Global and regional trends of Aerosol Optical Thickness derived using satellite- and ground-based observations

Atmospheric aerosol plays a critical role for human health, air quality, long range transport of pollution, and the Earth s radiative balance, thereby influencing global climate change. To test our scientific understanding and provide an evidence base for policymakers, long-term temporal changes of local, regional, and global aerosols are needed. Remote sensing from satellite borne and ground based observations offers unique opportunities to provide such data. However, only a few studies have discussed the limitations, associated with unrepresentative sampling originating from large/persistent cloud disturbance and limited/different sampling (limited orbital periods and different sampling times) in the trend analysis. Using a linear weighted model, the long-term trends of global AOTs from various polar orbiting satellites and ground observations: MODIS (aboard Terra), MISR (Terra), SeaWiFS (OrbView-2), MODIS (Aqua), and AERONET have been analyzed. In this manner, the present study attempts to minimize the influence of unrepresentative sampling in the trend analysis. Throughout terrestrial and marine regions, temporal increase of cloud-free AOTs were dominat over the globe (GL), northern (NH), and southern hemisphere (SH) (up to 0.00348±0.00185 for GL, 0.00514±0.00272 for NH, and 0.00232±0.00124 per year for SH). Generally, consistently in all observations, the weighted trends over Eastern US and OECD Europe showed a strong decreasing AOT (up to -0.00376±0.00174 for Eastern US and -0.00530±0.00304 per year for OECD Europe) attributed to the recent environmental legislation and resulting regulation of emissions. A significant increase was observed over Saharan/Arabian deserts, South, and East Asia (up to 0.00618±0.00326, 0.01452±0.00615, and 0.01939±0.00986 per year, respectively). These in part dramatic increases are caused by the enhanced amount of aerosol transported/emitted from industrialization, urbanization, deforestation, desertification, and climate change. Overall large/persistent cloud disturbance all year round and the limited/different sampling of polar orbiting satellites represent a challenge, which has been addressed successfully in this study for the accurate determination of aerosol amount and its trends

Clean Energy Equity

Solar, wind, and other clean, renewable sources of energy promise to mitigate climate change, enhance energy security, and foster economic growth. But many of the policies in place to promote clean energy today are marred by an uneven distribution of economic opportunities and associated financial burdens. Tax incentives for renewables cost American taxpayers billions of dollars every year, yet the tax code effectively precludes all but the largest banks and most profitable corporations from reaping the benefits of these tax breaks. Other policies, such as renewable portfolio standards that set minimum quota to create demand for renewable electricity require such high levels of market expertise and financial acumen that they engender similarly disparate social impacts—all in the name of an environmentally sustainable energy future. To date, policymakers and scholars have focused primarily on the efficacy and, more recently, the efficiency of clean energy policy. This Article makes the case that the next generation of policies should incorporate equity as another first-order consideration in policy design and implementation. Properly defined as the commensurate matching of costs and benefits, equity offers a more reliable metric for distributional impacts than the multitude of competing, normatively charged notions of fairness that currently dominate the public discourse. Empirical assessment and qualitative analysis of today’s leading clean energy policies reveal widespread issues related to equity. Insights gleaned from a representative sampling of the global policy potpourri yield valuable design recommendations for the next generation of clean energy policies—a generation that, ideally, will be at once effective, efficient, and more equitable. As the greening grid becomes ever more interactive, so, too, should the process that produces the policy landscape driving the clean energy transition become more participatory. This Article suggests Elinor Ostrom’s polycentricity model as a powerful governance tool to help produce more equitable clean energy policies

Clean Energy Equity

Solar, wind, and other clean, renewable sources of energy promise to mitigate climate change, enhance energy security, and foster economic growth. But many of the policies in place to promote clean energy today are marred by an uneven distribution of economic opportunities and associated financial burdens. Tax incentives for renewables cost American taxpayers billions of dollars every year, yet the tax code effectively precludes all but the largest banks and most profitable corporations from reaping the benefits of these tax breaks. Other policies, such as renewable portfolio standards that set minimum quota to create demand for renewable electricity require such high levels of market expertise and financial acumen that they engender similarly disparate social impacts—all in the name of an environmentally sustainable energy future.To date, policymakers and scholars have focused primarily on the efficacy and, more recently, the efficiency of clean energy policy. This Article makes the case that the next generation of policies should incorporate equity as another first-order consideration in policy design and implementation. Properly defined as the commensurate matching of costs and benefits, equity offers a more reliable metric for distributional impacts than the multitude of competing, normatively charged notions of fairness that currently dominate the public discourse.Empirical assessment and qualitative analysis of today’s leading clean energy policies reveal widespread issues related to equity. Insights gleaned from a representative sampling of the global policy potpourri yield valuable design recommendations for the next generation of clean energy policies—a generation that, ideally, will be at once effective, efficient, and more equitable.As the greening grid becomes ever more interactive, so, too, should the process that produces the policy landscape driving the clean energy transition become more participatory. This Article suggests Elinor Ostrom’s polycentricity model as a powerful governance tool to help produce more equitable clean energy policies

Representing Aerosol Optical Properties with Theoretical Modelling and Global Observations

Aerosols are an important factor in biogeochemical cycles, climate variability and air quality. In the context of monitoring the marine ecosystems, a proper definition of the inherent optical properties of the aerosols is needed to perform radiative transfer simulations. These are useful to build inversion schemes, that will quantify the aerosol load and type and define the spectral signature of the ocean surface, and to quantify the aerosol direct radiative effect. This report describes tools that link size distribution of aerosol particles, assumed homogeneous spheres, and refractive index to optical properties through Mie theory. Then, it provides a brief survey of generic aerosol models, that is completed by a broad review of the measurements that are relevant for the definition of aerosol optical properties.JRC.H.5-Rural, water and ecosystem resource

Stratospheric aerosol - Observations, processes, and impact on climate

Interest in stratospheric aerosol and its role in climate have increased over the last decade due to the observed increase in stratospheric aerosol since 2000 and the potential for changes in the sulfur cycle induced by climate change. This review provides an overview about the advances in stratospheric aerosol research since the last comprehensive assessment of stratospheric aerosol was published in 2006. A crucial development since 2006 is the substantial improvement in the agreement between in situ and space-based inferences of stratospheric aerosol properties during volcanically quiescent periods. Furthermore, new measurement systems and techniques, both in situ and space based, have been developed for measuring physical aerosol properties with greater accuracy and for characterizing aerosol composition. However, these changes induce challenges to constructing a long-term stratospheric aerosol climatology. Currently, changes in stratospheric aerosol levels less than 20% cannot be confidently quantified. The volcanic signals tend to mask any nonvolcanically driven change, making them difficult to understand. While the role of carbonyl sulfide as a substantial and relatively constant source of stratospheric sulfur has been confirmed by new observations and model simulations, large uncertainties remain with respect to the contribution from anthropogenic sulfur dioxide emissions. New evidence has been provided that stratospheric aerosol can also contain small amounts of nonsulfate matter such as black carbon and organics. Chemistry-climate models have substantially increased in quantity and sophistication. In many models the implementation of stratospheric aerosol processes is coupled to radiation and/or stratospheric chemistry modules to account for relevant feedback processes

Ozone depletion, greenhouse gases, and climate change

This symposium was organized to study the unusual convergence of a number of observations, both short and long term that defy an integrated explanation. Of particular importance are surface temperature observations and observations of upper atmospheric temperatures, which have declined significantly in parts of the stratosphere. There has also been a dramatic decline in ozone concentration over Antarctica that was not predicted. Significant changes in precipitation that seem to be latitude dependent have occurred. There has been a threefold increase in methane in the last 100 years; this is a problem because a source does not appear to exist for methane of the right isotopic composition to explain the increase. These and other meteorological global climate changes are examined in detail

The Atmospheric Effects of Stratospheric Aircraft: a First Program Report

Studies have indicated that, with sufficient technology development, high speed civil transport aircraft could be economically competitive with long haul subsonic aircraft. However, uncertainty about atmospheric pollution, along with community noise and sonic boom, continues to be a major concern; and this is addressed in the planned 6 yr HSRP begun in 1990. Building on NASA's research in atmospheric science and emissions reduction, the AESA studies particularly emphasizing stratospheric ozone effects. Because it will not be possible to directly measure the impact of an HSCT aircraft fleet on the atmosphere, the only means of assessment will be prediction. The process of establishing credibility for the predicted effects will likely be complex and involve continued model development and testing against climatological patterns. Lab simulation of heterogeneous chemistry and other effects will continue to be used to improve the current models

A review of coarse mineral dust in the Earth system

Mineral dust particles suspended in the atmosphere span more than three orders of magnitude in diameter, from <0.1 µm to more than 100 µm. This wide size range makes dust a unique aerosol species with the ability to interact with many aspects of the Earth system, including radiation, clouds, hydrology, atmospheric chemistry, and biogeochemistry. This review focuses on coarse and super-coarse dust aerosols, which we respectively define as dust particles with a diameter of 2.5–10 µm and 10–62.5 µm. We review several lines of observational evidence indicating that coarse and super-coarse dust particles are transported farther than previously expected and that the abundance of these particles is substantially underestimated in current global models. We synthesize previous studies that used observations, theories, and model simulations to highlight the impacts of coarse and super-coarse dust aerosols on the Earth system, including their effects on dust-radiation interactions, dust-cloud interactions, atmospheric chemistry, and biogeochemistry. Specifically, coarse and super-coarse dust aerosols produce a net positive direct radiative effect (warming) at the top of the atmosphere and can modify temperature and water vapor profiles, influencing the distribution of clouds and precipitation. In addition, coarse and super-coarse dust aerosols contribute a substantial fraction of ice-nucleating particles, especially at temperatures above –23 °C. They also contribute a substantial fraction to the available reactive surfaces for atmospheric processing and the dust deposition flux that impacts land and ocean biogeochemistry by supplying important nutrients such as iron and phosphorus. Furthermore, we examine several limitations in the representation of coarse and super-coarse dust aerosols in current model simulations and remote-sensing retrievals. Because these limitations substantially contribute to the uncertainties in simulating the abundance and impacts of coarse and super-coarse dust aerosols, we offer some recommendations to facilitate future studies. Overall, we conclude that an accurate representation of coarse and super-coarse properties is critical in understanding the impacts of dust aerosols on the Earth system

Renewable Energies for Sustainable Development

In the current scenario in which climate change dominates our lives and in which we all need to combat and drastically reduce the emission of greenhouse gases, renewable energies play key roles as present and future energy sources. Renewable energies vary across a wide range, and therefore, there are related studies for each type of energy. This Special Issue is composed of studies integrating the latest research innovations and knowledge focused on all types of renewable energy: onshore and offshore wind, photovoltaic, solar, biomass, geothermal, waves, tides, hydro, etc. Authors were invited submit review and research papers focused on energy resource estimation, all types of TRL converters, civil infrastructure, electrical connection, environmental studies, licensing and development of facilities, construction, operation and maintenance, mechanical and structural analysis, new materials for these facilities, etc. Analyses of a combination of several renewable energies as well as storage systems to progress the development of these sustainable energies were welcomed