Evaluation of a regional reanalysis and ERA-Interim over East Asia using in situ observations during 2013-2014

Abstract

n this study, the East Asia Regional Reanalysis (EARR) is developed for the period 2013-2014 and characteristics of the EARR are examined compared to ERA-Interim (ERA-I) reanalysis. The EARR is based on the Unified Model with 12 km horizontal resolution, which has been an operational numerical weather prediction model at the Korea Meteorological Administration since being adopted from the United Kingdom Meteorological Office in 2011. Compared to the ERA-I, in terms of skill scores, the EARR performance for wind, temperature, relative humidity, and geopotential height improves except for mean sea level pressure, the lower-air geopotential height, the upper-air wind, and the upper-air relative humidity. Similarly, RMSEs of the EARR are smaller than those of ERA-I for wind, temperature, and relative humidity, except for the upper-air wind and the upper-air relative humidity. With respect to the near-surface variables, the triple collocation analysis and the correlation coefficients confirm that EARR provides a much improved representation compared to ERA-I. In addition, EARR reproduces the fine-scale features of near-surface variables in greater detail than ERA-I and the kinetic energy (KE) spectra of EARR agree more with the canonical atmospheric KE spectra than ERA-I KE spectra. Based on the fractions skill score, the near-surface wind of EARR is statistically significantly better simulated than that of ERA-I for all thresholds, except for the higher threshold at smaller spatial scales. Therefore, although special care needs to be taken when using the upper-air wind and relative humidity from EARR, the near-surface variables of the EARR developed are found to be more accurate than those of ERA-I.