en-us FAQ from the NASA GES DISC. http://disc.sci.gsfc.nasa.gov/ http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=2 The URL for the Giovanni-3 Users Manual is: http://disc.gsfc.nasa.gov/techlab/giovanni/G3_manual_table_of_contents.shtml Alternatively, the first element in the URL can be either "daac.gsfc.nasa.gov" or "disc.sci.gsfc.nasa.gov". Thu, 04 Oct 2007 16:10:54 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=2 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=3 The time values (TAI93: International Atomic Time 1993) are elapsed time in seconds since Jan 1, 1993, Coordinated Universal Time (UTC). For example, a time value of 410227204.00 corresponds to 12/31/2005 23:59:59.00 UTC. Note that a leap second was added at the end of 2005 (i.e. December 31, 2005). Therefore, TAI93 value of 410227206.00 (2 seconds after the above example) is 01/01/2006 00:00:00.00 UTC (not 01/01/2006 00:00:01.00 UTC) due to the leap second. The addition of another leap second in the near future is unlikely. Thu, 01 Nov 2007 22:02:05 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=3 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=4 AIRS monthly data require a complete set of the daily Level 3 global products, which in turn require a complete-as-possible set of of the Level 2 orbital products (given that orbital maneuvers, data dropouts, etc. affect the completeness of the data). It sometimes takes several days to complete the processing of the daily data [closing out the data processing stream] to the point where a monthly Level 3 data product can be created. Thu, 01 Nov 2007 22:17:07 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=4 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=5 All of the data products and services provided by the GES DISC are available free of any charges. Fri, 09 Nov 2007 21:42:19 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=5 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=7 No. A tsunami moves too quickly to affect the biological systems in the ocean, or ocean optical properties. However, if a large tsunami affected a land area, the outflow as the tsunami receded could cause a significant suspension of coastal sediments, which might be visible in ocean color data, and this effect would last for several hours. The satellites still have to observe the correct area without clouds. The December 26, 2004 tsunami in the Indian Ocean happened to occur when the Jason-1 altimeter was observing the area, and the tsunami wave was detected as an increase in the height of the ocean surface. Thu, 03 Jan 2008 20:18:53 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=7 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=8 MODIS land surface data are archived at the Land Processes DAAC (LPDAAC). Here is the contact information for the LPDAAC: URL: http://edcdaac.usgs.gov/main.asp ... ADDRESS: LP DAAC User Services, U.S. Geological Survey (USGS), Center for Earth Resources Observation and Science (EROS), 47914 252nd Street, Sioux Falls, SD 57198-0001 USA ... PHONE AND EMAIL: 605-594-6116 voice, 605-594-6963 fax, E-mail:LPDAAC@eos.nasa.gov Thu, 03 Jan 2008 20:39:19 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=8 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=9 No. The answers to these questions are provided to assist you with the use of the data in the GES DISC archives, and the related tools we provide. Many of these answers will guide you to other NASA Web sites and data archives, which are part of the NASA network. For our users, we strive to provide pertinent and correct information to assist with their scientific research. Thu, 03 Jan 2008 20:44:10 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=9 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=10 Mirador is a simplified interface for finding Earth science data files at NASA Goddard Earth Sciences Data and Information Services Center (GES DISC). Because Mirador is dedicated to and designed for the data archived at the GES DISC, it works better than a general Google search to find data files in the GES DISC system, especially for specific space or time criteria. You can find some answers to questions about Mirador at the URL below (cut and paste the URL into a Web browser): ... URL: http://mirador.gsfc.nasa.gov/cgi-bin/mirador/help.pl ... Mirador actually employs Google search technology for keyword-based searches. Thu, 03 Jan 2008 20:45:59 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=10 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=11 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). Tue, 08 Jan 2008 17:46:57 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=11 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=12 The GES DISC has been in a long process of eliminating its distribution of and support for AVHRR data. We are pleased to inform you that the Global Land Cover Facility (GLCF) at the University of Maryland is now the public site for providing AVHRR data and support services. URL: http://glcf.umiacs.umd.edu/data/gimms/. Tue, 08 Jan 2008 17:48:41 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=12 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=13 MODIS atmospheric data are now available from the LAADS Web, http://ladsweb.nascom.nasa.gov/. Note the differences in spelling between *LAADS Web* and *ladsweb* in the URL. Tue, 08 Jan 2008 17:51:36 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=13 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=14 The MODIS ATBDs (Algorithm Theoretical Basis Documents) can still be found on the MODIS Web: cut and paste this URL into a Web browser -- (http://modis.gsfc.nasa.gov/data/atbd/index.php) Under each discipline, the latest revision date is listed next to the ATBD title in the table listing. Some of the ATBDs have been revised; others have not been revised, but the basic algorithm described in the document is still in use. Other ATBDs (notably for the MODIS Ocean products) may no longer apply to the products which are available, but the ATBD may still contain useful reference information. If the information in an ATBD is to be utilized for research, it would be wise to contact the authors, if possible, to determine the current status of the algorithms used to generate MODIS geophysical data products. Tue, 08 Jan 2008 17:54:51 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=14 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=15 The initial plans for MODIS Ocean data products were for a suite of 40 or more data products. MODIS-Terra had significant calibration problems, which affected the development of these products. A significant change in the MODIS Ocean data processing system took place in 2003, with the responsibility for producing data products from MODIS-Aqua transferring to the SeaWiFS Project, now called the Ocean Biology Processing Group (OBPG). This change resulted in a major reduction in the number of data products from MODIS, and the OBPG also undertook distribution of these data products. MODIS Ocean data products were deleted from the GES DISC archive. All of the MODIS-Aqua data products are available from the Ocean Color Web site (http://oceancolor.gsfc.nasa.gov). MODIS-Terra provides sea surface temperature, and efforts are continuing to produce useful ocean color data products from the raw data. The GES DISC Giovanni system also provides data analysis and visualization capabilities for the MODIS-Aqua and SeaWiFS ocean color data products. Tue, 08 Jan 2008 18:03:00 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=15 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=16 The Global Land Data Assimilation System (GLDAS) data products consist of time series of land surface state (e.g., soil moisture and surface temperature) and flux (e.g., evaporation and sensible heat flux) parameters simulated by four land surface models (CLM, Mosaic, Noah and VIC). The 1.0 degree resolution data range from 1979 to present for the four models. The 0.25 degree data cover 2000 to present for the NOAH model. For more information about GLDAS, see http://ldas.gsfc.nasa.gov/. Fri, 25 Jan 2008 21:23:03 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=16 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=17 The GRIB (GRIdded Binary) format is a mathematically concise data format commonly used in meteorology to store historical and forecasted weather data. For more details about the GRIB format, please see http://www.nco.ncep.noaa.gov/pmb/docs/on388/ WGRIB, GrADS, or other GRIB readers are required for reading the GLDAS data. WGRIB is a program to manipulate, inventory, and decode GRIB files. The source code and installation instructions for WGRIB are available from http://www.cpc.ncep.noaa.gov/products/wesley/wgrib.html The Grid Analysis and Display System (GrADS) is an interactive desktop tool for easy access, manipulation, and visualization of earth science data. The format of the data may be either binary, GRIB, NetCDF, or HDF. The documentation and software for GrADS can be found at http://grads.iges.org/grads/. Fri, 25 Jan 2008 21:24:36 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=17 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=18 The GLDAS products were created using the GRIB format, but a specific parameter table was used in the encoding process. To read the GLDAS GRIB data, it is necessary to download the GRIBTAB and set the environmental variables first before using any GRIB readers! For more information, please see http://disc.gsfc.nasa.gov/hydrology/README.GLDAS.pdf. Fri, 25 Jan 2008 21:25:00 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=18 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=19 Currently, GLDAS drives four land surface models: Mosaic, Noah, the Community Land Model (CLM), and the Variable Infiltration Capacity (VIC). More information about the models is available at the Land Data Assimilation Systems (LDAS) Web site, http://ldas.gsfc.nasa.gov/, and Land Information System (LIS) Web site, http://lis.gsfc.nasa.gov/. Fri, 25 Jan 2008 21:26:53 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=19 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=20 Yes. The source codes for the land surface models can be obtained from the Land Information System (LIS) website, http://lis.gsfc.nasa.gov/. The LIS source code currently includes 3 land surface models: CLM, Noah and VIC. Fri, 25 Jan 2008 21:28:14 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=20 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=21 Forcing data are atmospheric inputs to the land surface models, including precipitation, radiation, and surface wind, temperature, pressure and humidity. They can be obtained from http://lis.gsfc.nasa.gov/FAQ/forcing.shtml Fri, 25 Jan 2008 21:28:47 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=21 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=22 Land surface parameters are properties of the land surface (e.g., soil, land cover, and topography) that change at a time step of a day or longer. They can be obtained from http://lis.gsfc.nasa.gov/FAQ/params.shtml. Fri, 25 Jan 2008 21:29:13 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=22 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=23 The Land Data Assimilation Systems (LDAS) are being developed to enable more accurate reanalysis and forecast simulations by numerical weather prediction (NWP) models. Specifically, these systems will reduce the errors in the stores of soil moisture and energy which are often present in NWP models and which degrade the accuracy of forecasts. The LDAS are being implemented at 1/8 degree (about 15 kilometer) resolution across North America (NLDAS) and at 1/4 degree resolution globally (GLDAS). The systems are currently forced by terrestrial (NLDAS) and space-based (GLDAS) precipitation data, space-based radiation data, and numerical model output. NLDAS is currently running retrospectively and in near real-time. For more information about LDAS, see http://ldas.gsfc.nasa.gov. Fri, 25 Jan 2008 21:29:45 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=23 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=25 The 3B42-V6 rain rate is a 3-hourly average centered at the middle of each 3-hour period (i.e., 0Z, 3Z, 6Z, 9Z, 12Z, 15Z, 18Z, and 21Z). To convert these rainfall rates to total daily rainfall, first multiply each 3-hourly rainfall rate by 3 hours, to get the total rainfall for each 3-hour period. Then, for your desired 24-hour-day begin and end times, sum all the 3-hourly total rainfalls in your defined 24-hour period, to get the total daily rainfall. Fri, 29 Feb 2008 18:45:23 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=25 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=26 The data in the HDF file are written in the following order, (-49.875, -179.875), (-49.625, -179.875), (-49.375, -179.875), (-49.125, -179.875)......(49.875, -179.875), (-49.875, -179.625), (-49.625, -179.625)...... The dimension for longitude is 1440 and the dimension for latitude is 400. The value used to indicate missing data is "-9999.9". Fri, 29 Feb 2008 18:46:00 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=26 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=27 More information on the TRMM instruments and science can be found at the GES DISC/DAAC TRMM Data Web site: http://disc.sci.gsfc.nasa.gov/precipitation/ Fri, 29 Feb 2008 18:46:26 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=27 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=28 The GES DISC/DAAC receives, under normal circumstances, processed standard orbital/swath data products about 2-3 days after satellite data acquisition, depending on the level of processing required. In addition to this ongoing collection of data, archives of older data are maintained. Fri, 29 Feb 2008 18:46:54 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=28 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=29 The GES DISC/DAAC data search and order interface is a simple point-and-click web interface that is based on a hierarchical organization of data, displayed as tables. At different levels of the hierarchy, the tables contain some or all of the following: a particular data product grouping such as data product name, year, or month in the first column on the left; followed by columns of short description, begin date, end date, number of items available in the archives, average item size, a preview feature (if a data product has browse images), and documentation ("readme"). The last column on the right allows one to "Select" an item. At certain levels of the hierarchy, you can also use orbital and parameter search features to customize your search. Specific help is provided at the top of each page of this system. URL: http://disc.sci.gsfc.nasa.gov/data/datapool/TRMM/index.html Fri, 29 Feb 2008 18:47:29 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=29 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=30 http://disc.gsfc.nasa.gov/precipitation/documentation.shtml: TRMM related documentation, describing the science, the instruments, data processing, and data access. http://disc.gsfc.nasa.gov/precipitation/TRMM_README/: documents on the data products and direct data access. http://tsdis.gsfc.nasa.gov/: "TSDIS Documentation," providing the details of all the products. http://tsdis.gsfc.nasa.gov/tsdis/Documents/Tutorial.pdf: "Tutorial for Reading TRMM Data Products." Fri, 29 Feb 2008 18:49:34 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=30 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=31 Information about algorithms used for the TRMM products can be found in the Algorithm Status Page, where the links to the products take you to brief descriptions of the status of the products and, for some products, key references. URL: http://trmm.gsfc.nasa.gov/data_dir/ProductStatus.html Fri, 29 Feb 2008 18:50:41 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=31 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=32 Yes, just contact help@disc.gsfc.nasa.gov (or 301-614-5224, voice; or 301-614-5268, fax) and request a "subscription." Information that would be needed from you are data product(s) desired, begin date, and end date. You will receive an email notification whenever data are ready for FTP pickup. Fri, 29 Feb 2008 18:53:22 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=32 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=33 These daily products are computed by averaging all the estimates available in the eight observation times of a given UTC day, namely 00, 03, ..., 21 UTC. Formally, this "day" covers the period from 2230 UTC of the previous day through 2230 UTC of the given day. Other "day" products can be computed interactively for 3B42RT and Version 6 3B42 by specifying similar 8-period runs of data. For example, a day that starts at 09 UTC can be approximated by taking data from 09 UTC of one day through 06 UTC of the next. At present, there is no capability in TOVAS for a more exact approximation of a "day" for these data sets. Fri, 29 Feb 2008 18:53:45 +0000 http://disc.sci.gsfc.nasa.gov/faq/faq_detail.html?ii=33