Katrin Lonitz

Scientist (Eumetsat Fellow)
Research Department, Earth System Assimilation Section, Microwave Radiance Observations Group

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Katrin Lonitz is working on the all-sky assimilation (assimilation under clear, cloudy and rainy conditions) of microwave imager radiances. Her focus is on the analysis of systematic biases and improving formulations inside the observation operator.



Professional interests: 
  • all-sky assimilation of microwave radiances
  • observation operator for microwave radiances
  • satellite remote sensing instruments (SSMIS-F17, GMI, AMSR-2)
  • combination of observations with numerical models
  • microphysical properties of clouds and precipitation


Career background: 

Katrin Lonitz received her Ph.D. at the Max Planck Institute for Meteorology under the supervision of Bjorn Stevens in 2014. In her thesis she studied the interaction between aerosols and trade wind cumuli analysing cloud radar data at Barbados and looking into the organization of those clouds using high-resolution imagery from ASTER. Her interest in clouds and microwave radiances remained until now. Since 2014, she has been working on improving the assimilation of rainy, cloudy and clear-sky affected radiances (all-sky assimilation) from microwave imagers SSMIS-F17, AMSR-2 and GMI at the ECMWF.


04/2014 - today     EUMETSAT fellow at the ECMWF

02/2014 - 03/2014 PostDoc, Max Planck Institute for Meteorology in Hamburg (Germany)

06/2010 - 01/2014 Doctoral Student, Max Planck Institute for Meteorology in Hamburg (Germany)

04/2010 - 05/2010 Research Assistant onboard of R/V Polarstern cruise trip ANT-XXVI/4 from Punta  Arenas (Chile) to Bremerhaven (Germany)

10/2004 - 03/2010 Diploma student, University of Leipzig (Germany)


Peer-reviewed publications

Lonitz, K. and A. J. Geer (2018): Assessing the impact of different liquid water permittivity models on the fit between model and observations, Atmos. Meas. Tech. Discuss., in review, doi.org/10.5194/amt-2018-152

A. J. Geer, K. Lonitz, P. Weston, M. Kazumori, K. Okamoto, Y. Zhu, E. Huichun Liu, A. Collard, W. Bell , S. Migliorini, P. Chambon, N. Fourrié, M.-J. Kim, C. Köpken-Watts and C. Schraff (2018): All-sky satellite data assimilation at operational weather forecasting centres, Quarterly Journal of the Royal Meteorological Society, Vol. 144 (713), p.1191-1217, doi.org/10.1002/qj.3202

A. J. Geer, F. Baordo, N. Bormann, P. Chambon, S. J. English, M. Kazumori, H. Lawrence, P. Lean, K. Lonitz and C. Lupu (2017): The growing impact of satellite observations sensitive to humidity, cloud and precipitation, Quarterly Journal of the Royal Meteorological Society, Vol. 143 (709), p.3189–3206, doi:10.1002/qj.3172

Stevens, B., D. Farrell, L. Hirsch, F. Jansen, L. Nuijens, I. Serikov, B. Brügmann, M. Forde,  H. Linne, K. Lonitz and J. M. Prospero (2016): The Barbados Cloud Observatory: Anchoring Investigations of Clouds and Circulation on the Edge of the ITCZ, Bulletin of the American Meteorological Society, Vol. 97 (5), p.787-801, doi:10.1175/BAMS-D-14-00247.1

Lonitz, K., B. Stevens, L. Nuijens, V. Sant, L. Hirsch and A. Seifert (2015): The Signature of Aerosols and Meteorology in Long-Term Cloud Radar Observations of Trade Wind Cumuli, Journal of the Atmospheric Sciences, Vol. 72 (12), doi:10.1175/JAS-D-14-0348.1

Nuijens, L., I. Serikov, L. Hirsch, K. Lonitz and B. Stevens (2014): The distribution and variability of low-level cloud in the North-Atlantic trades, Quarterly Journal of the Royal Meteorological Society, Vol. 140(684), doi:10.1002/qj.2307

Lonitz, K. and A. Horváth (2011): Comparison of MISR and Meteosat-9 cloud motion winds, Journal of Geophysical Research - Atmospheres, Vol. 116, doi:10.1029/2011JD016047.


Other publications

Lonitz, K. and A. Geer (2017): Effect of assimilating microwave imager observations in the presence of a model bias in marine stratocumulus, EUMETSAT/ECMWF Fellowship Programme Research Report 44 [elibrary]

Lean, P., A. Geer, and K. Lonitz (2017): Assimilation of Global Precipitation Mission (GPM) Microwave Imager (GMI) in all-sky conditions, ECMWF Technical Memorandum 799 [elibrary]

Forbes, R., A. Geer, K. Lonitz and M. Ahlgrimm (2016): Reducing systematic errors in cold-air outbreaks, ECMWF Newsletter Feature Article 146, doi:10.21957/s41h7q7l

Lonitz, K. and A. J. Geer (2015): New screening of cold-air outbreak regions used in 4D-Var all-sky assimilation, EUMETSAT/ECMWF Fellowship Programme Research Report 35 [elibrary]

thumbnail photo of Katrin Lonitz
Contact Details:
katrin . lonitzecmwf . int
Tel. +44 (0) 118 9499649