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Ice Nucleating Particles in the Marine Atmosphere

Periodic Reporting for period 3 - MarineIce (Ice Nucleating Particles in the Marine Atmosphere)

Reporting period: 2018-08-01 to 2020-01-31

The formation of ice in clouds is fundamentally important to life on our planet since clouds play a key role in climate and the hydrological cycle. Despite the significance of ice formation, our quantitative understanding of sources, properties, mode of action and transport of Ice-Nucleating Particles (INP) is poor. In order to improve our representation of clouds in models we need to understand the ice-nucleating ability of all major aerosol types, including those from the world’s oceans as well as those from the terrestrial environment.

Despite oceans covering over 70% of the planet and sea spray being one of the dominant aerosol types in the atmosphere, its role in the formation of ice in clouds remains poorly understood. There are strong indications that biological organic components of sea spray can nucleate ice, but there is a lack of data to quantify it. In contrast, the ice-nucleating ability of major aerosol species from terrestrial sources, such as mineral dusts or bacteria, has received significant attention over the past few decades. A similar effort now needs to be made to understand marine INP. The key limitation to accurately representing INP in models over the world’s oceans is the lack of field data, a deficiency which the MarineIce team is addressing through this project.

The specific objectives were to develop novel instrumentation for quantifying INP concentrations cover the full range of mixed phase cloud conditions. These instruments will be housed in a unique highly instrumented mobile laboratory, which will allows us to access challenging environments on land based field sites and research ships. In parallel, we are developing the representation of marine and terrestrial INP in a state-of-the-art global aerosol model and are using this to define cloud glaciation processes in climate and weather models.
In the following I set out how my team have addressed the individual ‘activities’ set out in my original proposal.
Activity 1. Construct a new-concept semi-autonomous ultra-sensitive INP counter (MicroINP)
We recently published the first paper using this new and exciting technique (Tarn et al., 2018). This paper demonstrates one of the first uses of microfluidically generated droplets in studies of heterogeneous freezing. Microfluidics has the advantage over other techniques in that it generates a very large number of droplets in a short period of time. We demonstrated that the technique works for a range of atmospherically relevant ice nucleating particle types and also some samples of aerosol sampled from the air. It has also been used to quantify ice nucleation by field collected samples, which will be included in upcoming papers. At the end of this reporting period we were developing the next generation of this instrument where we intend to count the freezing droplets in flow on the chip. This aspect of the work has been very challenging, but we are now in a position where we have an instrument to quantify ice nucleation in flowing droplets. The advantage of this technique is the huge number of droplets that can be analysed, while also working all the way down to homogeneous freezing at around -37 C..

Activity 2: Developing new capacity to make INP measurements in the remote marine atmosphere

2a; commissioning the IcePod and aerosol instrumentation: The IcePod: INP concentrations in many environments are poorly constrained, in part, because the community has not had adequate means to access those environments. We have constructed the IcePod, a mobile laboratory based around a converted shipping container. The IcePod is an insulated, air conditioned, facility which allows my team to perform aerosol sampling and ice nucleation experiments in environments were ice nucleation has never been measured. The laboratory is equipped with an inlet system, aerosol instrumentation, filter sampling systems, capacity for an aerosol based INP system (the PINE chamber), the NIPI suite of instruments including the microfluidics instrument. The first campaign for the IcePod where we studied the competition between marine sources and terrestrial sources of INP in Yorkshire was recently published (O’Sullivan et al. 2018).

2b) Testing and developing of the filter based INP technique. We have made a great effort developing and using multiple filter based technique for quantifying atmospheric ice nucleation. We now routinely use a method with track etched polycarbonate filters where we wash the particles off the filter (O’Sullivan et al. 2018; Tarn et al. 2018) and a method using teflon filters where we place an array of droplets onto the filters (Price et al. 2018). This allows us to quantify low concentrations of INP relevant for mixed phase cloud conditions. A major advantage of the wash-off technique is that it allows us to treat aliquots of the samples in different ways which helps us to distinguish between biogenic (e.g. marine) and desert dust INP, for example. An addition development is the IR-NIPI instrument for quantifying low concentrations of INP using a novel IR camera technique together with multiwell plates commonly used in microbiology (Harrison et al. 2018).

2c) Construction and testing of an aerosol based INP instrument for cirrus and mixed phase cloud work. We refer to the expansion chamber as PINE (Portable expansion chamber for Ice Nucleating particle mEasurements). There are problems with CFDCs related to frost formation, which limits the detection limit, and their non-automated nature, which limits the data collection to intensive field campaign periods. I decided, in collaboration with Karlsruhe Institute of Technology (KIT), to develop an instrument using a different concept. We now have two working instruments, one owned by KIT and one funded by MarineIce. Both instruments have been put through an intensive testing period and were deployed in a field station for a campaign in late winter 2018.

2d) Bubble tank work. We have made use of existing bubble tanks in collaborative efforts rather than develop an independent instrument. We made use of a bubble tank in the OCEANS03 campaign at the AIDA chamber cloud simulation chamber in KIT and also on board the Oden Ice breaker at the North pole. In the OCEANS03 campaign we tested a range of samples (sea water and cultures) from marine sources for their ice nucleating ability and quantified the fraction of aerosol which activate to ice.

2e) Applying Scanning Electron Microscopy (SEM) to ice nucleation studies. We have developed a technique for quantifying the size resolved composition of aerosol samples which we do in parallel to the filter based INP studies to inform us of the composition of aerosol and help relate INP concentrations to aerosol size and composition. We used the SEM technique in a recent paper (O’Sullivan et al. 2018) and a detailed methodology paper is in preparation.

2f) Validation of instruments. In addition to ongoing work to test and validate our instruments, we took part in a major international instrument intercomparison, the first paper of which is under review at present.

Activity 3: Quantify and characterise INP in marine environments
My team have engaged in three significant field campaigns in the 1st reporting period
1. Cape Verde, summer 2015. We took part in the ICE-D field campaign, an aircraft based campaign using the FAAM aircraft. The advice from the ERC interview panel was to conduct some measurements from aircraft, which I agree with. Hence, when the opportunity arose to take part in this campaign early in the MarineIce project, I took it since it is in a region I identified as a key area for measurements in my proposal and there was considerable synergy with other participants in the campaign. We used a drop-on Teflon filter based technique to quantify INP concentrations alongside other cloud and aerosol measurements in the dusty air of the tropical Atlantic. This allowed us to study the competition of INP from marine sources and a major dust source, North Africa. These measurements were contrasted with our global model predictions of INP from marine and desert locations. We also contrasted our measurements against our laboratory based understanding of dust INP. This work was recently published (Price et al. 2018).
2. Yorkshire, Summer 2016. For the first campaign in the IcePod we made the first long term (over 6 weeks) measurements of INP concentrations in the UK and one of the first in the world. These measurements allowed us to study the relative contribution of INP from marine, desert and mid-latitude terrestrial sources. Our model suggested marine organics would be important in this location above ~-15oC, but the measurements had never been made to test this. We developed a heat test for biogenic material and concluded that INP in this location are dominated by what is most likely a terrestrial biogenic source of INP (O’Sullivan et al. 2018), which is perhaps related to ice active proteins bound to soil particles (O’Sullivan et al. 2016).
3. Barbados, Summer 2017. Barbados is situated in a location which is strongly affected by marine aerosol from the tropical Atlantic as well as dust transported across the Atlantic from Africa. No measurements of INP had been made at this location prior to ours. The results are intriguing and we are in the process of analysing the data.
4. EMERGE, summer 2017. This was an aircraft based campaign above the North sea and S.E England region. We found very high concentrations of INP in this region. We are still working on this data and the associated SEM analysis, but the INP concentrations were much higher than we had expected and this seems to be related to long range transported dust.
5. Vanaheim campaign in 2017. This was an aircraft based campaign in the North Atlantic in the region of Iceland. We had anticipated an influence of the volcanic sulphate on the local marine INP. However, we were surprised that mineral dust, possibly locally produced, seemed to dominate the INP. We are still analysing this data and are still processing filters with our SEM technique.

In addition to these core MarineIce campaigns, I have also been involved in campaigns in the remote Canadian Arctic quantifying INP in sea water samples (Irish et al. 2017) and aerosol samples (Si et al. 2018). We also contributed to a paper detailing the composition of materials associated with INP in sea water (Aller et al. 2017).

During the 1st reporting period we were also planning the next phase of field campaigns, including one to the North Pole. This campaign is on-board the Swedish Ice breaker. We will have our IcePod and will aim at measuring remote sources of INP from the high Artic Ocean, both above and below the clouds present there. We anticipate terrestrial sources will be much less important in this environment and local sources may dominate. These results will be exciting because we do not understand ice production in clouds in this region, yet they are of first order importance for climate.

Activity 4: Modelling the global distribution of marine INP
As part of this activity we now have a global distribution of INP associated with marine sources (Vergara-Temprado et al. 2017). In this work we parameterised INP measurements from Wilson et al. (2015) and linked this to the production of sea spray in a global aerosol model (GLOMAP). We also represented desert dust using our previous work (Atkinson et al. 2013) in order that we could study the competition between desert dust and marine sources of INP. We conclude that marine INP dominate in the world’s remote oceans, such as the Southern Ocean. This is particularly interesting because clouds in the Southern Ocean region are known to be poorly represented in global climate and weather models which leads to major biases in radiation fluxes.

We then went on to incorporate the model INP concentrations in a global weather model. We demonstrated that with our representation of marine INP (i.e. low concentrations) we could reproduce the cloud fields in this region, which we argue helps to solve the Southern Ocean bias (Vergara-Temprado et al. 2018).

We are also in the process of modelling the completion of INP over the tropical Atlantic and their impact on clouds there.

Atkinson, J. D., Murray, B. J., Woodhouse, M. T., Whale, T. F., Baustian, K. J., Carslaw, K. S., Dobbie, S., O'Sullivan, D., and Malkin, T. L.: The importance of feldspar for ice nucleation by mineral dust in mixed-phase clouds, Nature, 498, 355-358, 2013.

Aller, J. Y., J. C. Radway, W. P. Kilthau, D. W. Bothe, T. W. Wilson, R. D. Vaillancourt, P. K. Quinn, D. J. Coffman, B. J. Murray, and D. A. Knopf (2017), Size-resolved characterization of the polysaccharidic and proteinaceous components of sea spray aerosol, Atmos. Environ., 154, 331-347, doi:

Harrison, A. D., Whale, T. F., Rutledge, R., Lamb, S., Tarn, M. D., Porter, G. C. E., Adams, M., McQuaid, J. B., Morris, G. J., and Murray, B. J.: An instrument for quantifying heterogeneous ice nucleation in multiwell plates using infrared emissions to detect freezing, Atmos. Meas. Tech. Discuss., in review, 2018.

Irish, V. E., Elizondo, P., Chen, J., Chou, C., Charette, J., Lizotte, M., Ladino, L. A., Wilson, T. W., Gosselin, M., Murray, B. J., Polishchuk, E., Abbatt, J. P. D., Miller, L. A., and Bertram, A. K.: Ice-nucleating particles in Canadian Arctic sea-surface microlayer and bulk seawater, Atmos. Chem. Phys., 17, 10583-10595, 2017

Sullivan, D., B. J. Murray, J. F. Ross, and M. E. Webb (2016), The adsorption of fungal ice-nucleating proteins on mineral dusts: a terrestrial reservoir of atmospheric ice-nucleating particles, Atmos. Chem. Phys., 16(12), 7879-7887, doi:10.5194/acp-16-7879-2016.

O’Sullivan, D., et al. (2018), Contributions of biogenic material to the atmospheric ice-nucleating particle population in North Western Europe, Scientific Reports, 8(1), 13821, doi:10.1038/s41598-018-31981-7.

Price, H. C., et al. (2018), Atmospheric Ice‐Nucleating Particles in the Dusty Tropical Atlantic, J. Geophys. Res., 123(4), 2175-2193, doi:doi:10.1002/2017JD027560.

Si, M., Irish, V. E., Mason, R. H., Vergara-Temprado, J., Hanna, S., Ladino, L. A., Yakobi-Hancock, J. D., Schiller, C. L., Wentzell, J. J. B., Abbatt, J. P. D., Carslaw, K. S., Murray, B. J., and Bertram, A. K.: Ice-nucleating efficiency of aerosol particles and possible sources at three coastal marine sites, Atmos. Chem. Phys. Discuss., in review, 2018.

Tarn, M. D., et al. (2018), The study of atmospheric ice-nucleating particles via microfluidically generated droplets, Microfluid. Nanofluid., 22(5), 52, doi:10.1007/s10404-018-2069-x.

Vergara-Temprado, J., et al. (2017), Contribution of feldspar and marine organic aerosols to global ice nucleating particle concentrations, Atmos. Chem. Phys., 17(5), 3637-3658, doi:10.5194/acp-17-3637-2017.

Vergara-Temprado, J., Miltenberger, A. K., Furtado, K., Grosvenor, D. P., Shipway, B. J., Hill, A. A., Wilkinson, J. M., Field, P. R., Murray, B. J., and Carslaw, K. S.: Strong control of Southern Ocean cloud reflectivity by ice-nucleating particles, P. Natl. Acad. Sci. USA, doi: 10.1073/pnas.1721627115 2018. 2018.

Wilson, T. W., Ladino, L. A., Alpert, P. A., Breckels, M. N., Brooks, I. M., Browse, J., Burrows, S. M., Carslaw, K. S., Huffman, J. A., Judd, C., Kilthau, W. P., Mason, R. H., McFiggans, G., Miller, L. A., Najera, J. J., Polishchuk, E., Rae, S., Schiller, C. L., Si, M., Temprado, J. V., Whale, T. F., Wong, J. P. S., Wurl, O., Yakobi-Hancock, J. D., Abbatt, J. P. D., Aller, J. Y., Bertram, A. K., Knopf, D. A., and Murray, B. J.: A marine biogenic source of atmospheric ice-nucleating particles, Nature, 525, 234-238, 2015.
Key progress beyond the state-of-the-art:
1. We demonstrated that the low sea spray related INP concentrations over the Southern Ocean are key to understanding the clouds that exist there (Vergara-Temprado et al. PNAS, 2018). We demonstrate that ice nucleation in these shallow clouds has the potential to remove them and that the low concentrations that persist there allow them to exist.
2. The Development of the PINE chamber. This single instrument has the potential to transform the ice nucleation community. It is the first instrument that operates on a semiautonomous basis, producing INP concentrations over an extended period of time. We already have a company working on a commercial version.
3. We have clearly demonstrated that there is a strong terrestrial biogenic source of INP in the mid-latitudes in addition to the marine and desert sources (e.g. O’Sullivan et al. Sci Reps., 2018). This is an exciting result because it has been suggested that there is an important biological source of INP, but very few experiments have been done to test this hypothesis.
By the end of the project I anticipate the following key results beyond what we already have:
1. An unprecedented global picture of INP around the globe from our field and model work. This will highlight what we know well and where in the world we are missing sources of INP. But, overall, it will help us to underpin the description of cloud glaciation in global climate and weather models.
2. An unprecendented understanding of the impact of INP on different cloud types in marine locations.
3. An unprecedented understanding of INP in the atmosphere across the Tropical Atlantic from the comparison of our field work in Cape Verde and Barbados.
4. Evidence from multiple locations that INP of biological origin are critically important in the mid-latitude terrestrial environment.
5. A unique set of tools for quantifying INP concentrations over the full range of atmospheric concentrations and relevant for the full range of cloud types.
6. Achieved a major impact on the field with the introduction of a commercial instrument for quantifying INP concentrations.
7. The first measurements of INP from above clouds near the North Pole, which we can contrast to measurements at the surface.