Observations in aid of weather prediction for North America: Report of Prospectus Development Team Seven

One of the most significant impediments to progress in forecasting weather over North America is the relative paucity of routine observations over data-sparse regions adjacent to the United States. Prospectus Development Team Seven was convened to consider ways to promote research that seeks to determine implementations of observing systems that are optimal for weather prediction in the United States. An "optimal" measurement system is considered to be one that maximizes the ratio of societal benefit to overall cost. The thrust of the conclusions is that existing means of estimating the value of current observing systems and the potential benefits of new or proposed observing systems are underutilized. At the same time, no rational way exists for comparing the cost of observations across the spectrum of federal agencies responsible for measuring the atmosphere and ocean. The authors suggest that a rational procedure for configuring an observation system that is optimal for weather prediction would consist of the following steps. 1) Identify specific forecast problems arising from insufficient data. Examples might include hurricane landfall and intensity forecasts, 24-h forecasts of intense extratropical cyclones affecting the West Coast and Alaska, and medium-range forecasts of severe weather for all of North America. 2) Use contemporary modeling techniques, such as observing system simulation experiments, ensemble forecasting, and model adjoint-derived sensitivities, to delineate measurement requirements for each specific forecasting problem and identify candidate observing systems and data assimilation techniques that could be brought to bear on each problem. 3) Estimate the incremental forecast improvements that could plausibly result from the added or reconfigured data and the societal benefits that would accrue from such improvements. 4) Estimate the overall cost (to the nation, not to specific federal agencies) of obtaining the data by the various candidate techniques and the benefits that are projected to result. 5) Use standard cost-benefit analysis as a basis for deciding the optimal deployment of measuring systems. The authors believe that a rational approach to atmospheric measurement is critical to further improvements in weather prediction and that such improvements might very well be made within the current budget of routine observations, integrated across all of the responsible federal agencies. This document outlines a proposed strategy for rationalizing atmosphere observations in aid of weather prediction in the United States. The paper begins with a summary of recommendations.