ABLE 3A EXPEDITION
                          July and August 1988
                Carbon Monoxide (CO) and Methane (CH4) data
                           G. W. Sachse, P. I.
                          Phone (804) 864-1566
                           FAX (804) 864-1762

    The accompanying data files contain 5 second averages of CO and CH4
measurements taken by a tunable diode laser instrument (DACOM) that was
flown on the NASA Electra aircraft during the ABLE 3A expedition. Data 
from flights 11-26 and 29-33 have been submitted to the GTE data archive.
No data is available for flights 3 - 10,  27 and 28 due to instrument difficulties. 

    Filenames have the format COM3Axx.MD2 where xx identifies the flight 
number. The first line of each file has the following header:
HR MN SC     ALT      CO     CH4   DEWPT

where:
    HR MN SC universal time at the midpoint of the 5 sec average
    ALT - average pressure altitude in feet
    CO - CO mixing ratio in ppbv
    CH4 - CH4 mixing ratio in ppbv
    DEWPT - Dewpoint temperature in degrees C
 
    Dewpoint and altitude data are listed for the user's convenience,
however independent verification of these values should be made by the user
of these files. Where CO and CH4 data is missing, the value -9999 appears
in the appropriate column. CO and CH4 values may be missing for several
reasons: (1) a calibration took place, (2) the instrument experienced 
difficulties or (3) a CO/CH4 flux measurement run was in progress. During
flux measurements the CO and CH4 measurement accuracy is poorer and for 
this reason these data have been deleted.