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The MILAF meetings


The MILAF meetings: Enabling early career scientists for interdisciplinary research on land-atmosphere feedbacks.

Mentoring of early career scientists is commonly an integral part of projects funded by the US National Science Foundation. In the context of the RAINS [i] project, setting-up a mentoring workshop was the responsibility of the two most senior of the RAINS PIs – David Sands (Montana State University, Bozeman) and myself. The workshop has turned into a series of meetings and has added a dynamic branch to the network of scientists working on bioaerosols and land-atmosphere feedbacks. Happily, the transformation of the initial workshop into a series of meetings and into a tight-linked community arose by popular demand. Nevertheless, it corresponds to our intention to create common goals for research on land-atmosphere feedback – launched with the 2006 Microbial Meteorology meeting – and to create a cohesive and cooperative community.


[i] Research on Airborne Ice Nucleating Species, NSF Dimensions: Collaborative Research Program, 2013-2016 The MILAF meetings were organized with funds from the RAINS project, from INRA’s Plant Health and Environment division and from the European Academy of Bolzano (EURAC).


The RAINS project was motivated by the potential of ice nucleating microorganisms in the atmosphere to use precipitation as a dispersal strategy and the eventuality that this could result in feedbacks between land sources of these microorganisms and the atmosphere. The project was born in a period of growing concern that science needs to facilitate research on interdisciplinary questions of broad importance for society and for the environment (see Nature’s special issue on interdisciplinarity). The goal of RAINS’ mentoring workshops has been to enable a corps of early career scientists with passion for research about Microorganisms at the Interface of Land-Atmosphere Feedbacks (MILAF), with excellent disciplinary competences, and with strong wills to engage in interdisciplinary research in spite of the potential obstacles and inconveniences. Here is an account of how the MILAF meetings are becoming an important stimulus to setting and advancing a research agenda on land-atmosphere feedbacks.

Scouting and stimulating talent. As organizers, our goal was to create an open and informal forum for the exchange of ideas among i) talented early career scientists with high potential to contribute to the bioprecipitation research community in the future, ii) the Principle Investigators (PIs) of the RAINS project, iii) additional mentors with competences outside the expertise of the RAINS PIs, and iv) stakeholders representing perspectives from legal systems, land use and reforestation movements and enterprises, and the direction of research institutes. Early career scientists were selected through an application procedure that included, in addition to a CV, a 2-page essay on how they foresee themselves contributing to the theme of the workshop in the coming decade, the grand research challenges to which they want to contribute and how their participation in the workshop would facilitate achievement of their goals. After hours of discussion among four of the RAINS PIs during a pleasant train trip from Avignon to Switzerland, 14 early career scientists were selected. Although our selection criteria focused on excellence and the capacity to contribute to an interdisciplinary group, we also ended up with an equal balance of women and men from the physical and biological sciences.

The workshop format was initially perceived as unconventional by some of the RAINS PIs, but we felt that it would maximize discussion and interaction of participants.  We favored question sessions, ensuing discussions and break-out groups more so than formal presentations of each person’s research (Fig. 1).  To jump-start the process of getting to know each other, before the workshop everyone uploaded to the shared Dropbox folder a half-page brief CV with a photo. And to maximize the efficiency of our interactions, a reading list of 30 core papers was provided 3 months before the workshop (Fig. 1).


Figure 1. Participant list, program and the reading list for the first MILAF meeting (Oct 2014, Ste. Maxime, France). Click here for the full file


Creating a community with long-term goals. The format of the first meeting revealed that many of the participants were, themselves, inherently polyvalent, multidisciplinary and very skilled in interdisciplinary communication. Perhaps it was this realization among the participants and the solace and excitement of working with like-minded colleagues – a rarity in a world reigned by well-defined disciplines – that we rapidly moved to defining long term goals for our nascent community. We felt that our future interactions could focus on 5 types of activities:

  • Coordinating research activities that target the main scientific challenges that we identified for the upcoming decades
  • Promoting the cohesiveness of the bioprecipitation community, mentoring young scientists and fostering deployment of interdisciplinary competences
  • Creating a sense of urgency and educating the public
  • Identifying and engaging stakeholders
  • Translating research into practical applications to mitigate drought.

We specified the details underlying these activities in a more precise plan for the upcoming decades (Fig.2)

bioprecpvisionFigure 2. MILAF-2014 conclusions: Challenges for bioprecipitation research. Click here for larger pdf version


This plan oriented two subsequent videoconferencing meetings (21 May and 29 0ct 2015, ca. 15 participants each meeting) that were coordinated by Christopher Carr (MIT) and myself. These meetings revealed that participants had continued networking since the 2014 meeting. Videoconferencing also served to reinforce the desire for another in-person meeting. With contributions from a few outside sources, we managed to stretch the NSF funding to organize MILAF-2016 at the European Academy of Bolzano, Italy in March 2016. Additional early career scientists and mentors were brought in to re-inforce the activities of the working groups that were emerging from MILAF-2014. The program included formal presentations of research and also allowed several early career scientists to take leadership roles in pushing forward the main research themes (Fig. 3). It also included a stimulating visit to Bolzano’s South Tyrol Museum of Archeology and an overview of the research to identify the origin of the Helicobacter pylori strain in the stomach of the 5300 year-old Iceman mummy housed by this museum.


Figure 3. Participant list and program for MILAF-2016. Click here for the full file.

Achieving goals.  The MILAF meetings sparked camaraderie and cohesiveness of the participants and the budding of diverse initiatives to achieve the goals we identified. Here are our major achievements.

  • Coordinating research activities that target the main scientific challenges for the upcoming decades

Directly measure microbial flux and create relevant tools. Quantification of the flux of microorganisms or of ice nucleating particles (INPs) over land has stagnated since the publications of Lighthart and of Lindemann in the 1990’s because of the complexity of the required experimental field set-ups. Via the MILAF meetings a few scientists have joined forces and shared materials and competence to simplify the techniques and to obtain direct measurements of flux. During MILAF-2014, Yves Brunet (INRA-Bordeaux) led a really informative discussion about the physics underlying flux and different approaches to its measurement for microorganisms based on the gradient method and on relaxed eddy accumulation (see Yves’ work on REA flux measurements).  As part of his PhD thesis research, Federico Carotenuto (Univ. Innsbruck and CNR IBIMET – Florence, Italy) was attempting to measure microbial flux and simplify the task of the gradient method. He came to Avignon to hone his skills -and where I made an instructive video of his work.

After meeting Danny O’Sullivan (University of Leeds, UK) at MILAF-2016, they launched a collaboration to set up a field campaign to investigate emissions and characteristics of ice nucleating aerosols in England’s atmosphere (Fig. 4).  The campaign is bringing together expertise in the chemical, atmospheric, and biological fields needed to tackle this complex topic. And importantly, manuscripts are in the making.


Figure 4. Microbial flux platform set up by Danny O’Sullivan, Federico Carotenuto and colleagues from the University of Leeds (autumn 2016).


Build evidence from field campaigns for the impact of biological aerosols on precipitation. Hari Mix (Santa Clara University, California) and Jessie Creamean (NOAA, Boulder, Colorado) are collaborating on Hari’s NSF RAPID project on “Investigating the mechanisms driving extreme precipitation in atmospheric rivers with an integrated stable isotope and aerosol chemistry approach” where they will link isotope, INPs, and compositional measurements of rainwater samples in California during the CalWater 2015 field campaign. Their current analysis focuses on evaluating relationships between these parameters and air mass source and meteorology during atmospheric river events. The goals of the project include an examination of the rainout of bioaerosols on coast-to-interior transects in northern California. According to Hari, this work was largely motivated by the research of another MILAF participant Emiliano Stopelli (University of Basel, Switzerland) (viz., Stopelli et al 2015) and whom Hari was really happy to meet at MILAF-2016.

Elucidate and explicate component processes and limiting factors of bioprecipitation feedback. The process of bioprecipitation feedback implies an increase of cloud-active aerosols after rainfall and their effect on subsequent rainfall. To ferret out the component processes of bioprecipitation, we need to select cohorts of field sites where specific hypotheses about processes could be tested. Therefore, the task of developing criteria for creating these cohorts has become an important goal for bioprecipitation research. We developed these criteria as described in a previous blog post. The MILAF meetings contributed to this work by bringing to our attention the expertise of Jessie Creamean (NOAA, Boulder, Colorado) in atmospheric sciences and her capacity for teamwork in constructing the scientific arguments underlying the link between rainfall patterns and biological aerosols. She accepted our offer to participate in the development of these ideas and to interact mostly by email with statisticians, atmospheric physicists and microbiologists on several continents through multiple revisions of our manuscript to achieve publication of our method (Morris et al 2015).

Coordinate field campaigns. This goal is of utmost importance to account for geographic and land cover variability in the amount and types of bioaerosols in the atmosphere and their possible impact on atmospheric processes. To get the ball rolling, Pierre Amato (CNRS, Aubière, France) and Emiliano Stopelli and Franz Conen (mentor) (both from University of Basel, Switzerland) are verifying whether their recent observations in support of the bioprecipitation hypothesis from the Jungfraujoch observatory in Switzerland are valid more broadly. An observatory was set up in October 2015 in France (Fig. 5) for monitoring ice nuclei in precipitation, including meteorological and biological data, ice nuclei concentration and rain water atmospheric isotope ratios. One entire year of data (ca. 100 rain events) has been collected so far.

Figure 5. Site of the observatory in France to confirm bioaerosol observations made on the Jungfraujoch in Switzerland.


  • Creating a sense of urgency and educating the public

To address the need for outreach and educating the public identified during MILAF-2014, Renée Pietsch (Virginia Tech) developed a lesson on biological ice nucleation as part of her Ph.D. thesis work that was just published in the Science Teacher (Turning into ice: Teaching ice nucleation and the global water cycle).

Jessie Creamean (NOAA, Boulder, Colorado) has become the aerosol working group leader for the IASOA (International Arctic Systems for Observing the Atmosphere) and has been encouraging other MILAF participants interested in Arctic research to join the group.

Participation in the MILAF meetings pushed several of the mentors to become more engaged in creating a sense of urgency for understanding the land-atmosphere link. Jane Cohen (University of Texas School of Law, Austin), David Sands (Montana State University, Bozeman) and I participated in the conference sponsored by WeForest that led to the policy brief about the importance of vegetated land cover in the water cycle described in an earlier posting. The fruit of the interdisciplinary conference sponsored by WeForest has also become a manuscript that we hope will be accepted shortly (to be announced later).


  • Promoting the cohesiveness of the bioprecipitation community, mentoring young scientists and fostering deployment of interdisciplinary competences.

Strive to set up more collaborations relevant to bioaerosols and their impact on the atmosphere. There has been an exceptional flurry of efforts to continue working together on diverse subjects:

  • Jessie Creamean (NOAA, Boulder, Colorado), Erik Thomson (University of Gothenburg, Sweden) and Tina Santl-Temkiv (Aarhus University, Denmark) submitted a proposal on “Riders on the storm: Microbe-aerosol-gas interaction as a mechanism of active aerial cell dispersal” to the Human Frontier Science Program this year.
  • Jessie has also brought David Schmale (mentor) (Virginia Tech) on board to help analyze aerosol samples that she collected in summer 2016 on a cruise in the western Arctic Ocean in terms of the INPs, the overall aerosol composition and culturable bacteria.
  • Thanks to an announcement provided by Tina, Jessie (as PI), Christopher Carr and Brent Christner (mentor and PI of the RAINS project) (University of Florida, Gainesville) have a proposal pending with NSF Arctic System Sciences for the MOSAiC field campaign. It is a $3.2M project to understand aerosol properties in the context of clouds during a year-long trans-Polar drift cruise. They have proposed to deploy a series of aerosol and trace gas samplers and collectors to develop an unprecedented characterization of high Arctic aerosols over the course of an entire sea ice cycle. Franz Conen, Erik Thomson and Tina Santl-Temkiv will be external collaborators on the project.
  • To add on to her initiatives to exploit Arctic contexts to understand the interaction of bioaerosols and the atmosphere, Jessie (as PI) and Chris are constructing a proposal to the Arctic Natural Sciences program to conduct filter-based and real-time measurements on the upcoming joint US/SE summertime cruise on the Oden in 2018. This cruise will align with a cruise this coming summer and with MOSAiC, but focuses on biological and biogenic cloud nuclei in the eastern Arctic Ocean.
  • Christopher Carr  led up a proposal to NASA’s biodiversity solicitation – including colleagues in the MILAF network and other scientists – specifically geared to fund development of an exploration aerobiology sampling campaign for NASA.
  • Chris also set up a collaboration with Noelle Bryan (Louisiana State University, Baton Rouge) and Brent Christner  to sequence the genomes of bacterial strains that Noelle collected from the stratosphere and to perform de-novo genome assembly using single molecule sequencing.

Create more opportunities to meet and to expand our community. To enrich the context that has been established by the MILAF meetings we are planning for future meetings. Erik Thomson and I have recently succeeded in obtaining funds through the University of Gothenburg, Sweden to organize a meeting in the same spirit as the previous MILAF meetings. So you should be hearing soon about the next MILAF meeting.

Below are photos from MILAF-2014 and MILAF-2016 to further illustrate the settings and ambiance of these meetings.
























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