Two Years of Operational Comprehensive Hydrostatic Quality Control at the National Meteorological Center

Abstract

A comprehensive hydrostatic quality control (CHQC) procedure for rawinsonde heights and temperatures was implemented into operational use at the National Meteorological Center (NMC) in December 1988. The CHQC uses a sophisticated decision-making algorithm to detect so-called rough errors in rawinsonde observations and to confidently correct many of them. Statistics gathered over a two-year period are presented to provide information on the frequency, geographical distribution, and origin of these errors. During this period, approximately 7% of the rawinsonde reports received at the NMC contained a hydrostatically detectable error. The number of errors has stayed relatively constant over the two-year period. The geographic distribution of the errors is uneven, with most of them originating in countries where many of the steps involved in computing and coding the reports are performed manually. Other characteristics as well indicate that almost all problems that are detected by the CHQC are caused by human error. This article proposes several measures as a means of reducing these errors. An analysis of the performance of the CHQC, which reveals that fully 50% of the errors that are detected by the CHQC are corrected automatically by it as well, is also presented. Information about the remaining errors along with suggested corrections is made available to specialists in NMC's Meteorological Operations Division where a final decision is made. This type of information has been discovered to also be quite useful in monitoring the quality of data in near-real time. Its use has led to a quick resolution of many problems associated with data transmission and decoding procedures. Several examples are discussed.