Jani Tyynelä's homepage

Who am I

I am a post-doctoral researcher in planetary astronomy and atmospheric sciences. I study light and microwave scattering from surfaces and single particles. A copy of my dissertation is here .

Lunar surface simulator (under work)

I have made a java application, which creates a synthetic lunar surface. User can add craters and select other surface features. The simulator can be found here .

Internal field studies

I have studied the influence of the internal electric fields of wavelength-scale particles on the far-field scattering characteristics (see Publ. 2, 4, 8, and 9). Introduction to the problem can be found here.

Winter-type precipitation

I have also studied how winter-type precipitation can be modeled using the discrete-dipole approximation (DDA). One publicly-available implimentation of DDA is A-DDA. A database for the single-scattering properties (cross sections, asymmetry parameters, and phase functions) of falling snowflakes at microwave frequencies can be found here. The database has been used in Publ. 11, 16, 18, and 19.

List of Publications

  1. Kahanpää J. et al. (1999). Time series analysis of V 368 Cephei photometry, Astron. Astrophys. 350, 513-516
  2. Tyynelä J., Zubko E., Videen G., and Muinonen K. (2007). Interrelating angular scattering characteristics to internal electric fields for wavelength-scale spherical particles. JQSRT 106, 520-534
  3. Muinonen K., Zubko E., Tyynelä J., Shkuratov Yu. G., and Videen G. (2007). Light scattering by Gaussian random particles with discrete-dipole approximatio. JQSRT 106, 360-377
  4. Tyynelä J, Muinonen K., Zubko E., and Videen G. (2008). Interrelating angular scattering characteristics to internal electric fields of wavelength-scale Gaussian particles. JQSRT 109, 2207-2218
  5. Hook R. et al. (2008). ESO Reflex: A Graphical workflow engine for data reduction. Messenger 131, 42-44.
  6. Hook R. et al. (2008). ESO Reflex: A graphical workflow engine for running recipes, in: The 2007 instrument Calibration Workshop (Kaufer A. and Kerber F.), Springer, 169-175.
  7. Tyynelä J., Nousiainen T., Göke S., and Muinonen K. (2009). Modeling C-band single scattering properties of hydrometeors using Discrete-Dipole Approximation and T-Matrix Method. JQSRT 110, 1654-1664
  8. Muinonen K., Tyynelä J., Zubko E., and Videen G. (2010). Scattering parameterization for interpreting asteroid polarimetric and photometric phase effects. Earth Planets Space 62, 47-52
  9. Tyynelä J., Zubko E., Muinonen K., and Videen G. (2010). Interpretation of single-particle negative polarization at intermediate scattering angles. Appl. Opt. 49, 5284-5296
  10. Muinonen K., Tyynelä J., Zubko E., and Videen G. (2010). Coherent backscattering in planetary regoliths, in: Light scattering reviews 5 (Kokhanovsky A. A.), Springer, Berlin, 477-518
  11. Tyynelä J., Leinonen J., Moisseev D., and Nousiainen T. (2011). Radar backscattering from snowflakes: comparison of fractal, aggregate, and soft-spheroid models. J. Atmos. Oceanic Technol. 28, 1365-1372
  12. Muinonen K., Tyynelä J., Zubko E., Lindqvist H., Penttilä A., and Videen G. (2011). Polarization of light backscattered by small particles. JQSRT 112, 2193-2212
  13. Leinonen J., Kneifel S., Moisseev D., Tyynelä J., Tanelli S., and Nousiainen T. (2012). Evidence of nonspherical behavior in millimeter-wavelength radar observations of snowfall. JGR 117, D18205.
  14. Nousiainen T., Zubko E., Lindqvist H., Kahnert M., and Tyynelä J. (2012). Comparison of scattering by different nonspherical, wavelength-scale particles, JQSRT 113, 2391-2405.
  15. Kahnert M., Nousiainen T., Thomas M. A., and Tyynelä J. (2012). Light scattering by particles with small-scale surface roughness: comparison of four classes of model geometries. JQSRT 113, 2356-2367.
  16. Tyynelä J., Leinonen J., Westbrook C. D., Moisseev D., and Nousiainen T. (2013). Applicability of the Rayleigh-Gans approximation for scattering by snowflakes at microwave frequencies in vertical incidence. JGR 118, 1826-1839.
  17. Tyynelä J., Leinonen J., Moisseev D., Nousiainen T., and von Lerber A. (2014). Modeling radar backscattering from melting snowflakes using spheroids with nonuniform distribution of water. JQSRT 133, 504-519.
  18. Battaglia A., Westbrook C. D., Kneifel S., Kollias P., Humpage N., Löhnert U., Tyynelä J., and Petty G. W. (2014). G-band atmotspheric radars: new frontiers in cloud physics. Atmos. Meas. Tech. 7, 1527-1546.
  19. Tyynelä J. and V. Chandrasekar (2014). Characterizing falling snow using multi-frequency dual-polarization measurements. JGR 119, 8268-8283.
  20. Virkki A., Markkanen J., Tyynelä. J., Peltoniemi J.I., and Muinonen K. (2015). Polarized backscattering by clusters of spherical particles. Opt. Lett. 40, 3663-3666.
  21. Moisseev D., Lautaportti S., Lim S., and Tyynelä J. (2015). Dual-polarization radar signatures in snowstorms: role of snowflake aggregation, J. Geophys. Res. Atmos. 120, 12644-12655.
  22. Hogan R., Honeyager R., Tyynelä J., and Kneifel S. (2017). Calculating the millimetre-wave scattering phase function of snowflakes using the self-similar Rayleigh-Gans Approximation. QJRMS 143, 834-844.
  23. Kneifel S., Neto J. D., Ori D., Moisseev D., Tyynelä J., Adams I., Kuo K.-S., Bennartz R., Berne A., E. E. Clothiaux, Eriksson P., Geer A., Honeyager R., Leinonen J., and Westbrook C. D. (2018). The First International Summer Snowfall Workshop: Scattering properties of realistic frozen hydrometeors from simulations and observations, as well as defining a new standard for scattering databases. Bull. Amer. Meteor. Soc., March, 55-58.
  24. Mehri T., Kemppinen O., David G., Lindqvist H., Tyynelä J., Nousiainen T., Rairoux P., and Miffre A. (2018). Investigating the size, shape and surface roughness dependence of polarization lidars with light-scattering computations on real mineral dust particles: Application to dust particles' external mixtures and dust mass concentration retrievals. Atmos. Res. 203, 44-61.

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