Characteristics of Jet Streams

Characteristics of Jet Streams

Once you load the bundle, you should be able to view an image similar to Figure 1. This image is from the NAM model on January 30, 2004 at 00Z (7pm Eastern Time). The NAM model is a regional mesoscale model using enhanced terrain and improved parameterization of surface and precipitation processes. It produces forecasts out to 84 hours. There are two jet streams found in North America, the polar jet stream and the sub-tropical jet stream. However, the polar jet stream is more prominent because it is more influential on North American weather than the sub-tropical jet stream. The polar jet stream plays an important role in helping to forecast the tracks of storms and their development, especially during the northern hemispheric winter. It tends to move in a general west to east direction but often meanders into large loops to the north and south. These large loops in the jet stream are called troughs and ridges. Also, the strength and direction of the jet varies from day to day.

Figure 1 shows the polar jet stream as isosurface of wind speed at 45, 55, 65, and 75 m/s. Also plotted is: colored contours of surface temperatures, black contours of 300 mb geopotential heights with an interval of 120m, and 300 mb wind barbs. The contours of surface temperature illustrate the polar jet stream’s effect on surface temperature. The 300 mb geopotential height and wind barbs are to exemplify the polar jet stream's effect on the upper-level ridge and trough patterns as well as the direction of the polar jet stream (west to east).

Figure 1

Now click and hold the right mouse button and move the mouse up to rotate the IDV bundle so you can have a view of the jet stream from the ground to 16 km. It is hard to really visualize a jet stream from a 2-D map. Therefore, the ability to rotate this 3-D image in IDV really demonstrates the structure and elevation of the polar jet stream. It should appear like Figure 2:

Figure 2

Home Back Next