TITLE: Aircraft C-130 Radiation TSBR and FSBR Measurements (Valero)

AUTHOR(S): PI: Francisco P.J. Valero
               University of California, San Diego
               Scripps Institution of Oceanography
               9500 Gilman Drive, Dept 0242
               La Jolla, CA 92092-0242
               Phone: 858-534-2701
                 FAX: 858-822-0517
               email: fvalero@ucsd.edu

           Co-PI: Brett C. Bush
               (Same address as above)
               Phone: 858-822-0514
               email: bcbush@ucsd.edu

           Co-PI: Shelly K. Pope
               (Same address as above)
               Phone: 858-534-9619
               email: spope@ucsd.edu

1.0 DATA SET OVERVIEW: 
       This data set contains radiation measurements made during ACE-ASIA
       on the C-130 aircraft. Archived data consists of four broadband
       radiometers (two uplooking and two downlooking). In each location,
       one of the broadbands (TSBR or Total Solar Broadband Radiometer)
       measured the "total" solar bandpass (roughly 0.3 to 3.8 microns)
       and the other (FSBR or Fractional Solar Broadband Radiometer)
       measured the "fractional" solar bandpass (about 0.68 to 3.3 microns).
       Each TSBR and FSBR had hemispherical fields-of-view.

       RAMS measurements on the NCAR C-130 were made on each of the research
       flights during the intensive field phase of ACE-ASIA in 2001:
        March 31
        April 2, 4, 6, 8, 11, 12, 13, 17, 18, 20, 23, 24, 25, 27, 30
        May 1, 2, 4

2.0 INSTRUMENT DESCRIPTION: 

       The accuracy of the broadband broadband measurements is typically
       1-2%. All of the uplooking instruments have had navigation corrections
       applied that are functions of the aircraft pitch, roll, and heading.
       These corrections are made to account for any mounting offsets between
       the radiometers and the aircraft as well as relate the measurements
       to a level platform. All radiometric measurements are acquired at
       approximately 5Hz.

3.0 DATA COLLECTION AND PROCESSING: 

       All radiometric measurements are acquired using the RAdiation
       Measurement System (RAMS). The raw measurements are converted to
       fluxes using the following steps, briefly summarized below:
        1) Subtract "dark" signal
        2) Apply calibration constant
        3) Correct downwelling fluxes for slight deviations of the angular
           response from an ideal cosine using estimates of the direct:total
           ratio as well as the aircraft attitude.

       Data quality control consists of eliminating periods of data deemed
       unsuitable for flux measurements (i.e. warm up periods, large
       pitch and roll excursions, etc.)

4.0 DATA FORMAT: 

       All data is archived in NetCDF format. A list of the variables is
       summarized below:
        base_time - "seconds since 00:00:00 1 Jan 1970 GMT" ;
        time_offset - "seconds since base time" ;
        Zen_TSBR - "Downwelling Total Solar Broadband Flux (W/m2)"
        Nad_TSBR - "Upwelling Total Solar Broadband Flux (W/m2)"
        Zen_FSBR - "Downwelling Fractional Solar Broadband Flux (W/m2)"
        Nad_FSBR - "Upwelling Fractional Solar Broadband Flux (W/m2)"

       The "base_time" variable is always defined to be an integral number
       of whole days so that all time offset is also the offset from
       00:00:00 GMT on the given measurement day. (Note: because the GMT day
       changed during some of the research flights, it is possible to have
       "negative" times.)

       Bad broadband fluxes are flagged with a value of "-99.999".

5.0 DATA REMARKS: 

       Any questions or comments regarding this data set should be addressed
       to the the PI or Co-PIs listed at the top of this README file.

6.0 REFERENCES:

       Broadband Reference:
         Valero et al. 1982, Radiative Flux Measurements in the Troposphere,
         Applied Optics 21, p. 831