Table 1. Twin Otter Payload Description	
Instrument	Data
Condensation particle counter (CPC)a	aerosol number concentration
Cloud condensation nucleus counter (CCN)	cloud condensation nucleus number concentration at 3 supersaturations
Counterflow virtual impactor (CVI)	virtual impactor for isolating cloud droplets
Dual automated classified aerosol detector  (DACAD)	submicrometer aerosol size distribution (10–800 nm) at low and high RH
Aerosol spectrometer probe (PCASP), aerodynamic particle sizer (APS), forward scattering spectrometer probe (FSSP), cloud and aerosol particle spectrometer (CAPS)	aerosol/cloud droplet size distribution (120 nm to 1.6 mm)
Aerodyne aerosol mass spectrometer (AMS)a	nonrefractory aerosol chemistry
Particle-into-liquid sampler (PILS)a	submicrometer aerosol chemistry (IC: inorganic and some organic acid ions)
Filters	bulk aerosol chemistry (FTIR: functional group analysis)
PSAP,a photoacoustic, SP2	soot absorption (multiwavelength/incandescence)
Miscellaneous navigational and meteorology probes	navigational data, temperature, dew point, RH, pressure, liquid water content, wind direction/speed, updraft velocity, etc.
aThese are the only instruments that sampled air coming through the CVI inlet.