Long-range transport patterns into the tropical northwest Pacific during the CAMP<sup>2</sup>Ex aircraft campaign: chemical composition, size distributions, and the impact of convection

Abstract

Abstract. The tropical Western North Pacific (TWNP) is a receptor for pollution sources throughout Asia and is highly susceptible to climate change, making it imperative to understand long-range transport in this complex aerosol-meteorological environment. Measurements from the NASA Cloud, Aerosol, and Monsoon Processes Philippines Experiment (CAMP2Ex; 24 Aug to 5 Oct 2019) and back trajectories from the National Oceanic and Atmospheric Administration Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT) were used to examine transport into the TWNP from the Maritime Continent (MC), Peninsular Southeast Asia (PSEA), East Asia (EA), and West Pacific (WP). A mid-campaign monsoon shift on 20 Sep 2019 led to distinct transport patterns between the southwest monsoon (before 20 Sep) and monsoon transition (after 20 Sep). During the southwest monsoon, long-range transport was a function of southwesterly winds and cyclones over the South China Sea. Low (high) altitude air generally came from MC (PSEA), implying distinct aerosol processing related to convection and perhaps wind shear. The monsoon transition saw transport from EA and WP, driven by Pacific northeasterly winds, continental anticyclones, and cyclones over the East China Sea. Composition of transported air differed by emission source and accumulated precipitation along trajectories (APT) as an indicator of convection. MC air was characterized by biomass burning tracers while major components of EA air pointed to Asian outflow and secondary formation. Convective scavenging of PSEA air was evidenced by considerable vertical differences between aerosol species but not trace gases, as well as notably higher APT and smaller particles than other regions. Finally, we observed a possible wet scavenging mechanism acting on MC air aloft that was not strictly linked to precipitation. These results are important for understanding the transport and processing of air masses with further implications for modeling aerosol lifecycles and guiding international policymaking on public health and climate.

Seasonal updraft speeds change cloud droplet number concentrations in low-level clouds over the western North Atlantic

“…Submicron non-refractory aerosol chemical composition was measured by a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS; Aerodyne Research Inc. De-Carlo et al, 2006;Hilario et al, 2021). Mass concentrations of sulfate, nitrate, chloride, ammonium and organic matter were recorded at 1 Hz and averaged to 30 s for all subsequent analyses.…”

“…This study reports on sea salt concentrations by attributing Na + , Cl − and Mg 2+ exclusively to sea salt and adding SO 2− 4 (0.25), K + (0.036) and Ca 2+ (0.039) fractions based on their ratio to Na + in seawater (Bowen, 1979;Farren et al, 2019;Ma et al, 2021). The PILS samples particles up to roughly 4 µm in diameter (McNaughton et al, 2007;Hilario et al, 2021).…”

Assessment of NAAPS-RA performance in Maritime Southeast Asia during CAMP2Ex

“…The NASA P-3 aircraft carried out 19 research flights (RFs) equipped with a payload of instruments and remote sensors to sample the microphysical, hydrological, dynamical, thermodynamic, and radiative properties of the environment in and around the Philippines. Specific air masses sampled include long-range transport of peat burning and pollution from Borneo, Asian pollution, Philippine outflow, and cleaner marine conditions (Hilario et al, 2021). Some of the specific interests include (i) investigating relationships between aerosol particle properties (e.g., number concentrations, composition, and spatial distribu-tion) and shallow cumulus and congestus cloud features (e.g., optical properties, microphysical properties, and their transition from shallow to deep convection), (ii) assessing how the region's meteorology both influenced and was influenced by aerosol-cloud interactions, and (iii) developing remote sensing, modeling, and technology advances to improve regional monitoring and Earth system assessment.…”

“…As mentioned above, the Philippines region is influenced by a range of aerosol types (Hilario et al, 2021). Aerosol models, such as NAAPS-RA, are heavily parameterized and are often challenged by the properties of individual air masses.…”

Evidence of haze-driven secondary production of supermicrometer aerosol nitrate and sulfate in size distribution data in South Korea

“…Carbon monoxide concentrations in Seoul exceeded Incheon by 177 ppb on average during the polluted period, suggestive of added influence from local emissions in Seoul superimposed on top of the transported pollution. Carbon monoxide is commonly used in calculations related to aerosol transport studies (e.g., Dadashazar et al, 2021;Hilario et al, 2021b) as it is relatively insensitive to wet scavenging processes with a long lifetime in the atmosphere (∼ 1 month) compared to aerosol particles (Weinstock, 1969).…”