Click on any of the questions below regarding the Giovanni MOVAS instance for further information.
- What is MOVAS?
- Is data available from both MODIS-Terra and MODIS-Aqua in Giovanni 3 MOVAS? What collection number are these data?
- What MODIS data types are available in Giovanni 3 MOVAS?
- What data parameters are currently available from MODIS in Giovanni 3 MOVAS?
- How are data parameters selected in Giovanni-3 MOVAS?
- What are the current data analysis and visualization (output) capabilities in Giovanni-3 MOVAS?
- How is the spatial area of interest selected in Giovanni 3 MOVAS?
- How is the temporal range of interest selected in Giovanni 3 MOVAS?
- Are there any limits on the time range that can be selected?
- What are the plotting preference options for data visualization in MOVAS?
- Why does it take such a long time to generate my first plot when using Giovanni-3 MOVAS?
What is MOVAS?
MOVAS stands for the MODIS (MOderate-resolution Imaging Spectroradiometer) Online Visualization and Analysis System. MOVAS was created by the technical staff of the Goddard Earth Sciences Data and Information Services Center (GES DISC), and is part of the GES DISC Online Visualization ANd aNalysis Infrastructure "Giovanni".
The current MOVAS (released in May 2007) is for MODIS Daily data files.
Is data available from both MODIS-Terra and MODIS-Aqua in Giovanni 3 MOVAS? What collection number are these data?
Data from both MODIS-Terra and MODIS-Aqua will be found in MOVAS. MODIS-Terra data begin in February 2000. MODIS-Aqua data begin in July 2002. Both Collection 4 and Collection 5 data are available. The Collection 4 data set terminates in August 2006 for MODIS-Terra, June 2006 for MODIS-Aqua. The Collection 5 data set is available through the current month.
What MODIS data types are available in Giovanni 3 MOVAS?
The data types currently available are MODIS atmospheric data related to aerosols and atmospheric optical conditions.
What data parameters are currently available from MODIS in Giovanni 3 MOVAS?
The data parameters now available in MOVAS are listed below. Each name is linked to a short description in the Data Parameter Appendix.
- Aerosol Small Mode Fraction
- Aerosol Optical Depth at 0.55 µm
- Angstrom Exponent Over Land, 470-660 nm
- Angstrom Exponent Over Ocean, 470-660 nm
- Atmospheric Water Vapor (Full, High, Low)
- Cirrus Reflectance
- Cloud Condensation Nuclei over Ocean (QA-weighted)
- Cloud Effective Radius Combined (QA-weighted)
- Cloud Effective Radius Ice Phase (QA-weighted)
- Cloud Effective Radius Liquid Phase (QA-weighted)
- Cloud Fraction (Day and Night)
- Cloud Fraction (Day Only)
- Cloud Fraction (Night Only)
- Cloud Optical Thickness Combined
- Cloud Optical Thickness, Ice Phase
- Cloud Optical Thickness, Water Phase
- Cloud Top Pressure (Day and Night)
- Cloud Top Pressure (Day Only)
- Cloud Top Pressure (Night Only)
- Cloud Top Temperature (Day and Night)
- Cloud Top Temperature (Day Only)
- Cloud Top Temperature (Night Only)
- Effective Radius Over Ocean
- Mass Concentration Over Land
- Mass Concentration Over Ocean
- Scattering Angle
- Water Vapor, NIR Method, Clear Sky
- Water Vapor, NIR Method, Above Cloud
How are data parameters selected in Giovanni-3 MOVAS?
Individual parameters are selected by clicking in the check boxes. An entire group may be selected by clicking the group box (leftmost column heading bar, next to the collection name and date range information). If this selection is performed, individual parameters may then be deselected by clicking in the appropriate check box(es).
What are the current data analysis and visualization (output) capabilities in Giovanni-3 MOVAS?
There are currently 12 data analysis and visualization options in MOVAS:
How is the spatial area of interest selected in Giovanni 3 MOVAS?
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. Note that decimal and not degree (seconds and minutes) coordinates must be entered.
How is the temporal range of interest selected in Giovanni 3 MOVAS?
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 beginning month or the end month are out of the data set time range, or if the end month is before the beginning month. Note that the time ranges are shown, but these are currently for the MODIS-Terra Collection 5 data set.If a temporal range in the MODIS-Terra dataset time range is chosen, but with MODIS-Aqua data selected for analysis, an error message will be generated if this temporal range is not in the MODIS-Aqua dataset time range. This error will be generated primarily with an incorrect starting date.
Are there any limits on the time range that can be selected?
No. Longer time ranges will take considerably more time for initial data acquiisition from the archive (fetching) and a longer period of elapsed time for processing.
What are the plotting preference options for datavisualizationin MOVAS?
The plotting preference options are described in the Plot Preferences section of the 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.
Why does it take such a long time to generate my first plot when using Giovanni-3 MOVAS?
When a data visualization is first generated, the data necessary for the visualization must be requested and acquired from the MODIS data archive before the data can be processed and the visualization generated. Once this data has been acquired, it is placed in a data "cache", allowing subsequent refinements to be made and generated much faster.