Aerosol trends as a potential driver of regional climate in the central United States: evidence from observations

Cusworth, Daniel H.; Mickley, Loretta J.; Leibensperger, E. M.; Iacono, Michael J.

doi:10.5194/acp-17-13559-2017

Cited by 11 publications

(8 citation statements)

References 53 publications

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“…A continuous decrease of PM 2.5 from 2007 to 2014 at Baltimore, United States was found based on the monthly anomalies of PM 2.5 observations calculated from the EPA hourly average PM 2.5 ( Figure 1). A long-term decrease of aerosol loading in the recent decade was also found at other places in the United States in previous studies using different aerosol observations-AOD, PM 10 , or PM 2.5 [15,32,38]. Different from aerosols, there is no trend found for the CBH and LCL monthly anomalies from 2007 to 2014 (Figure 2a,b).…”

Section: Resultssupporting

confidence: 72%

Observed Correlation between Aerosol and Cloud Base Height for Low Clouds at Baltimore and New York, United States

Gebremariam

Weldegaber

2018

Atmosphere

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The correlation between aerosol particulate matter with aerodynamic diameter ≤2.5 µm (PM 2.5) and cloud base height (CBH) of low clouds (CBH lower than 1.5 km a.g.l.) at Baltimore and New York, United States, for an 8 year period (2007-2014) was investigated using information from the Automated Surface Observing System (ASOS) observations and collocated U.S. Environmental Protection Agency (EPA) observations. The lifting condensation level (LCL) heights were calculated and compared with the CBH. The monthly average observations show that PM 2.5 decreases from 2007 to 2014 while there is no significant trend found for CBH and LCL. The variability of the LCL height agrees well with CBH but LCL height is systematically lower than CBH (~180 m lower). There was a significant negative correlation found between CBH-LCL and PM 2.5. All of the cloud cases were separated into polluted and clean conditions based on the distribution of PM 2.5 values. The distributions of CBH-LCL in the two groups show more cloud cases with smaller CBH-LCL in polluted conditions than in clean conditions.

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Section: Resultssupporting

confidence: 72%

Observed Correlation between Aerosol and Cloud Base Height for Low Clouds at Baltimore and New York, United States

Gebremariam

Weldegaber

2018

Atmosphere

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“…This research highlights an interesting aspect of climate in the region, namely that of the warming hole due to aerosol effects. There are dueling perspectives on climate and radiation impacts of aerosol effects from both natural and anthropogenic sources [29][30][31]. The research here does not necessarily seek to answer this debate, however, the hypothesis of Y. Lee et al [32] does offer intriguing insights into a future climate scenario where air pollution control policies may have in had an impact.…”

Section: Discussionmentioning

confidence: 95%

Assessment of Aerosol Radiative Forcing with 1-D Radiative Transfer Modeling in the U. S. South-East

Alston

Sokolik

2018

Atmosphere

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Aerosols and their radiative properties play an integral part in understanding Earth’s climate. It is becoming increasingly common to examine aerosol’s radiative impacts on a regional scale. The primary goal of this research is to explore the impacts of regional aerosol’s forcing at the surface and top-of-atmosphere (TOA) in the south-eastern U.S. by using a 1-D radiative transfer model. By using test cases that are representative of conditions common to this region, an estimate of aerosol forcing can be compared to other results. Speciation data and aerosol layer analysis provide the basis for the modeling. Results indicate that the region experiences TOA cooling year-round, where the winter has TOA forcings between −2.8 and −5 W/m2, and the summer has forcings between −5 and −15 W/m2 for typical atmospheric conditions. Surface level forcing efficiencies are greater than those estimated for the TOA for all cases considered i.e., urban and non-urban background conditions. One potential implication of this research is that regional aerosol mixtures have effects that are not well captured in global climate model estimates, which has implications for a warming climate where all radiative inputs are not well characterized, thus increasing the ambiguity in determining regional climate impacts.

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“…In contrast, the observational study of Tosca et al (2017) , which also relied on satellite AOD, pointed to aerosol–radiation interactions as the driver of surface temperature trends in the southeast. Analysis of ground-based observations in Mississippi, however, found little covariability between AOD and clear-sky solar radiation at the surface, casting doubt on the importance of aerosol–radiation interactions in driving the observed cooling in this region ( Cusworth et al, 2017 ).…”

Section: Chemistry–climate Interactionsmentioning

confidence: 99%

Southeast Atmosphere Studies: learning from model-observation syntheses

et al. 2018

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Concentrations of atmospheric trace species in the United States have changed dramatically over the past several decades in response to pollution control strategies, shifts in domestic energy policy and economics, and economic development (and resulting emission changes) elsewhere in the world. Reliable projections of the future atmosphere require models to not only accurately describe current atmospheric concentrations, but to do so by representing chemical, physical and biological processes with conceptual and quantitative fidelity. Only through incorporation of the processes controlling emissions and chemical mechanisms that represent the key transformations among reactive molecules can models reliably project the impacts of future policy, energy and climate scenarios. Efforts to properly identify and implement the fundamental and controlling mechanisms in atmospheric models benefit from intensive observation periods, during which collocated measurements of diverse, speciated chemicals in both the gas and condensed phases are obtained. The Southeast Atmosphere Studies (SAS, including SENEX, SOAS, NOMADSS and SEAC4RS) conducted during the summer of 2013 provided an unprecedented opportunity for the atmospheric modeling community to come together to evaluate, diagnose and improve the representation of fundamental climate and air quality processes in models of varying temporal and spatial scales.This paper is aimed at discussing progress in evaluating, diagnosing and improving air quality and climate modeling using comparisons to SAS observations as a guide to thinking about improvements to mechanisms and parameterizations in models. The effort focused primarily on model representation of fundamental atmospheric processes that are essential to the formation of ozone, secondary organic aerosol (SOA) and other trace species in the troposphere, with the ultimate goal of understanding the radiative impacts of these species in the southeast and elsewhere. Here we address questions surrounding four key themes: gas-phase chemistry, aerosol chemistry, regional climate and chemistry interactions, and natural and anthropogenic emissions. We expect this review to serve as a guidance for future modeling efforts.

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Aerosol trends as a potential driver of regional climate in the central United States: evidence from observations

Cited by 11 publications

References 53 publications

Observed Correlation between Aerosol and Cloud Base Height for Low Clouds at Baltimore and New York, United States

Observed Correlation between Aerosol and Cloud Base Height for Low Clouds at Baltimore and New York, United States

Assessment of Aerosol Radiative Forcing with 1-D Radiative Transfer Modeling in the U. S. South-East

Southeast Atmosphere Studies: learning from model-observation syntheses

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