SPS can be optimally and iteratively obtained; (2) The impact of ice crystal surface roughness plays minor effects on the retrieval results; (3) SGS and SSA show an inverse linear relationship; (4) The retrieval of SSA assuming non-convex particle shape, compared to convex particle (e.g. sphere) shows larger results; (5) Aerosol/cloud contamination due to unperfected atmospheric correction and cloud screening introduces underestimation of SGS, inaccurate SPS and overestimation of SSA.

scholarly journals Modelling the impact of noctilucent cloud formation on atomic oxygen and other minor constituents of the summer mesosphere

2004 ◽  
Vol 4 (6) ◽  
pp. 7181-7216 ◽  
Author(s):  
B. J. Murray ◽  
J. M. C. Plane
Keyword(s):  
Gas Phase ◽  
Atomic Oxygen ◽  
Solid Phase ◽  
Cloud Formation ◽  
Noctilucent Cloud ◽  
Ice Particles ◽  
Order Of Magnitude ◽  
Mesospheric Clouds ◽  
The Impact ◽  
Odd Oxygen

Abstract. The formation, evolution and eventual sublimation of noctilucent clouds (NLC) could have a significant effect on the odd oxygen and hydrogen chemistry of the high latitude summer mesosphere. Three mechanisms are considered here: the direct uptake of atomic oxygen on the surface of the ice particles; the redistribution of water vapour, which changes the photochemical source of odd hydrogen species; and the direct photolysis of the ice particles themselves to produce odd hydrogen species in the gas phase. A 1-D photochemical model is employed to investigate the potential importance of these mechanisms. This shows, using the recently measured uptake coefficients of O on ice, that the heterogeneous removal of O on the surface of the cloud particles is too slow by at least a factor of 5×103 to compete with gas-phase O chemistry. The second and third mechanisms involve the solar Lyman-α photolysis of H2O in the gas and solid phase, respectively. During twilight, Lyman-α radiation is severely attenuated and these mechanisms are insignificant. In contrast, when the upper mesosphere is fully illuminated there is a dramatic impact on the O profile, with depletion of O at the base of the cloud layer of close to an order of magnitude. A correspondingly large depletion in O3 is also predicted, while H, OH, HO2 and H2O2 are found to be enhanced by factors of 3–5. In fact, rocket-borne mass spectrometer measurements during summer have revealed local H2O2 enhancements in the region of the clouds. Rocket-borne measurements of atomic O and O3 profiles in the presence of mesospheric clouds in the daytime are highly desirable to test the predictions of this model and our understanding of the genesis of mesospheric clouds.

scholarly journals Investigating the sensitivity to resolving aerosol interactions in downscaling regional model experiments with WRFv3.8.1 over Europe

2020 ◽  
Vol 13 (6) ◽  
pp. 2511-2532
Author(s):  
Vasileios Pavlidis ◽  
Eleni Katragkou ◽  
Andreas Prein ◽  
Aristeidis K. Georgoulias ◽  
Stergios Kartsios ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Statistical Significance ◽  
Regional Climate ◽  
The Black Sea ◽  
Radiative Effect ◽  
Surface Solar Radiation ◽  
Aerosol Cloud ◽  
Aerosol Cloud Interactions ◽  
The Impact ◽  
Aerosol Radiative

Abstract. In this work we present downscaling experiments with the Weather Research and Forecasting model (WRF) to test the sensitivity to resolving aerosol–radiation and aerosol–cloud interactions on simulated regional climate for the EURO-CORDEX domain. The sensitivities mainly focus on the aerosol–radiation interactions (direct and semi-direct effects) with four different aerosol optical depth datasets (Tegen, MAC-v1, MACC, GOCART) being used and changes to the aerosol absorptivity (single scattering albedo) being examined. Moreover, part of the sensitivities also investigates aerosol–cloud interactions (indirect effect). Simulations have a resolution of 0.44∘ and are forced by the ERA-Interim reanalysis. A basic evaluation is performed in the context of seasonal-mean comparisons to ground-based (E-OBS) and satellite-based (CM SAF SARAH, CLARA) benchmark observational datasets. The impact of aerosols is calculated by comparing it against a simulation that has no aerosol effects. The implementation of aerosol–radiation interactions reduces the direct component of the incoming surface solar radiation by 20 %–30 % in all seasons, due to enhanced aerosol scattering and absorption. Moreover the aerosol–radiation interactions increase the diffuse component of surface solar radiation in both summer (30 %–40 %) and winter (5 %–8 %), whereas the overall downward solar radiation at the surface is attenuated by 3 %–8 %. The resulting aerosol radiative effect is negative and is comprised of the net effect from the combination of the highly negative direct aerosol effect (−17 to −5 W m−2) and the small positive changes in the cloud radiative effect (+5 W m−2), attributed to the semi-direct effect. The aerosol radiative effect is also stronger in summer (−12 W m−2) than in winter (−2 W m−2). We also show that modelling aerosol–radiation and aerosol–cloud interactions can lead to small changes in cloudiness, mainly regarding low-level clouds, and circulation anomalies in the lower and mid-troposphere, which in some cases, mainly close to the Black Sea in autumn, can be of statistical significance. Precipitation is not affected in a consistent pattern throughout the year by the aerosol implementation, and changes do not exceed ±5 % except for the case of unrealistically absorbing aerosol. Temperature, on the other hand, systematically decreases by −0.1 to −0.5 ∘C due to aerosol–radiation interactions with regional changes that can be up to −1.5 ∘C.

scholarly journals Impact of mineral dust on cloud formation in a Saharan outflow region

2012 ◽  
Vol 12 (23) ◽  
pp. 11383-11393 ◽  
Author(s):  
L. Smoydzin ◽  
A. Teller ◽  
H. Tost ◽  
M. Fnais ◽  
J. Lelieveld
Keyword(s):  
Radiative Forcing ◽  
Mineral Dust ◽  
Eastern Mediterranean ◽  
Cloud Condensation Nuclei ◽  
Coupled Model ◽  
Cloud Formation ◽  
Dust Particles ◽  
Ice Nuclei ◽  
Outflow Region ◽  
The Impact

Abstract. We present a numerical modelling study investigating the impact of mineral dust on cloud formation over the Eastern Mediterranean for two case studies: (i) 25 September 2008 and (ii) 28/29 January 2003. In both cases dust plumes crossed the Mediterranean and interacted with clouds forming along frontal systems. For our investigation we used the fully online coupled model WRF-chem. The results show that increased aerosol concentrations due to the presence of mineral dust can enhance the formation of ice crystals. This leads to slight shifts of the spatial and temporal precipitation patterns compared to scenarios where dust was not considered to act as ice nuclei. However, the total amount of precipitation did not change significantly. The only exception occurred when dust entered into an area of orographic ascent, causing glaciation of the clouds, leading to a local enhancement of rainfall. The impact of dust particles acting as giant cloud condensation nuclei on precipitation formation was found to be small. Based on our simulations the contribution of dust to the CCN population is potentially significant only for warm phase clouds. Nevertheless, the dust-induced differences in the microphysical structure of the clouds can contribute to a significant radiative forcing, which is important from a climate perspective.

scholarly journals Mechanisms of hydrological responses to volcanic eruptions in the Asian monsoon and westerlies-dominated subregions

2021 ◽  
Author(s):  
Zhihong Zhuo ◽  
Ingo Kirchner ◽  
Ulrich Cubasch
Keyword(s):  
Response Pattern ◽  
Asian Monsoon ◽  
Coupled Model ◽  
Volcanic Eruptions ◽  
Stratospheric Aerosol ◽  
Cloud Formation ◽  
Radiative Effect ◽  
Asian Monsoon Region ◽  
Hydrological Responses ◽  
Near Term

Abstract. Explosive volcanic eruptions affect surface climate especially in monsoon regions, but responses vary in different regions and to volcanic aerosol injection (VAI) in different hemispheres. Here we use six ensemble members from last millennium experiment of the Coupled Model Intercomparison Project Phase 5, to investigate the mechanism of regional hydrological responses to different hemispheric VAI in the Asian monsoon region (AMR). It brings a significant drying effect over the AMR after northern hemisphere VAI (NHVAI), spatially, a distinct “wet get drier, dry gets wetter” response pattern emerges with significant drying effect in the wettest area (RWA) but significant wetting effect in the driest area (RDA) of the AMR. After southern hemisphere VAI (SHVAI), it shows a significant wetting effect over the AMR, but spatial response pattern is not that clear due to small aerosol magnitude. The mechanism of the hydrological impact relates to the indirect change of atmospheric circulation due to the direct radiative effect of volcanic aerosols. The decreased thermal contrast between the land and the ocean after NHVAI results in weakened EASM and SASM. This changes the moisture transport and cloud formation in the monsoon and westerlies-dominated subregions. The subsequent radiative effect and physical feedbacks of local clouds lead to different drying and wetting effects in different areas. Results here indicate that future volcanic eruptions may alleviate the uneven distribution of precipitation in the AMR, which should be considered in the near-term decadal prediction and future strategy of local adaptation to global warming. The local hydrological responses and mechanisms found here can also provide reference to stratospheric aerosol engineering.

Apportionment of the present-day forcing by methane using UKESM1: The role of chemistry-aerosol-cloud interactions 

2021 ◽  
Author(s):  
Fiona O'Connor ◽  
Omar Jamil ◽  
Timothy Andrews ◽  
Ben Johnson ◽  
Jane Mulcahy ◽  
...  
Keyword(s):  
Indirect Effects ◽  
Radiative Forcing ◽  
Cloud Droplet ◽  
Aerosol Size Distribution ◽  
Radiative Effect ◽  
Liquid Water Path ◽  
Model Estimate ◽  
Aerosol Cloud ◽  
Cloud Radiative Effect ◽  
Aerosol Cloud Interactions

&lt;p&gt;The pre-industrial (PI; Year 1850) to present-day (PD; Year 2014) increase in methane concentration leads to a global mean effective radiative forcing (ERF) of 0.97 &amp;#177; 0.04 W m&lt;sup&gt;-2&lt;/sup&gt; in the UK&amp;#8217;s Earth System Model, UKESM1. In comparison with the multi-model estimate of 0.75 &amp;#177; 0.10 W m&lt;sup&gt;-2 &lt;/sup&gt;from the Aerosol and Chemistry Model Intercomparison Project (AerChemMIP), UKESM1 has the highest methane ERF and lies outside the 1-sigma range. This is, in part, due to UKESM1 including interactive chemistry and positive indirect effects, such as methane-driven changes in tropospheric ozone. However, UKESM1 is the only model within AerChemMIP whose contribution to the methane ERF from tropospheric adjustments is positive &amp;#8211; this is largely driven by the strong positive cloud adjustment in UKESM1, in contrast to other models. In this work, we apportion the total methane ERF between direct and indirect effects (including adjustments) and provide a process-based understanding of what is driving the positive cloud adjustment in UKESM1.&lt;/p&gt;&lt;p&gt;Using additional UKESM1 paired simulations, we apportion the total methane ERF between its direct methane contribution and indirect contributions from ozone, water vapour, and aerosols. This approach offers the advantage that linearity is not assumed and it distinguishes between cloud effects that are dynamically-driven via changes in temperature and those that are aerosol-mediated. By analysing the chemistry-aerosol budgets and the cloud responses, we find that the PI to PD increase in methane leads to an indirect positive aerosol ERF of up to 0.3 &amp;#177; 0.06 W m&lt;sup&gt;-2&lt;/sup&gt;, with a near-zero contribution from the instantaneous radiative forcing from aerosol-radiation interactions. Methane-driven changes in oxidants alter the relative contributions of the different sulphur dioxide oxidation pathways, causing a change in new particle formation rates and a shift in the aerosol size distribution towards fewer but larger particles. There is a resulting decrease in cloud droplet number concentration, an increase in cloud droplet effective radius, and a decrease in liquid water path in marine stratocumulus regions from aerosol-cloud interactions (mainly through the cloud lifetime effect). There is a subsequent change in the cloud radiative effect, with the positive change in the shortwave dominating over the negative change in the longwave. However, when aerosol-cloud interactions are disabled, the change in the cloud radiative effect is negative and is dominated by the reduction of cirrus clouds in the tropics, thus making UKESM1 more consistent with the other AerChemMIP models.&lt;/p&gt;&lt;p&gt;These results can explain some of the diversity in multi-model estimates of methane forcing and highlight the importance of chemistry-aerosol-cloud interactions when quantifying climate forcing by reactive greenhouse gases.&lt;/p&gt;

scholarly journals Modelling the impact of noctilucent cloud formation on atomic oxygen and other minor constituents of the summer mesosphere

2005 ◽  
Vol 5 (4) ◽  
pp. 1027-1038 ◽  
Author(s):  
B. J. Murray ◽  
J. M. C. Plane
Keyword(s):  
Gas Phase ◽  
Atomic Oxygen ◽  
Solid Phase ◽  
Cloud Formation ◽  
Noctilucent Cloud ◽  
Ice Particles ◽  
Order Of Magnitude ◽  
Mesospheric Clouds ◽  
The Impact ◽  
Odd Oxygen

Abstract. The formation, evolution and eventual sublimation of noctilucent clouds (NLC) may have a significant effect on the odd oxygen and hydrogen chemistry of the high latitude summer mesosphere. Three mechanisms are considered here: the direct uptake of atomic oxygen on the surface of the ice particles; the redistribution of water vapour, which changes the photochemical source of odd hydrogen species; and the direct photolysis of the ice particles themselves to produce odd hydrogen species in the gas phase. A 1-D photochemical model is employed to investigate the potential importance of these mechanisms. This shows, using the recently measured uptake coefficients of O on ice, that the heterogeneous removal of O on the surface of the cloud particles is too slow by at least a factor of 5x103 to compete with gas-phase O chemistry. The second and third mechanisms involve the solar Lyman-α photolysis of H2O in the gas and solid phase, respectively. During twilight, Lyman-α radiation is severely attenuated and these mechanisms are insignificant. In contrast, when the upper mesosphere is fully illuminated there is a dramatic impact on the O profile, with depletion of O at the base of the cloud layer of close to an order of magnitude. A correspondingly large depletion in O3 is also predicted, while H, OH, HO2 and H2O2 are found to be enhanced by factors of 3-5. In fact, rocket-borne mass spectrometer measurements during summer have revealed local H2O2 enhancements in the region of the clouds. Rocket-borne measurements of atomic O and O3 profiles in the presence of mesospheric clouds in the daytime are highly desirable to test the predictions of this model and our understanding of the genesis of mesospheric clouds.

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