Help for java ACARS Display

HELP FOR THE MAP (the main page)

Detailed video tutorials are available at http://acweb.fsl.noaa.gov/videos/.

Move the mouse cursor over the map to display data whenever the cursor is over a data point. The data shown is, clockwise from the upper right:
- altitude in ft (assuming a standard atmosphere)
- altitude in mb (true)
- Aircraft ID (FSL's unique encoded value)
- Origin and -> Destination airports
- Wind direction and speed (kts)
- Temperature (Celsius)
- Observation time (UTC)
To zoom, drag the mouse (hold the mouse button down while moving the mouse) diagonally across a region to create a zoom box. When you release the mouse button, the zoom-boxed region will zoom to fill the screen. (The zoom-box shape may not follow the mouse cursor as you expect. This is because the zoom-box is constrained to have the same aspect ratio as the overall map.)
Click on an ascent or descent portion of a flight track to produce a sounding, which will come up in a separate window. Ascent and descent segments that are likely to provide useful soundings are indicated by solid lines. (See instructions below on how to use the sounding window.)
Right-click the mouse anywhere on a flight track to get textual data (in a separate window).
Shift-click (hold down shift while clicking the mouse) anywhere on the display to reveal a window with map parameters that can be used in setting a new default map.
Drag one of the orange balls on the altitude bar on the right to change the altitude range displayed. If you are displaying a limited altitude range, you can also drag the color bar between the balls to shift the range. Click anywhere on the altitude bar to (re)display the entire altitude range.
Use the WindSpd button to color-code data by wind speed rather than by altitude.
Use the Barbs button to display or hide wind barbs.
Drag the orange ball on the min spacing slider to show fewer data. (This is particularly useful when displaying wind barbs.)
Use the Overlays button to display or hide airports and/or U.S. VORs. (The name, location and elevation will be displayed when the cursor is over the airport or VOR.)

HELP FOR SOUNDINGS (the soundings window)

Once you have clicked on the map to generate a sounding, it will appear in the sounding window. Sounding points further than 100 nm from the airport are coded in gray. The sounding consists of a Skew-T plot, a hodograph or flight track map, and a wind speed plot. The following thermodynamic indices are also shown, if available:

CAPE (Convective Available Potential Energy) in J/Kg
CIn (Convective inhibition) in J / Kg
PW (Precipitable water) in Kg/m^2
Helic (storm-relative helicity) in m^2/s^2
TT (Total Totals index)
KI (K index)
LI (Lifted index)
SW (Showalter index)
LCL (Lifted Condensation Level)
iCAPE (approximate CAPE based on the lifting of a parcel that you input)
iCIn (approximate CIn based on the lifting of a parcel that you input)
iLCL (LCL based on the lifting of a parcel that you input)

A parcel may be specified by clicking with the mouse at any point. The parcel will ascend from that point (using the environmental dewpoint at that pressure), and regions of CAPE and CIn will be indicated. The Lifted Condensation Level (cloud base) for the parcel is indicated by a short horizontal black line on the parcel trajectory. Right-clicking with the mouse will bring up a selection window that will allow you to select the initial parcel dewpoint, temperature, and pressure. Click on a sounding's button to remove the parcel trajectory. Thanks to Tom Whittaker of the University of Wisconsin for providing the core of the code that performs this task.

(Against Tom's advice, and to facilitate stability calculations using ACARS soundings that often lack humidity data, iCAPE and iCIn are calculated using the temperature difference between the parcel and the sounding, rather than the virtual temperature difference. According to Doswell and Rasumssen (1994, Weather and Forecasting, 9, pp 625-629), this may cause errors > 30% for values of CAPE below 500 J/Kg and similar errors in CIn, but smaller error for larger values.)

The hodograph shows wind speed in kts, and height in km. For aircraft soundings, the hodograph window optionally shows the bearing and range from the airport to the aircraft. A "Toggle button" in the hodograph window switches between the two.

The sounding has two default altitude ranges, one extending up to 150 mb and the other to 10 mb. Each of these ranges can be zoomed by dragging the mouse diagonally across the portion of the Skew-T plot desired. Unzoom by clicking a 'scale' button. (To drag, hold the mouse button down while moving the mouse. When you release the mouse button, the zoomed region will fill the plot.) (The zoomed region will have the same aspect ratio as the main plot, so the red rectangle that appears may not follow the mouse quite the way you think it should.)

Some aircraft, because of hardware limitations, report altitude as barometrically-adjusted below 17,000 ft (the AMDAR standard is to always report altitude with respect to a standard atmosphere). For these aircraft, we use barometric-altitude if standard pressure altitude is not available. On sounding plots, the temperature trace is shown in brown is the altitude reported was barometrically adujsted.

Other functions are as follows:

Move the mouse along the sounding to see the following printed at the level of the mouse point (from left to right):

The pressure in mb, and the pressure altitude in km and feet. (For ACARS data, the time, bearing and range from the airport are also shown.)
The dewpoint in Celsius (and also Fahrenheit below 750 mb).
The temperature in Celsius (and also Fahrenheit below 750 mb).
The wind direction and speed in knots.
A highlighted wind barb.
A highlighted portion of the wind speed curve.
A highlighted portion of the hodograph or flight track

In addition, the temperature and pressure for the cursor point is indicated below the cursor.

Click on the Load Other Soundings button to pop up the choose sounding window. In this window you can

Enter a 3- or 4-letter METAR, RAOB, or ACARS-airports site name. (Contact Bill Moninger if your favorite METAR site is missing.)
OR, enter a latitude and longitude (in decimal, with west and south being negative), separated by a comma.
Enter a starting valid time by choosing a year, month, day, and hour (UTC).
Enter the number of hours of soundings you would like to display. MAPS (RUC) soundings are generally available for the past 16 hours, and for intermittent hours up to 36 hours into the future. Remember that RAOBs are only available at 0 UTC and 12 UTC.
Click on a data source, MAPS, RUC2, RAOB(s), Profiler(s) or ACARS.
Soundings will appear one after another on the plot as soon as they're ready, and a button with each sounding's information will appear below the plot.

Once a sounding is loaded, you can use its button to (re)display it.

Click on a button to clear the display, and display one sounding. It generally takes less than a second for an already-loaded sounding to reappear.
Shift-click one or more buttons to add additional soundings to the plot. (Shift-click means hold down the shift key while clicking the mouse button.)
Control-click a sounding's button to remove the sounding and its button.

The sounding information shown on each button consists of the site name, and a code:

code R indicates a RAOB sounding
code P indicates a Profiler sounding
code A indicates a sounding from a MAPS analysis
code a indicates a sounding from a RUC-2 analysis
code Fn indicates a sounding from a MAPS n-hour forecast
code fn indicates a sounding from a RUC-2 n-hour forecast.
For instance "DEN(F9)" indicates that the sounding data are from a MAPS forecast based on an analysis from 9 hours before the indicated valid time.
codes Up and Dn indicate ACARS ascent or descent soundings, respectively.

HELP FOR PRINTING

Unfortunately, java doesn't have convenient printing capabilities, so you will have to use a screen capture program, or cut-and-paste, to capture and print windows showing graphical data. In Microsoft Windows, you can use alt+prtscn to capture the browser window, then use ctrl+v to paste the image into MS paint or some graphics manipulation package. You can crop the imaage by drawing a box around the area of interest, then select, copy, and paste the cropped region into, for instance, powerpoint or word. We have also had good experiences with HyperSnap-Dx, a shareware program from Hyperionics.

In Unix, a shareware program called XView does the job.

For java windows that show textual data, you can copy the data in the usual way and paste it into another program for printing, e-mailing, or other processing.

Known bugs, or "issues"

Satellite images are not supported

Detailed help

Solid lines connect data points that can probably make useful soundings. Lines are shown if:

Barbs are not being shown, and
The max altitude of the flight is > 10,000 ft, and
The minimum (pressure) altitude of the aircraft is within 2000 ft of the (true) elevation of the airport, and
There is no data gap greater than 2500 ft in altitude for data points below 10,000 ft.

Data points taken within the last 20 min (with respect to the latest time loaded) are plotted at twice the size of other points (unless barbs are being displayed).

Buttons on the map window:

Several of the buttons reveal other windows. These windows can be closed in the normal way, or by clicking the button again.

(If a button is indented, it means its corresponding window is displayed, but it may be covered by other windows. To bring a window to the front, click the indented button twice.)

Load lets you load data. Over a 28.8k modem, it takes about 7 sec per hour of data. To save time, it is possible to load data of only a particular type or with a particular location. On a slow connection, this can speed up loading. But, the program on our server that subsections the data is itself slow, so you may be better off downloading the entire data set for a particular time range. The latest option loads the latest n hours of data.
Select lets you display data from various sensors and/or sources.
Available sensor types are
- g - vertical acceleration data. THESE DATA ARE KNOWN TO BE INCORRECT!
- edr - eddy dissipation rate (a measure of turbulence). These data are not quality-controlled and should not be used for turbulence verification. We expect quality-controlled edr data to be available sometime in 2005.
- vapor - only 9 vapor sensors remain good (Feb 2003), and these will fail over the next several months.
- vg - vertical gust. These data are believed to be correct.
- icing - this is experimental icing data from Delta airlines, in support of an FAA sponsored research project.
Data sources are probably of interest to quality control researchers. Possible data sources are
- ACARS - data found in only the ACARS data stream (i.e., decoded by FSL)
- MDCRS - data found in only the MDCRS data stream (i.e., decoded by ARINC)
- ACARS & MDCRS - data found in BOTH the ACARS and MDCRS data streams.
- AMDAR - AMDAR data
- TAMDAR - TAMDAR data
WindSpd lets you color-code the observations by wind speed.
Barbs lets you display or hide wind barbs.
Soundings reveals the Soundings window.
Un-zoom undoes your most recent zoom or roam.
Default sets the projection to your default map. If you haven't set a default, this will be the U.S. (Lambert Conformal Conic Projection.) To set a default map other than the U.S., follow the Set initial defaults link above the display.
World sets the projection to the world (Cylindrical Equidistant). Zooming in on any region of the world will result in a Lambert Conformal Conic projection of the zoomed-in region.
Overlays lets you display or hide various overlays, such as Airports and U.S. VORs. When these are displayed, moving the cursor over an an will display its identification.
Lat/Lon readout indicates the position of the cursor.
Overview reveals an overview window, which shows where your zoomed region is. You can drag the little window that shows in the Overview window to change the focus of (roam) the big map. The Un-zoom button also undoes roaming.

Other information

Soundings are identified with the origin or destination airport listed in the ACARS reports. This is unlike what is done in the non-java displays in which soundings are associated with the nearest airport. We hope this new identification will be more accurate.
Clicking the right button, or shift-clicking (holding down the shift key and clicking the left mouse button) anywhere on a flight track will generate textual output for the entire flight. The columns in this output should be self-explanatory, with the exception of the first two columns on the left. The first, "S", is the data source. Possible values are
- 0 - data found in the ACARS data stream (i.e., decoded by FSL) only
- 1 - data found in the MDCRS data stream (i.e., decoded by ARINC) only
- 2 - data found in BOTH the ACARS and MDCRS data streams.
- 3 - AMDAR data
- 4 - TAMDAR data
- 9 - data source not determined (before Feb 2003)
The second column, "F" is the data quality flag. Its possible values are:
- 0 - good data
- 1 - bad temp
- 2 - bad wind
- 3 - both bad
- the above value + 4 if the altitude was barometrically-adjusted.

Please send comments or suggestions to Bill Moninger at Bill.Moninger@noaa.gov. If you're reporting a problem, please indicate what browser (with version number), operating system, and hardware you are running on. Also, it would be helpful if you could open your browser's 'java console' and send me the last several lines.