In situ measurements of tropospheric volcanic plumes in Ecuador and Colombia during TC^4

A NASA DC-8 research aircraft penetrated tropospheric gas and aerosol plumes sourced from active volcanoes in Ecuador and Colombia during the Tropical Composition, Cloud and Climate Coupling (TC^4) mission in July–August 2007. The likely source volcanoes were Tungurahua (Ecuador) and Nevado del Huila (Colombia). The TC^4 data provide rare insight into the chemistry of volcanic plumes in the tropical troposphere and permit a comparison of SO_2 column amounts measured by the Ozone Monitoring Instrument (OMI) on the Aura satellite with in situ SO_2 measurements. Elevated concentrations of SO_2, sulfate aerosol, and particles were measured by DC-8 instrumentation in volcanic outflow at altitudes of 3–6 km. Estimated plume ages range from ~2 h at Huila to ~22–48 h downwind of Ecuador. The plumes contained sulfate-rich accumulation mode particles that were variably neutralized and often highly acidic. A significant fraction of supermicron volcanic ash was evident in one plume. In-plume O_3 concentrations were ~70%–80% of ambient levels downwind of Ecuador, but data are insufficient to ascribe this to O_3 depletion via reactive halogen chemistry. The TC^4 data record rapid cloud processing of the Huila volcanic plume involving aqueous-phase oxidation of SO_2 by H_2O_2, but overall the data suggest average in-plume SO_2 to sulfate conversion rates of ~1%–2% h^(−1). SO_2 column amounts measured in the Tungurahua plume (~0.1–0.2 Dobson units) are commensurate with average SO_2 columns retrieved from OMI measurements in the volcanic outflow region in July 2007. The TC^4 data set provides further evidence of the impact of volcanic emissions on tropospheric acidity and oxidizing capacity

In situ measurements of tropospheric volcanic plumes in Ecuador and Colombia during TC

A NASA DC‐8 research aircraft penetrated tropospheric gas and aerosol plumes sourced from active volcanoes in Ecuador and Colombia during the Tropical Composition, Cloud and Climate Coupling (TC4 ) mission in July–August 2007. The likely source volcanoes were Tungurahua (Ecuador) and Nevado del Huila (Colombia). The TC4 data provide rare insight into the chemistry of volcanic plumes in the tropical troposphere and permit a comparison of SO2 column amounts measured by the Ozone Monitoring Instrument (OMI) on the Aura satellite with in situ SO2 measurements. Elevated concentrations of SO2, sulfate aerosol, and particles were measured by DC‐8 instrumentation in volcanic outflow at altitudes of 3–6 km. Estimated plume ages range from ∼2 h at Huila to ∼22–48 h downwind of Ecuador. The plumes contained sulfate‐rich accumulation mode particles that were variably neutralized and often highly acidic. A significant fraction of supermicron volcanic ash was evident in one plume. In‐plume O3 concentrations were ∼70%–80% of ambient levels downwind of Ecuador, but data are insufficient to ascribe this to O3 depletion via reactive halogen chemistry. The TC4 data record rapid cloud processing of the Huila volcanic plume involving aqueous‐phase oxidation of SO2 by H2O2, but overall the data suggest average in‐plume SO2 to sulfate conversion rates of ∼1%–2% h−1 . SO2 column amounts measured in the Tungurahua plume (∼0.1–0.2 Dobson units) are commensurate with average SO2 columns retrieved from OMI measurements in the volcanic outflow region in July 2007. The TC4 data set provides further evidence of the impact of volcanic emissions on tropospheric acidity and oxidizing capacit

A kapwa-infused paradigm in teaching Catholic theology/catechesis in a multireligious classroom in the Philippines

The increasing religious diversity in educational space has raised a legitimate question on how Catholic theology/ catechesis must be taught in Philippine Catholic universities given the institutional mandate to educate students “into the faith of the Church through teaching of Christian doctrine in an organic and systematic way” (Wuerl, 2013, 1). On this note, the paper makes reference to “centered plural- ism” (CP), a positional posture espoused by Georgetown University in dealing with this predicament. In an attempt to (re) appropriate CP into local context, there is a need to explore the Filipino conception of self/others as enveloped within the indigenous concept of kapwa. Hereon, the paper finds that CP is not just feasibly suitable in local context but with kapwa's more inclusive description of the relationship of self and others, a CP‐based teaching paradigm in theology/ catechesis is a promising project in the educational scene of the Philippines

Radiative and chemical implications of the size and composition of aerosol particles in the existing or modified global stratosphere

The size of aerosol particles has fundamental effects on their chemistry and radiative effects. We explore those effects using aerosol size and composition data in the lowermost stratosphere along with calculations of light scattering. In the size range between about 0.1 and 1.0 µm diameter (accumulation mode), there are at least two modes of particles in the lowermost stratosphere. The larger mode consists mostly of particles produced in the stratosphere, and the smaller mode consists mostly of particles transported from the troposphere. The stratospheric mode is similar in the Northern and Southern Hemisphere, whereas the tropospheric mode is much more abundant in the Northern Hemisphere. The purity of sulfuric acid particles in the stratospheric mode shows that there is limited production of secondary organic aerosol in the stratosphere, especially in the Southern Hemisphere. Out of eight sets of flights sampling the lowermost stratosphere (four seasons and two hemispheres) there were three with large injections of specific materials: volcanic, biomass burning, or dust. The stratospheric and tropospheric modes have very different roles for radiative effects on climate and for heterogeneous chemistry. Because the larger particles are more efficient at scattering light, most of the radiative effect in the lowermost stratosphere is due to stratospheric particles. In contrast, the tropospheric particles can have more surface area, at least in the Northern Hemisphere. The surface area of tropospheric particles could have significant implications for heterogeneous chemistry because these particles, which are partially neutralized and contain organics, do not correspond to the substances used for laboratory studies of stratospheric heterogeneous chemistry. We then extend the analysis of size-dependent properties to particles injected into the stratosphere, either intentionally or from volcanoes. There is no single size that will simultaneously maximize the climate impact relative to the injected mass, infrared heating, potential for heterogeneous chemistry, and undesired changes in direct sunlight. In addition, light absorption in the far ultraviolet is identified as an issue requiring more study for both the existing and potentially modified stratosphere.</p

Cloud condensation nuclei as a modulator of ice processes in Arctic mixed-phase clouds

We propose that cloud condensation nuclei (CCN) concentrations are important for modulating ice formation of Arctic mixed-phase clouds, through modification of the droplet size distribution. Aircraft observations from the Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC) study in northern Alaska in April 2008 allow for identification and characterization of both aerosol and trace gas pollutants, which are then compared with cloud microphysical properties. Consistent with previous studies, we find that the concentration of precipitating ice particles (&gt;400 μm) is correlated with the concentration of large droplets (&gt;30 μm). We are further able to link the observed microphysical conditions to aerosol pollution, originating mainly from long range transport of biomass burning emissions. The case studies demonstrate that polluted mixed-phase clouds have narrower droplet size distributions and contain 1–2 orders of magnitude fewer precipitating ice particles than clean clouds at the same temperature. This suggests an aerosol indirect effect leading to greater cloud lifetime, greater cloud emissivity, and reduced precipitation. This result is opposite to the glaciation indirect effect, whereby polluted clouds are expected to precipitate more readily due to an increase in the concentration of particles acting as ice nuclei

Surface Dimming by the 2013 Rim Fire Simulated by a Sectional Aerosol Model

The Rim Fire of 2013, the third largest area burned by fire recorded in California history, is simulated by a climate model coupled with a size-resolved aerosol model. Modeled aerosol mass, number and particle size distribution are within variability of data obtained from multiple airborne in-situ measurements. Simulations suggest Rim Fire smoke may block 4-6 of sunlight energy reaching the surface, with a dimming efficiency around 120-150 W m(exp -2) per unit aerosol optical depth in the mid-visible at 13:00-15:00 local time. Underestimation of simulated smoke single scattering albedo at mid-visible by 0.04 suggests the model overestimates either the particle size or the absorption due to black carbon. This study shows that exceptional events like the 2013 Rim Fire can be simulated by a climate model with one-degree resolution with overall good skill, though that resolution is still not sufficient to resolve the smoke peak near the source region

Negative responses of highland pines to anthropogenic activities in inland Spain: a palaeoecological perspective

Palaeoecological evidence indicates that highland pines were dominant in extensive areas of the mountains of Central and Northern Iberia during the first half of the Holocene. However, following several millennia of anthropogenic pressure, their natural ranges are now severely reduced. Although pines have been frequently viewed as first-stage successional species responding positively to human disturbance, some recent palaeobotanical work has proposed fire disturbance and human deforestation as the main drivers of this vegetation turnover. To assess the strength of the evidence for this hypothesis and to identify other possible explanations for this scenario, we review the available information on past vegetation change in the mountains of northern inland Iberia. We have chosen data from several sites that offer good chronological control, including palynological records with microscopic charcoal data and sites with plant macro- and megafossil occurrence. We conclude that although the available long-term data are still fragmentary and that new methods are needed for a better understanding of the ecological history of Iberia, fire events and human activities (probably modulated by climate) have triggered the pine demise at different locations and different temporal scales. In addition, all palaeoxylological, palynological and charcoal results obtained so far are fully compatible with a rapid human-induced ecological change that could have caused a range contraction of highland pines in western Iberia

Characteristics, sources, and transport of aerosols measured in spring 2008 during the aerosol, radiation, and cloud processes affecting Arctic Climate (ARCPAC) Project

We present an overview of the background, scientific goals, and execution of the Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC) project of April 2008. We then summarize airborne measurements, made in the troposphere of the Alaskan Arctic, of aerosol particle size distributions, composition, and optical properties and discuss the sources and transport of the aerosols. The aerosol data were grouped into four categories based on gas-phase composition. First, the background troposphere contained a relatively diffuse, sulfate-rich aerosol extending from the top of the sea-ice inversion layer to 7.4 km altitude. Second, a region of depleted (relative to the background) aerosol was present within the surface inversion layer over sea-ice. Third, layers of dense, organic-rich smoke from open biomass fires in southern Russia and southeastern Siberia were frequently encountered at all altitudes from the top of the inversion layer to 7.1 km. Finally, some aerosol layers were dominated by components originating from fossil fuel combustion. &lt;br&gt;&lt;/br&gt; Of these four categories measured during ARCPAC, the diffuse background aerosol was most similar to the average springtime aerosol properties observed at a long-term monitoring site at Barrow, Alaska. The biomass burning (BB) and fossil fuel layers were present above the sea-ice inversion layer and did not reach the sea-ice surface during the course of the ARCPAC measurements. The BB aerosol layers were highly scattering and were moderately hygroscopic. On average, the layers produced a noontime net heating of ~0.1 K day&lt;sup&gt;&amp;minus;1&lt;/sup&gt; between 3 and 7 km and a slight cooling at the surface. The ratios of particle mass to carbon monoxide (CO) in the BB plumes, which had been transported over distances &gt;5000 km, were comparable to the high end of literature values derived from previous measurements in wildfire smoke. These ratios suggest minimal precipitation scavenging and removal of the BB particles between the time they were emitted and the time they were observed in dense layers above the sea-ice inversion layer