Desired Number of Participants: 1
Background Information: Sulphur dioxide (SO2) occurs naturally in the stratosphere, where it is oxidised to form aerosols which in turn have an important effect on the Earth's climate. The main natural source of stratospheric SO2 is volcanic eruptions. One possible geo-engineering approach to mitigate anthropogenic climate change is the deliberate release of SO2 into the stratosphere. It is therefore important for us to understand its behaviour in as much detail as possible. The MLS instrument (http://mls.jpl.nasa.gov) on the Aura satellite has operated for five years, returning almost continuous measurements of the chemistry of the stratosphere and upper troposphere. Sulphur dioxide (SO2) is one of the large suite of chemical species that MLS is capable of detecting. For most of the mission, the atmosphere contained too little SO2 for MLS to detect. However on a few occasions moderate-sized volcanic eruptions have injected substantial quantities of SO2 into the upper troposphere and lower stratosphere (UTLS) where they can be recorded by MLS. The largest of these eruptions were that of Sarychev in the Kuril islands in June 2009 and of Mt. Kasatochi in Alaska, in August 2008. Little work has so far been done on the MLS SO2 data. The aim of this project is to characterise it in some detail, assess whether the observations agree with other observations of SO2 and to investigate how much more information could be extracted with a future MLS-type instrument (currently on the drawing board) which would have much improved horizontal resolution.
Project Description: The raw MLS data are routinely processed to give data in the form of SO2 mixing ratio which are shipped to Edinburgh every day. The student would begin by analysing these data in some detail to identify all events in the record which could be potentially caused by a volcanic eruption. The air parcels which are observed to have high levels of SO2 will then be traced back to their source using a trajectory model such as HYSPLIT (http://www.arl.noaa.gov/HYSPLIT.php) or FLEXTRA (http://transport.nilu.no/flexpart) and thus linked to a specific volcanic event. As the MLS SO2 data have not been validated in great detail, the student will compare the MLS observations with those taken by other instruments such as OMI (which is on the same satellite). OMI provides far more horizontal detail than MLS, but can provide no information at all on the altitude of the SO2 plume. The student will attempt to confirm that the data from the two instruments are consistent. A more detailed picture of how the plume develops over time will emerge from this effort. Armed with a detailed view of how a particular plume developed, the student will then attempt to assess the level of detail with which a proposed instrument would have observed the same plume. The proposed instrument is also of the MLS type, but would have far greater horizontal coverage: tens of thousands of locations per day compared to 3500 for the current instrument.
Web or Literature References:
http://mls.jpl.nasa.gov/, plus see other references above.
Suggested/required Background/skills, Courses: Undergraduate degree in physics, chemistry, geoscience or related fields.