Observations of the temporal variability in aerosol properties and their relationships to meteorology in the summer monsoonal South China Sea/East Sea: the scale-dependent role of monsoonal flows, the Madden–Julian Oscillation, tropical cyclones, squall lines and cold pools

摘要: Abstract. In a joint NRL/Manila Observatory mission, as part of the Seven SouthEast Asian Studies program (7-SEAS), 2-week, late September 2011 research cruise in northern Palawan archipelago was undertaken to observe nature southwest monsoonal aerosol particles South China Sea/East Sea (SCS/ES) and Sulu region. Previous analyses suggested this region receptor for biomass burning from Borneo Sumatra boundary layer air entering trough. Anthropogenic pollution biofuel emissions are also ubiquitous, is heavy shipping traffic. Here, we provide an overview regional environment during cruise, time series key meteorological parameters, their interrelationships. Overall, provides narrative processes that control loadings possible feedbacks with clouds precipitation. While moderate El Nino–Southern Oscillation (ENSO) La Nina year, higher activity lower precipitation more typical neutral conditions. The large-scale modulated by Madden–Julian (MJO) its associated tropical cyclone (TC) manner consistent conceptual analysis performed Reid et al. (2012). Advancement MJO phase 3 6 accompanying cyclogenesis period strengthened flow patterns SCS/ES life cycle. TC inflow arms significant convection sometimes span Luzon, resulting very low particle concentrations (minimum condensation nuclei CN 3000 cm−3 non-sea-salt PM2.5 10–25 μg m−3). These cases corresponded two different mechanisms suppression: free-tropospheric dry-air intrusion Indian Ocean, TC-induced subsidence. Veering vertical wind shear resulted transport into being mainly marine (MBL), although free troposphere on western sides Borneo. At hourly scale, were observed be integer factors through cold pools. Geostationary satellite observations suggest often takes form squall lines, which bowed up 500 km across 50 wide. initiated pools large thunderstorms likely sustained veering aforementioned mid-troposphere dry layers, propagated over 1500 entirety SCS/ES, effectively cutting swaths MBL out Our conclusion while important modulating convection, hence allowing long-range smoke pollution, short-lived phenomena can modulate cloud (CCN) region, pockets clean polluted air. This will no doubt complicate scale comparisons aerosol–cloud interaction.