RV Investigator Ultrafine Aerosol Volatility and Hygroscopicity (VH-TDMA) - Selected Voyages (2016 onwards)

The VHTDMA was constructed at QUT for measurement of ultrafine aerosol volatility and hygroscopicity. It uses electrostatic classifiers to select particles of a particular electrical mobility diameter, conditions them (using a thermodenuder and humidifier) and re-measures the particle diameter. The VH-TDMA is made up of three purpose built electrostatic classifiers and two condensation particle counters (CPCs). One TSI 3010 CPC and one TSI 3787 CPC.The pre-classifier (used to select particles of a particular dry diameter) most commonly cycled between measuring 40, 100 and 150 nm diameter particles during IN2016_v02. For short periods other particle diameters were selected (20, 30, 60,80 nm), to examine features in the ambient size distribution. The thermodenuder was set to 250 °C for the majority of IN2016_v02, with short periods at other temperatures (150°C, 200°C). The relative humidity of the H-SMPS was set to 90% RH for most of the voyage, however it was periodically lowered for size calibration scans and to measure the deliquescence RH for ambient particles. The sample was passed through a nafion drier and inlet RH logged to ensure that dry particle diameter was selected i.e. RH < 30%, the efflouresence RH for common marine salts.

VHTDMA由QUT搭建，用于超微气溶胶的挥发性与吸湿性测量。该装置通过静电分类器筛选特定电迁移率直径的粒子，经热脱除器与增湿器进行条件化处理后，重新测量粒子直径。VH-TDMA由三台定制静电分类器与两台凝聚核粒子计数器（condensation particle counter, CPC）组成，分别为一台TSI 3010型凝聚核粒子计数器与一台TSI 3787型凝聚核粒子计数器。在IN2016_v02批次中，预分类器（用于筛选特定干粒径的粒子）通常在40 nm、100 nm与150 nm三种粒径的粒子间循环筛选；在短时段内，也会选取20 nm、30 nm、60 nm、80 nm等其他粒径的粒子，以探究环境气溶胶的粒径分布特征。在IN2016_v02的大部分实验时段中，热脱除器的温度设置为250℃，仅在短时段内采用150℃、200℃等其他温度。H-SMPS的相对湿度（Relative Humidity, RH）在大部分航次中设置为90% RH，不过为了进行粒径校准扫描以及测量环境粒子的潮解相对湿度，会定期调低相对湿度。采样气流先经过纳菲隆干燥器，同时对进气口的相对湿度进行记录，以确保筛选的是干态粒子（即相对湿度<30%，该值为常见海盐的结晶相对湿度）。