About the Project
’Space weather’ describes changing environmental conditions in near-Earth space. Severe space weather can impact technology and human health. A recent Royal Academy of Engineering report indicated that impacts of an extreme space weather event in the UK could include local electricity interruptions for a few hours, outage of around 10% of spacecraft, considerably increased risk to aircraft avionics and partial or total global navigation satellite system (GNSS) outage for 1-3 days.
The Met Office now provides operational space weather alerts and forecasts. A strategic goal of the research programme that supports the Met Office space weather service is the development of a coupled Sun-to-Earth modelling system for improved forecast capability, based around the development of an extended version of the Unified Model (UM), extending from the Earth’s surface to the thermosphere and ionosphere.
By developing and implementing a mesosphere/thermosphere chemistry scheme in the extended UM, this PhD project will considerably increase the accuracy of the model, thus moving it closer to the point where it can be used for operational space weather forecasting. Such improved forecasts from the extended UM will be particularly important for power grid, satellite, GNSS and High Frequency radio users.
Research Project:
Variations in solar ultraviolet (UV) radiation due to the 11-year solar cycle cause changes to stratospheric ozone which in turn can affect tropospheric weather and climate. Space weather events can also lead to enhanced precipitation of energetic particles, which can produce HOx and NOx in the upper atmosphere. Since the NOx perturbations are long-lived they can be transported to the stratosphere where they can deplete ozone and thus also affect the troposphere. The impact of these separate processes on surface weather and climate, and how they interact, remains to be quantified.
The Met Office has a new extended version of the Unified Model with a top boundary at 100 km (with research underway to increase this up to 140 km). The raised lid allows a representation of mesosphere / lower thermosphere (MLT) chemistry to be added to the UM, which will be a key part of the proposed project. The model will then be used to investigate the UV and particle precipitation impacts on ozone more realistically than hitherto attempted in the UM.
Project Objectives:
• Add a detailed description of MLT neutral and ion chemistry to the extended UM.
• Investigate the impact of UV changes and precipitating energetic particles on stratospheric ozone.
• Investigate the impact of these changes in ozone on tropospheric climate, via multi-year simulations with a coupled ocean-atmosphere-chemistry version of the UM.
Detailed and efficient neutral / ion chemistry schemes have been developed for the NCAR Whole Atmosphere Community Climate Model (WACCM) by the University of Leeds and collaborators. A similar scheme will be implemented in the UM framework, including neutral chemical species and in particular excited electronic states. As large amounts of chemical energy are stored in the MLT (following O2 photolysis) chemical heating and cooling play an important role in the energy budget. Hence the coupling of this scheme should lead to more realistic temperature simulations in the UM.
Ionization through particle precipitation in the auroral regions and extreme UV at all latitudes is another distinguishing feature of the MLT. Leading high-top models such as WACCM currently use simplified E region ion chemistry, solving only for O+, O2+, N+, N2+, NO+ and electrons. The Sodankylä Ion and Neutral Chemistry (SIC) model is generally recognised to contain the most detailed and complete description of ion chemistry in the D region and lower E region. However, SIC treats 55 ions using >400 reactions, and hence is much too complex for inclusion in climate models. Recent mechanism reduction work in Leeds has developed an efficient version of the SIC chemistry which will be included in the UM.
Validation of the new model will be carried out by comparison with satellite data from the Microwave Limb Sounder (MLS) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER), and with WACCM simulations. With a UM lid at 120-140 km, further validation can include comparing the UM iron and sodium chemistry with correlative data from ground-based lidar stations and satellite observations of the metal atom layers.
Funding Notes
This is a 4-year fully-funded NERC Industrial CASE award, and eligibility will normally be UK candidates and EU nationals who have spent at least 3 years immediately preceding the start of the PhD undertaking undergraduate or undergraduate plus postgraduate Masters study.
The student will be co-supervised by Prof. David Jackson, Manager of Space Weather Research at the Met Office. The student will spend periods of time (perhaps 4-6 weeks per year) working at the Met Office in Exeter. The student will have various opportunities to share his/her work with Met Office operational forecasters and Met Office scientists.
References
Chartier, A.T., D.R. Jackson, and C.N. Mitchell, A comparison of the effects of initializing different thermosphere-ionosphere model fields on storm time plasma density forecasts, J. Geophys. Res., 118, 7329-7337, doi:10.1002/2013JA019034, 2013.
Feng, W., D.R. Marsh, M.P. Chipperfield, D. Janches, J. Hoffner, F. Yi and J.M.C. Plane, A global atmospheric model of meteoric iron, J. Geophys. Res., 118, 9456-9474, doi:10.1002/jgrd.50708, 2013.
Plane, J.M.C., W. Feng; Dawkins, E.C.M.: The Mesosphere and Metals: Chemistry and Changes, Chemical Reviews, 115, 4497 - 4541, doi:10.1021/cr500501m, 2015.
Plane, J.M.C.; Feng, W.; Dawkins, E.; Chipperfield, M.P.; Höffner, J.; Janches, D.; Marsh, D.R.: Resolving the strange behavior of extraterrestrial potassium in the upper atmosphere, Geophys. Res. Lett., 41, 4753-4760, doi:10.1002/2014GL060334, 2014.
Royal Academy of Engineering, Extreme Space Weather: Impact on engineered systems and infrastructure, 2013.
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