Based upon a submitted Scientific Program Overview (SPO) document for the Deep Convective Clouds and Chemistry (DC3) field campaign, this preliminary effort will focus on support of required coordination of potential DC3 investigators planning this large experiment.
If supported, DC3 will investigate the impact of deep, mid-latitude continental convective clouds, including their dynamical, physical, and lightning processes, on upper tropospheric (UT) composition and chemistry. DC3 will be requesting access to extensively instrumented aircraft platforms and ground-based observation systems. The NSF/NCAR Gulfstream-V (GV) aircraft would be the primary platform to study the high altitude outflow of the storms, and would be instrumented to measure a variety of gas-phase species, radiation, and cloud/precipitation particle characteristics. The GV would also document the downwind chemical evolution of the convective plume. The NSF/NCAR C-130 (or possibly the NASA DC-8) aircraft would complement the GV via in situ observations to characterize the convective storm inflow and provide remote sensing to aid in GV flight plan optimization and column characterization. Ground-based radar networks would depict the volumetric precipitation and kinematic characteristics of storms and provide guidance to the aircraft operations. The impact of lightning on outflow composition would be constrained through detailed measurements from VHF lightning mapping arrays. DC3 would thus surpass earlier experiments that addressed these topics by using advanced instrumentation not previously available. Satellite data would place the airborne and ground-based measurements in the context of the wider geographical region and help guide sampling strategies. At the same time, DC3 measurements would serve to augment satellite retrievals of atmospheric constituents such as nitrogen dioxide near storms.
Broader impacts of the planned field program would include extensive education and outreach activities and via improved understanding of sources of UT ozone, which is important to climate forcing and air quality, for assessment reports and resulting policy implications. Further, DC3 measurements would be instrumental in improving model parameterizations of convective transport, production of nitric oxide by lightning, and wet deposition of chemical species. Undergraduate and graduate students would participate in DC3 in a variety of ways including airborne and ground-based observations, design and construction of instruments, operation and improvement of numerical models, precipitation collection and analysis, and reporting of the results to the scientific community through presentations and publications. Outreach and media days during the field campaign would provide a valuable means to engage the public in atmospheric science.
The Deep Convective Clouds and Chemistry Field Campaign The upper troposphere (8-14 km above sea level) is an important region for Earth’s climate because water vapor, ozone, cirrus clouds and aerosols in this region strongly contribute to radiative forcing of the climate system. The upper troposphere composition is modified by intrusions from the stratosphere above and mixing within the troposphere. Transport via thunderstorms is a major pathway for moving chemical constituents and water rapidly from the boundary layer to the upper troposphere. The Deep Convective Clouds and Chemistry (DC3) field campaign was planned and executed to determine the impact of thunderstorms, including their dynamical, physical, and lightning processes, on upper tropospheric composition and chemistry over the United States. The DC3 field campaign was conducted in May-June 2012. The base of operations was located in Salina, Kansas for the NSF GV, the NASA DC-8, the DLR (German Aerospace Center) Falcon aircraft, and the operations and forecasting center. The three aircraft were all extensively instrumented to measure a variety of gases, aerosols, and cloud particle characteristics in situ as well as the NASA DC-8 measuring the ozone and aerosol distribution by lidar. The aircraft targeted storms predicted to occur within range of coverage by ground-based radar pairs, lightning mapping arrays, and frequent launches of balloon-borne instruments that could measure the storm’s physical, kinematic, and lightning characteristics. This coverage occurred in three regions: 1) northeastern Colorado, 2) central Oklahoma to western Texas, and 3) northern Alabama. The DC3 campaign demonstrated that it is possible to sample simultaneously the inflow and outflow of storms that were also observed by the ground-based facilities. In total, the aircraft sampled the chemical composition near sixteen thunderstorms, including eight Colorado storms, six Oklahoma-Texas storms, and two Alabama storms. These unique, synchronized measurements provide data that will generate new understanding of thunderstorms and chemistry and lead to better research and forecast models of clouds, regional and global chemical transport, weather, and climate. The NSF/NCAR GV and NASA DC-8 aircraft chased the convective outflow of storms the following day five different times after sampling near the storm. These flights provide insight on how the plume in the upper troposphere chemically ages during the first 24 hours since being lofted from the boundary layer. The best opportunity for sampling the chemical aging of convective outflow occurred when first the DC-8 and then the GV sampled the outflow of a mesoscale convective system from early morning to late afternoon. These measurements are providing the necessary information to estimate ozone sources and sinks in the upper troposphere where ozone is radiatively active as a greenhouse gas. These estimates are useful for assessment reports on ozone and aerosols and for policy implications. The DC3 planning phase and field campaign provided opportunities for undergraduate and graduate student, and post-doctoral scientist training. Over 100 undergraduate and graduate students participated in either the planning or operations of the field campaign. There were 30 post-doctoral young scientists participating in DC3. These students were involved with aircraft instrumentation, weather forecasting and nowcasting, chemical tracer forecasting, balloon launching, and radar operations. During the field campaign, there were several outreach activities including K-12 teacher training, public lectures in Salina, KS, and media interviews.
