MPO 674 Lecture 1

1. MPO 674 Lecture 1 1/17/12

2. Evolution of ECMWF forecast skill for varying lead times (3 days in blue; 5 days in red; 7 days in green; 10 days in yellow) as measured by 500-hPa height anomaly correlation. Top line corresponds to the Northern Hemisphere; bottom line corresponds to the Southern hemisphere. Large improvements have been made, including a reduction in the gap in accuracy between the hemispheres. SOURCE: ECMWF, adapted from Simmons and Hollingsworth (2002). f = forecast value, a = analyzed / observed value, c = climate

4. “Perhaps some day in the dim future it will be possible to advance the computations faster than the weather advances and at a cost less than the saving to mankind due to the information gained. But that is a dream.” L. F. Richardson Locations of meteorological stations from which Richardson obtained upper-air observations for his first numerical weather prediction. Squares marked 'P' provided atmospheric pressure values; those marked 'M' gave atmospheric momentum.

5. The ENIAC forecast starting at 0300 UTC, January 5, 1949. Left panel: Analysis of 500 hPa geopotential (thick lines) and absolute vorticity (thin lines). Right panel: Forecast height and vorticity (from Charney, et al., 1950). Height units are hundreds of feet, contour interval is 200 ft. Vorticity units and contour interval are 10–5 s–1.

6. Data Assimilation