Evaluating WRF-Chem aerosol indirect effects in Southeast Pacific marine stratocumulus during VOCALS-REx

Saide, Pablo E.; Carmichael, Gregory R.; Mena‐Carrasco, M.; Yang, Qing; Howell, S. G.; Leon, D.; Snider, Jefferson R.; Bandy, A. R.; Collett, Jeffrey L.; Benedict, Katherine B.; Szoeke, Simon de; Hawkins, Lisa; Allen, Grant; Crawford, Ian; Crosier, Jonathan; Springston, Stephen

doi:10.5194/acp-12-3045-2012

Cited by 82 publications

(119 citation statements)

References 94 publications

(129 reference statements)

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“…The model considers both the direct and indirect effects (Chapman et al, 2009) of aerosols. Details on this configuration and validation against VOCALS measurements are thoroughly described in Saide et al (2012a).…”

Section: H Twohy Et Al: Stratocumulus Clouds Over the Southeast mentioning

confidence: 99%

Impacts of aerosol particles on the microphysical and radiative properties of stratocumulus clouds over the southeast Pacific Ocean

et al. 2013

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The southeast Pacific Ocean is covered by the world's largest stratocumulus cloud layer, which has a strong impact on ocean temperatures and climate in the region. The effect of anthropogenic sources of aerosol particles on the stratocumulus deck was investigated during the VOCALS field experiment. Aerosol measurements below and above cloud were made with a ultra-high sensitivity aerosol spectrometer and analytical electron microscopy. In addition to more standard in-cloud measurements, droplets were collected and evaporated using a counterflow virtual impactor (CVI), and the non-volatile residual particles were analyzed.

Many flights focused on the gradient in cloud properties on an E-W track along 20° S from near the Chilean coast to remote areas offshore. Mean statistics, including their significance, from eight flights and many individual legs were compiled. Consistent with a continental source of cloud condensation nuclei, below-cloud accumulation-mode aerosol and droplet number concentration generally decreased from near shore to offshore. Single particle analysis was used to reveal types and sources of the enhanced particle number that influence droplet concentration. While a variety of particle types were found throughout the region, the dominant particles near shore were partially neutralized sulfates. Modeling and chemical analysis indicated that the predominant source of these particles in the marine boundary layer along 20° S was anthropogenic pollution from central Chilean sources, with copper smelters a relatively small contribution.

Cloud droplets were smaller in regions of enhanced particles near shore. However, physically thinner clouds, and not just higher droplet number concentrations from pollution, both contributed to the smaller droplets. Satellite measurements were used to show that cloud albedo was highest 500–1000 km offshore, and actually slightly lower closer to shore due to the generally thinner clouds and lower liquid water paths there. Thus, larger scale forcings that impact cloud macrophysical properties, as well as enhanced aerosol particles, are important in determining cloud droplet size and cloud albedo.

Differences in the size distribution of droplet residual particles and ambient aerosol particles were observed. By progressively excluding small droplets from the CVI sample, we were able to show that the larger drops, some of which may initiate drizzle, contain the largest aerosol particles. Geometric mean diameters of droplet residual particles were larger than those of the below-cloud and above cloud distributions. However, a wide range of particle sizes can act as droplet nuclei in these stratocumulus clouds. A detailed LES microphysical model was used to show that this can occur without invoking differences in chemical composition of cloud-nucleating particles

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Section: H Twohy Et Al: Stratocumulus Clouds Over the Southeast mentioning

confidence: 99%

Impacts of aerosol particles on the microphysical and radiative properties of stratocumulus clouds over the southeast Pacific Ocean

et al. 2013

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“…To evaluate model performance, regression statistics along with three measures of bias (the mean bias (MB), normalized MB (NMB) and normalized MB factor, NMBF), three measures of error (the root mean square error (RMSE), normalized mean error (NME) and normalized mean error factor, NMEF), and the correlation coefficient (r) (Yu et al, 2006, Gustafson andYu, 2012) were calculated. Following the protocol of the IMPROVE network, the daily (24 h) PM 2.5 concentrations at the AQS sites were calculated from midnight to midnight local time of the next day on the basis of hourly PM 2.5 observations.…”

Section: Model Evaluation Protocolmentioning

confidence: 99%

“…Aerosol particles can influence the earth's climate both directly by scattering and absorption of incoming solar radiation and terrestrial outgoing radiation, and indirectly by affecting cloud radiative properties through their role as cloud condensation nuclei (CCN) and ice nuclei (IN) (Twomey, 1974(Twomey, , 1991Charlson et al, 1992;Yu, 2000;Yu et al, 2000Yu et al, , 2001aYu et al, , b, 2003Yu and Zhang, 2011;Lohmann and Feichter, 2005;Menon et al, 2002Menon et al, , 2008IPCC, 2007;DeFelice et al, 1997;Chapman et al, 2009;Gustafson et al, 2007;Zhang et al, 2010aZhang et al, , b, 2012Tao et al, 2012;Hansen et al, 1997;Haywood and Boucher, 2000;Ramanathan et al, 2001;Rosenfeld et al, 2008;Saxena and Yu, 1998;Saxena et al, 1997;F. Yu et al, 2012a, b;Saide et al, 2012;Yang et al, 2011;Liu et al, 2011;McKeen et al, 2007;Yu et al, 2004Yu et al, , 2007bYu et al, , 2008.…”

Section: Introductionmentioning

confidence: 99%

Aerosol indirect effect on the grid-scale clouds in the two-way coupled WRF–CMAQ: model description, development, evaluation and regional analysis

Mathur

Pleim

et al. 2014

Atmos. Chem. Phys.

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Abstract. This study implemented first, second and glaciation aerosol indirect effects (AIE) on resolved clouds in the two-way coupled Weather Research and Forecasting Community Multiscale Air Quality (WRF-CMAQ) modeling system by including parameterizations for both cloud drop and ice number concentrations on the basis of CMAQpredicted aerosol distributions and WRF meteorological conditions. The performance of the newly developed WRF-CMAQ model, with alternate Community Atmospheric Model (CAM) and Rapid Radiative Transfer Model for GCMs (RRTMG) radiation schemes, was evaluated with observations from the Clouds and the See http://ceres.larc. nasa.gov/. Earth's Radiant Energy System (CERES) satellite and surface monitoring networks (AQS, IMPROVE, CASTNET, STN, and PRISM) over the continental US (CONUS) (12 km resolution) and eastern Texas (4 km resolution) during August and September of 2006. The results at the Air Quality System (AQS) surface sites show that in August, the normalized mean bias (NMB) values for PM 2.5 over the eastern US (EUS) and the western US (WUS) are 5.3 % (−0.1 %) and 0.4 % (−5.2 %) for WRF-CMAQ/CAM (WRF-CMAQ/RRTMG), respectively. The evaluation of PM 2.5 chemical composition reveals that in August, WRF-CMAQ/CAM (WRF-CMAQ/RRTMG) consistently underestimated the observed SO 2− 4 by −23.0 % (−27.7 %), −12.5 % (−18.9 %) and −7.9 % (−14.8 %) over the EUS at the Clean Air Status Trends Network (CAST-NET), Interagency Monitoring of Protected Visual Environments (IMPROVE) and Speciated Trends Network (STN) sites, respectively. Both configurations (WRF-CMAQ/CAM, WRF-CMAQ/RRTMG) overestimated the observed mean organic carbon (OC), elemental carbon (EC) and and total carbon (TC) concentrations over the EUS in August at the IMPROVE sites. Both configurations generally underestimated the cloud field (shortwave cloud forcing, SWCF) over the CONUS in August due to the fact that the AIE on the subgrid convective clouds was not considered when the model simulations were run at the 12 km resolution. This is in agreement with the fact that both configurations captured SWCF and longwave cloud forcing (LWCF) very well for the 4 km simulation over eastern Texas, when all clouds were resolved by the finer resolution domain. The simulations of WRF-CMAQ/CAM and WRF-CMAQ/RRTMG show dramatic improvements for SWCF, LWCF, cloud optical depth (COD), cloud fractions and precipitation over the ocean relative to those of WRF default cases in August. The model performance in September is similar to that in August, except for a greater overestimation of PM 2.5 due to the overestimations of SO

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“…We present two case studies, which correspond to the use of AOD (Saide et al, 2013) and cloud number droplet satellite retrievals (N d ) (Saide et al, 2012a). The WRF-Chem configuration is based on Saide et al (2012b).…”

Section: Satellite Data Assimilation Into Wrf-chemmentioning

confidence: 99%

Data assimilation in atmospheric chemistry models: current status and future prospects for coupled chemistry meteorology models

et al. 2015

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Abstract. Data assimilation is used in atmospheric chemistry models to improve air quality forecasts, construct re-analyses of three-dimensional chemical (including aerosol) concentrations and perform inverse modeling of input variables or model parameters (e.g., emissions). Coupled chemistry meteorology models (CCMM) are atmospheric chemistry models that simulate meteorological processes and chemical transformations jointly. They offer the possibility to assimilate both meteorological and chemical data; however, because CCMM are fairly recent, data assimilation in CCMM has been limited to date. We review here the current status of data assimilation in atmospheric chemistry models with a particular focus on future prospects for data assimilation in CCMM. We first review the methods available for data assimilation in atmospheric models, including variational methods, ensemble Kalman filters, and hybrid methods. Next, we review past applications that have included chemical data assimilation in chemical transport models

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Evaluating WRF-Chem aerosol indirect effects in Southeast Pacific marine stratocumulus during VOCALS-REx

Cited by 82 publications

References 94 publications

Impacts of aerosol particles on the microphysical and radiative properties of stratocumulus clouds over the southeast Pacific Ocean

Impacts of aerosol particles on the microphysical and radiative properties of stratocumulus clouds over the southeast Pacific Ocean

Aerosol indirect effect on the grid-scale clouds in the two-way coupled WRF–CMAQ: model description, development, evaluation and regional analysis

Data assimilation in atmospheric chemistry models: current status and future prospects for coupled chemistry meteorology models

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