Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites (BORTAS)

Completed

Not Energy Related
Renewable Energy Sources(Bio-Energy, Other bio-energy)

Basic and strategic applied research

PHYSICAL SCIENCES AND MATHEMATICS (Chemistry)

Not Cross-cutting
Sociological economical and environmental impact of energy (Environmental dimensions)

Prof A Lewis
Chemistry
University of York

R&D

NERC

01 April 2009

31 March 2012

36 months

£395,268

Transport Systems and Vehicles

Yorkshire & Humberside

Prof A Lewis, Chemistry, University of York

Professor PF Bernath, Chemistry, University of York
Dr J Lee, Chemistry, University of York

The overall goal of BORTAS is to investigate the connection between the composition and the distribution of biomass burning outflow, ozone production and loss within the outflow, and the resulting perturbation to oxidant chemistry in the troposphere. We have five science objectives: (1) sample biomass burning outflow from boreal North America over the western boundary of the North Atlantic duringsummer 2010 using the FAAM146; (2) describe observed chemistry within plumes by using the measurements to constrain the Master Chemical Mechanism (MCM), with particular attention to the NOy and organic chemistry; (3) derive a reduced chemical mechanism suitable for a global CTM that accurately describes chemistry within the plumes; (4) quantity the impact of boreal forest fires on oxidant chemistry over the temperate and subtropical Atlantic using a nested 3-D chemistry transportmodel, driven by a subset of MCM chemistry and by assimilated field measurements; and (5) detect, validate and quantify the impact of boreal biomass burning on global tropospheric composition using data from space-borne sensors.

The burning of biomass (e.g., shrubs, grasslands, trees) has an ongoing role in determining the composition of Earth's surface and atmosphere, and in some regions subsequent emissions of trace gases to the atmosphere rival those from fossil fuel burning. For nearly 40 years the scientific community has studied rates of emissions of trace gases from different types of biomass and associated amospheric gaseous concentrations but our knowledge remains incomplete, reflecting the heterogeneous and stochastic nature of this Earth System process. The advent of space-borne observations of land-surface and tropospheric chemistry provided the first glimpse of the large-scale nature and impact of burning in the global troposphere. These data remain key to scaling-up detailed point- or regional-scale measurements related to burning emissions or associated atmospheric concentrations. However,Earth Observation (EO) data products are difficult to interpret without the aid of computer models of atmospheric chemistry and transport and in situ measurements. In this proposal we have assembled an integrative programme of measurements and modelling of biomass burning that encompasses ground-based and aircraft in situ data, space-borne observations of tropospheric trace gases and particles, and a hierarchy of computer models of atmospheric chemistry (detailed point models to state-of-the-art global 3-D models). Here, we focus on biomass burning over northern boreal regions, with the aircraft missions sampling outflow from North America. Our research focus is to better understand atmosphericchemistry within air masses originating from regions of biomass burning. In particular, we follow up and expand upon surprising results from a recent NERC-funded aircraft campaign (Intercontinental Transport of Ozone and Precursors, ITOP) over the North Atlantic that measured and characterised outflow from the North American boundary layer as it travelled over the North Atlantic towards Europe. During ITOP the aircraft unintentionally sampled outflow from biomass burning and found that models analysing those data were unable to reproduce the large concentrations of organic molecules and the speciation of nitrogen species. As part of this proposal we plan to fly over the North Atlantic specifically to sample outflow from North American biomass burning equipped with a more suitable suite of aircraft instruments that will help to understand and resolve this unexplained discovery in atmospheric chemistry. The resulting data will be analysed by the gold standard Master Chemical Mechanism, an explicit model description of the degradation of relevant atmospheric compounds.One of the biggest challenges that atmospheric scientists typically face is the scaling-up from detailed in situmeasurements to regional and larger spatial scales. Here, we address this challenge by using global 3-D models of atmospheric chemistry and transport and data from space-borne sensors by using the model as an intermediary between the aircraft data and the relatively course satellite data. By statistically "tuning" the model using the detailed aircraft data (data assimilation) we can better estimatethe magnitude and 3-D distribution of outflow from North American biomass burning and its resulting effects on atmospheric composition over the northern hemisphere. The proposal will provide us with a better fundamental understanding of the evolving atmospheric chemistry within biomass burning, an improved understanding of how to combine data from in situ and space-borne sensors to relate detailed small-scale data to larger spatial scales, and a better quantitative understanding of the impact of boreal forest fires on the atmospheric composition of the northern hemisphere.

15/09/08