In-situ total aerosol number using condensation particle counters as observed during the SIPEX II voyage of the Aurora Australis, 2012

Brief description

The current dataset includes total aerosol count from two different Condensation Particle Counters (CPCs). The two CPCs measure total aerosol number in two different size ranges:
- TSI Model 3025A measures particles with diameters larger than 3 nm (files are in the 3025_3nm folder)
- TSI Model 3772 measures particles with diameters larger than 10 nm (files are in the 3772_10nm folder)
The two CPCs are measuring from the same sample air and as such, the difference between the two measurements gives a measurement of total aerosol concentration in the 3-10 nm size range, known as the nucleation mode.

Instrument setup:
The instruments are setup inside an insulated shipping container mounted on the hatch covers directly aft of the forecastle. A 100 L pump is used to pull sample air from a 3 m high mast located on the starboard side of the forecastle. The air is pulled through 17 m of 50 mm antistatic (copper coil) polyurethane tubing and 2 m of 50 mm stainless steel pipe for connection and extensions. A 1 m length of one quarter inch stainless steel tubing penetrates into the container and directly through the wall of the polyurethane tubing for sampling off the primary flow to the CPCs. The inserted stainless steel tubing is oriented in such a way that sampled aerosol experience minimal turns to avoid sample loss. Approximately 1.7 m of flexible conductive tubing extends to a Y-piece which directs flow into each CPC. Butanol contaminated exhaust from the CPCs is pushed out of the container by two 10 LPM pumps.

Data Processing:
Raw data is calibrated for each instrument's recorded flow rate, and an inlet efficiency to correct for losses in the long inlet. Data is then resampled to minute time resolution, and filtered for logged events, wind directions which sampled ship exhaust, and outliers in the dataset. This produced a dataset which represented the sampling of clean Antarctic background atmosphere.

The dataset includes both aerosol number concentrations from each instrument giving total number of particles above 3 nm and 10 nm respectively, as well as the different between these values, which gives a measure of newly formed particles in the nucleation mode between 3-10 nm (New Particle Formation, NPF). Associated uncertainties are included in the dataset.