Hourly non-gridded volcanic ash properties retrieved from SEVIRI measurements for the Eyjafjallajökull 2010 eruption

- Publishing date:
  14.05.2020

- Title:
  Hourly non-gridded volcanic ash properties retrieved from SEVIRI
  measurements for the Eyjafjallajökull 2010 eruption  

- Authors of data set:
  Arve Kylling ([e-mail]), NILU - Norwegian Institute for Air Research
  Espen Sollum, NILU - Norwegian Institute for Air Research

- Description:
  Ash satellite detection and retrievals were made using infrared
  measurements by SEVIRI on board the MSG-2 satellite. MSG-2 is
  geostationary, centred at approximately 0N latitude, and has a 70
  degree view coverage (Schmetz et al., 2002). Pixel resolution is 3 ×
  3 km at nadir, while at the edge of the coverage it increases to 10
  × 10 km. Observations are available every 15 min. Pixels are
  identified as containing ash if the brightness temperature
  difference (BTD) between the SEVIRI 10.8 and 12.0 μm channels
  (Prata, 1989) is below a certain threshold value, here −0.5 K. The
  BTDs have been adjusted for water vapour absorption using the approach of
  Yu et al. (2002). Ash clouds give negative BTDs, ice give positive
  BTDs, and BTDs of water clouds are closer to zero. The ash mass
  loading and effective ash particle radius are retrieved as described
  in Kylling et al. (2015). The retrieval is based on a modification
  of the Bayesian optimal estimation technique used by Francis et
  al. (2012). We assume andesite ash with refractive index from Pollack
  et al. (1973), spherical ash particles, and a lognormal size
  distribution. The lognormal size distribution is described by the
  geometric mean radius and the geometric standard deviation. The data
  set includes retrievals for geometric standard deviation of 1.5,
  1.75, 2.0, and 2.25, which is a subset of the values used by Francis
  et al. (2012). The data set has been used by Steensen et al. (2017).

  Data comes as hourly files broadly covering Iceland, Europe and the
  surrounding oceans. The files are in bzip2 netcdf-format which
  should be self-explanatory.  

- Version:
  1.0

- Language:
  English

- Keywords
  Volcanic ash, remote sensing, SEVIRI, Eyjafjallajökull 2010

- Additional notes
  None

- Access right:
  Open access

- License:
  CC BY-SA 4.0  

- Funding:
  Partly funded by the Norwegian ash project financed by the Norwegian
  Ministry of Transport and Communications and Avinor. 

- References:
  Francis, P. N., Cooke, M. C., and Saunders, R.W.: Retrieval of
  physical properties of volcanic ash using Meteosat: A case study
  from the 2010 Eyjafjallajokull eruption, J. Geophys. Res. Atmos.,
  117, D00U09, https://doi.org/10.1029/2011JD016788, 2012.

  Kylling, A., Kristiansen, N., Stohl, A., Buras-Schnell, R., Emde,
  C., and Gasteiger, J.: A model sensitivity study of the impact of
  clouds on satellite detection and retrieval of volcanic ash, Atmos. 
  Meas. Tech., 8, 1935-1949, https://doi.org/10.5194/amt-8-1935-
  2015, 2015.

  Pollack, J. B., Toon, O. B., and Khare, B. N.: Optical properties of
  some terrestrial rocks and glasses, Icarus, 19, 372-389,
  https://doi.org/10.1016/0019-1035(73)90115-2, 1973. 

  Prata, A. J.: Observations of volcanic ash clouds in the 10-12 um
  window using AVHRR/2 data, Int. J. Remote Sens., 10, 751-761,
  1989.

  Schmetz, J., Pili, P., Tjemkes, S., and Just, D.: An introduction to
  Meteosat second generation (MSG), B. Am. Meteorol. Soc., 83,
  977-992, 2002.

  Steensen, B. M., Kylling, A., Kristiansen, N. I., and Schulz, M.:
  Uncertainty assessment and applicability of an inversion method for
  volcanic ash forecasting, Atmos. Chem. Phys., 17, 9205-9222,
  https://doi.org/10.5194/acp-17-9205-2017, 2017. 

  Yu, T., Rose, W. I., and Prata, A. J.: Atmospheric correction for
  satellite-based volcanic ash mapping and retrievals using "split
  window" IR data from GOES and AVHRR, J. Geophys. Res. Atmos., 107,
  https://doi.org/10.1029/2001JD000706, 2002.