Global distribution of tropospheric ozone and its precursors:
An interactive web interface to display GEOS-CHEM results

With this web interface your will be able to interactively display global concentrations of tropospheric species (O₃, CO, NOx, and related species). The monthly averaged concentrations are calculated with a global three-dimensional model of tropospheric chemistry, GEOS-CHEM.

START THE INTERACTIVE DISPLAY PROGRAM

This interface is still work in progress, so I would love to hear your suggestions ! (jaegle@atmos.washington.edu). I haven't tested it with internet explorer or early versions of netscape. So if you have any trouble, let me know, and I will try to make the interface browser independent.

This web module was written using ION Script (IDL On the Net), which allows to publish interactive IDL applications over a networked environment. ION can call a set of IDL subroutines to generate the graphics based on user inputs, in this particular case I have used routines from the GAMAP package. The web site is run on a dedicated Linux web server (733 MHz Pentium III and 256 MB of memory). It was developed with funding from a NASA New Investigator Program in Earth Science grant to Lyatt Jaeglé. More interactive web tools are available here.

QUICKSTART GUIDE

Here is a rapid guide to using the web interface. Two plots will be displayed side by side. In General Options you can choose the type of plot you want, as well as the species to display for a given year and month of simulation. Region Selection will allow to you choose the latitude and longitude range of the plot, as well as the range of values to be displayed. Finally you have the choice of either directly plotting the result to the screen, saving it to a postscript file, or generate an animation over 1 year of model simulation. For more information, see below.

GENERAL OPTIONS:
For each plot you can select the following:

1. Select a plot type:

Zonal Average
Surface map
Map at 800 hPa (2km)
Map at 500 hPa (5 km)
Map at 300 hPa (10 km)
Map at 180 hPa (12 km)

Note that the levels are approximate. The GEOS meteorological dataset uses different vertical resolutions depending on the year.

2. Select a Month: You can either select a month between January and December or choose the annual average.

3. Select a species to plot: OH, NOx, O3, PAN (Peroxyacetyl Nitrate), CO, ALK4 (Lumped >= C4 Alkanes), ISOPRENE, HNO3, H2O2, ACETONE, MEK (Methyl Ethyl Ketone), ALD2 (Acetaldehyde) , RCHO (Lumped Aldehyde >= C3), MVK (Methyl Vinyl Ketone), MACR (Methacrolein), PMN (Peroxymethacroyl Nitrate), PPN (Lumped Peroxymethacroyl Nitrate), R4N2 (Lumped Alkyl N), PRPE (Lumped >= C3 Alkenes), C3H8, CH2O, C2H6, N2O5, HNO4, CH3OOH.
Please refer to the GEOS-CHEM tracers list for more information.

4. Select a year to plot: The following years and model versions are available:

1994, version 3.2. Contact person: Isabelle Bey (bey@epfl.ch)

Bey I., et al.,"Global modeling of tropospheric chemistry with assimilated meteorology: Model description and evaluation", J. Geophys. Res., 106, 23,073-23,096, 2001.

Bey I. et al.,"Asian chemical outflow to the Pacific: origins, pathways and budgets", J. Geophys. Res., 106, 23,097-23,114, 2001.

1995, version 4.16. Contact person: Arlene Fiore (afiore@fas.harvard.edu)

1996, version 4.6. Contact Person: Hongyu Liu (hyl@io.harvard.edu)

Liu H., et al., Sources of tropospheric ozone along the Asian Pacific Rim: An analysis of ozonesonde observations, J. Geophys. Res., 107(D21), 4573, doi:10.1029/2001JD002005, 2002.

1997, version 4.11. Contact person: Randall Martin (rvmartin@fas.harvard.edu)

2001, version 4.33. Contact person: Arlene Fiore (afiore@post.harvard.edu)

Fiore, A.M., et al., "Variability in surface ozone background over the United States: Implications for air quality policy", submitted to J. Geophys. Res., 2003.

2001, version 5.04. Contact person: Rokjin Park (rpark@fas.harvard.edu)

Benchmark run for version V5.04

All years are run with a horizontal resolution of 4x5, unless otherwise noted. To access the publications, please go to the GEOS-CHEM publications web page.

REGION SELECTION:
1. Select a latitude range between -90 and 90 degrees N.

2. Select a longitude range between -180 and 180 degrees E.
For the map plots, your latitude/longitude selection will determine the region to be plotted. For the zonal average plot, the concentrations will be averaged over the selected region.
Special cases:
**Minimum latitude=maximum latitude. If you select a single latitude by entering maximum=minimum (for example minimum latitude= 10 and maximum latitude= 10), then a 1-D plot of the concentrations will be displayed. For the map plots, you will see a line plot of concentrations as a function of longitude. For the zonal average plot you will see a line plot of concentrations as a function of altitude (the concentrations will be averaged over the range of longitude)

** Minimum longitude=maximum longitude. If you select a single longitude by entering maximum =minimum longitude, the result will be a line plot as a function of latitude for a map plot. The zonal average plot will display a cross-section at the chosen longitude.

Note: for now if you choose a single latitude and longitude for the map plots (resulting in a point), no results will be displayed.

3. Select a range of values to be plotted. You have two options:

Automatic selection of maximum and minimum value ranges (this is the default)
Manual selection: you choose a minumum and a maximum for each plot. For manually setting the value ranges you need to disable the Automatic option (click on the Automatic button).

Note: for OH the number you enter will have units of 10⁶ molec/cm³(if you enter a minimum of 1 and maximum of 5, the plot will only plot OH values between 1 10⁶ molec/cm³and 5 10⁶ molec/cm³).

DISPLAY OPTIONS
You can choose one of three display options:

Smooth pixel plot.
Coarse pixel plot. This will enable you to see the resolution of the model grid..
Black & White contour plot.

ACTION
Once all of the above options have been modified to your liking, you can choose one of three options to display the results:

PLOT. This will directly display the results on the screen after a few seconds.
Animation. With this option, twelve plots will be generated, corresponding to each month of the year you selected. This will take longer to generate. Once a plot appears on the screen, then click on the link as indicated. A separate window will appear with the animation. You will also be able to change the speed of the animation, stop and restart it.
Save as postscript file. In the plotting window you will see the following message: Click here to download the postscript file. Depending on your system you might need to right click on the link or to press the shift key and click.

Pressing EXIT will kill the plot control window.