scholarly journals Assessing the Challenges of Surface‐Level Aerosol Mass Estimates From Remote Sensing During the SEAC 4 RS and SEARCH Campaigns: Baseline Surface Observations and Remote Sensing in the Southeastern United States

2018 ◽  
Vol 123 (14) ◽  
pp. 7530-7562 ◽  
Author(s):  
K. C. Kaku ◽  
J. S. Reid ◽  
J. L. Hand ◽  
E. S. Edgerton ◽  
B. N. Holben ◽  
...  
Keyword(s):  
United States ◽  
Remote Sensing ◽  
Southeastern United States ◽  
Surface Level ◽  
Aerosol Mass ◽  
Surface Observations

scholarly journals Aerosol optical properties in the southeastern United States in summer – Part 2: Sensitivity of aerosol optical depth to relative humidity and aerosol parameters

2016 ◽  
Vol 16 (8) ◽  
pp. 5009-5019 ◽  
Author(s):  
Charles A. Brock ◽  
Nicholas L. Wagner ◽  
Bruce E. Anderson ◽  
Andreas Beyersdorf ◽  
Pedro Campuzano-Jost ◽  
...  
Keyword(s):  
United States ◽  
Refractive Index ◽  
Relative Humidity ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Mixed Boundary ◽  
Southeastern United States ◽  
Geometric Standard Deviation ◽  
Aerosol Mass ◽  
Southeastern Us

Abstract. Aircraft observations of meteorological, trace gas, and aerosol properties were made between May and September 2013 in the southeastern United States (US). Regionally representative aggregate vertical profiles of median and interdecile ranges of the measured parameters were constructed from 37 individual aircraft profiles made in the afternoon when a well-mixed boundary layer with typical fair-weather cumulus was present (Wagner et al., 2015). We use these 0–4 km aggregate profiles and a simple model to calculate the sensitivity of aerosol optical depth (AOD) to changes in dry aerosol mass, relative humidity, mixed-layer height, the central diameter and width of the particle size distribution, hygroscopicity, and dry and wet refractive index, while holding the other parameters constant. The calculated sensitivity is a result of both the intrinsic sensitivity and the observed range of variation in these parameters. These observationally based sensitivity studies indicate that the relationship between AOD and dry aerosol mass in these conditions in the southeastern US can be highly variable and is especially sensitive to relative humidity (RH). For example, calculated AOD ranged from 0.137 to 0.305 as the RH was varied between the 10th and 90th percentile profiles with dry aerosol mass held constant. Calculated AOD was somewhat less sensitive to aerosol hygroscopicity, mean size, and geometric standard deviation, σg. However, some chemistry–climate models prescribe values of σg substantially larger than we or others observe, leading to potential high biases in model-calculated AOD of  ∼  25 %. Finally, AOD was least sensitive to observed variations in dry and wet aerosol refractive index and to changes in the height of the well-mixed surface layer. We expect these findings to be applicable to other moderately polluted and background continental air masses in which an accumulation mode between 0.1–0.5 µm diameter dominates aerosol extinction.

Spectral reflectance characteristics and digital imagery of a pine needle blight in the southeastern United States

1996 ◽  
Vol 26 (3) ◽  
pp. 402-407 ◽  
Author(s):  
Gregory A. Carter ◽  
William G. Cibula ◽  
Tommy R. Dell
Keyword(s):  
United States ◽  
Remote Sensing ◽  
Spectral Reflectance ◽  
Southeastern United States ◽  
Visible Spectrum ◽  
Pine Needle ◽  
Black And White ◽  
Optimal Approach ◽  
Relative Change ◽  
Needle Blight

A field study determined an optimal approach for the remote sensing of a pine needle blight of unknown cause that occurs frequently in the southeastern United States. Needle spectral reflectance was measured in five pairs of slash pines (Pinuselliottii Engelm. var. elliottii), each comprising a blighted and a nonblighted tree. Reflectance of blighted needles generally was greater within the 400–700 nm wavelength range and less in the 720–850 nm range compared with nonblighted needles (p ≤ 0.050). The relative change in reflectance, or reflectance sensitivity to the blight, was greatest near 680 nm. As predicted by the reflectance sensitivity, a black and white digital image at 680 ± 5 nm revealed strong contrast of a blighted compared with a nonblighted tree; the blighted canopy was nearly white in the image, while the nonblighted canopy was dark grey. Contrasts were much less at 560 ± 5, 694 ± 3, and 700 ± 5 nm, in the panchromatic visible spectrum (410–740 nm), and at 760 ± 5 nm. Remote sensing of southeastern pine forests at 680 ± 5 nm ultimately could provide regional estimates of blight occurrence and distribution, and thus contribute to determining its cause.

scholarly journals Influence of crustal dust and sea spray supermicron particle concentrations and acidity on inorganic NO<sub>3</sub><sup>−</sup> aerosol during the 2013 Southern Oxidant and Aerosol Study

2015 ◽  
Vol 15 (18) ◽  
pp. 10669-10685 ◽  
Author(s):  
H. M. Allen ◽  
D. C. Draper ◽  
B. R. Ayres ◽  
A. Ault ◽  
A. Bondy ◽  
...  
Keyword(s):  
United States ◽  
Inorganic Nitrogen ◽  
Southeastern United States ◽  
The United States ◽  
Sea Spray ◽  
Aerosol Composition ◽  
Phase Partitioning ◽  
Aerosol Mass ◽  
Sea Spray Aerosol ◽  
Fine Mode

Abstract. Inorganic aerosol composition was measured in the southeastern United States, a region that exhibits high aerosol mass loading during the summer, as part of the 2013 Southern Oxidant and Aerosol Study (SOAS) campaign. Measurements using a Monitor for AeRosols and GAses (MARGA) revealed two periods of high aerosol nitrate (NO3−) concentrations during the campaign. These periods of high nitrate were correlated with increased concentrations of supermicron crustal and sea spray aerosol species, particularly Na+ and Ca2+, and with a shift towards aerosol with larger (1 to 2.5 μm) diameters. We suggest this nitrate aerosol forms by multiphase reactions of HNO3 and particles, reactions that are facilitated by transport of crustal dust and sea spray aerosol from a source within the United States. The observed high aerosol acidity prevents the formation of NH4NO3, the inorganic nitrogen species often dominant in fine-mode aerosol at higher pH. Calculation of the rate of the heterogeneous uptake of HNO3 on mineral aerosol supports the conclusion that aerosol NO3− is produced primarily by this process, and is likely limited by the availability of mineral cation-containing aerosol surface area. Modeling of NO3− and HNO3 by thermodynamic equilibrium models (ISORROPIA II and E-AIM) reveals the importance of including mineral cations in the southeastern United States to accurately balance ion species and predict gas–aerosol phase partitioning.

scholarly journals Aerosol loading in the Southeastern United States: reconciling surface and satellite observations

2013 ◽  
Vol 13 (18) ◽  
pp. 9269-9283 ◽  
Author(s):  
B. Ford ◽  
C. L. Heald
Keyword(s):  
United States ◽  
Fine Particulate Matter ◽  
Southeastern United States ◽  
Vertical Mixing ◽  
Lower Troposphere ◽  
Organic Aerosol ◽  
Surface Mass ◽  
Fine Particulate ◽  
Surface Network ◽  
Surface Observations

Abstract. We investigate the seasonality in aerosols over the Southeastern United States using observations from several satellite instruments (MODIS, MISR, CALIOP) and surface network sites (IMPROVE, SEARCH, AERONET). We find that the strong summertime enhancement in satellite-observed aerosol optical depth (AOD) (factor 2–3 enhancement over wintertime AOD) is not present in surface mass concentrations (25–55% summertime enhancement). Goldstein et al. (2009) previously attributed this seasonality in AOD to biogenic organic aerosol; however, surface observations show that organic aerosol only accounts for ∼35% of fine particulate matter (smaller than 2.5 μm in aerodynamic diameter, PM2.5) and exhibits similar seasonality to total surface PM2.5. The GEOS-Chem model generally reproduces these surface aerosol measurements, but underrepresents the AOD seasonality observed by satellites. We show that seasonal differences in water uptake cannot sufficiently explain the magnitude of AOD increase. As CALIOP profiles indicate the presence of additional aerosol in the lower troposphere (below 700 hPa), which cannot be explained by vertical mixing, we conclude that the discrepancy is due to a missing source of aerosols above the surface layer in summer.

scholarly journals Aerosol loading in the Southeastern United States: reconciling surface and satellite observations

2013 ◽  
Vol 13 (4) ◽  
pp. 9917-9952 ◽  
Author(s):  
B. Ford ◽  
C. L. Heald
Keyword(s):  
United States ◽  
Southeastern United States ◽  
Vertical Mixing ◽  
Lower Troposphere ◽  
Organic Aerosol ◽  
Satellite Observations ◽  
Seasonal Differences ◽  
Surface Mass ◽  
Surface Network ◽  
Surface Observations

Abstract. We investigate the seasonality in aerosols over the Southeastern United States using observations from several satellite instruments (MODIS, MISR, CALIOP) and surface network sites (IMPROVE, SEARCH, AERONET). We find that the strong summertime enhancement in satellite-observed aerosol optical depth (factor 2–3 enhancement over wintertime AOD) is not present in surface mass concentrations (25–55% summertime enhancement). Goldstein et al. (2009) previously attributed this seasonality in AOD to biogenic organic aerosol; however, surface observations show that organic aerosol only accounts for ~35% of PM2.5 mass and exhibits similar seasonality to total PM2.5. The GEOS-Chem model generally reproduces these surface aerosol measurements, but under represents the AOD seasonality observed by satellites. We show that seasonal differences in water uptake cannot sufficiently explain the magnitude of AOD increase. As CALIOP profiles indicate the presence of additional aerosol in the lower troposphere (below 700 hPa), which cannot be explained by vertical mixing; we conclude that the discrepancy is due to a missing source of aerosols above the surface in summer.

Does Enhancing Mind Perception Affect Conspiracy Belief?

2019 ◽  
Author(s):  
Jorge Noguera
Keyword(s):  
United States ◽  
Southeastern United States ◽  
Social Discourse ◽  
Psychological Processes ◽  
Social Psychological ◽  
Conspiracy Theories ◽  
Mind Perception ◽  
Mixed Anova ◽  
Interaction Term ◽  
The Mind

This study was conducted to determine the effectiveness of a novel mind perception manipulation. Mind perception is currently theorized to be an essential aspect of a number of human social psychological processes. Thus, a successful manipulation would allow for the causal study of those processes. This manipulation was created in an attempt to explore the downstream impact of mind perception on the endorsement of conspiracy theories. Conspiracy theories are steadily becoming more and more prominent in social discourse. Endorsement of conspiracy theories are beginning to show real world ramifications such as a danger to human health (e.g., in the anti-vaccination movement). A sample of college students (valid N = 53) from a large rural institution in the southeastern United States participated for course credit. These participants completed a mind perception pretest, were randomly assigned to either the manipulation in question (in which participants are asked to consider the ‘mind’ of several targets and write their thoughts about them) or the control condition, and then they completed a posttest. The mixed ANOVA revealed that the interaction term between Time and Condition was not significant. Because the manipulation did not work, other analyses were aborted, in accord with the pre-registration. My Discussion focuses on the procedures and potential shortcomings of this manipulation, in an effort to lay the groundwork for a successful one.

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