Four-Dimensional Model Assimilation of Data A Strategy for the Earth System Sciences (1991) / Chapter Skim
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1 Introduction
1 Introduction
Pages 9-15
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From page 9... ...
These limitations and the need to describe the state of the evolving geophysical system as accurately as possible have led to the development of geophysical model data assimilation as a rational method to infer the state of the system within which dynamical, physical, chemical, and biological processes can be coupled interactively. With funding from several federal agencies, the National Research Council's Board on Atmospheric Sciences and Climate established the Panel on ModelAssimilated Data Sets for Annosphenc and Oceanic Research.
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From page 10... ...
This model has the capability to predict the dynamic changes occurring in the system, accept the insertion of new observational data distributed heterogeneously in time and space, and blend earlier information and current information objectively under rigorous quality control. This data assimilation technology leads to an estimate of the state of the system that is more complete and more accurate, and thus of higher value, than can be achieved from direct analysis of a single set of observations taken at a particular time.
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From page 11... ...
The approach has been exploited in operational meteorology with unusual success and has contributed to remarkable gains in forecast skill over the last decade (Figure 1~. Dynamically consistent fields of model-assimilated data have also proven RMS error of the 1000 hPa height (in Teters)
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From page 12... ...
This confrontation presents a rich opportunity for a structured, iterative, and open-ended learning process about the behavior of atmospheric, oceanic, and other geophysical systems; the quality of the observations; the interpretation of observational evidence; and the accuracy of the assimilating model. In the last decade, observational research has used model-assimilated data sets as a primary source material for the study of a wide range of atmospheric phenomena and processes.
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From page 13... ...
Many of these difficulties arise because the measured quantity, usually a radiance, is an integrated nonlinear function of the variable being inferred, such as a vertical profile of atmospheric temperature. Many shortcomings in the current procedures can be removed through variational procedures that explicitly recognize the integrated and nonlinear nature of the remotely sensed data These procedures reduce the difficulties arising from the integrated nature of the measurements by using information from Me background field to compensate for the nonlinearity of the radiative transfer equation.
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From page 14... ...
Currently, the assimilated data sets being made available for research are generated as a by-product of operational weather prediction. Not all operationally generated model-assimilated data sets are readily accessible in general by the larger scientific research community in the United States or abroad.
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From page 15... ...
As a starting point for action, the report emphasizes the need for an integrated national effort for the generation, archiving, and service-oriented publication of model-assimilated data sets that will serve a broad range of operational and research programs in annospheric, oceanographic, and earth sciences. To ensure that the needs of the coming decades are met, the panel includes in this report a recommendation that an integrated national program be developed to provide the focus for and implementation of the full range of effort needed to meet these needs.
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