Investigating the impact of new active remote sensing instruments on Numerical Weather Prediction (NWP) models and developing observing strategies for these instruments for future field campaigns and operational applications
Zusammenfassung der Projektergebnisse
A large fraction of the project work was devoted to answer the question if observation targeting is effective and which strategies should be used. Overall, it seems that targeted dropsonde have a beneficial influence on typhoon (and hurricane) track forecasts, but the benefit decreases with the complexity of the data assimilation system and the number of satellite observations used in the modeling system. The use of observations in the typhoon core and eyewall region in global assimilation systems is still challenging and several open questions remain for their optimal use. Dropsondes in the near-surrounding of the typhoon turned out to be most effective for improvements of ECMWF track forecasts rather than dropsondes in the typhoon core and eye-wall region or distant areas indicated to be sensitive by singular vector calculations. T-PARC dropsondes in mid-latitudes launched during extra-tropical transition of tropical cyclones near Japan did not lead to a reduction of forecast error in the ECMWF model. Based on these results and other recent studies, it remains questionable if targeted dropsonde observations in mid-latitudes can significantly reduce the forecast errors of models using 4D-Var assimilation systems and millions of satellite observations per day. Different methods were investigated to assimilate airborne water vapor lidar data in the ECMWF global model. The assimilation of the data was technically successful and the validation with independent dropsondes showed that the analysis with lidar observations is closer to dropsonde humidity. However, the forecast influence of the data appears to be limited and in particular systematic errors of different observing systems and models (dropsondes, lidar, satellite radiances) pose a significant challenge for humidity assimilation. The analysis of the results is still ongoing. Observations near tropical cyclones before recurvature appeared to be most influential on mid-latitude forecast errors. Mid-latitude dropsonde observations in comparison had a comparably small effect. This may be related to the fact that the potential for improvement is largest near tropical cyclones as analysis errors are larger than in mid-latitudes. The comparison of ECMWF and NRL analysis and forecast errors quantified with wind lidar data is ongoing.
Projektbezogene Publikationen (Auswahl)
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Lessons learned from Falcon observations in T-PARC. International Workshop on Advancement of Typhoon Track Forecast Technique, December 2009, Tsukuba, Japan
Weissmann, M.
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Observation impact of dropsonde data. Third THORPEX International Science Symposium, September 2009, Monterey, CA, USA
Harnisch, F. and M. Weissmann
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Overview of T-PARC Falcon operations and first results from ECMWF data denial experiments. Third THORPEX International Science Symposium, September 2009, Monterey, CA, USA
Weissmann, M.
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2010. Aircraft observations of tropical cyclones. In: Global Perspectives on Tropical Cyclones: From Science to Mitigation, 2nd edition, World Scientific Publishing Company Ltd, J.C.L. Chan and J. Kepert, editors, pp 227-240
Aberson, S., C.-C. Wu, M. Bell, J. Halverson, C. Fogarty, J. Cione, and M. Weissmann
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2010. Sensitivity of typhoon forecasts to different subsets of targeted dropsonde observations. Mon. Wea. Rev., 138, 2664-2680
Harnisch, F., and M. Weissmann
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2010. The influence of dropsondes on typhoon track and mid-latitude forecasts. Mon. Wea. Rev., 2010
Weissmann, M., F. Harnisch, C.-C. Wu, P.-H. Lin, Y. Ohta, K. Yamashita, Y. Kim, E.-H. Jeon, T. Nakazawa, S. Aberson
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2010. The influence of special T-PARC observations of typhoon track and mid-latitude forecasts. 29th Conference on Hurricanes and Tropical Meteorology, May 2010, Tucson, AZ, USA
Weissmann, M., F. Harnisch, S. Rahm, T. Nakazawa, C. C. Wu, S. D. Aberson, Y. H. Kim, K. Yamashita, and Y. Ohta
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Assimilation of DIAL water vapour observations into the ECMWF global model. 5th ESA Earth Observation Summer School on Earth System Monitoring & Modelling, August 2010, Frascati, Italy
Harnisch, F. and M. Weissmann, M. Wirth, C. Cardinali and P. Bauer
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Sensitivity of typhoon forecasts to different subsets of targeted observations. 29th Conference on Hurricanes and Tropical Meteorology, May 2010, Tucson, AZ, USA
Harnisch, F. and M. Weissmann
