Review of Efforts to Minimize the Data Set Needed for Initialization of a Macroscale Prognosis

Abstract

For reasons of economy, it is necessary to minimize the size and scope of the data set to be collected for global analysis and prognostication of macroscale weather phenomena. For this purpose, it is generally agreed that a 12-hr observational frequency and a 500-km upper-air network spacing are adequate and consistent with each other. However, inasmuch as the observations may be influenced by mesoscale activity, may contain errors, or may not survive transmission, some redundancy is desirable. The requirement for covering the globe with a complete network of stations, based in large part on ships, buoys, and inhospitable land sites that are expensive to maintain, has been greatly alleviated by the success of satellite-borne indirect sounding systems. However, numerical weather prediction specialists are now faced with the problem of developing a four-dimensional data assimilation procedure to cope with the continuous influx of asynoptic reports from satellites, aircraft, balloons, and other moving platforms along with the reports from conventional stations. Studies to date have brought out one factor of special interest to the designers of a global observing system; that is, the data requirements for successful NWP may be substantially less stringent than is generally believed with respect to synopticity, errors, and variables to be reported.