A Comparison of Cyclone Track Statistics between the 7-km Cubed-Sphere GEOS-5 Nature Run (G5NR) and the GDAS Analysis

Validation of a nature run is a crucial step for an Observing System Simulation Experiment system. In this study, a new Nature Run (NR, called the G5NR) generated with the GEOS-5 system at very high resolution—using approximately 7 km grid point spacing on the cubed sphere)—at the NASA Global Modeling and Assimilation Office (GMAO) is validated by comparing cyclone track statistics between the G5NR and the analyses from NCEP Global Data Analysis System (GDAS). The number of cyclone genesis and lysis, cyclone speed and direction in extratropical regions are diagnosed using sea level pressure with the algorithm of Terry and Atlas (1996). It is found that the averaged minimum of sea level center pressure, cyclone direction and speed are well simulated in the G5NR. However, G5NR produces a greater number of cyclone than those in the GDAS analysis.