Airborne Holographic Imaging Probe

Lead Research Organisation: University of Manchester
Department Name: Earth Atmospheric and Env Sciences

Abstract

Clouds play a key role in understanding future climate change and their representation in global models represents the biggest uncertainty in predicting future climate change. Clouds containing the ice phase are among those about which least is known and as a result are the most poorly represented in climate models. Correct representation of these clouds in weather forecasting models is also very important. The concentration of aerosol particles in the atmosphere that can initiate the ice phase (ice forming nuclei) at temperatures slightly below 0C is small. The ice phase, once formed, very effectively converts cloud water into snow and hail. This falls from the cloud depleting it of water, leading to its break-up, as well as producing precipitation at the surface. The development of ice also has a marked influence on the interaction of the cloud with short wave radiation from the sun. This is because numerous small water droplets are partly replaced by fewer larger ice crystals with complex shapes. New measurements of the microphysics of the cloud are needed to improve the understanding and treatment of these issues in atmospheric models. Current instruments used on research aircraft have difficulty measuring small ice crystals associated with the origin of the ice phase. The way these interact with the cloud is often determined by their nearest neighbour water droplets and larger ice particles. At temperatures slightly below 0C (down to -20C) the shortage of ice-forming aerosols means that natural processes which lead to the multiplication (sometimes by several orders of magnitude) of the ice particles present are very important, and depend on the interactions between ice particles and other cloud particles present.

This proposal is to acquire a new instrument, an Airborne Holographic Imaging Probe, which will give us the ability to simultaneously measure all the cloud particles, their shape, size and relative positions within its sample volume, at high resolution. In addition, these measurements will not suffer from many of the artefacts associated with other current measurement techniques. Key components of the new instrument will be constructed for us by the University of Mainz in Germany who developed the previous version of this probe. Other components will be purchased from the same suppliers as used by the University of Mainz to maintain compatibility with their tried and tested system. However we will construct an instrument with a faster camera and a larger sample volume to more reliably detect the position of small ice crystals and their relative position in the cloud, as well as measuring their size distribution and shape. This instrument will then be installed and flown on the UK community research aircraft, the FAAM BAE 146, to provide this improved capability to the UK cloud science community. We already operate a range of other probes to measure larger ice particles, water droplets and precipitation on this and other aircraft. With this new instrument we will make a significant step forward in our cloud microphysics measurement capability and understanding, bridging an important gap by providing new and improved data that can be made available to those developing climate and weather forecasting models.

Planned Impact

The new instrument will provide scientists that are involved with the IPCC information to quantify the dominant uncertainties in cloud-feedback processes which remain a fundamental problem in climate science. Beneficiaries will include UK scientists working in the NERC strategic Uncertainty in Climate Sensitivity due to Clouds programme. These aim to exploit existing and new observations, together with new capacity in climate modelling, to enable a step change in quantifying and reducing uncertainty in cloud feedbacks under climate change. The IPCC acknowledges that cloud-climate feedbacks are now the greatest uncertainty in the modelling of our future climate. MU-HOLO data sets will support key UK research activities aimed at reduction in those uncertainties. General access to real-time, high resolution, digital holographic measurements from MU-HOLO, will undoubtedly lead to improved international collaboration.

Improved planning for climate change mitigation will deliver enormous economic benefits to society as a whole. The absence of such plans could lead to losses of billions of pounds. Improved planning for climate change will deliver large economic and societal benefits and will greatly help with designing mitigation strategies. Governments and businesses worldwide, and the general public will benefit greatly from this research because of the greater accuracy (reduced uncertainty) in climate model predictions that will result from this research. Advancing understanding and modelling of cloud processes, particularly the ice process, is also very important for improving Numerical Weather Prediction models. This will have the effect of improving forecasts of heavy precipitation and other severe weather. For example, programmes such as the Global Energy and Water Cycle Exchanges Project (GEWEX) Aerosols, and the Clouds, Precipitation and Climate (ACPC) programme will ultimately benefit from the new understanding provided by MU-HOLO data sets.

Social and economic benefits are likely to be significant as a result of improvements in modelling of cloud and precipitation processes. Improved forecasting of flash flooding will benefit the insurance industry (who can take measures to avoid losses), flood forecasting agencies (e.g. Environment Agency, Scottish Environmental Protection Agency who can issue warnings) and ultimately, the wider public affected by flooding episodes.

There is an ever-growing public awareness and sense of urgency about climate change across the globe. We have been active participants in a number of public outreach activities: talks to schools during national science week, the NERC "Into the blue" environmental science showcase to parents and children, public talks etc. We will continue to engage in such events and MU-HOLO can be a novel attraction. We also engage with the public through social media (twitter) and blogs (e.g. the popular podcast 'The Barometer' produced by us). These will be used to provide public information on the research and its implications for climate change. We will continue to take up outreach opportunities that arise; Manchester atmospheric science staff are regular guests on national and local broadcast media (occasionally on international videos) and recently at the Paris Airshow. Several investigators on this project are active in teaching atmospheric science and climate change, and regularly use examples drawn from their research to illustrate points related to their lecture courses. Practical courses include use of research aerosol and cloud instrumentation to encourage students to consider careers in these fields. Measurement results from research projects are also used as the basis for undergraduate dissertation projects. Several of the Investigators have also supervised undergraduates as summer research interns, funded through the NERC Research Training Placements and departmental intern funding schemes.

Publications

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