Evaluation of Four Reanalysis Datasets against Radiosonde over Southwest Asia
Ali S. Alghamdi
Abstract
Upper-air observational networks in Southwest Asia (SWA) are geographically sparse and reanalysis datasets (RDs) are a typical alternative. However, RDs can perform with varying degrees of quality and accuracy due to differences in assimilation schemes and input observations, among other factors. Geopotential height (gph), air temperature (tmp) and horizontal wind (U and V) modelled by the Japanese 55-year Reanalysis (JRA-55), the European Centre for Medium-Range Weather Forecasts Reanalysis Interim (ERA-I), the ERA fifth-generation (ERA-5), and the National Aeronautics and Space Administration (NASA) Modern Era Retrospective Analysis for Research and Applications version 2 (MERRA), are compared with radiosonde observations at three standard vertical levels (850, 500 and 300 hPa). Results showed that most RDs represent the general climatology, and ERA-5 tended to show the smallest agreements in most cases. RDs did not show consistent performance across seasons, variables, and pressure levels. RDs tended to conduct reasonable estimates over subregions with less complex topography. RDs showed better resampling performance at the upper and lower ends of sounding data distributions more frequently than around the means for most of the variables. This highlights the high potential usefulness of RDs in studying extremes over the region.