TEsting isotopologues as Diabatic heating proxy for atmospheric Data analYses

• Applicant: Dr. Matthias Schneider
• Subject Area: Atmospheric Science
• Term: from 2019 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 416767181

Clouds and water vapour control atmospheric radiative heating/cooling and condensation or evaporation of water determines where latent heating or latent heat consumption takes place. The heating patterns then drive atmospheric circulation, thereby causing additional evaporation/condensation and impacting on the distribution of water vapour and clouds, which in turn again modify the latent and radiative heating patterns of the atmosphere. This strong coupling between moisture pathways, diabatic heating and atmospheric circulation is responsible for important climate feedback mechanisms and for the evolution of many severe weather events. In this context it is rather worrisome that the diabatic heating rates obtained from different current global reanalyses show significant inconsistencies.The aim of this project is to develop and evaluate a novel method for bringing atmospheric reanalyses in better accordance to the actual atmospheric heating rates. The method consists in exploring the process information present in the atmospheric water vapour isotopologue composition within a novel data assimilation framework. Because the isotopologue composition is closely linked to atmospheric diabatic moist processes, its additional assimilation offers a promising possibility for better constraining the analysed atmospheric state towards the actual atmospheric heating rates. The aim will be efficiently achieved by a close collaboration between experts. German experts in space-based remote sensing of water vapour isotopologues will use spectra measured by the sensor IASI (Infrared Atmospheric Sounding Interferometer) and generate a comprehensively characterized observational data set representative for clear sky and homogeneously low cloud conditions and offering quasi global coverage two times per day for the three years 2014-2016. Japanese experts in global isotopologue modelling and data assimilation will refine their Local Ensemble Transform Kalman Filter (LETKF) assimilation tool in order to ensure a computationally efficient and accurate assimilation of global isotopologue observations twice per day. The German and Japanese scientists will together run different assimilation experiments for the 2014-2016 time period and document the challenges of the approach and its potential for improving atmospheric analyses. A particular focus of this evaluation will be on the heating rates and precipitation patterns of the Madden-Julian oscillation and the heating rates, horizontal winds and vertical velocities of the Hadley and Walker circulations. The observational data and the developed tools will be made freely available, thereby permitting continual usage of the isotopologue assimilation tool with any isotopologue enabled atmospheric general circulation model.

• DFG Programme: Research Grants
• International Connection: Japan
• Partner Organisation: Japan Society for the Promotion of Science (JSPS)
• Cooperation Partner: Professor Dr. Kei Yoshimura