Cirrus Coupled Cloud-Radiation Experiment: CIRCCREX

Lead Research Organisation: Imperial College London
Department Name: Dept of Physics

Abstract

Climate and weather prediction models demand understanding of how cirrus clouds, high in the troposphere (6-14km in altitude) affect our climate. Cirrus covers up to 30% of the globe and its effects should be accurately included in global climate models. Clouds have two main effects; they are the main atmospheric component in the hydrological cycle, but they also trap radiation, both reflecting sunlight back to space (cooling the Earth's surface) and trapping the thermal energy emitted from the surface (as they are cold, emitting less energy to space than an equivalent cloudless sky). The balance between the shortwave (sunlight) and longwave (thermal radiation) effect depends on factors such as altitude and thickness of the cloud, and the size and shape of the ice crystals that make up the cloud. The crystals can take on myriad shapes, and the shapes existing in particular clouds depend on conditions and on the evolutionary sequence that the particles experience; growing, aggregating and/or dissipating over time, dependant on the changes in temperature, humidity and meteorological environment they experience. Different crystal sizes and shapes reflect and scatter light in different ways. Some crystal shapes are efficient at reflecting sunlight, but not thermal radiation and some the other way round. The net effect of a cloud on the radiation budget depends on the microscopic shapes of the crystals inside it. By measuring both the heat emitted by the cloud and its internal crystal properties ('microphysics') we can determine the link between the two, and hence the overall effect the cloud is having on the climate.
Cirrus models have been derived that calculate expected response of different crystal types across the spectrum, and these are usually combined with predicted particle size and shapes (Particle Size Distributions, PSD) found from in-situ flight campaign measurements using cloud probes. These are parameterised (simplified) and used in climate models and general circulation models (GCMs), eg. in numerical weather prediction (NWP) and climate change, but these cirrus models have not been tested across the full spectrum. Some studies have been made of specific radiative properties of some crystal types in the shortwave, and of other crystal types in parts of the longwave, but there has not been a successful measurement covering the full spectrum simultaneously measuring the precise make up of the crystal sizes and types in a cloud.
We plan a novel flight campaign combining full spectrum radiative measurements (125-0.3 microns) from longwave to shortwave, with state-of-the-art measurements of crystal PSDs, the ice water content and temperature etc. We will test scattering models and PSD parameterisations used to describe cirrus cloud in atmospheric models, such as the UK MetOffice (MO) Unified model Numerical Weather Prediction (NWP) with model improvements implemented by our MO project partners. Our project is possible because of NERC funded research that led to: state-of-the-art cloud probe instruments and software tools that addressed problems of ice crystal shattering at the inlet apertures and the great uncertainty in ice crystal size distributions of the past; and the development of the unique far-IR instrument TAFTS at Imperial College (IC). The ability to measure the entire spectrum from an aircraft, and so simultaneously measure the cirrus crystal types, sizes, temperature and IWC, roughness etc., is a unique facility only available on the UK FAAM aircraft. We combine radiometry in the far-IR of IC, in mid-IR to solar of MO, cloud microphysics instrumentation and expertise of Manchester and Hertfordshire Universities, and UKMO/FAAM with complementary cloud and atmospheric state measurements. This will give a leap forward to cirrus modelling, our datasets allowing testing and development of models and parameterizations used to predict the effect of cirrus in climate models and NWP.

Planned Impact

1)Specific users this work might be of interest to and how they will benefit:

Immediate beneficiaries are given in "Academic Beneficiaries".

The Intergovernmental Panel on Climate Change has identified understanding of the effects of cloud as one of the key uncertainties in climate change predictions. The most direct users of our cirrus project are atmospheric scientists, climate and numerical weather prediction (NWP) modellers, who will use the anticipated improved and validated cirrus parameterizations to improve GCM ability to capture cirrus impact and evolution. The new cirrus parameterizations will be available through our project partner,the Met Office, for incorporation into global climate models. We will demonstrate the accuracy improvement possible for NWP models by tests with the new cirrus models. The expected result will be improved ability to capture correctly cirrus effects on weather forecasts and climate predictions. We will work directly with modellers to facilitate this, with:

(i)The Met Office (MO) who run the Unified Model (UM), used internationally, http://www.metoffice.gov.uk/research/collaboration/um-collaboration, for weather prediction and climate models. The MO will use evidence from our CIRCCREX collaborative project to inform on including paradigm shift cloud-radiation coupled cirrus parameterizations in the UM.

(ii) USA cirrus modellers (Baum, Yang and ice cloud research team http://www.ssec.wisc.edu/ice_models/) who will provide us with their cirrus models for testing with our observational data (see support letter). This allows them to improve their models using unique datasets. These cirrus models are used in climate models and satellite retrievals, ensuring wide impact internationally.

Other impacts follow indirectly,eg from studies of cirrus, contrails,aerosols, chemical transport, to studies using energy transport, radiative transfer, and climate change. Indirect users include those reliant on climate and atmospheric models, or satellite retrieval data for clouds.

Results will be published in international journals with press releases to raise profile of our research.The greatest impact will be incorporation of the new cirrus cloud-radiation parameterizations into climate and NWP model codes used worldwide.

2)Wider user benefits:
Most relevant is the impact for Government policy makers responsible for action on climate change, who benefit from more reliable climate models (eg MO UM), strengthening the international community's case for taking action to avert climate change -the IPCC highlighted clouds as a key uncertainty. Improved MO weather forecasting accuracy has societal and economic benefits to the wider public.

Wider user benefit is achieved by:
A project website suitable for scientists and the general public including school children, with "news releases" ,press articles on CIRCCREX research and its impacts, for example on climate models.
Public Outreach: IC staff are involved in engaging with the next generation, for example giving outreach lectures 'The Science of Climate Change' to schools.
our strong links to our project partners at the UK MetOffice, who advise the Government regarding climate change.

3)Other impacts: UK competitiveness.The NERC funded TAFTS instrument is the only high resolution far-IR spectrometer for in-situ measurements of up- and down-welling radiances in the troposphere. The far-IR region has great uncertainties in radiative transfer and climate models.To realise the impact of TAFTS in terms of new science, and to maintain our position at the forefront of this field internationally we continue to seek support for science with TAFTS. Far-IR expertise of TAFTS scientists is forming a strong base for future world class instrumentation projects: eg. our involvement in recent bids for new IR satellite instrumentation and membership of the Science Definition Team of NASA's proposed far IR satellite instrument CLARREO.
 
Description This grant is funding a project to investigate the properties of cirrus cloud. We have completed two campaigns of flight measurements with the FAAM aircraft, Facility for Airborne Atmospheric Measurements based out of the UK that have given us a unique dataset for this cirrus cloud project. The latest flight campaign was in Spring 2016. New measurements over Greenland allowed us to look at far ir surface emissivity. We have applied for a further grant to study this.
Exploitation Route this project is not completed. We are preparing papers to report our findings, and are still involved in the analysis of cirrus.
Sectors Environment

 
Description Our findings have been used to investigate the radiative effects of cirrus. Our work is ongoing, and will be reported when completed.
First Year Of Impact 2014
Sector Environment
Impact Types Societal,Policy & public services

 
Description Collaboration with Bryan Baum, SSEC, Wisconsin 
Organisation University of Wisconsin-Madison
Country United States 
Sector Academic/University 
PI Contribution We are in the process of acquiring novel datasets from flight campaigns with the FAAM (Facility for Airborne Atmospheric Measurements), as part of our CIRCCREX project. These can be used to test the cirrus models of SSEC, University of Wisconsin.
Collaborator Contribution Help and advice from our collaborator at SSEC, U. Wisconsin, on running their state of the art cirrus models.
Impact Work is ongoing, and will be published later in the grant time period.
Start Year 2014
 
Description Physics talk at Engineering Headstart course 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach National
Primary Audience Schools
Results and Impact talk generated questions and discussions

I have seen applications to Physics from some of the school pupils attending the Engineering Headstart courses
Year(s) Of Engagement Activity 2014,2015,2016
 
Description Physics talk at University Open Day 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach National
Primary Audience Schools
Results and Impact Talk generated many questions and discussions.

We receive applications from school pupils who have attended our Open Days
Year(s) Of Engagement Activity 2014,2015,2016
 
Description School Visit, Ealing, 2013 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact 48 year 5 pupils in girls primary school attended my workshop/talk on the size of the Universe, with many many questions being asked by the pupils!

I was asked by the teachers if I would be willing to return to give more talks as the girls were very enthusiastic.
Year(s) Of Engagement Activity 2013
 
Description School workshop/Assembly for the 50th Anniversary of the First Lunar Landing 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact I ran an interactive Assembly for the Junior School of a local girls school - year 2 to year 6 - approx 200 pupils, in celebration of the 50th Anniversary of the first Lunar Landing. Over 40 minutes I covered topics in space science, including latest research, with examples of women scientists carrying out the research. The pupils asked and answered many questions - a very enthusiastic audience! The school fed back that interest was increased, with more questions on science from pupils.
Year(s) Of Engagement Activity 2019
 
Description Women in Physics Open Day 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact I gave a talk at the Imperial College "Women in Physics Open Day", attended by approx 200 school pupils aged 16-17. I answered questions on studying physics. My talk was part of a programme with other colleagues presenting also. Feedback from forms completed by the attendees was positive that the event had helped them consider physics as a degree course.
Year(s) Of Engagement Activity 2019
 
Description Women in Physics Open Day, Imperial College London 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact Approximately 300 pupils from schools across the country came of our Women In Physics events held at Imperial College London. The PI of the grant was involved in talks to these girls, encouraging them to think about applying to study physics. The research of the grant award was describe in these talks as an example on ongoing research. Impact may be seen in increased applications from women to us to study physics.
Year(s) Of Engagement Activity 2015,2016
 
Description Women in physics talk 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact Presentations and special event to encourage more women to study physics at university
Year(s) Of Engagement Activity 2014,2015,2016,2017
 
Description Workshops at Imperial Festival on Spectroscopy and applications to science Spring 2018 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Approx 450 children took part in science workshops "Discovering Light" that our team ran over two days during the Imperial Festival, and we also engaged with several hundred parents. Hands on science experiments which sparked many questions and discussions. Good feedback reported.
Year(s) Of Engagement Activity 2018
URL http://www.sp.ph.ic.ac.uk/~julietp/FTS/Recent_Highlights.htm