Evaluation of the Atmospheric and Hydrological Cycle in the NCEP Reanalyses

An evaluation is carried out of the moisture fields, the precipitation P and evaporation E, and the moisture transport and divergence in the atmosphere from the global atmospheric National Centers for Environmental Prediction (NCEP) reanalyses produced with four-dimensional data assimilation. The moisture fields are summarized by the precipitable water which is compared with analyzed fields from NVAP based primarily on Special Sensor Microwave Imager (SSM/I) over the oceans and rawinsonde measurements over land, plus TIROS Operational Vertical Sounder (TOVS). The moisture budgets are evaluated through computation of the freshwater flux at the surface E - P using residual techniques from the divergence of the total moisture transport, and this is compared with the reanalysis E - P that is based upon a 6-hour integration of the assimilating model and thus depends on the model parameterizations. The P field is evaluated using Xie-Arkin Global Precipitation Climatology Project (GPCP) estimates. An atlas presents climatological means for the period 1979 to 1995 (17 years) and standard deviations for annual; seasonal and monthly values, and the differences between estimates. Anomalies for all the seasons throughout this period are presented for many fields.