All of the questions below are linked to descriptive answers in this chapter of the Giovanni Online Users Manual regarding the Giovanni OMI Level-3 instance and the OMI L2G instance. Click the question of interest.
- What does OMI stand for? What satellite is OMI on?
- For what time period is OMI data available in Giovanni?
- What version of OMI data is currently provided in the Giovanni OMI?
- What OMI data types are available?
- What data parameters are available in the Giovanni OMI instance?
- What projections of the data are available? What is the spatial resolution of the data?
- What are the current data analysis and visualization (output) options in Giovanni OMI?
- How is the spatial area of interest selected in Giovanni OMI?
- How is the time period of interest selected in Giovanni OMI?
- Are there any limits on the time-period or spatial area that can be selected?
- What are the plotting preference options for this instance?
- What do the statistics mean in the time-series statistics output?
- I've always seen the Antarctic ozone hole depicted with TOMS data. Does OMI detect the Antarctic ozone hole too?
Go to the OMI L2G page >
What does OMI stand for? What satellite is OMI on?
OMI stands for Ozone Monitoring Instrument. OMI was built by the Netherlands's Agency for Aerospace Programs (NIVR) in collaboration with the Finnish Meteorological Institute (FMI). OMI is an instrument on NASA's EOS Aura satellite.
For what time period is OMI data available in Giovanni?
OMI data currently available in Giovanni is from October 1, 2004 to present.
What version of OMI data is currently provided in the Giovanni OMI?
Almost all of the OMI data available in the Giovanni are from the current version which is V003.
What OMI data types are available?
The OMI data types in Giovanni are Level 3 and Level-2G geophysical products.
What Level-3 (global gridded) parameters are available in the Giovanni OMI instance?
The Level-3 data parameters currently available in the Giovanni OMI instance are listed below. Each data parameter is linked to a short description in the Data Parameter Appendix. New data parameters will be added in the near future (see above) when available. The value in the parentheses indicates the data product(s) containing that parameter.
Daily 0.25 x 0.25 degree grid
Daily 1.00 x 1.00 degree grid
What projections of the data are available? What is the spatial resolution of the data?
Four data projections are available in this Giovanni instance; Cylindrical Equidistant, which is the default projection; North Polar Stereo and South Polar Stereo; and Robinson. Note that the data for area maps and animations will always be plotted in the default projection (i.e Cylindrical Equidistant) first. The other projections can be selected in the "Submit Refinements" step (see the question on plotting preferences below).
Giovanni provides Level-3 data at two spatial resolutions: 1.0° x 1.0°, and high-resolution 0.25° x 0.25°.
What are the current data analysis and visualization (output) options in Level-3 OMI Giovanni?
The Giovanni for Level-3 OMI instance provides the following analysis and visualization options:
How is the spatial area of interest selected in the OMI Giovanni?
The spatial area of interest can be selected by either of the two methods described below
Java applet map: The Java applet map can be utilized to "click and drag" a selection box to designate the spatial area of interest.
Geographic coordinates: The geographic coordinates of the corners of the spatial area box can be input individually. This method can be used if Java is not enabled.
How is the time period of interest selected in the OMI Giovanni?
The starting date (year/month/day), and the ending date (year/month/day) for the analysis are selected using the calendrical menus on the Giovanni interface page. Error messages will be generated if the submitted selections for year, month, and day do not correspond to the data set time range, or if the end month or end day precede the start month or start day.
Are there any limits on the time-period or spatial area that can be selected?
As described in the answer above, the selected time-period must correspond to a time-period occurring within the time range of OMI mission data. If the start date or end date is not in the time range, an error will be generated and data processing will not be possible.
What are the plotting preference options for this instance?
The plotting preference options are described in the Plot Preferences chapter of the Giovanni Online Users Manual.
After the initial output has been generated, the temporal and spatial ranges (constraints) and plotting preferences can be changed, and a new output generated, using the "Submit Refinements" button. For the TOMS or OMI Giovanni instance, this is when the North or South Polar Projections can be selected. Note: If a region in the Southern Hemisphere is selected and the "North Polar Stereo" option is chosen by mistake, the system will revert to the original interface so that correct selections can be entered.
What do the statistics mean in the time-series statistics output?
The statistics that are provided with the time-series output are grid count, Standard Deviation, Maximum, and Minimum. Grid Count indicates the number of grid cells used to generate the mean value shown in the time-series. Standard Deviation is a measure of the variability in the data. Maximum indicates the maximum value within the selected plot area for each time step (a day in this instance), and Minimum indicates the minimum value within the selected plot area for each time step. Further detail on these statistical quantities can be found in the documention of the Time-Series Statistics operation.
I've always seen the Antarctic ozone hole depicted with TOMS data. Does OMI detect the Antarctic ozone hole too?
Yes, it does. In fact, OMI data is now the official NASA ozone hole monitoring data, as the Earth Probe TOMS mission has ended.The EP-TOMS satellite transmitter failed in December 2006.