The Near-Real-Time, Global, Four-Dimensional Analysis Experiment During the GATE Period, Part I

Abstract

Global upper air and surface data for the entire GATE period from 15 June to 24 September 1974, were collected by the Data Assimilation Branch of NMC and mailed to GFDL. After processing these data, a four-dimensional analysis technique was applied for the entire GATE period, using a global numerical model. For a selected period, several different versions of the data processing scheme were tested. The resulting analyses were compared with each other and with the objective analysis of NMC in Washington D.C., and ANMRC in Melbourne. Overall, the analyses for the extratropics were satisfactory for the Northern Hemisphere, and to a lesser extent, for the Southern Hemisphere, though flow patterns are somewhat excessively smoothed. The analyses for the tropics were not of the same quality as those for the extratropics, and yet they were much improved compared with those of several years ago. A noteworthy point is that tropical cyclones were successfully represented in several cases.