The NCEP/NCAR 40-Year Reanalysis Project

Abstract

This chapter aims to update the documentation of the National Centers for Environmental Prediction (NCEP)/ National Center for Atmospheric Research (NCAR) system design, output, and plans for distribution. It summarizes the coupling with the ocean reanalysis and contains an assessment of the reliability of the reanalysis output and the impact of changes in the observing system. The NCEP/NCAR Reanalysis Project has two unique characteristics: the length of the period covered and the assembly of a very comprehensive observational database. The complex quality control (CQC) system is included in the preprocessor but without the use of the first guess of the model. The method of CQC is used to quality control the rawinsonde heights and temperatures. The NCEP/NCAR reanalysis will produce 40 years of daily atmospheric and surface fields, which, for some variables, are close to a best estimate of the evolving state of the atmosphere.