A miniature Atmospheric Particle Classifier (APC)

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


The single greatest source of uncertainty in the estimates of climate sensitivity to either natural or man-made changes continues to be clouds (IPCC 2001, 2007). Much of this uncertainty arises from the lack of information relating to the properties of smaller cloud particles (droplets, ice crystals) and aerosol. These particles directly and indirectly affect how much sunlight the clouds reflect back into space (ie: cooling the Earth) and how much infrared or heat radiation from the Earth's is trapped (ie: warming the Earth). Climate scientists therefore need accurate information on the sizes, shape, and abundance of these different types of atmospheric particle so that the effect of cloud properties on our future climate can be predicted. Cloud microphysicists have at their disposal several types of in-situ instrument for counting and sizing atmospheric particles down to sub-micrometre sizes, whilst other instruments can capture real images of larger individual particles. Such images are especially valuable as they provide detailed particle shape data, but instrument optical aberrations and depth of field limitations result in image blurring, restricting such imaging techniques to particles greater than ~25um in size. The greatest lack of knowledge, and therefore potentially the greatest source of uncertainty, surrounds smaller particles, such as ice crystals down to a micrometre in size, well below the resolution limits of cloud particle imaging probes. An alternative approach that can provide detailed information on these smaller cloud particles is that of spatial light scattering, in which the unique patterns of light scattered by individual particles passing through a laser beam is recorded and analysed. In the past, the University of Hertfordshire has developed several types of aircraft instrument based on spatial light scattering (so called SID probes) and these have been procured by meteorological research organisations in the USA, UK, and Europe. However, SID probes are large (each requiring a 'PMS' wing-mounted canister) and expensive (>£80k). This limits their deployment to the relatively small numbers of research aircraft that carry PMS canisters (and where competition for such canisters is normally intense). This Proof-of-Concept proposal therefore seeks to address this by developing a small, low-cost (<£3k) and light-weight (<1kg) 'miniature SID' sensor, referred to as the Atmospheric particle Classifier. The APC would exploit recent major technological advances in diode laser and detector array technologies developed for mass consumer markets (such as DVD R/RW players, security systems, etc.) to achieve similar performance to the predecessor SID probes but at a small fraction of the cost, size and weight. The APC would count, size and classify atmospheric particles down to micrometre sizes at rates of several thousand per second, differentiating droplets, solid aerosol, and ice crystals on the basis of shape and determining the extinction coefficient of each particle (an important parameter in understanding cloud radiative properties). The sensor would be small enough to be borne by balloon or UAV, or to be part of a combination probe in a single PMS canister (potentially freeing other PMS mountings). It could potentially be carried by civilian passenger aircraft, thus generating a huge source of cloud data. Beyond this, the APC could also find wider application in general aerosol monitoring (see 'Beneficiaries') in areas of environmental health, pollution monitoring, etc., where a knowledge of the aerosol's constituent particle types is essential. The APC sensor would built and tested at UH, with performance validation and calibration being carried out by the University of Manchester in their cloud simulation chamber. The finished APC would become available for use by all of the UK science community through NERC's Facility for Ground-based Atmospheric Measurement (FGAM).
Description New instrument technology has been developed and tested. This technology is being realised in commercial products.
Exploitation Route New miniature instruments are being developed for network of sensors and are being included in further research applications to NERC as well as being commercialised. This technology has been used to further develop commercially available instruments with a CDT partner in the USA - Droplet Measurement Technology. The technology is now also used as part of the IAGOS Global Atmospheric Watch Infrastructure (iagos.org) to monitor climate using commercial airlines operated by Lufthansa, Air France, Cathay Pacific, Iberia, Hawaiian Airlines and China Airlines.
Sectors Electronics,Environment

Description A scanning cloud particle droplet gun calibration facility was constructed. This is currently used for calibration of Airbus mounted cloud/ash detectors as well as NERC FAAM core cloud droplet spectrometers. This facility enabled participation in the new UE FP7 iGAS programme by the UK. A facility (unique to the UK) that allows critical airborne spectrometers for the measurement of cloud particle concentration and size has been constructed.This has allowed various users (Airbus and FAAM) to make use of this for calibration of mission critical instruments for absolute concentration determination. Ongoing modification of the instrument has been incorporated into IAGOS GRI core monitoring aircraft fleet - Lufthansa, Air France, Iberia, Cathay Pacific, China Airlines and Hawaiian Airlines. Discussions with Finnair are ongoing to include their aircraft in the IAGOS core fleet.
First Year Of Impact 2015
Sector Aerospace, Defence and Marine,Electronics,Environment,Transport
Impact Types Societal,Economic,Policy & public services

Description CLouds and Aerosol Radiative Impacts and Forcing: Year 2016 (CLARIFY-2016)
Amount £605,765 (GBP)
Funding ID NE/L013584/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 01/2016 
End 12/2020
Description Characterisation and Modelling of Climatically Relevant Primary Biogenic Ice Nuclei in the BEACHON Southern Rocky Mountain Project
Amount £244,499 (GBP)
Funding ID NE/H019049/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 03/2011 
End 09/2013
Description Demonstration of an Aircraft System for Real-Time Discrimination & Reporting of Dust, Volcanic Ash, Ice and Super-cooled Water Particles.
Amount £142,070 (GBP)
Funding ID NE/I023058/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 10/2011 
End 08/2014
Title EUFAR ICCP Cloud Expert Workshop 
Description The EUFAR ICCP Workshop on Data Processing, Analysis and Presentation Software of Cloud Probes took place at the University of Manchester from 23 to 24 July 2016. More than 60 cloud measurement experts and students from Europe, America, Asia and Australia participated in the workshop with the objectives to summarise current data processing algorithms for measurements made with cloud spectrometers operated on research aircraft, to discuss differences in the data processing methods, to assess optimum practices and to recommend a way forward in improving data quality from cloud probes. After a welcome and introduction to the workshop by Darrel Baumgardner (Droplet Measurement Technologies), Christiane Voigt (leader of EUFAR's expert working group on In Situ Characterisation of Cloud and Precipitation Particles) presented an overview of EUFAR activities. Colin Gurganas (SPEC) showed a new study that addressed the oversizing of out-of-focus particles by the 2D-S. The session continued with a discussion of open issues related to cloud data processing. Darrel Baumgardner presented a summary of results from a questionnaire on data processing issues that had been responded to by 15 participants. The summary included current practices on data corrections for airspeed, out of focus particles, shattering and ice crystal size/habit definition. Greg McFarquhar (University of Illinois) showed a study that underscored the uncertainties in deriving particle size distributions, using the same data set from optical array probes (OAP) but processed by three separate groups. Although the same algorithms were supposed to be implemented in the processing, there were significant differences that still remained due to different criteria for accepting particles. The next session introduced eight different software packages to process and display measurements from cloud probes. These were developed and are maintained by the University of North Dakota (David Delene), University of Manchester (Jonathan Crosier), University of Illinois (Greg McFarquhar/Wu Wei), NCAR (Aaron Bansemer), previous standards & protocols engineer under EUFAR 2008-2013 (Matt Freer), SPEC (Colin Gurganas) and Environment Canada (Alexei Korolev). The day ended with an introduction and a tutorial to Python by Nick Guy and Matt Freer. A discussion on the way forward in cloud data analysis was opened on day two. This included a dialogue on definitions of microphysical cloud parameters and corrections to be applied to cloud data analysis. The urgent need for a common international reference library that includes the individual processing algorithms was agreed upon by the 43 participants in attendance. The reference database should be a living document with a quality control by referencing to existing literature or by an internal review process and an easy follow up of track changes. The possibility to assign a DOI for individual processing algorithms was emphasised. Simulated or experimentally derived data sets can serve as reference cases to test, evaluate or compare the processing algorisms. EUFAR, who currently maintains EGADS (EUFAR Airborne Data-processing Software), was recommended as a possible first choice to host such a database. In addition, an intercomparison paper on cloud data processing algorithms is planned as one outcome of the workshop. These actions will be initiated by Darrel Baumgardner, David Delene and the international cloud community possibly in connection to the EUFAR expert working group on cloud instrumentation. The progress can be followed in workshops linked to the ICARE2 international conference on aviation research hosted by EUFAR in 2017 and the AMS/ICCP conferences in 2018 and 2020. In summary, the workshop offered a unique opportunity to bring together leading experts and young scientists to exchange information in the challenging and fast evolving field of airborne cloud measurements. The action items that were identified in this workshop and that will be carried out in the near future will be an important step forward in the interaction within and outside of the cloud physics community to improve the quality and fidelity of cloud measurements. 
Type Of Material Improvements to research infrastructure 
Year Produced 2016 
Provided To Others? Yes  
Impact Collaboration between Manchester Centre for Atmospheric Science, NCAS and NCAR-USA have resulted in improved data quality control protocols for cloud microphysical data products delivered by the NERC FAAM aircraft faiclity. This has been achieved in the UK through software tools (OASIS - Dr. J. Crosier) delivered by Manchester and is not comemrcialised by one of the leading cloud instrument manufacturers, DMT, USA. 
URL http://www.dropletmeasurement.com/optical-array-shadow-imaging-software-oasis
Description Cloud Microphysics Data Analysis Workshop - ICCP 2016 Manchester 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Study participants or study members
Results and Impact This workshop, hosted and funded by the International Conference on Clouds & precipitation and EUFAR was an Expert Workshop on Data Processing, Analysis & Presentation of Software of Cloud Probes.
The International Commission on Clouds and Precipitation (ICCP) together with the EUFAR Expert Working Group dedicated to In Situ Characterisation of Cloud and Precipitation Particles are organising a 2-day workshop on data processing, analysis and presentation of software of cloud probes, prior to the 17th International Conference on Clouds & Precipitation.
The workshop took place in Manchester from 23 to 24 July 2016. Click here to see the workshop agenda.
The previous 2014 workshop on analysis of cloud measurements confirmed that there is a serious lack of consistency in not only what correction/analysis algorithms are applied to cloud measurements but also in how they are implemented. An informal poll at the close of the meeting indicated that the majority of the participants were supportive of action to bring consensus, when possible, to issues related to "best practices" when processing data and reporting results. This is the motivation for this workshop.

The particular objectives of the 2016 meeting were as follows:
1. Identify those processing algorithms that are critical for producing results with the
lowest uncertainties.
2. Reach consensus on optimum practices for as many of these algorithms as possible, including all aspects of their implementation and documentation.
3. Identify aspects of algorithms that cannot be optimised in general and that must be set for individual probes or individual datasets

4. Organise a working group (similar to or possibly complementary to the EUFAR EWG group) that will oversee the development and maintenance of a data base of processing algorithms and, if supported by community consensus, direct the development of a common data processing and analysis package that will incorporate all the algorithms identified in objective (1)


The outcomes of the meeting were:

A document describing approved processing algorithms by the consensus of participants at the meeting and via a questionnaire sent to the cloud physics community at large.
A new working group whose responsibilities will be clearly defined. Some members will be drawn from participants at the workshop while others may come from the cloud physics community at large.
A new data processing and analysis system will be defined with an outline of its future structure and implementation based on discussion of this document.
Research students were engaged at the highest level with respect to approved data analysis techniques and approaches for their cloud microphysics research relevant to their approved practice for inclusion in PhD theses and their publications.
Year(s) Of Engagement Activity 2016
URL http://www.eufar.net/weblog/2016/06/23/iccp-eufar-expert-workshop-data-processing-analysis-presentat...