Interaction between biomass-burning aerosol and clouds under different climate/weather regimes

2020 ◽  
Author(s):  
Azusa Takeishi ◽  
Chien Wang
Keyword(s):  
Biomass Burning ◽  
Extended Period ◽  
Climate Regime ◽  
Maritime Continent ◽  
Convective Clouds ◽  
Wide Range ◽  
Biomass Burning Aerosol ◽  
Biomass Burning Particles ◽  
Insight Into

<p>The maritime continent in Southeast Asia is characterized by the frequent convective activities on a wide range of scales, as well as by the seasonal emissions of biomass-burning particles. The emission of biomass-burning particles in this region typically peaks in September and October, whereas its intensity varies considerably from year to year. Since the atmospheric circulation over the region is heavily influenced by a range of meteorological and climatological variabilities, such as ENSO, it is important to quantitatively examine the impacts of biomass-burning particles on clouds while taking weather/climate regimes into account. We investigate the effects of biomass-burning particles on clouds, especially convective ones, with cloud-resolving simulations by the WRF-CHEM model. Instead of focusing on a particular case, our simulations cover an extended period of time in the month of September, allowing us to examine both individual convection and an ensemble of convective clouds developing under different weather/climate regimes and hence different aerosol abundance and distributions. Such long-term and high-resolution simulations over the region will give us an insight into the climate-regime dependent two-way interaction between aerosols and clouds.</p>

scholarly journals Closing up onto our sun: solar imaging

2020 ◽  
Vol 240 ◽  
pp. 07011
Author(s):  
Kushagra Shrivastava ◽  
Keith Wen Kai Chia ◽  
Kang Jun Wong ◽  
Alfred Yong Liang Tan ◽  
Hwee Tiang Ning
Keyword(s):  
Solar Activity ◽  
The Sun ◽  
Research Needs ◽  
Large Numbers ◽  
Wide Range ◽  
Future Science ◽  
Insight Into ◽  
Term Data ◽  
Made In

Solar activity research provides insight into the Sun’s past, future (Science Daily, 2018). The solar activity includes observations of large numbers of intense sunspots, flares, and other phenomena; and demands a wide range of techniques and measurements on the observations. This research needs long term data collection before critical analyses can occur, to generate meaningful learning and knowledge. In this project, we will use solar imaging to make observations of solar activity, and take our baby steps to make contributions in citizen science. Observations will be made in 3 wavelengths to gain a more thorough analysis by looking at different perspectives of the Sun, namely H-Alpha, Calcium-K, and white light.

scholarly journals Concentration-discharge relationships vary among hydrological events, reflecting differences in event characteristics

2020 ◽  
Author(s):  
Julia L. A. Knapp ◽  
Jana von Freyberg ◽  
Bjørn Studer ◽  
Leonie Kiewiet ◽  
James W. Kirchner
Keyword(s):  
Trace Metals ◽  
Major Ions ◽  
Low Frequency ◽  
Solute Concentration ◽  
Biologically Active ◽  
Concentration Data ◽  
Event Scale ◽  
Wide Range ◽  
Insight Into

Abstract. Studying the response of streamwater chemistry to changes in discharge can provide valuable insights into how catchments store and release water and solutes. Previous studies have determined concentration-discharge (cQ) relationships from long-term, low-frequency data of a wide range of solutes. These analyses, however, provide little insight into the coupling of solute concentrations and flow during individual hydrologic events. Event-scale cQ relationships have rarely been investigated across a wide range of solutes and over extended periods of time, and thus little is known about differences and similarities between event-scale and long-term cQ relationships. Differences between event-scale and long-term cQ behavior may provide useful information about the processes regulating their transport through the landscape. Here we analyze cQ relationships of 14 different solutes, ranging from major ions to trace metals, as well as electrical conductivity, in the Swiss Erlenbach catchment. From a 2-year time series of sub-hourly solute concentration data we determined long-term cQ relationships for each solute and compared them to cQ relationships of 30 individual events. The long-term cQ behavior of groundwater-sourced solutes was representative of their cQ behavior during hydrologic events. Other solutes, however, exhibited very different cQ patterns at the event and long-term scale. This was particularly true for trace metals as well as atmospheric and/or biologically active solutes, many of which exhibited highly variable cQ behavior from one event to the next. Most of this inter-event variability in cQ behavior can be explained by factors such as catchment wetness, season, event size, input concentrations, and event-water contributions. We present an overview of the processes regulating different groups of solutes, depending on their origin in and pathways through the catchment. Our analysis thus provides insight into controls on solute variations at the hydrologic event scale.

scholarly journals Above Cloud Aerosol Optical Depth from airborne observations in the South-East Atlantic

2019 ◽  
Author(s):  
Samuel E. LeBlanc ◽  
Jens Redemann ◽  
Connor Flynn ◽  
Kristina Pistone ◽  
Meloë Kacenelenbogen ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Biomass Burning ◽  
Aerosol Layer ◽  
The South ◽  
East Atlantic ◽  
Vertical Column ◽  
Biomass Burning Aerosol ◽  
Aerosol Plume

Abstract. The South-East Atlantic (SEA) is host to a climatologically significant biomass burning aerosol layer overlying marine stratocumulus. We present directly measured Above Cloud Aerosol Optical Depth (ACAOD) from the recent ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) airborne field campaign during August and September 2016. In our analysis, we use data from the Spectrometers for Sky-Scanning Sun-Tracking Atmospheric Research (4STAR) instrument and found an average ACAOD of 0.32 at 501 nm, with an average Ångström exponent (AE) of 1.71. The AE is much lower at 1.25 for the full column (including below cloud level aerosol), indicating the presence of large aerosol particles, likely marine aerosol, embedded within the vertical column. ACAOD is observed to be highest near coast at about 12° S, whereas its variability is largest at the southern edge of the average aerosol plume, as indicated by 12 years of MODIS observations. In comparison to MODIS derived ACAOD and long term fine-mode plume-average AOD, the directly-measured ACAOD from 4STAR is slightly lower than the ACAOD product from MODIS. The peak ACAOD expected from long term retrievals is measured to be closer to coast in 2016 at about 1.5°–4° W. By spatially binning the sampled AOD, we obtain a mean ACAOD of 0.37 for the SEA region. Vertical profiles of AOD showcase the variability of the altitude of the aerosol plume and its separation from cloud top. We measured larger AOD at high altitude near coast than farther from coast, while generally observing a larger vertical gap further from coast. Changes of AOD with altitude are correlated with a gas tracer of the biomass burning aerosol plume. Vertical extent of gaps between aerosol and cloud show a large distribution of extent, dominated by near zero gap. The gap distribution with longitude is observed to be largest at about 7° W, farther from coast than expected.

scholarly journals Above-cloud aerosol optical depth from airborne observations in the southeast Atlantic

2020 ◽  
Vol 20 (3) ◽  
pp. 1565-1590 ◽  
Author(s):  
Samuel E. LeBlanc ◽  
Jens Redemann ◽  
Connor Flynn ◽  
Kristina Pistone ◽  
Meloë Kacenelenbogen ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Biomass Burning ◽  
Wide Distribution ◽  
Aerosol Layer ◽  
Modis Aod ◽  
First Results ◽  
Biomass Burning Aerosol ◽  
Aerosol Plume

Abstract. The southeast Atlantic (SEA) region is host to a climatologically significant biomass burning aerosol layer overlying marine stratocumulus. We present the first results of the directly measured above-cloud aerosol optical depth (ACAOD) from the recent ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) airborne field campaign during August and September 2016. In our analysis, we use data from the Spectrometers for Sky-Scanning Sun-Tracking Atmospheric Research (4STAR) instrument and found an average ACAOD of 0.32 at 501 nm (range of 0.02 to 1.04), with an average Ångström exponent (AE) above clouds of 1.71. The AE is much lower at 1.25 for the full column (including below-cloud-level aerosol, with an average of 0.36 at 501 nm and a range of 0.02 to 0.74), indicating the presence of large aerosol particles, likely marine aerosol, in the lower atmospheric column. The ACAOD is observed from 4STAR to be highest near the coast at about 12∘ S, whereas its variability is largest at the southern edge of the average aerosol plume, as indicated by 12 years of MODIS observations. In comparison to MODIS-derived ACAOD and long-term fine-mode plume-average AOD along a diagonal routine track extending out from the coast of Namibia, the directly measured ACAOD from 4STAR is slightly lower than the ACAOD product from MODIS. The peak ACAOD expected from MODIS AOD retrievals averaged over a long term along the routine diagonal flight track (peak of 0.5) was measured to be closer to coast in 2016 at about 1.5–4∘ E, with 4STAR ACAOD averages showing a peak of 0.42. When considering the full observation set over the SEA, by spatially binning each sampled AOD, we obtain a geographically representative mean ACAOD of 0.37. Vertical profiles of AOD showcase the variability in the altitude of the aerosol plume and its separation from the cloud top. We measured larger AOD at a high altitude near the coast than farther from the coast, while generally observing a larger vertical gap farther from the coast. Changes in AOD with altitude are correlated with carbon monoxide, a gas tracer of the biomass burning aerosol plume. Vertical extent of gaps between aerosol and cloud show a wide distribution, with a near-zero gap being most frequent. The gap distribution with longitude is observed to be largest at about 7∘ E, farther from coast than expected from previous studies.

scholarly journals Light absorption properties of aerosols over Southern West Africa

2019 ◽  
Author(s):  
Cyrielle Denjean ◽  
Thierry Bourrianne ◽  
Frederic Burnet ◽  
Marc Mallet ◽  
Nicolas Maury ◽  
...  
Keyword(s):  
Optical Properties ◽  
West Africa ◽  
Biomass Burning ◽  
Aerosol Particles ◽  
Anthropogenic Pollution ◽  
Absorption Properties ◽  
Air Masses ◽  
Carbon Particles ◽  
Biomass Burning Aerosol ◽  
Biomass Burning Particles

Abstract. Southern West Africa (SWA) is an African pollution hotspot but a relatively poorly sampled region of the world. We present an overview of in-situ aerosol optical measurements collected over SWA in June and July 2016 as part as the DACCIWA (Dynamics–Aerosol–Chemistry–Clouds Interactions in West Africa) airborne campaign. The aircraft sampled a wide range of air masses, including anthropogenic pollution plumes emitted from the coastal cities, long-range transported biomass burning plumes from Central and Southern Africa and dust plumes from the Sahara and Sahel region, as well as mixtures of these plumes. The specific objective of this work is to characterize the regional variability of the vertical distribution of aerosol particles and their spectral optical properties (single scattering albedo: SSA, asymmetry parameter, extinction mass efficiency, scattering Ångström exponent and absorption Ångström exponent: AAE). First findings indicate that aerosol optical properties in the planetary boundary layer were dominated by a widespread and persistent biomass burning loading from the Southern Hemisphere. Despite a strong increase of aerosol number concentration in air masses downwind of urban conglomerations, spectral SSA were comparable to the background and showed signatures of the absorption characteristics of biomass burning aerosols. In the free troposphere, moderately to strongly absorbing aerosol layers, dominated by either dust or biomass burning particles, occurred occasionally. In aerosol layers dominated by mineral dust particles, SSA varied from 0.81 to 0.92 at 550 nm depending on the variable proportion of anthropogenic pollution particles externally mixed with the dust. Biomass burning aerosol particles were significantly more light absorbing than those previously measured in other areas (e.g. Amazonia, North America) with SSA ranging from 0.71 to 0.77 at 550 nm. The variability of SSA was mainly controlled by variations in aerosol composition rather than in aerosol size distribution. Correspondingly, values of AAE ranged from 0.9 to 1.1, suggesting that lens-coated black carbon particles were the dominant absorber in the visible range for these biomass burning aerosols. Comparison with literature shows a consistent picture of increasing absorption enhancement of biomass burning aerosol from emission to remote location and underscores that the evolution of SSA occurred a long time after emission. The results presented here build a fundamental basis of knowledge about the aerosol optical properties observed over SWA during the monsoon season and can be used in climate modelling studies and satellite retrievals. In particular and regarding the very high absorbing properties of biomass burning aerosols over SWA, our findings suggest that considering the effect of internal mixing on absorption properties of black carbon particles in climate models should help better assessing the direct and semi-direct radiative effects of biomass burning particles.

scholarly journals Concentration-discharge relationships vary among hydrological events, reflecting differences in event characteristics

2020 ◽  
Author(s):  
Julia Knapp ◽  
Jana von Freyberg ◽  
Björn Studer ◽  
Leonie Kiewiet ◽  
James Kirchner
Keyword(s):  
Trace Metals ◽  
Major Ions ◽  
Low Frequency ◽  
Solute Concentration ◽  
Biologically Active ◽  
Storm Events ◽  
Event Scale ◽  
Wide Range ◽  
Insight Into

<p>Studying the response of streamwater chemistry to changes in discharge can improve our understanding of how catchments store and release water and solutes. Previous studies have determined concentration-discharge (cQ) relationships from long-term, low-frequency data for many different solutes. These analyses, however, provide little insight into the coupling of solute concentrations and flow during individual hydrologic events. Although intra-event cQ relationships have been determined for selected solutes and storm events, they have rarely been investigated across a wide range of solutes and over extended periods of time. Thus, little is known about how intra-event and longer-term cQ relationships may differ, potentially providing different perspectives on processes regulating transport through the landscape.</p><p>We present cQ relationships of 14 different solutes, ranging from major ions to trace metals, as well as electrical conductivity, in the Swiss Erlenbach catchment (0.7 km<sup>2</sup>). From a 2-year time series of sub-hourly solute concentration measurements, we determined long-term cQ relationships for each solute. We compared these to cQ relationships spanning the hydrograph recessions of 30 individual events. Solutes sharing the same dominant water sources exhibited similar behavior. Groundwater-sourced solutes exhibited dilution patterns, and their long-term cQ behavior was representative of their cQ behavior during hydrologic events. Other solutes, however, exhibited highly variable cQ behavior from one event to the next, and very different cQ patterns at intra-event and longer-term time scales. This was particularly true for trace metals as well as atmospherically derived and/or biologically active solutes. Most of the observed event-to-event variability in cQ behavior could be explained by factors such as catchment wetness, season, event size, input concentrations, and event-water contributions. These relationships help to clarify how the release of solutes depends on their catchment sources and pathways. Our analysis thus provides insight into controls on solute variations at the hydrologic event scale.</p>

Evaluating Preferred Augmentative and Alternative Communication Strategies for Patients in Long-Term Health Care Hospitals

2014 ◽  
Vol 23 (2) ◽  
pp. 99-103 ◽  
Author(s):  
Susan Fager ◽  
Jenna LeDoux ◽  
David Beukelman
Keyword(s):  
Augmentative And Alternative Communication ◽  
Extended Period ◽  
Ease Of Use ◽  
Special Treatment ◽  
Care Hospital ◽  
Medical Problems ◽  
Allied Health Professionals ◽  
Wide Range ◽  
Flat Screen

Long-term acute medical care hospital (LTACH) units serve a wide range of individuals, with serious medical problems requiring intense, special treatment for an extended period of time. Some of LTACH patients are unable to meet all of their communication needs using their natural speech, either temporarily or permanently. The purpose of this investigation was to survey personnel groups who routinely work in LTACH units regarding their preferences related to 3 communication options containing 27 representative communication boards, that were supported by mobile technology including an iPad only, an iPad with a flat screen that mirrored the iPad screen, and an iPad with a projected image that mirrored the iPad screen. Participants from 3 groups, (1) registered nurses and nursing assistants; (2) allied health professionals including respiratory, physical, and occupational therapists; and (3) speech-language pathologists, ranked the iPad-only AAC choice highest for patients in LTACH units followed by the iPad with screen, and iPad with projector. For the ease of use items by patients, families, and staff, all participant groups rated the iPad alone higher than the iPad with flat screen or the iPad with projector.

scholarly journals Microphysical characterization of long-range transported biomass burning particles from North America at three EARLINET stations

2016 ◽  
Author(s):  
Pablo Ortiz-Amezcua ◽  
Juan Luis Guerrero-Rascado ◽  
María José Granados-Muñoz ◽  
José Antonio Benavent-Oltra ◽  
Christine Böckmann ◽  
...  
Keyword(s):  
Long Range ◽  
Biomass Burning ◽  
Single Scattering ◽  
Particle Volume ◽  
Modeling Tools ◽  
Microphysical Properties ◽  
Color Ratio ◽  
Fire Smoke ◽  
Biomass Burning Aerosol ◽  
Biomass Burning Particles

Abstract. Strong events of long-range transported biomass burning aerosol were detected during July 2013 at three EARLINET stations, namely Granada (Spain), Leipzig (Germany) and Warsaw (Poland). Satellite observations from MODIS and CALIOP instruments, as well as modeling tools such as HYSPLIT and NAAPS have been used to estimate the sources and transport paths of those North American forest fire smoke particles. Multiwavelength Raman lidar technique was applied to obtain vertically-resolved particle optical properties, and further inversion of those properties with regularization algorithm allowed for retrieving microphysical information on the studied particles. The results highlight the presence of smoke layers of 1–2 km thickness, located at about 5 km asl altitude over Granada and Leipzig, and around 2.5 km asl at Warsaw. These layers were intense, as they accounted for more than 30 % of the total AOD in all cases, and presented optical and microphysical features typical for different aging degrees: color ratio of lidar ratios (LR532/LR355) around 2, α-related Angström exponents of less than 1, effective radii of 0.3 μm, and large values of single scattering albedos, nearly spectrally independent. The intensive microphysical properties were compared with columnar retrievals form co-located AERONET stations. The intensity of the layers was also characterized in terms of particle volume concentration, and then an experimental relationship between this magnitude and the particle extinction coefficient was established.

scholarly journals Optical Properties of Canadian Biomass Burning Particles Over Europe Observed with Calipso and Ground-Based Lidar Systems

2020 ◽  
Vol 237 ◽  
pp. 08016
Author(s):  
Christina-Anna Papanikolaou ◽  
Elina Giannakaki ◽  
Alex Papayannis ◽  
Maria Tombrou ◽  
Maria Mylonaki ◽  
...  
Keyword(s):  
Optical Properties ◽  
Biomass Burning ◽  
Depolarization Ratio ◽  
Backscatter Coefficient ◽  
Angstrom Exponent ◽  
Ångström Exponent ◽  
Biomass Burning Aerosol ◽  
The Mean ◽  
Ground Based Lidar ◽  
Biomass Burning Particles

A long-lasting biomass burning event affected Europe from 27 August to 3 September 2018. The biomass burning aerosol layers were observed with ground- and space-based lidars in heights ranged between 2-7 km (a.s.l.). The mean backscatter coefficient for the ground-based stations ranged between 0.29 and 1.51 Mm-1sr-1, while the CALIPSO retrieved values ranged between 0.43 and 1.83 Mm-1sr-1. Moreover, the mean Ångström exponent (AEb) values, relevant to backscatter, ranged from 0.83 to 1.04 for the aforementioned lidar stations. At the same time, the mean AEb values obtained from CALIPSO ranged between 0.17 and 1.89. The mean particle depolarization ratio ranged between 0.037 and 0.080.

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