Aircraft testing of the new Blunt-body Aerosol Sampler (BASE)

Abstract

Abstract. There is limited understanding of the role of aerosols in the formation and modification of clouds, partly due to inadequate data on such systems. Aircraft-based aerosol measurements in the presence of cloud particles have proven to be challenging because of the problem of cloud droplet/ice particle shatter and the generation of secondary artifact particles that contaminate aerosol samples. Recently, the design of a new aircraft inlet, called the Blunt-body Aerosol Sampler (BASE), which enables sampling of interstitial aerosol particles, was introduced. Numerical modeling results and laboratory test data suggested that the BASE inlet should sample interstitial particles with minimal shatter particle contamination. Here, the sampling performance of the inlet is established from aircraft-based measurements. Initial aircraft test results obtained during the PLOWS (Profiling of Winter Storms) campaign indicated two problems with the original BASE design: separated flows around the BASE at high altitudes and a significant shatter problem when sampling in drizzle. The test data were used to improve the accuracy of flow and particle trajectory modeling around the inlet, and the results from the improved flow model were used to guide design modifications of the BASE to overcome the problems identified in its initial deployment. The performance of the modified BASE was tested during the ICE-T (Ice in Clouds Experiment -Tropics) campaign, and the inlet was seen to provide near shatter-free measurements in a wide range of cloud conditions. The initial aircraft test results, design modifications, and the performance characteristics of the BASE relative to another interstitial inlet, the submicron aerosol inlet (SMAI), are presented.

Fine particle pH and the partitioning of nitric acid during winter in the northeastern United States

“…PM 1 (particles with aerodynamic diameters < 1.0 µm at ambient conditions) water‐soluble ions were measured with a Particle‐Into‐Liquid Sampler coupled with Ion Chromatographs (PILS‐IC; Metrohm 761 Compact ICs) [ Orsini et al ., ; Hennigan et al ., ; Sullivan et al ., ; Peltier et al ., ; Liu et al ., ; Guo et al ., ]. Ambient aerosol was sampled from a submicron aerosol inlet [ Craig et al ., ; Craig et al ., ; Craig et al ., ; Moharreri et al ., ] at a flow rate of 15.0 L min −1 . Residence time in the inlet and sample lines is estimated at 2 s. Upstream of the PILS‐IC, a nonrotating microorifice impactor [ Marple et al ., ] with a 1.0 µm cut size (at 1 atm and 273.15 K) restricted measurements to PM 1 to be comparable with the Aerosol Mass Spectrometer (discussed below).…”

“…[Orsini et al, 2003;Hennigan et al, 2006;Sullivan et al, 2006;Peltier et al, 2007a;Liu et al, 2012;Guo et al, 2015]. Ambient aerosol was sampled from a submicron aerosol inlet [Craig et al, 2013a;Craig et al, 2013b;Craig et al, 2014;Moharreri et al, 2014] at a flow rate of 15.0 L min À1 . Residence time in the inlet and sample lines is estimated at 2 s. Upstream of the PILS-IC, a nonrotating microorifice impactor [Marple et al, 1991] with a 1.0 μm cut size (at 1 atm and 273.15 K) restricted measurements to PM 1 to be comparable with the Aerosol Mass Spectrometer (discussed below).…”

Sources and Secondary Production of Organic Aerosols in the Northeastern United States during WINTER

“…The theory and operation of the AMS, including the key adaptations for aircraft sampling, have previously been described in detail (Canagaratna et al, ; DeCarlo et al, ; Dunlea et al, ; Jayne et al, ; Kimmel et al, ) and is only briefly summarized here. Ambient particles were sampled through an NCAR High‐Performance Instrumented Airborne Platform for Environmental Research Modular Inlet (HIMIL, ; Moharreri et al, ) at a flow rate of 10 L/min, into a pressure‐controlled inlet operated at 325 Torr (Bahreini et al, ). The particles were then focused into the high‐vacuum region of the mass spectrometer through an aerodynamic lens and transmitted into a detection chamber, where particles impacted on a porous tungsten standard vaporizer (600 °C).…”

Biomass Burning Markers and Residential Burning in the WINTER Aircraft Campaign

“…A PILS continuously collects ambient particles into purified water, providing a liquid sample for analysis (Orsini et al, ). Each PILS instrument sampled from a submicron aerosol inlet (Craig, Moharreri, Schanot, et al, ; Craig, Schanot, Moharreri, et al, ; Craig et al, ; Moharreri et al, ). Following each submicron aerosol inlet was a nonrotating MOUDI impactor with a 50% transmission efficiency of 1 μm (aerodynamic diameter) at 1 atmosphere ambient pressure (Marple et al, ).…”