All of the questions below are linked to descriptive answers in this chapter of the Giovanni Online Users Manual regarding the Giovanni Clouds and the Earth's Radiant Energy System (CERES) instance. Click the question of interest.
1. What is CERES?
2. What CERES data types are available in this instance?
3. What is the temporal resolution of the data in CERES Giovanni?
4. How are the Level 3 CERES data used in Giovanni gridded?
5. What is the current version of the CERES data available in Giovanni?
6. Which CERES data parameters are available for analysis?
7. How are data parameters selected for analysis?
8. What are the current data analysis and visualization (output) capabilities in CERES Giovanni?
9. How is the spatial range of interest selected?
10. How is the time range of interest selected?
11. Are there any limits on the spatial area or the time range that can be selected?
12. What are the plotting preference options for the data visualizations in CERES Giovanni?
13. Are there other sources of radiation data besides CERES Giovanni at the GES DISC?
14. Why is the time range of the data currently available in CERES Giovanni so short?
What is CERES?
CERES is a NASA instrument mission; the acronym stands for Clouds and the Earth's Radiant Energy System. The heritage of CERES is an Earth Observing System (EOS) instrument; there are actually two CERES instrument on both the Terra and Aqua satellites. A single CERES was orbited prior to the launch of the EOS satellites on the Tropical Rainfall Measuring Mission (TRMM). A CERES instrument is planned for the NPOESS Preparatory Phase (NPP) mission.
Each CERES instrument is a radiometer which has three channels - a shortwave channel to measure reflected sunlight in the 0.3 - 5 µm region, a channel to measure Earth-emitted thermal radiation in the 8-12 µm "window" region, and a total channel to measure entire spectrum of outgoing Earth's radiation. On Terra and Aqua, one CERES instrument operates in cross-track mode, to emulate the Earth Radiation Budget Experiment (ERBE) as well as the TRMM CERES mission, and the other operates in rotating azimuth plane (bi-axial scanning) mode. The acronym "RAP", for rotating azimuth plane, may be encountered in other CERES references.
What CERES data types are available in this instance?
CERES Giovanni currently provides Clear-Sky top-of-atmosphere (TOA) fluxes, Total-Sky (TOA) fluxes, Clear-Sky and Total-Sky surface fluxes, and one Region Parameter, Precipitable Water. Only data from CERES-Aqua is currently available in Giovanni.
What is the temporal resolution of the data in CERES Giovanni?
The Level 3 CERES data in Giovanni in Giovanni is available with monthly temporal resolution.
How are the Level 3 CERES data used in Giovanni gridded?
The Monthly Gridded TOA/Surface Fluxes data products contain hourly single scanner flux parameters averaged over regions in a 1.0° nested grid.
What is the current version of the CERES data available in Giovanni?
The data in CERES Giovanni is the Aqua Edition2A SRBAVG product.
Which CERES data parameters are available for analysis?
The following data parameters are provided in CERES Giovanni:
Top-of-Atmosphere (TOA) fluxes
How are data parameters selected for analysis?
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 CERES Giovanni?
How is the spatial range of interest selected?
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 range of interest selected?
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 for each data set.
Are there any limits on the spatial area or the time range that can be selected?
There are no limits on the spatial range of data than can be selected.
What are the plotting preference options for the data visualizations in CERES Giovanni?
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.
Are there other sources of radiation data besides CERES Giovanni at the GES DISC?
The GES DISC has other surface radiation data products, including model-assimilated data products in the MERRA 2D and the GLDAS Monthly interfaces. SeaWiFS Photosynthetically Active Radiation is expected to be added in the near future (as of December 2009) to Ocean Color Radiometry. An entry in the GES DISC FAQ describes other sources of Earth surface radiation data:
Do you have maps or data regarding surface solar radiation or solar irradiance?
The following is excerpted from the FAQ regarding actual data sources:
"The GES DISC has model-assimilated surface solar radiation data products from the Global Land Data Assimilation models (GLDAS):
and from atmospheric reanalysis and assimilation model runs (e.g MERRA): http://disc.sci.gsfc.nasa.gov/mdisc/ "
Why is the time range of the data currently available in CERES Giovanni so short?
The data set in CERES Giovanni corresponds to the current length of the processed CERES-Aqua data product suite. As more updates become available, the data in Giovanni will be updated accordingly. We do not have current information on when the CERES data set will be updated with more recent data products.