TITLE: INDOEX: Aircraft C-130 Chemistry CO (Campos) 


AUTHOR(S): 

     Teresa L Campos and Richard E Shetter
     NCAR Atmospheric Chemistry Division
     PO Box 3000
     Boulder, CO 80307-3000
     Phone: 303-497-1879
     Fax:     303-497-1411
     campos@acd.ucar.edu
     shetter@acd.ucar.edu

1.0 - 3.0 DATA SET SUMMARY AND INSTRUMENT DESCRIPTION: 

The NCAR C-130 platform measured carbon monoxide using a modified TECO Model 
48 gas filter correlation analyzer.  The data cover the INDOEX C-130 research 
flights occurring between 24 February, 1999 and 24 March, 1999.
 
General Comments on Data Collection, Data Processing, and Instrument 
Performance:

Signals were recorded on the NCAR data system. Therefore, the raw data values 
are synchronous with RAF netCDF data files.  The duty cycle consisted of 7 
minutes of measurements followed by a 5 minute zero reading.  Zero subtraction 
from measured voltages were performed using a spline fitting routine.  
This required that each data file contain only data gathered for a particular 
front panel zero offset.  Therefore, prior to processing each flight the data 
files were separated into subset files, each containing data gathered for a 
particular zero offset.  After processing, the data were re-combined into a 
single file for each flight. 

The raw data have a one sigma precision of 30 ppbv for a 10-second average.  
The data have been further processed with a 60-second running average digital 
filter to improve precision as much as possible.  Although recorded at an 
interval of 1 second, spectral analysis of the raw data imply that the inherent 
instrument time response is approximately 30-60 seconds.  Both raw and filtered 
data are included in the archived files.  

Informal intercomparisons with the Citation aircraft and the USS Ron Brown were 
conducted.  Good agreement in both trends and absolute mixing ratios were 
observed. Agreement between the NCAR(C-130) data and that of other platforms 
was typically +/- 5 ppbv.


Missing Data Listed by Flight:

Flights 1-3: no useable CO data due to instrument failure during ferry to 
Maldives.
Flight 17: no data after approximately 0600 UTC due to instrument failure
Flight 18: no data due to failure during Flight 17.


4.0 DATA FORMAT: 

Data file structure:  space delimited ASCII
File naming convention: c130.co.rf[4-17].txt
Header Example:
PI/DATA CONTACT= Campos, Teresa (NCAR), Shetter, Rick (NCAR)
DATA COVERAGE = START: 0821133500; STOP: 0821135500 UTC
PLATFORM/SITE = C130 
INSTRUMENT = C-130 carbon monoxide
DATA VERSION = 1.0 (25 March 2000), FINAL 
REMARKS = National Center for Atmospheric Research, INDOEX 
REMARKS = Data point Time provided in UTC in hh:mm:ss format
REMARKS = Raw data recorded by C-130 data system; CO_1s values are synchronous 
with RAF REMARKS= netCDF data files 
REMARKS= Although recorded at an interval of 1 second, spectral analysis of 
the raw data show REMARKS= that the inherent instrument time response is 
approximately 30-60 seconds.
REMARKS= CO_1min values reflect processing with a 60-second running average filter
REMARKS = Missing data = -32767; Bad data = -32767 
File Parameters:	UTC (time, hh:mm:ss)
CMODE (1=zero mode, 0=measure mode)
CO_1s (ppbv, 1 second raw data, 1-s sampling interval)
CO_1min (ppbv, filtered raw data, 1-second interval, filter: 1-min running average)
Version number: 1.00, 25 March 2000, FINAL DATA
Missing and Bad Data Flag: -32767.

Header Example:

PI/DATA CONTACT= Campos, Teresa (NCAR), Shetter, Rick (NCAR)
DATA COVERAGE = START: 0821133500; STOP: 0821135500 UTC
PLATFORM/SITE = C130 
INSTRUMENT = C-130 carbon monoxide
DATA VERSION = 1.0 (25 March 2000), FINAL 
REMARKS = National Center for Atmospheric Research, INDOEX 
REMARKS = Data point Time provided in UTC in hh:mm:ss format
REMARKS = Raw data recorded by C-130 data system; CO_1s values are synchronous 
with RAF netCDF REMARKS= data files 
REMARKS= Although recorded at an interval of 1 second, spectral analysis of the 
raw data show that the REMARKS= inherent instrument time response is 
approximately 30-60 seconds.
REMARKS= CO_1min values reflect processing with a 60-second running average 
filter
REMARKS = Missing data = -32767; Bad data = -32767