See files header for detailed info.


Please note:
=============

The gain used for these variables (below) is NOT 1.0

Var      Unit        Gain
----------------------------
"Na"   "(pptv)"      1.15
"NH4"  "(pptv)"      1.15
"Ca"   "(pptv)"      1.15
"K"    "(pptv)"      1.15
"Mg"   "(pptv)"      1.15
"Cl"   "(pptv)"      1.15
"NO3"  "(pptv)"      1.15
"SO4"  "(pptv)"      1.15

==============================================================================


Rodney J. Weber wrote:


After some effort to beg, borrow, and buy the necessary instrumentation to
do a more "complete" calibration of our system (PILS/IC) deployed on the P3
for TRACE-P and C 130 for Ace Asia, we have completed the instrument
calibration curve.  There are two points worth noting.

1.  According to the calibration, the upper size limit of the instrument
should be taken as 1.3 µm (that is the 50% cut off size).  In the data
archive we guessed it was 3 µm diameter.   Note that some fraction of
particles up to about 3µm are also measured.  In TRACE P, larger particles
are unlikely to be measured due to inlet and sample transmission line
losses.

2.  The instrument's sampling efficiency for smaller particles levels off
at about 87%.  This agrees with filter data we collected during TRACE-P to
monitor the performace of the instrument.  That means, I would recommend
that all data be multiplied by 1.15.


Bottom Line

- Fast IC data measured fine aerosol only.  (diameters less than
approximately 1.3µm)

- I recommend all fast IC data be multiplied by 1.15 to account for
instrument sampling losses, ie, apply this factor to all ion concentrations
reported.



Rodney J. Weber
Assistant Professor
School of Earth & Atmospheric Sciences
Georgia Institute of Technology
Atlanta, GA 30332-0340

Phone:  (404) 894-1750
Fax:  (404) 894-1106