Improving Atmospheric River forecasts with enhanced observations in moisture source regions

• Applicant: Dr. Alexandre M. Ramos
• Subject Area: Atmospheric Science
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 564641009

North Atlantic windstorms are among the most important natural hazards affecting Europe, often associated with damaging winds and heavy precipitation. Windstorms are intense extratropical cyclones, which often build cyclone families. Recent research has highlighted the intricate interplay within such a cluster of cyclones and their shared environmental conditions. Moisture uptake in the cold sector of a first cyclone could lead to stronger moisture transport in an Atmospheric River (AR) towards a subsequent cyclone. In this environment, moist diabatic processes become more vigorous making their development and potential impacts more difficult to predict. Within the context of the international “North Atlantic Waveguide, Dry Intrusion, and Downstream Impact Campaign” (NAWDIC), we aim to improving AR forecasts with additional observations in moisture source regions. Our hypothesis is that airborne observations from dropsondes in the warm sector of a cyclone improve predictions of the intensity of the corresponding cyclone and its associated AR, whereas additional observations in the cold sector of a cyclone improve predictions of a subsequent cyclone. The observations from KITsonde extensively deployed from HALO will be a crucial component of this proposal. To test the proposed hypothesis, three work packages are planned. The first focuses on assessing model representativeness errors during NAWDIC intense observational periods (IOPs). Special attention will be given to dropsonde observations collected during these IOPs, particularly those located in regions of significant moisture uptake and transport. These data will be used to quantify model errors and evaluate the uncertainty assigned to each individual dropsonde observation within the Integrated Forecasting System of the European Centre for Medium-Range Weather Forecasts. In the second task we will evaluate data denial experiments from two main global Meteorological Centers to evaluate the aggregate impact of the KITsonde on model performance. We will analyze the control and data denial experiments which will help to identify which observations have the most significant impact on improving the model's forecast accuracy while also providing insights into key atmospheric processes such as cyclone development or AR dynamics. Finally, we will quantify the added value of the observations by analyzing the same data denial experiments regarding the potential to improve forecast accuracy for cyclone and AR impacts in Western Europe. The forecasts will be evaluated against KITcube observations and meteorological station data. Ultimately, we envision that the KITsonde observations during NAWDIC will help to gain a deeper understanding of the processes involved in cyclone and AR development, and may also help to diagnose sources of model errors and to improve the predictability of high impact weather.

• DFG Programme: Infrastructure Priority Programmes
• Subproject of: SPP 1294: Atmospheric and Earth System Research with the "High Altitude and Long Range Research Aircraft" (HALO)
• International Connection: United Kingdom
• Co-Investigators: Professor Dr. Joaquim G. Pinto; Professor Dr. Julian Quinting
• Cooperation Partner: Dr. David Lavers, Ph.D.