Optimal Utilization and Impact of Water Vapor and Other High Resolution Observations in Storm-Scale Quantitative Precipitation Forecasts (QPF)

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In an effort to better characterize the four-dimensional distribution of water in the atmosphere with a view toward improving understanding of its impact on deep convection, the International H20 Project (IHOP-2002) field experiment will take place over the Southern Great Plains during May and June of 2002. The four focus areas of IHOP are: 1) quantitative precipitation forecasting (QPF); 2) convective initiation; 3) atmospheric boundary layer processes; and 4) instrumentation research.The Principal Investigators will conduct storm-scale research with particular emphasis on moisture sensitivity and data assimilation in the context of numerical quantitative precipitation forecasting. Specifically, they will:1. Develop new and improved techniques, based particularly on variational approaches, for the analysis and assimilation of water and related diabatic fields (e.g., latent and sensible heating) at the scale of individual convective storms and their larger mesoscale clusters.2. Study the impact of special and routinely available, high-resolution observations of water vapor and hydrometeor content on the forecasting of convective storm morphology and quantitative precipitation at resolutions of one to a few kilometers. Both forward and adjoint models will be used to assess sensitivity and data impact.3. Develop and evaluate techniques for estimating error characteristics (i.e., error covariance matrices) of numerical forecasts at the convective scale to improve the quality of three-dimensional and four-dimensional variational data assimilation.4. Apply newly developed single Doppler velocity and thermodynamic retrieval algorithms to mobile radar data collected during IHOP and assimilate the retrieved data into a forecast model. 5. Provide real-time, high resolution (2-3 km) analysis and forecasts for ranges between 6 and 12 hours, to assist the operational decision-making and targeting of mobile observations during the field phase of the IHOP.The project will provide much needed education and training for graduate students and a post-doc in the increasingly important areas of variational data assimilation, numerical weather prediction and ensemble forecasting. The research findings will have a direct path to operations through the PI's involvement as one of the lead scientists in the Weather Research and Forecast (WRF) model system development project. Although much of the work to be performed herein will use the Center for Analysis and Prediction of Storms' (CAPS) Advanced Regional Prediction System (ARPS) owing to its maturity and capability, the new WRF will be used whenever possible. Further, the results obtained here, and the software developed, will be applied to further the development of the WRF model as part of CAPS' involvement in the WRF project.