Evaluation of the Warm-Season Diurnal Variability over East Asia in Recent Reanalyses JRA-55, ERA-Interim, NCEP CFSR, and NASA MERRA

Abstract

Four recent reanalyses—the 55-yr Japanese Reanalysis Project (JRA-55), Interim ECWMF Re-Analysis (ERA-I), NCEP Climate Forecast System Reanalysis (CFSR), and NASA Modern-Era Retrospective Analysis for Research and Applications (MERRA)—are assessed to clarify their quality in representing the diurnal cycle over East Asia. They are found to present similar patterns/structure and summer progress of the mean wind diurnal cycle, whereas they exhibit some differences in diurnal amplitude, particularly for the low-level meridional wind. An evaluation with intense soundings suggests that the amplitude difference mainly results from the diurnal variation of mean bias that differs among reanalyses. The root-mean-square (RMS) error is found to have a diurnal variation more evident in CFSR and MERRA than that in JRA-55 and ERA-I, which strongly affects the representation of the varying diurnal amplitude at the peak hours of RMS error. Compared with satellite-derived rainfall, the four reanalyses are shown to reproduce well the rainfall diurnal cycle over East Asia in terms of large-scale terrain contrast, summer progress, and interannual variability. JRA-55 even presents a long-term increase of morning rainfall percentage over the east China plain over the past four decades, consistent with rain gauge observations. The four reanalyses exhibit some considerable discrepancies at regional scale; JRA-55 gives the best capture of the rainfall diurnal cycle over the Tibetan Plateau and the eastward propagation to the eastern lees. These results suggest that new reanalyses are potentially applicable for studying the large-scale diurnal variability over East Asia, whereas their different preferences, especially at regional scale, should be of concern in data application.

Equatorially Antisymmetric Features in the Initiation Processes of the Madden-Julian Oscillation Observed in Late October during CINDY2011

“…The assimilation scheme of the four-dimensional variational method was adopted in JRA55 using the forecast model T319/L60 (a spatial resolution of approximately 60 km). Satellite data including ocean surface wind microwave scatterometers and radiances from vertical sounders and micro-wave imagers were assimilated such that the quality of JRA55 was improved compared with the existing reanalysis datasets (e.g., Chen et al 2014). The qualitative patterns of averaged large-scale fields with the JRA55 in this study are largely consistent with other objective analysis datasets (e.g., ERA-Interim, Dee et al 2011).…”

The JRA-55 Reanalysis: Representation of Atmospheric Circulation and Climate Variability

“…Their evaluations revealed the improvement of JRA-55 in various aspects. For example, they evaluated the signatures of naturally induced variability in the atmosphere (Mitchell et al 2015), representation of the diurnal migrating tide in the stratosphere, extra-tropical cyclone activity, distribution of precipitation in the tropics, and diurnal cycle over East Asia (Chen et al 2014). Some of these evaluation studies are included in this paper.…”

Temporal and Spatial Variability of Wind Resources in the United States as Derived from the Climate Forecast System Reanalysis

“…Rahim et al (2013) showed a significant correlation between CFSR and QuikSCAT over the South China Sea. Most recently, Chen et al (2014) assessed the diurnal cycle of wind fields from the Japanese 55-year Reanalysis Project (JRA-55), ERA-Interim, CFSR, and the Modern-Era Retrospective Analysis for Research and Applications (MERRA) over East Asia using rawinsonde observation data from 22 sites over southern China. They noted that the four reanalysis datasets can represent the mean wind diurnal cycle, but they differ in the amplitude of the diurnal cycle.…”