Evaluation of tropical wind and reference pressure measurements: Numerical experiments for observing systems

This paper describes the results of numerical simulation experiments on observing systems conducted at the National Center for Atmospheric Research (NCAR) using a six-layer 5° mesh NCAR global circulation model. The first series of experiments is aimed at evaluation of proposed wind measurements at two levels in the tropical belt (25° N-25° S) and six levels in the equatorial belt (10° S-10° N), together with vertical temperature profiles including random and systematic errors. It is shown that the tropical wind measurements are needed in the tropics where temperature data alone are not sufficient to infer winds with acceptable accuracy. The second series is performed to determine the relative importance of reference pressure located at the surface and at the 12-km level for the hydrostatic pressure calculation from vertical temperature profiles. The third series is conducted to examine the desirability of temperature versus wind observations depending on geographical latitudes and to investigate minimum requirements of global meteorological observations.