December 2018
Message 45

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[Met-jobs] Postdoctoral fellow, model development and validation

From Roger Brugge <>
To "" <>
Date Wed, 12 Dec 2018 10:22:08 +0000


Postdoctoral fellow


PI Supervisor: Profs. Drs. Fábio L T Gonçalves/Vaughan Phillips

Contact to Email : /

Dept. of Atmospheric Sciences, São Paulo, Brazil/ University of Lund, Sweden

Type Pos-doc 24 months, 40 hours per week


FAPESP PROJECT (2016/06160-8), coordinators: Profs. Drs. Fábio L T Gonçalves/Vaughan Phillips



Airborne particles, also called particulate matter, can impact directly and indirectly on Earth's climate as well as on human and animal health. Aerosol particles range from a few microns down to very small sizes, such as a few tens of Angstroms. These particles can directly absorb or reflect solar radiation within the atmosphere affecting directly the Earth's energy balance, a major focus of the IPCC (Intergovernmental Panel on Climate Change). Another important effect is related to their ability to act as cloud condensation nuclei (CNN) and formation of ice nuclei (IN), which trigger cloud drops and ice formation respectively, also indirectly influencing the Earth’s energy balance, equally important to the IPCC approach. On the other hand, the Primary

Biological Aerosol Particles (PBAPs) are airborne solid and insoluble particles derived from living organisms (e.g. bacteria, fungi and pollen). These biological particles have properties that enable them to act as ice nuclei (IN), becoming PBAP-IN, as well as cloud condensation nuclei (CCN) and participate in the radiative forcing. In this research work, we will also explore the status of the current and incomplete global climatology of hail, hail formation, its relation to PBAP-IN to explain the observed behavior for Southern region of Brazil. Remote sensing techniques and downscaling scenarios will be considered in the analysis proposed in this project and methods able to assess the impact of future climate scenarios. Therefore, as a final product, the proposed research is expected to evaluate the knowledge about PBAP-IN and hail phenomena and improve the modern techniques of detection of hailstorms by satellites, including the assessment of any signal of climate change impact. Finally, the project will provide the community with observations of the local and specific conditions of hailstorms occurrence, related to PBAP-IN and, based on these conditions, establish the synoptic or large-scale circulation patterns under which the phenomena occur in the South and Southeast of Brazil and what behavior could be expected to the future.

Only recently, chemical, physical and microbiological researches took place individually, in parallel paths, and a closer multidisciplinary approach linking cloud and hail formation and PBAP-IN, which started in the last decade. These interactions lead to a potential increase in the multidisciplinary understanding of physical chemistry of biological particles from the atmosphere. These are issues (such as “How much PBAP-IN contributes to the radiative forcing at Southern Brazil region?”) that should be answered partially for this Project and link to other studies where the importance of microorganisms in cloud microphysics and its consequences. Moreover, since global models (GCMs) have a simple representation of cloud formation, any acquisition of the knowledge about clouds and hailstorms are very relevant, such as hail formation rates as a function of cloud-depth, CAPE and aerosol conditions (e.g. PBAP) in global models. The ability to preview climate change is based on GCMs where this improvement can be added. Finally, the PBAP-IN can be introduced to numerical modeling in order to evaluate its impact on cloud formation and rainfall.


The postdoctoral scholar will achieve these objectives:

· Schemes to treat ice nucleation by bacteria, fungal and other bio-aerosol (e.g. algal) particles separately will be created.

· These schemes will be implemented in the WRF cloud model of the Lund side and in the Brazilian model.

· Airborne concentrations and size distributions of bacteria and fungal particles will be specified for the cases to be simulated by both sides (Lund, Brazil).

· The WRF model will be validated against all available ground-based, satellite-based and aircraft (in similar Brazilian areas) observations, either for the clouds simulated or for clouds in a similar area and time of year.

· Optionally other model improvements will be done, such as inclusion of a fully spectral model approach for the microphysics and improved treatments of sticking efficiency for aggregation and hail wet growth.


First, our empirical parameterization (Phillips et al. 2008, 2013) of biological ice nucleation will be improved by resolving the separate species of bio-aerosol (bacteria, fungal, algal particles). Time-dependence of ice nucleation will be treated in an empirical way by inspecting and simulating off-line lab studies already published, in collaboration with other experts in observations of ice nucleation in USA. Next, field observations by satellite, aircraft and from the ground, will be gathered for the two locations of our observed cases near Sao Paulo and Paraná state. The observations will include radar reflectivity, lightning flash rate, surface precipitation rate, vertical velocity histograms, shortwave and longwave fluxes observed by satellite, CCN and IN concentrations, and cloud-droplet concentrations. Simulations with our cloud models of both locations will be validated with available observations. Prediction of measurements with hail-pads will be validated in particular.

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