FLEXPART Model/FlexplorerManual

This is the manual for Flexplorer. Use Flexplorer to browse and plot any of your flexpart output files, and overlay meteorological data from all available ECMWF data files.

Starting Flexplorer

To bring up the Flexplorer window, follow these steps:

  1. login on oluf

  2. change to user flexpart ( 'su flexpart' )

  3. type 'bash' to get a bash shell

  4. type 'mlj' at the bash shell prompt to start matlab, -or-

     type '/opt/matlab75/bin/matlab -nodesktop' to start matlab from any other shell

  5. type 'flexplorer' at the matlab prompt to start flexplorer

When you start flexplorer, it will show a toolbox window (Fig. 1) and an empty plotting window. It will also automatically load the current forecast/analysis data for the Asian tracer. The lists and options are populated according to the available dates and tracers. If you want to examine the data from a different FLEXPART run, click the "..." button next to the path box to bring up a pick-header-file-dialog, or type the path to the header file directly into the edit field.

• Fig. 1: Main settings window*

A Short Tutorial

This short walkthrough/tutorial describes how to produce the graphic shown below (Fig. 2). It shows CO tracer between 9-10km altitude as shading, overlaid by the 2pvu dynamical tropopause on a 315K isentrope in black contours, and wind speed at a 315K isentrope in green contours. The tutorial consists of 3 steps:

1. Specifying the projection
2. Plotting the FLEXPART tracer
3. Overlaying the meteorology fields

• Fig. 2: The aim of this tutorial: A figure showing CO tracer at 9-10km, PV at 315K, and velocity at 315K*

Specifying the projection

We want to use a stereographic projection, centered over the Alaska/Bering Strait region.

• Select "Stereographic" from the Proj pulldown (Fig. 1)

• Specify -180 as CLon (central longitude) and 65 as CLat (central latitude)

• Specify -130 as RLon (rectangle longitude) and 15 as RLat (rectangle latitude)

That's the projection. Other options include the Miller projection, which is of Lat-Lon type, and the Polar stereographic, which basically works as the stereographic projection. Good settings for a plot of the Arctic are for example CLon=0, CLat=90, RLon=90, RLat=70.

Plotting the FLEXPART tracer

Now we want to pick the tracer to be displayed, its level and date.

• Choose the 9-10km level from the levels list (Fig. 1)

• Choose the AS-CO tracer from the tracer list

• Choose "Concentration" from the Variable pull-down

• Chose a date that is at least 2 days before the current date (e.g. 29 Feb. 2008) from the date pull-down. ECMWF data are only available two days after the current date.

• Press "Plot" to get a first view of the tracer field.

Overlaying the meteorology fields

Finally, we want to overlay some meteorological fields. The easiest possibility is to pick one or two pre-defined overlays from the Overlays pull-down in the main window (Fig. 1). The most common fields are available there, such as

  MSL at SFC    Mean sea level pressure (hPa)
  IWV at SFC    Integrated water vapour (mm)
  T at 850hPa   Temperature at 850hPa (C)
  VEL at 200hPa Horizontal wind velocity at 200hPa (m/s)
  T2M at SFC    2m temperature (C)
  Z at 1000hPa  Geopotential at 1000hPa (mgp)
  TCC at SFC    Total cloud cover (0..1)
  W at 700hPa   Vertical velocity at 700hPa (m/s)
  TP at SFC     Total precipitation (mm)

Since the variables we want to overlay are not yet available from the pull-down, we have to define them first. This step is a bit complex, but provides quite powerful possibilities for interactive data exploration.

• Click the "..." button next to the Overlay 1 pull-down to bring up the Overlay settings window (Fig. 3).

• Select "PV" from the variable pull-down

• The Autorange check, or the min and max edit boxes, are only used if you are creating a shaded variable. We are creating a countour overlay, so just leave everything as it is.

• Enter the contour values "[1.0 1.5 2.0]" into the contour values edit box. Do not forget the squared brackets if you provide arbitrary values. You could also use the matlab notation "1.0:0.2:2.0" to create the contours at 1.0, 1.2, 1.4, 1.6, 1.8 and 2.0. The third alternative is to enter just one number, e.g. "5" without squared brackets, this will choose 5 contour levels according to the range of the data.

• Untick the Shading box to create a contour overlay.

• Untick the Labeling box, as drawing labels is quite time-consuming.

• Leave the Color edit at "k" for black.

• Leave the Opacity slider at 100%. This can be used to overlay several shaded variables, e.g. tracer and cloud cover.

• Select theta as the vertical level, and enter 315 into the level edit box.

• Press "Add" to add the new variable settings to the Overlay 1 pull-down. You have now created a new plot variable, named "PV at 315K (contour)". If you want to edit your settings (contour values, color), you can make your edits and then press the "Edit" button to update the settings.

• Press "Plot" to view the tracer with overlaid contours at the dynamical tropopause at 315K.

• Now, go ahead and create a new variable for velocity at the 315K isentrope as Overlay 2. Bring up the overlay settings, pick the variable "VEL", contour levels "[40 50 60 70]", color "g", and the vertical coordinate settings as before.

• Press "Plot", and hopefully you see a similar result as in Fig. 2.

• Fig. 3: Overlay display settings window*

Limitations

Several features still need to be implemented. These include:

• PV and altitude as vertical coordinates are not working yet

• Geopotential to be added as a variable

• Relative humidity to be added as a variable

• Vorticity to be added as a variable

• Divergence to be added as a variable

• The plot settings for the tracer variable have to be implemented