RICO: NCAR/NSF C-130 Chemistry Peroxides Data

The gas phase peroxide data reported herein were obtained using the method described in Lee et al., J. Atmos. Ocean. Tech., 1995, flown on board the NCAR C-130 platform during the RICO, Rain in Cumulus over the Ocean, experiment between December 3, 2004, and January 27, 2005, based out of Antigua. Hydrogen peroxide is symbolically represented by H2O2. Methylhydroperoxide is symbolically given by CH3OOH. The measurements are given as molecular mixing ratios; molecules of specific gas per molecules of whole air times 1,000,000,000,000. or ppt-v. The partial pressure of a specific gas can be calculated by: P(H2O2) = MixingRatio(pptv) * P(air) /1,000,000,000,000.

The goal of RICO was a detailed understanding of rain formation in shallow "warm" cumulus clouds over the ocean. Objectives included following the number density distributions and chemical evolution of aerosol, cloud condensation nuclei, cloud droplets, and precipitation. Sulfur gas and partcile chemistry leading to sulfate was consider a key process and the measurements of peroxides are directly related to particulate sulfate formation.

Updated on 2006/01/03 with revised data files:

• correct lag time errors in CVI to air_sample changes in sample mode (and vice versa).
• Remove H2O2 data during noted periods of inlet condensation; primarily during initial decent after 1st high altitude circle at 5km and 1/2 way through first lower altitude circle.
• Corrected limit of detection of methylhydroperoxide (15 -> 30 ppt) and its estimated uncertainty