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Kenneth H. Bergman

The theory of optimum interpolation analysis is presented, with emphasis on the role that observational errors have in the analysis scheme. It is shown that an estimate of the root-mean-square observational error is required and also that the correlations between errors of observations, if nonzero, must be specified. Methods of determining these quantities from observational data statistics are discussed and examples shown. Finally, error-checking routines that either accept or reject data are described. It is pointed out that care should be exercised when checking for errors so that good and useful data are not inadvertently rejected.

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Kenneth H. Bergman

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Kenneth H. Bergman

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Kenneth H. Bergman

Abstract

The design of a statistical “optimum interpolation” analysis system for multivariate analysis of temperature and wind fields is described. The scheme uses three-dimensional correlation functions, defined as products of quasi-horizontal and vertical correlations. A numerical prediction is used to provide background fields, and corrections to them are obtained using optimum interpolation. Observations are assigned rms error levels, and for some observational types the errors are assumed to be vertically or laterally correlated. A procedure for using oceanic surface data in the upper air analysis is included.

Some special design features, including data selection and error-checking procedures, are discussed. The mechanics of the analysis system are illustrated with a step-by-step example analysis. Several experimental analyses are compared in order to illustrate sensitivity of the analysis scheme to changes in design features and governing parameters.

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Kenneth H. Bergman
and
William D. Bonner

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Kenneth H. Bergman
and
Toby N. Carlson

Abstract

A method for objective analysis of aircraft observations in tropical cyclones has been developed. Quasi-horizontal fields of motion, temperatures, mixing ratios, and D-values are analyzed using a modified version of the method of successive corrections. The weighting functions are specified so that the high degree of circular symmetry characteristic of tropical cyclones is incorporated in the analyses. The analyses are performed on a 25 by 25 Cartesian grid of 5 n mi spacing which is centered on the storm. A special feature is the analysis of vertical motions as determined from aircraft flight characteristics. Three Atlantic storms are analyzed in detail: Hurricanes Inez (1966), Debbie (1969), and Ginger (1971). The analyses show the significant larger-scale features and major asymmetries of these storms. Both Inez and Debbie, which were well organized hurricanes, display characteristic vertical motion patterns in which a ring of strong ascent is found immediately surrounding the eye, with marked descent just outside of the annulus of strong ascent. Maximum ascent and descent rates were each indicated to be a few meters per second in these storms. Ginger was a marginal hurricane with poorly organized eye structure and relatively weak and disorganized patterns of vertical motion.

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Kenneth H. Bergman
and
William D. Bonner

Abstract

A simple numerical experiment demonstrates that if the errors in satellite-derived temperatures are correlated spatially, the error of an optimum interpolation objective analysis using such temperature data is increased. Moreover, increasing the density of such observations beyond a, threshold value (a spacing of about 400 km in the experiment) does not yield any significant improvement in analysis accuracy, in contrast to the cage of observations with spatially uncorrelated errors.

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Kenneth H. Bergman
and
Edward A. O'Lenic

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Frederick G. Finger
,
James D. Laver
,
Kenneth H. Bergman
, and
Vernon L. Patterson

A wide variety of current climate products are being developed, produced, and disseminated to a diverse group of users by the Climate Analysis Center (CAC). The Climate Assessment Data Base (CADB), a major resource used to generate many of these products, is described, with emphasis on its history, real-time global data input, quality control techniques, and data estimation procedures. Several sample products used for climate assessments are shown and discussed in detail. The full spectrum of product types ranges from simple automated tables, indices, and charts to more complex interactively derived products. Dissemination methods include mail, special dial-up communication computers, weather facsimile, internal National Weather Service communication links, and press releases. Future plans for CAC's User Information Service are summarized.

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