Complex quality control of rawinsonde heights and temperatures, principles and application at the National Meteorological Center

The Complex Quality Control of rawinsonde reports on mandatory level Heights and Temperatures (CQCHT) was designed at the National Meteorological Center in Washington, D.C. and implemented into the NMC operational quality control system in 1991, replacing the previously applied Comprehensive Hydrostatic Quality Control (Collins, Gandin, 1990). According to the CQC approach, various more or less independent checking methods are first applied to the data, and results of each check are expressed in quantitative form, by so-called residuals, rather than qualitatively, by flags. After all checks have been applied to a given part of the report, the Decision Making Algorithm (DMA) analyses the-pattern of large residuals (if any), in order to detect rough errors in the data, to explain the origin of the error(s) and, if possible, to automatically correct erroneous data. The CQCHT DMA is an advanced, logically complicated algorithm. Although it contains very large number of operations, the required computer time is rather small because most operations are logical and because an overwhelming majority of reports are not distorted by rough errors.This Office Note is intended primarily for those specialists in meteorology and related fields, who may be interested to know more about the present stage in development of the quality control methods and particularly in design and application of the CQC approach. Basic principles of this approach are considered in detail, and various CQCHT checks are described, as is its DMA. Numerous examples, taken from the CQCHT operational outputs, are presented to illustrate the CQCHT performance in comparison with that of the previously applied CHQC algorithm. Some statistics of this performance are presented in the final part of the Office Note. William G. Collins, Lev S. Gandin. "April 1995." "This is an informally reviewed manuscript, primarily intended for informal exchange of information among NMC staff members." System requirements: Adobe Acrobat Reader. 1995 NWS (National Weather Service) NCEP (National Centers for Environmental Prediction) Library Public Domain 2285