All of the questions below are linked to descriptive answers in this chapter of the Giovanni Online Users Manual regarding the Giovanni TOVAS instance. Click the question of interest.
1. What does TOVAS stand for? What does TRMM stand for ?
2. What are the instruments on the TRMM satellite? Does Giovanni have data from all of the instruments on TRMM?
3. Why are there two different Giovanni TOVAS instances?
4.. What time period does the TRMM data in Giovanni cover?
5. What version of TRMM data is currently provided in Giovanni TOVAS?
6. What TRMM data types are available?
7. What data parameters are currently available in the Giovanni TOVAS instances?
8. How are the data organized? What is the spatial resolution of the data?
9. What are the current data analysis and visualization (output) options in Giovanni TOVAS?
10. How is the area of interest selected in Giovanni TOVAS?
11. How is the time period of interest selected in Giovanni TOVAS?
12. Are there any limits on the area or time-period of interest that can be selected?
13. What are the plotting preference options for data visualization in TOVAS?
14. The 3-hourly TOVAS instance has a "precipitation" data parameter, while the TRMM Level-3 Monthly instance has a "Rain Rate" data parameter. Are these two different names for the same quantity?
15. Is a climatological anomaly function available in Giovanni TOVAS?
What does TOVAS stand for? What does TRMM stand for?
TOVAS stands for the "TRMM Online Visualization and Analysis System", where TRMM is the acronym for the Tropical Rainfall Measuring Mission.
What are the instruments on the TRMM satellite? Does Giovanni have data from all of the instruments on TRMM?
The instruments on TRMM are the Precipitation Radar (PR), the TRMM Microwave Imager (TMI), the Visible and Infrared Scanner (VIRS), the Cloud and Earth Radiant Energy Sensor (CERES), and the Lightning Imaging Sensor (LIS). Giovanni has data from the PR, TMI, and VIRS instruments. CERES data is available from the Langley DAAC.
Why are there two different Giovanni TOVAS instances?
Giovanni has two different TOVAS instances for TRMM Level-3 Monthly data and 3-hourly TRMM and Other Rainfall Estimate precipitation data. The 3-hourly TOVAS only provides preciptation and relative error data products. The larger and more refined data products from the mission are in the TRMM Level-3 monthly data TOVAS instance.
What time period does the TRMM data in Giovanni cover?
Most data productsin the TRMM Level-3 Monthly instance are from December 1997 to present; two products commence in January 1998. Data in the 3-hourly instance is from December 31, 1997 to present.
What version of TRMM data is currently provided in Giovanni TOVAS?
The current version of TRMMdata is Version 6, designated by the "006" in the data product shortname.
What TRMM data types are available?
Thedata types available in Giovanni TOVAS include precipitation-related parameters, related cloud properties (cloud water and cloud ice), and related atmospheric parameters (latent heating). Precipitation parameters are subdivided into stratiform or convective categories. Pixel count statistics are also included.
What data parameters are currently available in the Giovanni TOVAS instances?
The 3-hourly TRMM and Other Rainfall Estimate instance includes the following parameters:
The TRMM Level-3 Monthly Instance includes the following parameters:
How are the data organized? What is the spatial resolution of the data?
The data are organized according to different algorithm groups: Giovanni includes 3B42, 3B43, 3A12, and 3A25 data algorithm groups. The spatial resolution of the data is either 0.5 degree or 5.0 degree.
What are the current data analysis and visualization (output) options in Giovanni TOVAS?
There are currently 12 data analysis and visualization options in TOVAS:
- Overlay of Lat-Lon Maps
- Cross-Map Plot, Longitude-Pressure
- Cross-Map Plot, Latitude-Pressure
- Cross-Map Plot, Time-Pressure
- Latitude-Time Hovmöller diagram
- Longitude-Time Hovmöller diagram
- Lat-lon map, time-averaged
- Scatter plot, time-averaged
- Time Series, Area Statistics
- Vertical Profile
How is the area of interest selected in Giovanni-3 MLS?
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 time period of interest selected in Giovanni-3 MLS?
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. The date ranges for the data in Giovanni TOVAS are shown next to the menus and are updated as new data is received.
Are there any limits on the area or time-period of interest that can be selected?
The spatial area is limited by the orbit of the TRMM satellite, between 35° North and South. The scanning swath acquires data to approximately 45° North and South. The spatial limits of the data are shown on the selection map.
There is no time range limit. Longer time ranges will take considerably more time for initial data acquisition from the archive (fetching) and a longer period of elapsed time for processing. This limitation is particularly important for the large volume of data that could potentially be processed in the 3-hourly Giovanni TOVAS instance.
What are the plotting preference options for data visualization in TOVAS?
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.
The 3-hourly TOVAS instance has a precipitation data parameter, while the TRMM Level-3 Monthly instance has a Rain Rate data parameter. Are these two different names for the same quantity?
precipitation and Rain Rate are calculated with different algorithms, but they both have units of millimeters per hour (mm/hr). precipitation provides " gridded estimates are on a 3-hour temporal resolution and a 0.25-degree by 0.25-degree spatial resolution in a global belt extending from 50 degrees South to 50 degrees North latitude." Rain rate is defined as "the monthly mean of the instantaneous rain rate at the surface in 0.5° x 0.5° boxes from 40°N x 40°S."
The following links provide more information:
Is a climatological anomaly function available in Giovanni TOVAS?
Yes. The climatological anomaly function utilizes the TRMM data climatology and is available for the 3B43 Rain Rate data parameter only.