Campaign : Biomass Burning Observation Project - BBOP
2013.07.01 - 2013.10.24
Website : http://campaign.arm.gov/bbop/
Lead Scientist : Larry Kleinman
This field campaign will address multiple uncertainties in aerosol intensive properties, which are poorly represented in climate models, by means of aircraft measurements in biomass burning plumes. Key topics to be investigated are:
- Aerosol mixing state and morphology
- Mass absorption coefficients (MACs)
- Chemical composition of non-refractory material associated with light-absorbing carbon (LAC)
- Production rate of secondary organic aerosol (SOA)
- Microphysical processes relevant to determining aerosol size distributions and single scattering albedo (SSA)
- CCN activity.
These topics will be investigated through measurements near active fires (0-5 hours downwind), where limited observations indicate rapid changes in aerosol properties, and in biomass burning plumes aged >5 hours. Aerosol properties and their time evolution will be determined as a function of fire type, defined according to fuel and the mix of flaming and smoldering combustion at the source.
The DOE G-1 aircraft is being requested from June 1 to October 30, 2013, to be based at its home location in Pasco, Washington, except for a 4-week intensive operational period (IOP) in Little Rock, Arkansas. A sampling strategy has been devised that will maximize opportunities to sample both fresh biomass burn emissions and aged plumes. This strategy consists of an extended deployment of the G-1 in Pasco from July 1 – August 31, 2013, during which time targets of opportunity will be exploited, and an IOP in Little Rock in September-October 2013, where prescribed agricultural burns will be sampled.
This field campaign will leverage the capabilities of several new instruments or instrument combinations that have not been previously used in aircraft. Morphological studies will be made by electron microscopy (offline) and Single-Particle Soot Photometer (SP2) analysis. Growth of particles with diameters < 60 nm will be determined by the high time resolution measurements provided by the Fast Integrated Mobility Spectrometer (FIMS). Quantitative measurements of the refractory and non-refractory components of particles containing BC will be provided by the Soot Particle Aerosol Mass Spectrometer (SP-AMS). Deployment of four instruments devoted to light absorption or extinction (Particle Soot Absorption Photometer (PSAP); Photothermal Interferometer (PTI); Photoacoustic Spectrometer (PAS); and Cavity Attenuated Phase Shift (CAPS)) will better quantify the inherently difficult aircraft measurement of light absorption and determination of mass absorption coefficients (MAC).
The primary measurement objective is to:
Quantify the time evolution of microphysical, morphological, chemical, hygroscopic, and optical properties of aerosols generated by biomass burning from near the time of formation onward.
The extended deployment at Pasco together with the IOP at Little Rock will allow an examination of the dependence of evolution of biomass burn aerosol properties on fuel type. These properties will also be measured in plumes aged several days and compared with those of younger plumes.
The primary scientific objectives are to investigate:
- SOA Formation Rates
- Structure and/or Configuration of Biomass Burn Aerosol Particles
- Aerosol Light Absorption
- Composition of Brown Carbon (BrC)
- Time Evolution of the Composition of Refractory Black Carbon (rBC)
- Determination of Mass Absorption Coefficients (MAC)
- Determination of the Time-Series for Coagulation and Condensation
- CCN Evolution, and Relation to Condensed Organics
- Radiative Transfer of Biomass Burns.
These will be used to:
- Constrain processes and parameterizations in a detailed Lagrangian model to reproduce the time-dependent microphysics and chemistry of aerosol evolution
- Incorporate time evolution information into a single-column radiative model as a first step in translating observations into a forcing per unit mass carbon burned.
In the unlikely event that only a few fires can be sampled, a set of alternative objectives related to biogenic aerosols, new particle formation (NPF) and growth, and characteristics of black carbon-containing aerosols in various environments have been defined so that productive science can be done.
Co-Principal Investigator : Arthur Sedlacek