Satellite TV-based Ozone and OH Observations using Radiometic Measurements (STO3RM)

The aim of this proof-of-concept study is to determine the feasibility of new remote sensing observations that will capture, for the first time, detailed changes in the chemistry of the Earth's stratosphere, mesosphere, and lower thermosphere on short timescales that cannot be measured using other techniques. Such observations would address major gaps in our understanding of the links between solar variability & space weather, atmospheric chemistry, and the global climate system. The importance of the areas targeted by this project are highlighted by the Intergovernmental Panel on Climate Change Fifth Assessment Report (IPCC AR5) which states the need to 'assess climate change impact on - and the role of the mesosphere in radiative forcing of the atmosphere'.

Ozone and hydroxyl radical (OH) are important trace gases in the middle and upper atmosphere that respond strongly to solar forcing and, at high latitudes, geomagnetic activity associated with space weather. Energetic particles from space are guided by the Earth's magnetic field into the atmosphere at high latitudes. Important questions about this energetic particle precipitation remain unresolved. These include what are the key chemical changes in the middle and upper atmosphere and how are these changes are coupled to the atmospheric layers below? Following geomagnetic storms, energetic electron precipitation (EEP) into the polar middle atmosphere causes ionisation reactions that generate odd nitrogen and odd hydrogen species, in particular OH. These reactive chemicals take part in both short-duration and long-term catalytic destruction of ozone that modifies the radiative and thermal structure of the atmosphere, affecting temperatures down to the Earth's surface. EEP occurs very frequently and potentially has a more significant impact on the atmosphere than the impulsive but highly sporadic and well-studied effects of powerful solar proton storms. It has been difficult to estimate the effect of EEP on the atmosphere because of the challenge of making measurements of rapidly-evolving atmospheric chemical composition, in particular ozone and OH, at altitudes of 20-100 km.

Commercial satellite TV broadcasting is possible due to remarkable advances in microwave electronics, enabling weak signals transmitted over 36,000 km from geostationary orbit to be received by inexpensive rooftop dishes. We propose incorporating the highly-sensitive Ku-band satellite receiver technology in ground-based microwave radiometers to measure ozone and OH. The microwave spectrum of the atmosphere contains information about ozone from an emission line at 11.072 GHz and from OH at 13.44 GHz. Ku-band microwave radiometry will allow precise, quantitative characterisation of these atmospheric signals using the sensitive heterodyne detection technique combined with high-resolution radiofrequency analysis. We will use computer-based algorithms to investigate how ten-fold improvements in receiver sensitivity will allow detailed measurements of the spatial and temporal distributions of ozone and OH. The proposed instruments would be robust, semi-autonomous, and operate continuously making observations that are highly applicable to studies of EEP, atmospheric dynamics, planetary scale circulation, chemical transport, and the representation of these processes in global climate models, ultimately leading to advances in numerical weather prediction. They would provide a low cost, reliable alternative to increasingly sparse satellite measurements, extending long-term data records and also providing "ground truth" data for calibrating and validating scientific satellite data. The work is relevant to three NERC research subjects (Atmospheric physics and chemistry; Climate and climate change; Tools, technology & methods) and will build UK expertise in microwave remote sensing and atmospheric information retrieval.

1. Who will benefit from this research?
a) The academic and industrial community who develop and build instruments for environmental observations and monitoring. Microwave and terahertz technologies are advancing rapidly and the UK has been in the lead exploiting their use in potentially far-reaching applications that include industrial analysis, medicine, and security.
b) The academic community who work in atmospheric science, space weather, and climate science. We will present our results and make a particular effort to bridge the gaps between experimental scientists using various observing techniques to study different regions of the atmosphere and those using observational datasets for atmospheric and climate modelling.
c) Governments making policies about climate change and stratospheric ozone need to have explanations for observed changes in the environment and climate of the Polar Regions. The creation of accurate models that take into account natural variability and complex interactions between atmospheric processes, the ozone layer, and the impact of increased greenhouse gases is vital for Governments revising policy concerned with the Montreal Protocol for the protection of the ozone layer and its amendments. The scope of the Intergovernmental Panel on Climate Change Fifth Assessment Report (IPCC AR5) includes the need to 'assess climate change impact on - and the role of the mesosphere in radiative forcing of the atmosphere'.
d) The general public, which shows large and widespread interest in climate change and stratospheric ozone. Clear communication and engagement on how this research focuses on these questions would be in high demand by the public and media, and would clearly benefit society in general.

2. How will they benefit?
a) The main outputs of the project will be technical reports on the feasibility study and peer-reviewed publications. The research team will engage with the wider academic community and industry through NCAS, CEOI, BAS Innovation and the co funded NERC / University of Cambridge Aurora Cambridge initiative, and the UK's Knowledge Transfer Network. We will interact directly with the international community involved in ground-based atmospheric observations, e.g. through the Network for the Detection of Atmospheric Composition Change.
b) The academic community will benefit from an increased knowledge of fundamental processes in the atmosphere gained from new stratospheric and mesospheric observations.
c) The proposed study is aimed at providing high-quality atmospheric observations that cannot currently be made, filling a major gap in our ability to improve and verify atmospheric models that contribute towards environmental assessments used by governments to formulate policy.
d) The general public will benefit by having access to an exciting scientific / technical project via the BAS Communications team, thus raising awareness of STEM subjects. They will also benefit as users since our work will ultimately contribute to atmospheric and climate models becoming more accurate. It is hard to quantify the financial and operational benefits to general and specialist users of more accurate understanding of space weather and atmospheric modelling, but any reasonable estimate suggests they will be very considerable.

3. Timescales
All results will be released and available within the scientific literature within one year of the project's end (allowing for publication times).

4. Research & Professional Skills
The academic staff involved will benefit from exposure to the complementary expertise each holds, e.g., Dr Newnham and Professor Kosch have strong atmospheric instrumentation skills and Drs Clilverd and Verronen have strong understanding of energetic particle precipitation and research-modelling skills. They will all benefit from exposure to these different areas of expertise and develop and strengthen their technical skills in data analysis and science communication.