The Antarctic ice sheet is the largest on the planet by a factor 10. It holds enough ice to raise global sea level by ~65 m. Small changes in the balance between losses and gains (the mass balance) can have, therefore, profound implications for sea level, ocean circulation and our understanding of the stability of the ice mass. Local variations in mass balance may be driven by short or long term changes in ice dynamics that may or may not be related to recent climatic change. They may also be due to trends in snowfall. There is now a general consensus that the ice sheet is losing mass but the range of estimates and uncertainties are still, in most cases, larger than the signal. To solve the open question of what the time evolving mass change is, we propose combining satellite observations, climate modelling and physical constraints to solve for the independent and uncorrelated errors that have hampered previous approaches. Sea level rise (SLR) since 1992 has averaged around 3.2 mm/yr, ~ twice the mean for the 20th Century. The cause is uncertain, but it is clear that a significant component is due to increased losses from both Greenland and Antarctica. Recent advances in regional climate modelling and analysis of gravity anomalies from the GRACE satellites have greatly improved our knowledge of both the magnitude and origin of mass losses from Greenland. Unfortunately, this is not the case for Antarctica for a range of reasons. The aim of this project is to address this shortcoming using a similar, but more comprehensive, approach to the one we used to improve our understanding of changes in Greenland. To do this, we must employ additional data and methods because i) the uncertainty in post glacial rebound for the West Antarctic Ice Sheet , in particular, is of a similar magnitude to the signal (unlike Greenland), ii) errors in observed and modelled variables are generally larger because of the paucity of in-situ data sets in, and around, Antarctica, and iii) observations in time and space are poorer for most of the ice sheet and, in particular, the areas showing the greatest change.

The central Sahara has one of the most extreme climates on Earth. During the northern summer months, a large low pressure system caused by intense sunshine develops over a huge, largely uninhabited expanse of northern Mali, southern Algeria and eastern Mauritania. Temperatures in the high 40s are normal and uplift of dry air through more than 6000m of the atmosphere is routine in what is thought to be the deepest such layer on the planet. This large zone is also where the thickest layer of dust anywhere in the Earth's atmosphere is to be found. Although the central Sahara is extremely remote, it turns out to be vitally important to the world's weather and climate. The large low pressure system drives the West African Monsoon and the dry, dusty air layers are closely related to the tropical cyclones which form over the Atlantic Ocean. Likewise, the dusty air has a strong influence on the way the atmosphere is heated, a process which is poorly understood. It is not surprising that the models we use to predict weather and climate and which are a crucial tool for understanding how the atmosphere works, all have problems in dealing with the central Sahara. Insights into how the climate system works, improving the models and therefore the predictions have all been held back in the case of the Sahara by a lack of measurements of the atmosphere and the processes that make dust and extreme weather. This will always be the case until a team goes to the central Sahara and makes these measurements. A key part of this proposal aims to do just that. We want to set up an array of special instruments, at the surface in two carefully chosen places in the central Sahara, which will monitor the winds, temperatures, dust and so on for an entire year. We will add to this collection for a shorter period of even more intense measurements during the core summer month of June. We plan also to fly a instruments attached to an aeroplane overhead the surface array and across the desert so that we can get an idea of the structure of the atmosphere and how it changes through the day. To find out how dust storms work, we will leave 10 weather stations at places where we think dust storms happen frequently. Satellites play an essential role in measuring weather and climate and are especially useful in remote places. The best available information from satellites will help to quantify how weather and climate works in the Sahara. We also expect to improve the way the satellites are able to make their measurements too. Because models are so important to understanding and predicting weather, we will make heavy use of them in this work. We want to know how well the models work over the Sahara and what can be done to improve them. We are especially interested in seeing whether the models work better if we allow them to deal with small parts of the climate system or whether we can still represent extreme places in the Sahara by ignoring these details in the models.

Small particles (known as aerosol) in the atmosphere play several critical roles. They affect the transmission of sunlight to the underlying surface; they affect the formation of clouds, and they host and enhance important chemical reactions. When they are deposited on ice they leave a record of past conditions that can be accessed by drilling ice cores. The most significant aerosol component over marine areas is sea salt aerosol. Over most of the world's oceans this is created by bubble bursting in sea spray. However there is strong evidence that another source of sea salt aerosol is important in the polar regions, and that this ultimately derives from the surface of sea ice. The existence of this source forms the basis for a proposed method using ice core data for determining changes in sea ice extent over long time periods. Additionally sea salt aerosol, along with salty sea ice surfaces, is the host for the production of halogen compounds which seem to play a key role in the oxidation chemistry of the polar regions. It is therefore important to understand the sources of polar sea salt aerosol and therefore to be able to predict how they may vary with, and feedback to, climate. It was recently proposed that the main source of this polar sea salt aerosol was the sublimation of salty blowing snow. The idea is that snow on sea ice has a significant salinity. When this salty snow is mobilised into blowing snow, sublimation from the (top of) the blowing snow layer will allow the formation of sea salt aerosol above the blowing snow layer, that can remain airborne after the blowing snow has ceased. First calculations suggested that this would provide a strong source of aerosol (greater than that from open ocean processes over an equivalent area). It was proposed that this would have a strong influence on polar halogen chemistry and a noticeable influence on halogens at lower latitudes. However, this was based on estimates of the relevant parameters as there were no data about aerosol production from this source, and almost no data about blowing snow over sea ice in general. Here we propose to take advantage of a very rare opportunity to penetrate the Antarctic sea ice zone during winter, as we have been allocated spaces on an unusual winter cruise into the sea ice zone on the German icebreaker Polarstern. During this cruise, we will be able to confirm that the blowing snow sea ice source exists, and make measurements that will provide a soundly-based parameterisation of the source. This will be done by making measurements of the snow on sea ice, of the blowing snow itself, and of aerosol above the blowing snow, as well as before and after such episodes. Measurements will include salinity, chemistry (looking at the amount of bromine present in each medium), and for blowing snow and aerosol, the amounts and size distributions. By combining our data with meteorological data, and by comparing them to satellite observations that have recently attempted to identify blowing snow episodes, we will be able to make estimates of the spatial and temporal distribution of sea salt aerosol from this source over the entire Antarctic sea ice zone. This will allow us to assess the importance of this source of sea salt (and of halogens) compared to others that have been proposed. We will then use existing models to assess how important such a source is to sea salt deposition in Antarctica, allowing us to determine how sea salt in ice cores is related to sea ice extent. This opens the possibility of turning a qualitative sea ice proxy into a quantitative one. Models will also be used to re-assess the importance of this source for halogen chemistry in the polar regions and globally. In summary this proposal will provide the first targeted measurements of the parameters needed to assess the importance of blowing snow sublimation as a source of sea salt, and to quantify its most relevant impacts.

To minimize the risk of dangerous climate change associated with increasing concentrations of atmospheric greenhouse gases (GHG), as part of ongoing international efforts, the 2008 Climate Change Act requires that the UK reduces its GHG emissions by at least 80% by 2050, compared to 1990 levels. To support such legislation, methods must be developed to reduce uncertainty on existing national GHG emissions estimates and monitor the efficacy of emissions reduction strategies. In 2010, CO2 represented about 85% of total UK GHG emissions, with the remainder largely from methane (CH4) and nitrous oxide (N2O). In 2010, the main UK sources of CO2 were energy supply, road transport, business, and residential; the main sources of CH4 were agriculture and landfill with small sources from gas leakage and coal mines; and the main sources of N2O were agriculture, industrial process, and road transport. There are substantial associated uncertainties with sectoral estimates of these emissions, particularly for N2O. The main focus of Greenhouse gAs Uk and Global Emissions (GAUGE) is to quantify UK budgets of CO2, CH4, and N2O from different sectors, and to improve global GHG budgets. The UK study will focus on fossil fuels and agriculture, the two largest sources of the three GHGs. We will achieve this by combining atmospheric measurements with computer models of the atmosphere, which describe the movement of GHGs after emission. We already have a reasonable idea of where GHGs are emitted but the size of the emissions typically has a large associated error. Depending on the emission type it may also have a substantial seasonal cycle (e.g., agriculture). It is therefore important we make regular GHG measurements at different times of the year and in different places. The UK research aircraft will provide the broad-scale 3-D perspective on the inflow and outflow of UK GHG budgets, complementing information from existing tall towers. The network of tall towers measure GHGs at 100-200m above the surface to ensure that the sampled air is representative of larger areas, and the towers are intentionally sited to provide estimates of GHG emissions in the Devolved Administrations. As part of GAUGE we will add to this network with a tower in the Scottish borders that provides substantially more information about the north of England, Scotland, and the North Sea; a tower over SE England, downwind of London; and we will support existing instruments on the BT tower in central London. The SE London tower and the BT tower together will allow us to provide the first multi-year record of urban emissions from a megacity. We will use GHG isotopes to improve understanding of the fossil fuel sources. A detailed study of agricultural GHG emissions will be conducted over East Anglia, allowing us to quantify the importance of this sector in the UK GHG budget. Weekly measurements aboard a North Sea ferry will provide constraints on UK GHG fluxes by regularly sampling transects of UK outflow. Satellite observations of GHGs offer a unique global perspective, linking UK emissions to the rest of the world, and we will work with NASA to develop and apply new observations to quantify global GHG budgets on a sub-UK spatial scale. Embedded in this long-term measurement strategy will be a measurement intensive to quantify London GHG emissions, where we will use the UK research aircraft to sample profiles of upwind/downwind air, validate dedicated satellite observations, and link urban measurements with downwind in situ and tall tower measurements. In GAUGE we bring together computer models of the atmosphere, and a team of world-leading modellers, in order to relate observed variations of GHGs to estimates of the underlying emissions. Statistical approaches will be used to find emissions that best agree with the measurements, taking account of model and data uncertainties. The main outcome from GAUGE will be robust GHG emission estimates from the UK and from the world.

Over the past decades, computer simulations have played an increasingly important role in design of numerous complex systems. In particular, computer simulations have played a pivotal role in aerodynamic and structural design of aircraft. It is becoming apparent, however, that current generation software packages used for aerodynamics design are not fit for purpose. Newer software is required, that can make effective use of current and future computing platforms, to perform highly accurate so called 'scale-resolving' simulations of air flow over complex aircraft configurations. Such capability would lead to design of more efficient and capable aerospace technology. In particular, it would greatly improve design of next generation Unmanned Aerial Vehicles (UAVs), which in the coming decades are set to have a significant impact on our society, playing key roles in areas such as defense, border security, search and rescue, farming, fishing, cargo transport, wireless communications, and weather monitoring. The primary objectives of this research are to i.) develop software that can effectively leverage capabilities of current and future computing platforms (with many thousands or even millions of computing cores) to undertaken hitherto intractable simulations of airflow over complex UAV configurations ii.) test and demonstrate cutting edge functionality of this software, iii.) translate the technology to industry, such that it can be used to facilitate design of next generation UAVs. The research program will be lead by Dr. Peter Vincent (a Lecturer in the department of Aeronautics at Imperial College London). It will be undertaken in collaboration with various industrial partners including BAE Systems, NASA Glenn, Nvidia, and Zenotech, and with various academic partners including Stanford University, UC Berkeley, University of Swansea, and University of Utah. This assembled team of project partners, comprising a selection of the world's leading companies, and elite research institutions, will ensure the project successfully delivers its objectives.