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Atmospheric models of secondary organic aerosol (OA) (SOA) typically rely on parameters derived from environmental chambers. Chambers are subject to experimental artifacts, including losses of (1) particles to the walls (PWL), (2) vapors to the particles on the wall (V2PWL), and (3) vapors to the wall directly (VWL). We present a method for deriving artifact-corrected SOA parameters and translating these to volatility basis set (VBS) parameters for use in chemical transport models (CTMs). Our process involves combining a box model that accounts for chamber artifacts (Statistical Oxidation Model with a TwO-Moment Aerosol Sectional model (SOM-TOMAS)) with a pseudo-atmospheric simulation to develop VBS parameters that are fit across a range of OA mass concentrations. We found that VWL led to the highest percentage change in chamber SOA mass yields (high NO

The chemical composition, sources, and concentrations of aerosol particles vary on a seasonal basis in the Arctic. While existing research has focused on understanding the occurrence of aerosol particles during the Arctic winter and spring, less is known of their occurrence during the Arctic summer. In this study, atmospheric aerosol particle chemical composition and concentration were determined during July–September 2018 at Tuktoyaktuk, NT, Canada (69.4° N, 133.0° W) to coincide with the Year of Polar Prediction’s 2nd Special Observing Period in the Arctic. The chemical composition of fine (PM2.5) and coarse (PM10-2.5) aerosol filter samples suggests the ocean, mineral/road dust, and combustion were sources of the sampled aerosol particles. Mass concentrations of PM2 and PM10, estimated from optical particle counter measurements, remained within a similar range during the study. However, elevated mass concentrations coincided with a festival in the community of Tuktoyaktuk, suggesting local human activity was an important source of aerosol particles. Mass concentrations of PM2, which promote negative health effects in humans, were significantly lower at Tuktoyaktuk than the national air quality standard recommended by the Government of Canada. These measurements provide an important baseline to compare with future measurements associated with the assessment of aerosol chemistry and air quality in the Arctic.

Blocking artifact is a major limitation of DCT-based codec at low bit rates. This degradation is likely to influence the judgment of a final user. This work presents a powerful post-processing filter in the DCT frequency domain. The proposed algorithm adopts a shift block within four adjacent DCT blocks to reduce computational complexity. The artifacts resulting from quantized and de-quantized process are eliminated by slightly modifying several DCT coefficients in the shift block. Simulation results indicate that the proposed method produces the best image quality in terms of both objective and subjective metrics.

Blocking effect is the major drawback in DCT-based (discrete cosine transformation) codecs at low bit-rates. In this paper, a post-processing filter is proposed in DCT frequency domain. The proposed algorithm uses a shift block within four adjacent DCT blocks to reduce computational complexity. By slightly modifying several DCT coefficients in the shift block, the artifacts that result from quantization and dequantization process are alleviated. The simulation results show that both visual perception and objective image quality are improved noticeably.

The blocking effect is the major drawback in discrete cosine transform (DCT)-based codecs at low bit rates. When a high compression ratio is required, boundaries between adjacent image blocks become visible. This kind of degradation probably will affect the judgment of an end user. In this work, a four-neighboring-block zero-masking technique is proposed in the DCT frequency domain. The proposed algorithm uses a shift block within four adjacent DCT blocks to reduce computational complexity. By slightly modifying several DCT coefficients in the shift block, the artifacts that result from quantization and dequantization processes are alleviated. The simulation results show that both visual perception and objective image quality are noticeably improved.