Particle size distribution measurements on the NSF Gulfstream V during DC3

A Scanning Mobility Particle Sizer (SMPS) has been developed for airborne measurement of atmospheric aerosol size distributions from 8 to 600 nm at the altitudes relevant to GV aircraft missions. These pressure/altitude regimes include 80kPa (~2000 m) to 15 kPa (~13000 m), the latter of which is high enough to be in the Upper Troposphere - Lower Stratosphere (UTLS) region. This ability to characterize aerosols up to the UTLS directly addresses important gaps in our knowledge of the impacts of aerosols on climate. Among the different climate forcing mechanisms documented by the Intergovernmental Panel on Climate Change (IPCC), the role that aerosols play continues to have the greatest uncertainty as indicated in the past several assessment reports. In addition to climate, the size-resolved study of aerosol is also important in tropospheric chemistry. Here we report initial observations of aerosol size distributions from the Deep Convective Clouds and Chemistry Project (DC3). This field campaign was designed to investigate the impact of springtime deep, midlatitude continental convective clouds, including their dynamical, physical, and lightning processes, on upper tropospheric (UT) composition and chemistry. Based in Salina, KS during May and June 2012, the campaign made use of 3 aircraft flying at different layers in selected thunderstorms in 3 key areas: northeastern Colorado, West Texas and central Oklahoma and northern Alabama. The SMPS was on-board the NSF-NCAR Gulfstream V aircraft, which was primarily used to study the higher altitudes during coordinated flights. The SMPS was specifically configured to measure particles over the diameter range from 8 to 150 nm, which had a considerable overlap with the ultra-high sensitivity aerosol spectrometer (UHSAS) and can also be compared to total number concentration from the water-based condensation particle counter (CPC). The specific scientific questions that are addressed by our measurements include: What is the role of deep convection on particle transport and new particle formation, and how might this process influence climate through direct scatter/absorption or through cloud formation and modification? More specifically, this presentation will focus on several key areas: - Instrument design and performance - Quantifying small (sub-30 nm) particles at altiudes above 8000 m - Correlations between particle formation and other trace gas species (such as NOx, CO, O3 and volatile organic compounds - Comparisons of instrument performance to similar measurements aboard the NASA DC-8 during specific coordinated flight legs. - Comparisons to other aerosol instruments on board the GV (water CPC and UHSAS).