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Atmospheric Physics

The research activity carried out by the members of the Atmospheric Physics group deals with fundamental issues related to the dynamics, radiative transfer and thermodynamics of the atmosphere. The ultimate goal is to improve our knowledge on fundamental processes regulating the evolution of the terrestrial atmosphere, both in the short-term (meteorology) and long-term (climate).

The group is involved in the definition of innovative methods used to extract the maximum information content from in-situ and remote sensing measurements of the atmosphere either from active or passive sensors.

Research is fully integrated in the national and international context, it is funded by national and international projects. The group is active in numerous collaborations with several research institutions (local, national or international).

 

Physics of the Stratosphere

M. Ridolfi (Assoc. Prof.)

Accurate knowledge of the distribution and time evolution of minor stratospheric constituents is the basis to understand the chemical and physical processes that drive important issues such as stratospheric ozone depletion, climate change and global warming.

Spectrally resolved remote measurements of the atmospheric radiance are considered one of the most powerful tools to measure the composition of the atmosphere, and particularly of the stratosphere, on a global scale, with short re-visit time. Our specialization is in the design and implementation of state of the art inversion techniques for remote sensing emission and absorption measurements of the atmospheric spectrum, from mid- to far-infrared. These techniques allow to infer from measured spectra the vertical distribution of several atmospheric minor constituents. For inversion, analysis and characterization of data acquired by atmospheric experiments we developed algorithms that implement:

•          Radiative transfer through inhomogeneous, clear sky atmosphere (used for forward model simulations).

•          Retrieval of the spatial distribution of geophysical parameters (temperature, pressure and concentration of atmospheric constituents), with both one-dimensional (global-fit) and two-dimensional (tomography, with geo-fit) retrieval models. State-of-the-art self-adapting regularization techniques are developed to constrain ill-conditioned or ill-posed inversions.

•          Modeling of the whole chain of an atmospheric experiment with sensitivity functions. These allow to predict the quality of the retrieval results, on the basis of averaging kernels and covariance matrices.

In the frame of in international project, our team developed the algorithm used by the European Space Agency (ESA) to process the measurements acquired by MIPAS (Michelson Interferometer for Passive Atmospheric Sounding). This is a mid-infrared limb emission sounder that successfully operated on board of the ENVISAT satellite in the years from 2002 to 2012.

Web links:

  • MIPAS sensor: https://earth.esa.int/web/guest/missions/esa-operational-eo-missions/envisat/instruments/mipas

Scientific Collaborations:

  • Consiglio Nazionale delle Ricerche, Istituti IFAC (Firenze) e ISAC (Bologna), I
  • LISA – CNRS, Paris, Fr
  • KIT – Karlsruhe, D
  • Univ. of Oxford and Univ. of Leicester, UK
  • European Space Agency: ESRIN, ESTEC, N

Funding: European Space Agency (ESA), UniBo

 

Tropospheric Clouds

R. Rizzi (Assoc. Prof.), T. Maestri (Assist. Prof.)

Condensed phases in the Troposphere are studied through the exploitation of active and passive remotes sensing measures, in-situ data and theoretical modelling.

The research activity is based on the development and improvement of algorithms for the computation of radiances and fluxes at high spectral resolution in presence of multiple scattering layers.  Line-by-Line codes are used as a reference for theoretical investigations and for calibration/validation experiments of remote sensing sensors at microwave, infrared and shortwave wavelengths. A continually updated database for non-spherical ice crystals’ single scattering properties is used within an innovative inversion technique to infer optical and microphysical properties of ice clouds from remote sensing measurements at infrared wavelengths. This allows comparisons of cloud retrieval products from multiple data, the check of limits and consistency of available cloud radiative properties databases and the definition of cloud parameterizations for numerical weather prediction and climate models.

The research activity also includes the: i) characterization of particulates in the Upper Troposphere/Lower Stratosphere with focus on the detectability and optical/microphysical properties derivation of sub-visible cirrus clouds from limb observations; ii) application of statistical retrieval models to infer Venus tropospheric clouds’ properties and the use of radiative transfer Monte Carlo models at limb geometry to study the Venusian upper haze properties, iii) investigation of the average ice distribution vertical structure of cirrus clouds by means of active data aiming at developing a parameterization, depending on both physical and geographical parameters, implemented into inversion codes.

Scientific Collaborations:

  • SSEC-CIMSS Univ. of Wisconsin-Madison, Madison, USA (http://cimss.ssec.wisc.edu)
  • ISAC-CNR, Bologna
  • JSC, Forschungszentrum Jülich, Germany
  • INAF-IAPS, Roma, I (http://www.iaps.inaf.it)

Funding: PRIN, Eumetsat, ESA, UniBo

 

Radiance in the Far Infra-Red

R. Rizzi (Assoc. Prof.), T. Maestri (Assist. Prof.), William Cossich (PhD Student)

The Far InfraRed emission from the Earth is highly characteristic of our planet as a system seen from space, and it is of fundamental significance for planetary energy balance considerations and therefore for understanding the Earth's climate.

The study of FIR emission and of the main physical processes acting upon it is a long-term research project of APG. This line of research involves the characterization of the long-term downwelling radiance in the far infrared both in clear and cloudy conditions. This is fundamental either for the validation of water vapour continuum absorption parameterization and for the definition of the cloud optical properties databases in the 100-600 cm-1 spectral interval.

Data in the FIR are currently collected by the Fourier Transform Spectrometer REFIR-PAD (Radiation Explorer in the Far InfraRed - Prototype for Applications and Development) instrument that has successfully performed observations from high mountain sites and a balloon borne platform.

High spectral resolution radiance data in the infrared are also used for the definition of methodologies for the identification of clear sky, not-precipitating and precipitating clouds (in particular in the Artic region) by means of Linear Discriminant Analysis and Support Vector Machine algorithms. Machine learning algorithms based on principal component analysis are applied to (synthetic) satellite or (measured) airborne high spectral resolution measures in the far and mid infrared for cloud identification and classification.

The APG is working for the preparation of the FORUM (Far-infrared-Outgoing-Radiation Understanding and Monitoring) mission that aims at studying the radiative impact of atmospheric water, in the form of both vapour and clouds, on the climate system by measuring from space the spectrally resolved emission of the Earth in the spectral range from 100 to 1600 cm-1. FORUM has been recently selected as one of the two candidates for the Earth Explorer 9 Fast Track Mission Programme. Industrial and scientific Phase-A studies concerning the FORUM missions are supported by the European Space Agency (ESA).

Web links:

  • ECOWAR-COBRA experiment: http://www2.unibas.it/gmasiello/cobra/index.htm
  • PRANA experiment: http://www.ino.it/en/?p2=funding&p=project-detail&passo=151

Scientific Collaborations:

  • Dipartimento di Ingegneria e Fisica dell'Ambiente - Università della Basilicata, I
  • Istituto Nazionale di Ottica - CNR, Firenze, I
  • Istituto per le Applicazioni del Calcolo - CNR, Firenze, I
  • Istituto di Fisica Applicata “Nello Carrara” - CNR, Firenze, I
  • Deimos Elecnor Space (E)

Funding: ESA, ASI, PRIN, PNRA-PRANA, UniBo

 

Precipitation microphysics and remote sensing

F. Porcù (Assist. Prof.), T. Maestri (Assist. Prof.)

Precipitation is one of the atmospheric parameters with highest variability at all scales, and thus difficult to measure with the accuracy requested for climate studies and weather forecast.

The group is involved in the characterization of microphysical and radiative properties of precipitation particles, as measured in different experimental campaigns with disdrometers and ground based radar, with the goal to improve the knowledge of the involved microphysical processes, and the remote sensing of precipitation characteristics.

Particular interest is on the study of severe convective systems, carried on with remote sensing (satellite sensors and radar) and in situ instruments, such as lightning detectors, disdrometers and raingauge.

Further applications of precipitation studies are devoted to the prevention and mitigation of hydrogeological disasters, especially to monitor the effectiveness of Natural Based Solutions in reduce meteorological risks.

Web links:

  • Eumetsat H-SAF: hsaf.meteoam.it
  • H2020 OPERANDUM: https://site.unibo.it/operandum/en

Scientific Collaborations:

ARPA Emilia Romagna, Bologna, I (http://www.arpa.emr.it/sim/)

  • NASA-GSFC Greenbelt, USA (https://www.nasa.gov/centers/goddard/home/index.html)
  • University of Maryland, Baltimore County, Baltimore, MA, USA
  • ISAC-CNR, Bologna e Roma, I
  • Dipartimento della Protezione Civile, I

Funding: EU-FP7, PNRA, UniBo, EUMETSAT, H2020

 

Urban meteorology and climatology; Environmental fluid dynamics

S. Di Sabatino (Assoc. Prof.)E. Brattich (Junior Assist. Prof.), F. Barbano (PhD Student). F. Di Nicola (PhD Student)

The focus is on the understanding and modelling of flow and dispersion phenomena in the lower atmosphere and their role and feedbacks on climate.  The emphasis is on the thermodynamics of atmospheric/environmental systems at various spatial-temporal scales ranging from few meters to several kilometers and from fraction of seconds (turbulence) to years (climate). Specific effort is devoted to the urban environment tailored to the understanding of city system as a whole from its “breathability” i.e. to its ability to ventilate itself and to the understanding on how both flow and energy is exchanged, transported and distributed within it. In the context of urban meteorology and climatology the research developed within the group tackles different aspects: the connection between urban form, vegetation and the atmospheric processes; the urban heat island, air quality and their role on the climate systems. All these topics are essential within the EU H2020 research and innovation project iSCAPE (Improving the Smart Control of Air Pollution in Europe), of the group coordinated by Prof. Di Sabatino is partner representing the University of Bologna together with the Department of Industrial Engineering. The project works on the integration and control of air quality in urban environments in the context of climate change through the implementation of sustainable Passive Control Systems (PCSs) strategies, policy interventions and behavioral changes initiatives, via a cooperative approach between academicist, policy makers, agencies and citizens (Living Lab approach). The overall aim is to develop and evaluate an integrated strategy for air pollution control grounded on experimental and numerical analysis. Of applied nature within the project is the development of experimental measurements campaigns and numerical investigations to assess the role of vegetation in street canyons and co-adjuvate urban planners to construct sustainable yet smart cities. Small temporal and spatial scale turbulent processes are studied to determine the key mechanisms that regulate ventilation and thermal forcing within a street canyon, considering how trees impact on it during different period of the year. The scope is to evaluate the role of trees on air pollution local mitigation, and enhancement of street breathability and thermal comfort.

Prof. Di Sabatino is also coordinating the recently funded EU H2020 funded OPERANDUM (Open-air laboRAtories for Nature baseD solUtions to Manage environmental risks), a project involving 26 international partners for 4 years, focusing on environmental risks caused by meteorological extreme events. In particular, within OPERANDUM, nature-based solutions will be tested as mitigating factors to flooding, landslides, coastal erosion, droughts and salt intrusion on extra-urban territories. Nature-based solutions will include the use of vegetation to re-enforce river banks, basins and the co-design, co-development and realization of vegetated sand dunes to reduce the coastal erosion.

Web links:

Scientific Collaborations:

  • University of Notre Dame, South Bend (IN, USA),
  • University of Hong Kong, Hong Kong (CHINA),
  • University of Gavle, Gavle (Svezia),
  • CIEMAT, Madrid Spain,
  • Caledonian University, Glasgow (UK),
  • Lahti University, Lahti (Finland).
  • ARPA Emilia Romagna, Bologna, IT (https://www.arpae.it/)
  • Funding: Unibo, EU-INTERREG, TELECOM, EU-LLP, EU-H2020

Contacts

Silvana Di Sabatino

Associate Professor

Dipartimento di Fisica e Astronomia - DIFA

Viale Berti Pichat 6/2

Bologna (BO)

tel: +39 051 20 9 5215

Tiziano Maestri

Assistant professor

Dipartimento di Fisica e Astronomia - DIFA

Viale Berti Pichat 6/2

Bologna (BO)

tel: +39 051 20 9 5212

Federico Porcù

Assistant professor

Dipartimento di Fisica e Astronomia - DIFA

Viale Berti Pichat 6/2

Bologna (BO)

tel: +39 051 20 9 5214

Marco Ridolfi

Associate Professor

Dipartimento di Fisica e Astronomia - DIFA

Viale Berti Pichat 6/2

Bologna (BO)

tel: +39 051 20 9 5194

tel: +39 051 20 9 5215

tel: +39 051 20 9 3693

tel: +39 055 5226351

fax: +39 051 252774

Rolando Rizzi

Associate Professor

Dipartimento di Fisica e Astronomia - DIFA

Viale Berti Pichat 6/2

Bologna (BO)

tel: +39 051 20 9 5216

Erika Brattich

Junior assistant professor (fixed-term)

Dipartimento di Fisica e Astronomia - DIFA

Viale Berti Pichat 6/2

Bologna (BO)

tel: +39 051 20 9 5187