Regional effects of atmospheric aerosols on temperature: an evaluation of an ensemble of online coupled models

Abstract. The climate effect of atmospheric aerosols is associated with their influence on the radiative budget of the Earth due to the direct aerosol–radiation interactions (ARIs) and indirect effects, resulting from aerosol–cloud–radiation interactions (ACIs). Online coupled meteorology–chemistry models permit the description of these effects on the basis of simulated atmospheric aerosol concentrations, although there is still some uncertainty associated with the use of these models. Thus, the objective of this work is to assess whether the inclusion of atmospheric aerosol radiative feedbacks of an ensemble of online coupled models improves the simulation results for maximum, mean and minimum temperature at 2 m over Europe. The evaluated models outputs originate from EuMetChem COST Action ES1004 simulations for Europe, differing in the inclusion (or omission) of ARI and ACI in the various models. The cases studies cover two important atmospheric aerosol episodes over Europe in the year 2010: (i) a heat wave event and a forest fire episode (July–August 2010) and (ii) a more humid episode including a Saharan desert dust outbreak in October 2010. The simulation results are evaluated against observational data from the E-OBS gridded database. The results indicate that, although there is only a slight improvement in the bias of the simulation results when including the radiative feedbacks, the spatiotemporal variability and correlation coefficients are improved for the cases under study when atmospheric aerosol radiative effects are included.

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Regional effects of atmospheric aerosols on temperature: an evaluation of an ensemble of on-line coupled models

10.5194/acp-2016-1157 ◽

2017 ◽

Cited By ~ 1

Author(s):

Rocío Baró ◽

Laura Palacios-Peña ◽

Alexander Baklanov ◽

Alessandra Balzarini ◽

Dominik Brunner ◽

...

Keyword(s):

Atmospheric Aerosols ◽

Forest Fires ◽

Atmospheric Aerosol ◽

Correlation Coefficients ◽

Coupled Models ◽

Climate Effect ◽

On Line ◽

Simulation Results ◽

Radiative Feedbacks ◽

Aerosol Radiative

Abstract. The climate effect of atmospheric aerosols is associated to their influence on the radiative budget of the Earth due to direct aerosol-radiation interactions (ARI) and indirect effects, resulting from aerosol-cloud interactions (ACI). On-line coupled meteorology-chemistry models permit the description of these effects on the basis of simulated atmospheric aerosol concentrations, although there is still some uncertainty associated to the use of these models. In this sense, the objective of this work is to assess whether the inclusion of atmospheric aerosol radiative feedbacks of an ensemble of on-line coupled models improves the simulation results for maximum, mean and minimum temperature over Europe. The evaluated model outputs originate from EuMetChem COST Action ES1004 simulations for Europe, differing in the inclusion (or omission) of ARI and ACI in the various models. The case studies cover two important atmospheric aerosol episodes over Europe in the year 2010, a heat wave and forest fires episode (July–August 2010) and a more humid episode including a Saharan desert dust outbreak in October 2010. The simulation results are evaluated against observational data from E-OBS gridded database. The results indicate that, although there is only a slight improvement in the bias of the simulation results when including the radiative feedbacks, the spatio-temporal variability and correlation coefficients are improved for the cases under study when atmospheric aerosol radiative effects are included, especially for those areas closest to emissions sources of atmospheric aerosols.

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Radiative forcing of the desert aerosol at Ouarzazate (Morocco)

E3S Web of Conferences ◽

10.1051/e3sconf/20183703004 ◽

2018 ◽

Vol 37 ◽

pp. 03004

Author(s):

Abdelouahid Tahiri ◽

Mohamed Diouri

Keyword(s):

Optical Properties ◽

Atmospheric Aerosol ◽

Radiative Forcing ◽

Cloud Formation ◽

Optical Parameters ◽

Aerosol Radiative Forcing ◽

Daily Average ◽

Definition Of ◽

Aerosol Radiative

The atmospheric aerosol contributes to the definition of the climate with direct effect, the diffusion and absorption of solar and terrestrial radiations, and indirect, the cloud formation process where aerosols behave as condensation nuclei and alter the optical properties. Satellites and ground-based networks (solar photometers) allow the terrestrial aerosol observation and the determination of impact. Desert aerosol considered among the main types of tropospheric aerosols whose optical property uncertainties are still quite important. The analysis concerns the optical parameters recorded in 2015 at Ouarzazate solar photometric station (AERONET/PHOTONS network, http://aeronet.gsfc.nasa.gov/) close to Saharan zone. The daily average aerosol optical depthτaer at 0.5μm, are relatively high in summer and less degree in spring (from 0.01 to 1.82). Daily average of the Angstrom coefficients α vary between 0.01 and 1.55. The daily average of aerosol radiative forcing at the surface range between -150W/m2 and -10 W/m2 with peaks recorded in summer, characterized locally by large loads of desert aerosol in agreement with the advections of the Southeast of Morocco. Those recorded at the Top of the atmosphere show a variation from -74 W/m2 to +24 W/m2

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Dependence of direct aerosol radiative forcing on the optical properties of atmospheric aerosol and underlying surface

Light Scattering Reviews 8 ◽

10.1007/978-3-642-32106-1_11 ◽

2013 ◽

pp. 505-627

Author(s):

Claudio Tomasi ◽

Christian Lanconelli ◽

Angelo Lupi ◽

Mauro Mazzola

Keyword(s):

Optical Properties ◽

Atmospheric Aerosol ◽

Radiative Forcing ◽

Underlying Surface ◽

Aerosol Radiative Forcing ◽

Aerosol Radiative

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Sensitivity of atmospheric aerosol scavenging to precipitation intensity and frequency in the context of global climate change

10.5194/acp-2017-937 ◽

2017 ◽

Author(s):

Pei Hou ◽

Shiliang Wu ◽

Jessica L. McCarty

Keyword(s):

Climate Change ◽

Global Climate Change ◽

Atmospheric Aerosols ◽

Atmospheric Aerosol ◽

Model Simulation ◽

Global Climate ◽

Regional Scale ◽

Precipitation Intensity ◽

The Past ◽

Precipitation Changes

Abstract. Wet deposition driven by precipitation is an important sink for atmospheric aerosols and soluble gases. We investigate the sensitivity of atmospheric aerosol lifetimes to precipitation intensity and frequency in the context of global climate change. Our study, based on the GEOS-Chem model simulation, shows that the removal efficiency and hence the atmospheric lifetime of aerosols have significantly higher sensitivities to precipitation frequencies than to precipitation intensities, indicating that the same amount of precipitation may lead to different removal efficiencies of atmospheric aerosols. Combining the long-term trends of precipitation patterns for various regions with the sensitivities of atmospheric aerosols lifetimes to various precipitation characteristics allows us to examine the potential impacts of precipitation changes on atmospheric aerosols. Analyses based on an observational dataset show that precipitation frequency in some regions have decreased in the past 14 years, which might increase the atmospheric aerosol lifetimes in those regions. Similar analyses based on multiple reanalysis meteorological datasets indicate that the precipitation changes over the past 30 years can lead to perturbations in the atmospheric aerosol lifetimes by 10 % or higher at the regional scale.

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Direction Finding of Coherent Sources Using a MIMO Array of Triaxial Velocity Sensors

Mathematical Problems in Engineering ◽

10.1155/2019/7010389 ◽

2019 ◽

Vol 2019 ◽

pp. 1-6

Author(s):

Yuwei Song ◽

Guoping Hu ◽

Guimei Zheng

Keyword(s):

Cross Correlation ◽

Correlation Coefficients ◽

Direction Finding ◽

Covariance Matrices ◽

Smoothing Algorithm ◽

Arbitrary Configuration ◽

Effective Aperture ◽

Vector Sensors ◽

Coherent Sources ◽

Simulation Results

In the received side, triaxial velocity sensors of MIMO array are used to solve the problem of coherent source direction-finding in this paper. A new velocity field smoothing algorithm is presented to decorrelate coherent sources. The identically oriented velocity sensors of whole array are divided into three subarrays. Then, the covariance matrices of the three subarrays are smoothed to restore the rank of source covariance matrix (SCM). Lastly, the cross-correlation coefficients of the SCM after smoothing processing are calculated to analyze the performance of decorrelation. The proposed decorrelation algorithm (1) does not need the information of locations of velocity vector sensors; (2) is suitable for arbitrary configuration array; and (3) has no loss of array effective aperture. Simulation results prove the effectiveness of the proposed algorithm.

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How Well Can IMERG Products Capture Typhoon Extreme Precipitation Events over Southern China?

Remote Sensing ◽

10.3390/rs11010070 ◽

2019 ◽

Vol 11 (1) ◽

pp. 70 ◽

Cited By ~ 11

Author(s):

Chaoying Huang ◽

Junjun Hu ◽

Sheng Chen ◽

Asi Zhang ◽

Zhenqing Liang ◽

...

Keyword(s):

Extreme Precipitation ◽

Southern China ◽

Correlation Coefficients ◽

Heavy Precipitation ◽

Spatiotemporal Variability ◽

Bias Analysis ◽

Extreme Precipitation Events ◽

Precipitation Measurement ◽

Global Precipitation ◽

Precipitation Events

This study assesses the performance of the latest version 05B (V5B) Integrated Multi-Satellite Retrievals for Global Precipitation Measurement (GPM) (IMERG) Early and Final Runs over southern China during six extremely heavy precipitation events brought by six powerful typhoons from 2016 to 2017. Observations from a dense network composed of 2449 rain gauges are used as reference to quantify the performance in terms of spatiotemporal variability, probability distribution of precipitation rates, contingency scores, and bias analysis. The results show that: (1) both IMERG with gauge calibration (IMERG_Cal) and without gauge correction (IMERG_Uncal) generally capture the spatial patterns of storm-accumulated precipitation with moderate to high correlation coefficients (CCs) of 0.57–0.87, and relative bias (RB) varying from −17.21% to 30.58%; (2) IMERG_Uncal and IMERG_Cal capture well the area-average hourly series of precipitation over rainfall centers with high CCs ranging from 0.78 to 0.94; (3) IMERG_Cal tends to underestimate precipitation especially the rainfall over the rainfall centers when compared to IMERG_Uncal. The IMERG Final Run shows promising potentials in typhoon-related extreme precipitation storm applications. This study is expected to give useful feedbacks about the latest V5B Final Run IMERG product to both algorithm developers and the scientific end users, providing a better understanding of how well the V5B IMERG products capture the typhoon extreme precipitation events over southern China.

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The effects of simulating volcanic aerosol radiative feedbacks with WRF-Chem during the Eyjafjallajökull eruption, April and May 2010

Atmospheric Environment ◽

10.1016/j.atmosenv.2018.10.058 ◽

2019 ◽

Vol 198 ◽

pp. 194-206 ◽

Cited By ~ 5

Author(s):

Marcus Hirtl ◽

Martin Stuefer ◽

Delia Arnold ◽

Georg Grell ◽

Christian Maurer ◽

...

Keyword(s):

Volcanic Aerosol ◽

Radiative Feedbacks ◽

Aerosol Radiative

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Impacts of Meteorological Conditions, Aerosol Radiative Feedbacks, and Emission Reduction Scenarios on the Coastal Haze Episodes in Southeastern China in December 2013

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-16-0229.1 ◽

2017 ◽

Vol 56 (5) ◽

pp. 1209-1229 ◽

Cited By ~ 2

Author(s):

Jianqiong Zhan ◽

Wenyuan Chang ◽

Wei Li ◽

Yanming Wang ◽

Liqi Chen ◽

...

Keyword(s):

Air Quality ◽

Regional Cooperation ◽

Coastal Region ◽

Northern China ◽

Yangtze River Delta ◽

Meteorological Conditions ◽

Fujian Province ◽

The North ◽

Radiative Feedbacks ◽

Aerosol Radiative

AbstractFujian Province in southeastern coastal China is a relatively clean region with low emissions, as its high altitude isolates it from the rest of the country. However, the region experienced haze episodes on 3–14 December 2013. The authors performed simulations using the Weather Research and Forecasting Model coupled with chemistry (WRF-Chem) to examine the impacts of meteorological conditions, aerosol radiative feedbacks (ARFs; including aerosol direct and nearly first indirect effect), and internal and external emissions reduction scenarios on particulate matter smaller than 2.5 μm (PM2.5) concentrations. To the best of the authors’ knowledge, this is the first time the WRF-Chem model has been used to study air quality in this region. The model reasonably reproduced the meteorological conditions and PM2.5 concentrations. The analysis demonstrated that the highest-PM2.5 event was associated with a cold surge that promoted the impingement of northern pollutants on the region, and PM2.5 concentrations were sensitive to the emissions from the Yangtze River delta (16.6%) and the North China Plain (12.1%). This suggests that efforts toward coastal air quality improvement require regional cooperation to reduce emissions. Noticeably, ARFs were unlikely to increase PM2.5 concentrations in the coastal region, which was in contrast to the case in northern China. ARFs induced strong clean wind anomalies in the coastal region and also lowered the inland planetary boundary layer, which enhanced the blocking of northern pollutants crossing the high terrain in the north of Fujian Province. This indicates that ARFs tend to weaken the haze intensity in the southeastern coastal region.

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Angle Multiplexing Optical Image Encryption in the Fresnel Transform Domain Using Phase-Only Computer-Generated Hologram

Photonics ◽

10.3390/photonics7010001 ◽

2019 ◽

Vol 7 (1) ◽

pp. 1 ◽

Cited By ~ 2

Author(s):

Hsuan T. Chang ◽

Yao-Ting Wang ◽

Chien-Yu Chen

Keyword(s):

Computer Simulation ◽

Image Quality ◽

Image Encryption ◽

Correlation Coefficients ◽

Security Level ◽

Transform Domain ◽

Computer Generated Hologram ◽

Fresnel Transform ◽

Simulation Results ◽

Optical Image Encryption

We propose an angle multiplexing method for optics-based image encryption using a phase-only computer-generated hologram (POCGH) in the tilted Fresnel transform (TFrT) domain. Modified Gerchberg-Saxton algorithms, based on the three types of rotation manipulation in both the hologram and reconstruction planes, are used with their corresponding TFrT parameters to extract the phase-only functions (POFs) of the target images. All the extracted POFs are then phase-modulated and summed to obtain the final POCGH, which is capable of multiplexing and avoiding overlap in the reconstructed images. The computer simulation results show that the images corresponding to the various rotation manipulations at the hologram and image reconstruction planes can be successfully restored with high correlation coefficients. Due to the encrypted nature of the multiplexed images, a higher system security level can be achieved, as the images can only be correctly displayed when all the required parameters in the TFrT are available. The angle sensitivity on the image quality for each manipulation is also investigated.

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