For the visualization the researchers developed a specific algorithm that allowed them to distinguish the courses of “Christian” and “Haiyan” from the rest of the global simulation. Accordingly, they were able to determine the atmospheric pressure at the ocean’s surface and the highest wind speeds in the vicinity of the lowest atmospheric pressure values. In a subsequent step they combined the lowest values with data on the cyclones’ paths. By examining various criteria – like certain threshold values for the wind speed, the storm’s duration, or the maximum vertical wind shear, which represents the difference in wind speed between two points in the Earth’s atmosphere – they were able to clearly identify the respective cyclones. The resulting visualization presents the results of the complex numerical simulations of the two cyclones.
The video shows how the storm “Christian” formed near Newfoundland and moved rapidly eastward over the Atlantic, toward southern England and over the North Sea. On October 28 it hit Denmark with wind speeds reaching 193 kilometers per hour. But the cyclone also lashed northern Germany with 190-kilometer-per-hour winds. The storm caused serious damage in Germany’s northern coastal regions, Denmark, the Netherlands, southern England and southern Sweden before crossing Finland on its way toward Russia, after which it finally dissipated.
The tropical cyclone “Haiyan” was one of the four most powerful cyclones since the beginning of record keeping in 1969. Forming in the northwest Pacific, it devastated broad swathes of the Philippines, costing thousands of lives. As it moved westward, it grew into a category-five typhoon, reaching wind speeds of 285 kilometers per hour over the Philippines. It then continued westward over the South China Sea, reaching Vietnam before it subsided.
- About the visualization
- Schubert-Frisius, M., F. Feser, H. von Storch, S. Rast, 2016: Spectral Nudging Sensitivity Study using an AGCM. Submitted to Mon. Wea. Rev.