Four bar graphs from the paper.
Anomaly correlation (AC) scores of 500 hectopascals geopotential height reforecast (black) from using the operational uncoupled GEFSv12 at 25 kilometers horizontal resolution, the coupled systems CGEFS-L (red, 50 kilometers horizontal resolution) and CGEFS-H (green, 25 kilometers horizontal resolution). The AC scores are shown for forecast lead time of week-1, week-2, weeks 3 & 4, and monthly in the regions of the Northern Hemisphere (NH, top left), Southern Hemisphere (SH, top right), the Pacific-North American (bottom left), and the Tropics (TR, bottom right). The asterisks (*) above the color bars signify that the difference between CGEFS and the reforecast average AC score is statistically significant at 95%. Credit: Zhu et al. [2023], Figure 2
Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
Source: Journal of Geophysical Research: Atmospheres

Improving the skills of weather forecasts with longer lead time is a perpetual challenge to the scientific and operational weather forecast community. In a new study, Zhu et al. [2023] describe one milestone of the forecasting system at the National Centers for Environmental Prediction (NCEP) with lead time of one to two four weeks.

Built on top of the current operational Global Ensemble Forecast System version 12 (GEFSv12), a new system is developed by fully coupling the atmosphere, land, ocean, ice and waves. Forecasting skills are assessed by using anomalies of 500 hectopascals geopotential height, atmospheric zonal winds at different heights, tracks and intensity of tropical cyclones, and the Madden-Julian Oscillation (MJO) among others. The new system is shown to have better forecast skills at different lead times than the uncoupled system.  

Citation: Zhu, Y., Fu, B., Yang, B., Guan, H., Sinsky, E., Li, W., et al. (2023). Quantify the coupled GEFS forecast uncertainty for the weather and subseasonal prediction. Journal of Geophysical Research: Atmospheres, 128, e2022JD037757.

—Minghua Zhang, outgoing Editor in Chief, JGR: Atmospheres

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