VOCALS C-130 Gas Phase Dimethylsulfide (DMS) measurements, version 2, June 2009.

PI: Bandy Alan, Drexel University, Dept of Chemistry, bandyar@drexel.edu

Submitted by: Byron Blomquist, University of Hawaii, blomquis@hawaii.edu

Data in these files is in ASCII text format with tab delimiters. File headers conform to the NASA Ames 1001 format with 16 header lines: e.g.

16 1001 Header lines and format version
Bandy Alan PI
Drexel University, Dept of Chemistry Organization
Blomquist Byron Submitted by
VOCALS RFxx Project and flight number
1 1 Data management info
2008 mm dd 2008 mm dd Flight date and Data version date
1.0 Delta time
Time in seconds from 00Z UTC Time stamp identifier
1 Number of variables other than time
1.0 Scale factor for each variable
NaN Missing data specifier
DMS Mixing Ratio in parts per trillion by volume (pptv)Data identification and units
Seconds DMS Variable name header line

Data are 10 sec samples on a 1 Hz time base with identical timestamps to the most current RAF 1 Hz cdf data files (e.g. RF01.20081015.164800_201200.PNI.nc). Data is represented as repeated 1 Hz values for each 10 second interval. Periodic sements of missing data (~1 min) are from instrument background checks, usually at the beginning and end of each leg and more frequently during profiles.

The instrument suffered from sensitivity issues and electronic malfunctions throughout the project, and we were unable to ship spare parts into Chile to complete repairs. Longer segments of missing data are due to instrument malfunctions. Nevertheless, we were able to make measurements on all flights and the data will allow an assessment of the mean boundary layer DMS concentrations, vertical and horizontal gradients, and rate of change with time.

Under meteorological conditions for VOCALS, the free tropospheric concentration of DMS was near zero pptv. The detection limit on any given flight may therefore be assessed from the variance for free trop measurements. In general, the detection limit was better than 5 pptv.