Why are there gaps in a daily Level 3 data file?
Most remote-sensing instruments observe the Earth by scanning across the orbit track, which can be visualized as the line on the Earth surface directly below the orbital path traveled by the satellite. The scan area on either side of this line is called the scan swath. Most remote-sensing instruments do not have a scan swath wide enough so that the observational coverage on successive orbits overlaps. So for each day of observations, there are gaps between the scan swaths. However, the "polar orbit" configuration of many remote-sensing satellites can cause the scan swaths to overlap at higher latitudes, i.e., the polar regions, even though the scan swaths do not overlap over most of the Earth surface.
How can I put a Giovanni output image into Google Earth?
Giovanni output images from the "original" Giovanni system (now called Giovanni-2, or G2) are only in the GIF image format, and could not be put into Google Earth easily, if at all. Now, however, Giovanni-3 output images of area plots are available as KMZ files, which can be downloaded directly and opened in Google Earth. More capabilities of this download option were being developed at the time that this answer was written (December 2007).
How do I acknowledge the use of Giovanni in a research paper? If I use Giovanni should I have someone on the GES DISC staff as a co-author?
We have created a Web page which provides a basic acknowledgment statement, a general Giovanni reference, and considerations for co-authorship. Please consult this page for guidance. Note that the use of Giovanni should be acknowledged in any type of scientific media, particularly reports, posters, and meeting presentations, in addition to peer-reviewed papers published in scientific journals.
Recommended guidelines for use of Giovanni data in publications
How do I subscribe to the giovanni-news email mailing list for news about Giovanni development and related scientific and educational topics delivered in newsletters, approximately quarterly. ?
There are 2 ways to be subscribed to giovanni-news :
1. Send an email message (the content doesn't matter) to email@example.com, and reply to the confirmation message.
2. Or you can email the list owner (firstname.lastname@example.org) and ask to be subscribed.
I waited several hours to generate a Giovanni visualization, and then it appeared that my request had failed. Why did that happen?
Giovanni is capable of generating an extensive variety of analyses and visualizations, but its computational capabilities do have limits. In particular, Giovanni analysis and visualization requests which involve data averaging over long time periods, over large geographic areas, and/or with data of high temporal resolution (notably daily or 3-hour data) place considerable demand on the capabilities of the system. Data processing requests with those characteristics have occasionally required so much time and computer resources that the request processing had to be terminated before completion. We are currently evaluating high-demand requests to determine how best to configure the system to handle them, particularly by improving system efficiency and performance to reduce the likelihood of a failure.
At this time, we would suggest the following general guidelines:
- If daily data is being analyzed, limit the time range for a time-series or a spatially-averaged map to a year or less.
- If 3-hour data is being used, limit the time range for a time-series or spatially-averaged map to three months or less.
- Whenever possible, analyze data over a defined spatial region, rather than globally.
Is there a way to download several months of data at one time from Giovanni?
Note that it is not possible to download data in batch for a subsetted area. However, it is possible to download the global data used to create a time-series or time-averaged map. (Please read the question above to understand why large data requests may fail.)
For downloading multiple months of data, you may use the “Batch Download” function on the download page.
Here are the steps for acquiring ASCII data by batch download:
a) From the Result page, click on the “Download Data” tab.
b) In the “Initial Data Retrieval” section, click the box next to the “ASC” icon to select all ASCII files.
c) Click on the “Download in Batch” button directly above.
d) Wait for a few moments ... and a page will be created, showing you a compressed "tar" file.
e) Download this tar.gz file, uncompress and untar the file (gunzip <file.tar.gz>; tar <xvf file.tar>). This procedure provides all monthly ASCII data.
As noted above, the spatial coverage from “Initial Data retrieval” is global, not a user-selected subset area. To acquire monthly data for only a user-selected subset area, it must be done one month at a time.
To download HDF or netCDF files, follow the same procedure described above, except designate the requested data format by clicking the box next to the appropriate icon.
How can I download the Giovanni animation that I created?
Unfortunately, it is not currently possible to download the animations that are created using the Animation visualization service in Giovanni. We can offer four different ways of making animations out of the Giovanni images that can be dowloaded individually which comprise the image sequence in the animation.
1) There is a quick way to generate an animated gif which can be imported into Powerpoint. If you have a Linux machine, you could first download the images you want and execute this command (this example uses sequential image files named trmm_tmpx):
convert -delay 100 trmm_tmp1.gif trmm_tmp1.gif trmm_tmp2.gif
trmm_tmp3.gif trmm_tmp4.gif trmm_tmp5.gif trmm_tmp6.gif trmm_tmp7.gif trmm_tmp8.gif trmm_tmp9.gif -loop 0 output_ani.gif
output_ani.gif is the animated gif file.
2) A free image processing package called ImageJ (available from the National Institutes of Health) provides the capability to create animated GIFs. For an instructional movie on how to do this with ImageJ, go to this site from the Eyes in the Sky II project: Using Giovanni to Study Chesapeake Bay. Go to the section near the bottom entitled "Export Giovanni Images in an Animation to ImageJ, If You Have Time".
3) There are some free Web site utilities which can create an animation from submitted GIF images. Most of these limit the number of GIFs which can be uploaded to create the animation to 10 images. Two such sites are Picasion.com and Gickr.com. We offer these a possible way to accomplish this and do not endorse either the Web site or the results obtained.
4) Other software packages can be downloaded to your computer that can make animated GIFs. We have not tested them and thus we offer no recommendations. It is possible to create animated GIFs in Photoshop.
Why did I get a failure message when I attempted to plot a three-dimensional parameter?
Plotting three-dimensional (3D) profile parameters in Giovanni requires extra caution, particularly a complete examination of the plotting options. Some of the 3D parameters are not on a common vertical grid, e.g. CH4 vs Temperature_Profile. In other scenarios, only one vertical level at a time can be plotted as a two-dimensional (2D) map. Regrettably, complete validation of user input to insure that a legitimate plot scenario is being requested does not exist in the user interface at this time, even though some critical checks do exist.
As a general rule:
- select only one vertical layer for 2D plots (Lat-Lon map); and
- plot one 3D parameter layer at a time when targeting parameters on a different vertical grid.
Why are Java applications blocked by your security settings with the latest Java?
This is an issue with Java 7.
To remedy it, please follow the instructions on this page:
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