ACE-1 Ship Transit Aerosol Ion Data

This data set consists of high volume (1.15m3min-1) impactor measurements
of size distributed aerosol ions taken aboard the Discoverer ship by H.
Sievering and J. Salvich (University of Colorado-Denver) in collaboration with
NOAA/PMEL (P. Quinn and M. Hamilton) over the South Pacific (30S - 40S, 160W - 
155 E). The height of sampling at the ship's flying bridge level was 16-18 m
above sea level. Sampling could not be further forward during this ship
sampling due to the large ACE-1 sampling program aboard the Discoverer. Both
SO2 (Saltzman, Univ. of Miami) and CN (Carsey, NOAA/AOML) data, having inlets
co-located with the high volume impactor, indicate periods of ship stack caused
sample contamination. As a result, several impactor samples had to be discarded
from the ship collected dataset. Of the 12 samples remaining in this dataset,
10 are clearly without contamination. Samples 308-N and 309-D (note N is for
nighttime and D is for daytime samples) may have been slightly (i.e, SO2
contamination potential for <5% of sampling time) contaminated; however, no
evidence of contamination is to be found in the ion data. Finally, samples 306-D
and 311-D appear to have sampled the Ruapehu (New Zealand) volcanic plume. The
SO2 levels associated with these samples were 220 and 165 pptv, repsectively,
whereas the average SO2 level for the remaining samples was 26 pptv.

The dataset contains six size cuts of aerosol data (<0.4, 0.4-0.9, 0.9-2.3, 
2.3-4.5, 4.5-8, and >8 microns ambient dia.). All ion data are in units of 
nmol m-3. An update of the data regarding size cuts may be provided in the 
future.