Upper Air Plots
Radiosonde Observations (RAOBs)
Wind Profiler Plots

When you click on on the FX-Net menu bar, this menu opens up. The data within is all of upper air observations and forecasts. There are four main sections: upper air plots and graphics, **PROFILER**, **Aircraft**, and **RAOB** (radiosonde observations). Each will be described in more detail below.

Upper Air Plots
Upper air plots are plan view plots of data that are measured twice daily, at 0000Z and 1200Z, at the stations shown here in the continental U.S., and at others across the world. A balloon is released with measuring instruments attached (radiosondes) and measures temperature, humidity and wind as it rises through the atmosphere.
To load an upper air plot, choose from the menu bar and point to UA Plots. A new menu will open with two sections: **NCEP** and **RAOB**. Both have selections for the different pressure levels. NCEP plots display upper-air radiosonde observations (circle station symbol), aircraft reports (square symbol), and satellite measurements (star symbol). The RAOB plots will show the radiosonde observations only. Simply click on a level you want to display and it will load. If you choose one frame, the latest observations will plot, and if you choose more than one, you will get the latest number of observation times. Also, similar to plotting surface data, upper air plots will not plot all the observations initially. You will need to zoom once or twice to see all the data. This map has been zoomed once.

This upper air plot is from Sunday May 6, 2001 at 1200Z. The level is 500 mb. It is similar to a METAR surface plot, but has a couple differences. The parameters plotted are wind speed/direction indicated by the wind barb, sky cover, temperature, dew point depression, geopotential height and height tendency in tens of meters. These are usually available for the standard levels of 200 mb, 250 mb, 300 mb, 500 mb, 700 mb and 850 mb.

Radiosonde Observation Plots (RAOBS)

There are other types of plots that are created using these radiosonde data. Three that are available on FX-Net in the upper air menu are skew-T diagrams, hodographs and a list of convective parameters; and are brought up by clicking and then selecting a sub-menu under **RAOB**. When the sub-menu opens you would then choose your location to plot. The same applies to RAOB's that applied to Upper Air Plots, in that if you choose one frame, you get the latest observation, and more frames chosen give you that number of observations starting at the latest and going backward in time. When you load a station's RAOB, you get a window with a skew-T, a hodograph, a plot of 24-hour temperature change, and many convective weather parameters that are calculated from the data. To save space, I haven't shown the entire product as one piece, but you may take a look at what FX-Net loads when you select a RAOB station. For a better explanation of each, we will examine them seperately.

Skew-T diagram

This is just a part of what is loaded in the primary window when a RAOB site is selected. This is a skew-T diagram and is a trace of what the radiosonde recorded as it rose through the atmosphere. There is a temperature trace, a dewpoint trace and wind barbs plotted on the far right. For a short tutorial on skew-T diagrams see the Unisys Upper Air Sounding Details web page.

The skew-T usually loads ready to read and analyze, and zooming more than once is usually not necessary.



Hodograph

The image to the left is a hodograph that loads in the bottom left of the primary window when a RAOB station is selected and loaded. It appears just below the skew-T diagram. Notice that as it appears, it has very little available information. Once you zoom on it twice, all this information becomes available, as you can see by viewing this zoomed image.

For a short tutorial on reading hodographs, see this webpage from the College of DuPage.



Convective Parameters

Finally, when you choose a RAOB station from the upper air menu and load it into the primary window, you get these convective parameters listed in the bottom right of the window, to the right of the hodograph. As you can see in the image to the right, the information is cropped out of the window by FX-Net when it initially loads. If you zoom on the data once, it will all appear fully in the FX-Net window, and be readable. All this data is calculated using the data supplied by the radiosonde, and plotted on the skew-T and hodograph. For definitions of what these parameters are, see this Glossary of Weather Terms from NWSFO in Norman, Oklahoma.

Wind Profiler Plots
Wind profiler data comes from the profiler sites located at the points on this map. Wind profilers measure the atmoshpere with a longer wavelength than your standard radar, and measure the energy after reflection due to atmospheric density changes. Upon analyzing this type of radar data, wind speed and direction can be plotted from the ground up to about 11 km.


Here is an example of what you will see when you select , choose a profiler region under **PROFILER**, and then a profiler site in a cascading menu. Across the bottom is the time, on the image it is hourly on July 10, 2002. On the left vertical axis is height in meters; on the right, pressure in millibars. Thus, each vertical line of wind barbs represents the speed and direction of the wind in the atmosphere above the profiler at that time. If you select one frame, you will get the last 12 hours of data. If you select more than one frame, 6 frames for example, you will get 12 + 6 (18) hours of data in a loop of 12-hour increments.


When you choose Plots under **PROFILER**, a cascading menu opens and you may choose a level of the atmosphere for plotting profiler data. This loads differently than the other profiler data, as the data is hourly and shown in plan view. Selecting one frame gets you the last hourly observations, and more than one gets you that many hours previous, ending with the latest. The plot on the left is the profiler network's observations at 1200Z on April 13, 2005.