Title: C130 Hydrogen Peroxide Concentration

Contact:

   Greg Kok
   NCAR-RAF
   Box 3000
   Boulder, Colorado  80307
   phone 303-497-1070
   fax 303-497-1092
   E-Mail Address: kok@ucar.edu


Data Set Description:

     This data set contains the hydrogen peroxide
measurements made from the NCAR C-130 on the ACE-1 program.
Four data parameters are available:

     PERACAL:  This is the total soluble peroxide
concentration measured as hydrogen peroxide.  This is the
atmospheric hydrogen peroxide plus some fraction of the
soluble organic hydroperoxides.

     H2O2:  This is the concentration of gas-phase hydrogen
peroxide in ppbv.

     ROOH:  This is the concentration of soluble organic
hydroperoxides measured as hydrogen peroxide.  The
concentration of H2O2 + ROOH is equal to PERACAL.

     MHPEQ:  This is the equivalent concentration of
methylhydroperoxide assuming that all of the ROOH is
methylhydroperoxide.  The MHPEQ takes the ROOH and applies
the   Henry's law constant to generate the equivalent
atmospheric concentration of methylhydroperoxide.

     Hydrogen peroxide measurements were made using the
dual-enzyme analytical technique where catalase enzyme is
used to discriminate between hydrogen peroxide and the
organic hydroperoxides.  Quantitative analysis of the
hydroperoxides is accomplished by reaction with
p-hydroyphenyacetic acid and horseradish peroxidase; this
produces a fluorescent dimer that is quantitated by
fluorescence spectroscopy.  The instrument utilized a single
collection coil for the atmospheric hydroperoxides and the
resulting hydroperoxide solution was then split between the
analytical channels.   The pH of the final reaction mixture
was raised by a concentrated ammonium hydroxide added
through a Nafion membrane.  The instrument was calibrated
before each flight with aqueous standards.  The instrument
was zeroed every hour for five minutes.  All zero and
calibration data have been removed from the data set and
replaced with -32768.  The data has been shifted 4 minutes
at 1000 mbar and about 5 minutes at 400 mbar to remove the
sampling lag.

Format: space-delimited ASCII with fields:

Date : (UTC)
YYYY/MM/DD

Time : (UTC)
HH:MM:SS

XLATC :GPS-Corrected Inertial Latitude
deg

XLONC :GPS-Corrected Inertial Longitude
deg

PALT :NACA Pressure Altitude
M

H2O2 :Hydrogen Peroxide, Gas Phase
ppb

MHPEQ :MethylhydroPeroxide Equivalent
ppb

PERACAL :Hydrogen Peroxide Calibrated Ch A
ppb

ROOH :Organic Peroxide Concentration
ppb


File Name Conventions:
   rfxxx.dat where xxx is the flight number.
   An example for flight 1 is rf01.dat.

References: None.