Estimates of Global Analysis Error from the Global Weather Experiment Observational Network

Abstract Objective analysis provides a regular representation of the atmospheric state for numerical forecasting and climate studies. The present observing system has numerous deficiencies which present analysis techniques can only partly remedy. Consequently, objective analyses contain error—referred to here as E0. The present experiment provides estimates of E0. The experiment is based on the OSSE (Observation System Simulation Experiment) concept. Time mean and transient errors are calculated and displayed as a function of altitude, latitude, longitude and also spectrally. The experimental results show substantial analysis errors south of 60°S and in the stratosphere. For some variables, the relative error below 850 mb and in the tropics is also large.