Title: C130 Filter Chemistry Samples

Contact:

   Barry J. Huebert
   Department of Oceanography
   University of Hawaii
   1000 Pope Road
   Honolulu, HI, USA, 96822
   Telephone: (808) 956-6896
   Facsimile: (808) 956-9225
   E-Mail Address: huebert@okika.soest.hawaii.edu


Data Set Description:

Submitted by Steven Howell for Barry Huebert.

New data was received from Barry Huebert in December 1998.
See the caveats below.

If you wish to use this information in any publications, the
Huebert Group would appreciate citations and/or acknowledgments.
In addition, it would be wise to check whether the final
version of the data has been released!

The data here are derived from filter and single-stage impactor
samples drawn through the Community Aerosol Inlet.  Filter
and impactor deposits were analyzed by ion chromatography
for common inorganic ions and methanesulfonate.

CAVEATS:

The Huebert Group noticed a discrepancy between flow meter voltages
recorded by the data logger and the NCAR RAF data system
during flight 4. The Huebert Group has not yet had the time to establish
the cause.

In addition, the Huebert Group recently discovered a bug in the
chromatogram analysis software that occasionally identifies
the wrong peak. This bug appears to occur only when some
analytes have no detectable concentrations, and is thus a
problem chiefly in the blanks (not reported here, but mean
procedural blank values were subtracted from sample values).
It is believed that most of these instances have been identified
and corrected, but an exhaustive search has not been made.

Format:

There are 34 columns of data:

1) Start Date UTC (YYYY/MM/DD)
2) Start Time UTC (HH:MM:SS)
3) Latitude of aircraft at Start Time (deg N)
4) Longitude of aircraft at Start Time (deg E)
5) Altitude of aircraft at Start Time (m)

6) Stop Date UTC (YYYY/MM/DD)
7) Stop Time UTC (HH:MM:SS)
8) Latitude of aircraft at Stop Time (deg N)
9) Longitude of aircraft at Stop Time (deg E)
10) Altitude of aircraft at Stop Time (m)

11) Flight number  (01-33)
12) Yearday of sample start  (304-357)
13) Substrate:

      S is impactor Substrate (a Tedlar film).  The impactor
has a cut size of 1 micron.  Losses within the impactor rise
with particle size and are roughly 50% for 4 micron
particles, though this is not a sharp size cut.  Inlet
characteristics of the CAI are not yet known.
     The impactor was generally used only in the boundary
layer, as pressure drop precluded its use in the free
troposphere.

      T is a Teflon filter (Gelman Zefluor).  In the marine
boundary layer, this was a backup filter for the impactor,
so it collected only particles smaller than 1 micron
(this serves to increase sensitivity to non sea-salt
sulfate, found primarily on submicron aerosols).
     When no impactor was used, the filter collected all
incident particles.  Please note that the only reliable way
to determine whether a filter sampled all incident aerosol
or just particles less than 1 micron is to find whether an S
substrate sample occurred at the same time in the same
sampler.

14) Sampler (A or B). The Huebert Group had two samplers mounted
in the CAI. One was usually used for organic analysis (not
reported here), though there are instances when both were
used simultaneously for inorganic ions.

15, 16) Methanesulfonate concentration and estimated error bounds.

17, 18) Chloride concentration and errors.  Note that HCl is
volatile, so there is some possibility that aerosol chloride
can be collected, then evaporate during the sampling period.
Conversely, gaseous HCl can deposit on basic aerosols (such
as sea salt).

19, 20) Nitrate concentration and errors.  This has the same
caveats as HCl, above, since HNO3 is volatile.

21, 22) Sulfate concentration and errors.
23, 24) Sodium concentration and errors.
25, 26) Ammonium concentration and errors.  Since ammonia is
volatile, evaporation artifacts are possible as for chloride
and nitrate.

27, 28) Potassium concentration and errors.
29, 30) Magnesium concentration and errors.
31, 32) Calcium concentration and errors.
33, 34) Non Sea-Salt Sulfate (NSS) concentration and errors.
Defined as SO4 - 0.06020*Na (on a molar basis).

All concentrations are in picomoles of analyte per mole of
air drawn through the filter (parts per trillion on a mole
basis). Errors are calculated from detection limits and
variations in procedural blanks. Given the assumption of
normally distributed errors, error bounds are 95% confidence
limits.


File Name Conventions:
   c130filt.dat

References: None.