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Hurricane Data Analysis Tool FAQ

  • What is this tool for?

    To facilitate scientific users in accessing NASA satellite remote sensing data and increase interoperability among NASA data centers, the NASA Goddard Earth Sciences (GES) Data and Information Services Center (DISC), home of the GES Distributed Active Archive Center (DAAC), has recently developed a simple tool that allows users to visualize and analyze NASA's daily Quick Scatterometer (QuikSCAT) ocean surface wind, Tropical Rainfall Measuring Mission (TRMM) precipitation, TRMM Microwave Imager (TMI) sea surface temperature (SST)i, and TRMM global merged IR data. QuikSCAT, TRMM precipitation and TMI SST data are archived and distributed by the Physical Oceanography Distributed Active Archive Center (PO.DAAC) of the Jet Propulsion Laboratory (JPL), the DISC and the Remote Sensing Systems, respectively. Recently, we have added NCEP Reanalysis data products in order to provide users a better integrated tool. As a part of the DISC's Hurricane Portal, this tool is intended to facilitate researchers to investigate tropical cyclones, hurricanes and typhoons around the world without downloading data. It also helps them to investigate other oceanic and atmospheric events, such as, precipitation, monsoon events, island blocking effects, etc. Current functions include area (latitude-longitude) and time series (area averaging) plots and their overlays. More data and capabilities are coming.

  • How to use this tool?

    a) Select a data group from Select Map Feature
    b) Select a base dataset and an overlay dataset
    c) Select a plot type (lat-lon map or time series) and a plot type for wind (vector or streamline)
    d) Select a rainfall product
    e) Select an area of interest using a computer mouse or type in latitudes and longitudes
    f) Select a time period
    g) Select or provide information for the color bar (for lat-lon map only)

  • Can I get the data of a plot?

    No, currently this capability is not available but we have plans to add the capability in the future. Please go to data providers to obtain original data products. For TRMM, visit; for QuikSCAT, visit; for TMI SST, visit

  • How to plot a single dataset?

    Select the same dataset in both base dataset and overlay dataset.

  • What is the best way to use the color bar?

    We recommend using the default (pre-defined) for the first image or animation. You could also use the dynamic option for a single image, but not for an animation because for each image, the color bar could be different, making it difficult to view. After that, you could fine tune the color bar using the customized option.

  • What are the color bar options?

    For The color bar is only for False Color images. Currently there are 3 options: pre-defined (default); dynamic; and customized. For other data products there are dynamic and custom.
    The pre-defined color bar for the Merged IR False Color is set by a pair of pre-defined temperatures (-50, 50)
    The dynamic color bar is set depending on the minimum and maximum temperatures in the image and the system (GrADS) will decide the range.
    The customized color bar is set by a user with inputs of the minimum and maximum temperatures. The color bar interval is decided by (max - min)/10.

  • What are the data resolutions?

    For TRMM and TMI SST, both are 0.25 degree. For QuikSCAT, the original L-3 product resolution is 0.25, however, for better visualization, we use the software provided by PODAAC to reduce the resolution to 1 degree. The NCEP products are all 1 degree.

  • How frequently the datasets are updated?

    Typically 1-2 months because TRMM rainfall products are always delayed in that time frame.

  • What is the global merged IR product?

    The global merged IR product, also known as, the NCEP/CPC 4km Global (60N - 60S) IR Dataset. They are globally-merged (60N-60S) pixel-resolution IR brightness temperature data (equivalent blackbody temps), merged from all available geostationary satellites (GOES-8/10, METEOSAT-7/5 & GMS). The availability of data from METEOSAT-5, which is located at 63E at the present time, yields a unique opportunity for total global (60N-60S) coverage.

  • How do I create false color visualization and analysis for the merged IR product?

    For a single image:
    1. Select "Merged IR Data"
    2. Select "False Color" from the "Image Type" pull-down menu
    3. Select an area of interest (smaller than 40 deg. X 40 deg.)
    4. Select a beginning time
    5. Click on the "Generate Plot" button
    For an animation, follow the steps above and change the number (>1) in "No. of Images".
  • What NCEP data is used?

    The sea level pressure, zonal and meridional wind at 1000, 850, and 200 hPa level data available on the hurricane portal are obtained from NCEP's Global Forecast System analysis. The GFS analysis can be obtained from The GFS data archived on the hurricane portal are global (GFS product 003), have 1ºx1º spatial resolution and 4-times/day (6 hourly) temporal resolution. These data are available from NCEP beginning in February, 2004. A detailed description of the GFS model can be found on A number of additional parameters from GFS will be available soon on the hurricane portal, including mass divergence profiles, potential temperature profiles, and vertical wind shear derived from the GFS products.

  • What can this viewer do?

    The prototype allows to visualize and analyze over 10 TB of data archived at the DISC. Some of the benefits of this tool are the following:
    • Observe evolution of meteorological events, hurricanes, cyclones, mesoscale convection systems, etc.
    • Analyze cloud top temperature and its evolution.
    • Observe other events, such as, dust storm.
    • Serve as an excellent ancillary data for other satellite missions (e.g., TRMM, CloudSat, etc.) by providing background information and helping interpretation of events.
    • Serve as a foundation for multi-sensor integrated studies.
    • Serve as a prototype for other high resolution satellite data, such as, MODIS L1B RGB.

  • When I select Area Plot and a time period, what will happen?

    You will get a time-averaged map for the region of interest. For wind, it is vector averaging.

  • Which TMI SST product is used?

    The 3-day SST product. The daily will be added in near future.

  • What is "Skip" in the merged IR data tool?

    In order to quickly browse through a period of interest, one can choose "Skip". The default is the original temporal resolution, 30 min.

  • How to generate an animation file with the merged IR data?

    Select more than one image in "No. of Image" and the system will generate the animation file.

  • What is an efficient way to make animation with the merged IR data?

    It could be a time consuming task to make a customized animation. To save time, users should know an area of interest first. Before making an animation, you could check one image for the area of interest, making sure it is what you want. Secondly, a larger image size will also increase processing time and animation file size. Dont select larger image size at the beginning and always begin with a smallest size first.

  • How can I download an animation file?

    Right click (e.g., in Firefox) on the animation image, select "Save Image As". In the "Save Image" window, fill in "your_filename.gif" in "File name:". Click on "Save".

  • How can I import an animation file in MS PowerPoint?

    First, save an animation file (see 4.). In MS PowerPoint, click on "Insert" and choose "From File" from "Picture". Select the saved animation file. Note: you can only see the animation when you do a slide show.

  • When I see Entire Grid Undefined in the output image, what happened?

    That means the data are not available for the selected period. Please check the data availability in the interface page and make sure the time period selection is correct. For the time being, only the data in this hurricane season are available, but remember the data latency is at least two days.

  • I saw some salt like white spots in the output image of the merged IR data, what are they?

    They are missing data in the original data files. In the future, we will apply a standard image processing algorithm to remove them.

  • What is the default b/w color bar for the merged IR data?

    The temperature range for the default b/w color bar is between 150K (minimum) and 350K (maximum).

  • Any plan to add near-real-time products?

    Yes, if resources allowed.

  • Any plan to add monthly products and anomaly analysis?

    Yes, if resources allowed.

  • Any plan to overlay track data?

    Yes, it is under consideration.

  • Any plan to plot a time series along the track?

    Yes, it is under consideration.

  • Any references for this product?

    Janowiak J. E., R. J. Joyce, and Y. Yarosh, 2001: A Real-Time Global Half-hourly Pixel-Resolution Infrared Dataset and Its Applications. (Bull. Amer. Meteor. Soc., vol. 82, No.3., 205-217.)

    Liu, Z. D. Ostrenga and G, Leptoukh, 2011, Online Visualization and Analysis of Global Half-hourly Pixel-Resolution Infrared Dataset, Bulletin of the American Meteorological Society, Vol. 92, No. 4, 429-432.

  • How can I download the original data?

    You can download them from Mirador:

  • How to acknowledge this tool?

    GES DISC DAAC Data Use Acknowledgment The distribution of the GES DISC DAAC's data sets is funded by NASA's Earth-Sun System Division (ESSD). The data are not copyrighted; however, in the event that you publish data or results using these data, we request that you include the following acknowledgment: The data used in this study were acquired as part of the NASA's Earth-Sun System Division and archived and distributed by the Goddard Earth Sciences (GES) Data and Information Services Center (DISC) Distributed Active Archive Center (DAAC).

  • Is there any reference for this tool?

    Liu, Z. D. Ostrenga and G, Leptoukh, 2011, Online Visualization and Analysis of Global Half-hourly Pixel-Resolution Infrared Dataset, Bulletin of the American Meteorological Society, Vol. 92, No. 4, 429-432.


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Last updated: Feb 02, 2012 01:24 PM ET