Earth's surface, is a major source of particulate matter and trace gases in the atmosphere. Although fire in the Earth system can be a natural process, e.g. lightning-initiated, the majority of it is anthropogenic, e.g. for land clearing. The emissions from fires contribute to climate change and public health issues, however these emissions are not well constrained.
Satellite remote sensing is the best method to acquire quantitative information on the global magnitude and spatial distribution of biomass burning. From space one can observe fire activity via products such as fire radiative power (FRP), a measure of the rate of radiant heat output from a fire.
In addition, remote sensing generates data on species emitted into the atmosphere. The two Infrared Atmospheric Sounding Interferometer (IASI) instruments, on board the MetOp-A and MetOp-B satellites (a third should be launched in October 2018), detect trace gases in the atmosphere using their distinctive spectral infrared fingerprints, thereby allowing us to track biomass burning plumes as they spread further into the atmosphere. Monitoring plumes from satellite provides a global coverage not otherwise possible, with a high density of data.
This project involves using both full optimal estimation and fast linear retrieval schemes to provide quantitative information for a number of pyrogenic species, and provide better constraints on their pyrogenic emissions.
The analysis of satellite data for pyrogenic species present in individual plumes will focus on enhancement ratios relative to the reference species carbon monoxide (CO; a reasonably long-lived species associated with biomass burning). These are related to the ongoing chemistry within the plume at the time of measurement, and can be converted to emission ratios (ratios of the species relative to CO at the time of emission) by taking into account the decay of the chemical species, i.e. using atmospheric models. Ultimately, in order to estimate atmospheric emissions for these species one needs to know their emission factors, i.e. a measure of the quantity released into the atmosphere for every unit of biomass burned. These can be calculated from the appropriate emission ratio provided we know the emission factor for CO.
The student will identify fires from satellite FRP products, e.g. MODIS, and correlate these with trace gases present in plumes as measured by IASI.
The student will calculate enhancement ratios relative to CO for pyrogenic species present in individual plumes. Emission ratios will be derived from these enhancement ratios by taking into account the decay of the chemical species. The latter will be achieved by running simulations of the TOMCAT 3D chemistry transport model (CTM) in collaboration with researchers at NCEO-Leeds.
The student will classify plumes and their enhancement / emission ratios with the type of fuel burned.
The student will also use INVICAT, a variational (4D-VAR) inverse transport model based on TOMCAT, to perform inversions of the plume CO data and provide better constraints on CO emissions. From these data, the student will derive emission factors for CO (based on estimates of biomass burned), and ultimately emission factors for other pyrogenic species.
Training and Skills
This studentship provides an exciting multidisciplinary opportunity to work with cutting-edge satellite observations and modelling techniques in a challenging area of atmospheric science.
This project covers a wide range of topics: (1) atmospheric spectroscopy; (2) remote sensing techniques and the interpretation of retrieved quantities; (3) atmospheric chemistry & transport modelling; (4) data visualisation & analysis, including the comparison of model data with satellite observations.
The student will be affiliated to the National Centre for Earth Observation (NCEO), through which they will obtain additional training opportunities and interaction with scientists working in Earth observation (EO) and environmental science.
CENTA students are required to complete 45 days training throughout their PhD including a 10 day placement. In the first year, students will be trained as a single cohort on environmental science, research methods and core skills. Throughout the PhD, training will progress from core skills sets to master classes specific to CENTA research themes.
Year 1: Retrieval of the abundances of pyrogenic species from IASI radiances.
Year 2: Derivation of enhancement ratios and emission factors.
Year 3: Inverse modelling to better constrain the emissions of pyrogenic species.
Partners and collaboration (including CASE)
This studentship will be jointly supervised by NCEO researchers from the Universities of Leicester and Leeds. This studentship may be a CASE award with NCEO.
The TOMCAT CTM is hosted by the Atmospheric Chemistry Group based at the University of Leeds. The student will be expected to work closely with researchers in Leeds (including extended visits) to improve and develop computer code describing the emissions of pyrogenic species and their atmospheric chemistry, and to better understand the satellite observations.
The NCEO (www.nceo.ac.uk) is a distributed NERC centre providing the UK with national capability in EO science.
Dr Jeremy Harrison is the NCEO’s spectroscopy leader and capability leader in atmospheric radiative transfer. Based in the Earth Observation Science (EOS) group, his expertise lies in atmospheric spectroscopy and the remote sensing of trace gases.
Prof Martyn Chipperfield is the NCEO’s capability leader for atmosphere-land surface data assimilation. His expertise is in chemistry-transport modelling and the interpretation of satellite observations of atmospheric chemistry.
Prof John Remedios is the Director of the NCEO, and an expert in the remote sensing of trace gases.
Interested applicants are invited to contact Dr Jeremy Harrison (firstname.lastname@example.org). Note that all potential applicants are strongly advised to make contact before applying.