Evaluation of ERA-40, NCEP-1, and NCEP-2 reanalysis air temperatures with ground-based measurements in China Academic Article uri icon

abstract

  • We assess the correspondence of reanalysis air temperatures from ERA40, NCEP1, and NCEP2 with homogenized observational data from China for 19582001 and 19792001. Results indicate that climatologies for annual ERA40, NCEP1, and NCEP2 air temperatures are lower than observations by 0.93C, 2.78C, and 2.27C, respectively. Large negative differences for most of western China primarily contribute to this cool bias. Error analysis indicates that the internal coherence of ERA40 data is better than NCEP1 or NCEP2. Although NCEP2 air temperatures represent an improvement over NCEP1, biases of NCEP1 and NCEP2 data relative to observations are still much larger than for ERA40. Areas with positive/negative air temperature differences (dT) between reanalysis and observational data correspond to negative/positive elevation differences (dH). The high correlation coefficients of 0.94, 0.88, and 0.85 between dT and dH for ERA40, NCEP1, NCEP2, and observations, respectively, illustrate that the air temperature differences between reanalysis data and observations are primarily related to elevation differences. Furthermore, a spatial and temporal comparison of trends also indicates that ERA40 temperature changes correspond most closely to observed trends in China. In general, our comprehensive analysis of the three global reanalysis products indicates that, both on a seasonal and annual basis, ERA40 temperatures correspond most closely to observations, and biases are due mainly to the elevation differences.

published proceedings

  • JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES

author list (cited authors)

  • Ma, L., Zhang, T., Li, Q., Frauenfeld, O. W., & Qin, D.

citation count

  • 111

complete list of authors

  • Ma, Lijuan||Zhang, Tingjun||Li, Qingxiang||Frauenfeld, Oliver W||Qin, Dahe

publication date

  • August 2008