LANCE FAQ

What is LANCE?

LANCE (Land, Atmosphere Near real-time Capability for EO) is a group of near real-time data systems serving the Land and Atmosphere science community.

What is near real-time (NRT) data?

Near real-time data are defined as data that are available to users three hours or less after a satellite observation.

What near real-time systems are a part of LANCE?

LANCE consists of "elements" that process the NRT data made available through LANCE. These are listed in the table below.

What are standard products?

Standard products are products that are used for standard science processing and are generally available between 8-40 hours after observation.

What is the difference between near real-time and standard products?

Near real-time and standard products differ in the amount of processing the raw data receives. Near real-time data is processed with different, less accurate ancillary data to make it available to users within 3 hours of observation. The main difference is in geolocation due to the use of predictive orbit information vs waiting for definitive orbit information.

Where can I obtain standard products?

Each LANCE element provides standard products as well as near real-time products. Go to the Standard Products page for the data centers where the standard products are archived.

What LANCE data products are available?

Currently the following near real-time products are available under LANCE:

• Atmospheric Infrared Sounder (AIRS),
• Advanced Microwave Scanning Radiometer 2 (AMSR2),
• Lightning Imaging Sensor (LIS) on the International Space Station - LIS (ISS),
• Multi-Angle Imaging Spectroradiometer (MISR),
• Microwave Limb Sounder (MLS),
• Moderate Resolution Imaging Spectroradiometer (MODIS),
• Measurement of Pollution in the Troposphere (MOPITT),
• Ozone Monitoring Instrument (OMI),
• Ozone Mapping Profiler Suite (OMPS), and
• Visible Infrared Imaging Radiometer Suite (VIIRS-Land)
• Visible Infrared Imaging Radiometer Suite (VIIRS-Atmosphere).

Where do I go online to search and order LANCE data?

Go to the Near Real-Time Data page for more information or use search.earthata.nasa.gov

Who can order LANCE data products?

All NASA Earth Observing System (EOS) mission data including LANCE data is freely available to the public.

How long are LANCE near real-time data sets are available?

The near real-time data sets stay for about 7 days from the time they are generated.

How soon are LANCE near real-time data sets available?

The near real-time data that LANCE provides is available to users within 3 hours of observation.

Do I need to register to access LANCE data?

Yes, registration is required to obtain LANCE data. Please visit the Earthdata Login to register for a username and password.

Will there be a fee associated with accessing data?

Typically, there is no cost associated with accessing NASA Earth Science data. However, please refer to the Earth Science Data Systems (ESDS) Data and Information Policy for more information.

Who do I contact for support with LANCE data?

For questions about LANCE or user registration, contact Earthdata Support.

How do I stay informed about updates, announcements, data issues and scheduled maintenance?

Subscribe to receive notifications from LANCE about updates, announcements, data issues and scheduled maintenance. To subscribe to one of the mailing lists, send an e-mail 

• To subscribe: e-mail lance-modis-join@lists.nasa.gov (no subject or text is required).
• To unsubscribe: e-mail lance-modis-leave@lists.nasa.gov (no subject or text is required).

• To subscribe: e-mail floodmap-join@lists.nasa.gov (no subject or text is required).
• To unsubscribe: e-mail floodmap-leave@lists.nasa.gov (no subject or text is required).

Where can I go to interact with other users and NASA subject matter experts on a variety of Earth science research and applications topics?

Please visit the Earthdata Forum at https://forum.earthdata.nasa.gov

• Ozone mailing list - for updated regarding NRT data from OMI and OMPS
  • To subscribe: e-mail ozone-nrt-users-join@lists.nasa.gov (no subject or text is required).
  • To unsubscribe: e-mail:ozone-nrt-users-leave@lists.nasa.gov (no subject or text is required).
• LANCE-AIRS mailing list
  • To subscribe: e-mail lance-airs-join@lists.nasa.gov (no subject or text is required).
  • To unsubscribe: e-mail lance-airs-leave@lists.nasa.gov (no subject or text is required).
• LANCE-MLS mailing list
  • To subscribe: e-mail lance-mls-join@lists.nasa.gov (no subject or text is required).
  • To unsubscribe:e-mail lance-mls-leave@lists.nasa.gov (no subject or text is required).
• LANCE FIRMS mailing list
  • To subscribe: e-mail lance-firms-users-join@lists.nasa.gov (no subject or text is required).
  • To unsubscribe: e-mail lance-firms-users-leave@lists.nasa.gov (no subject or text is required).
• LANCE Users mailing list -please note, if you wish to receive information about data issues, use the relevant list above.
  • To subscribe: e-mail lance-users-join@lists.nasa.gov (no subject or text is required).
  • To unsubscribe: e-mail lance-users-leave@lists.nasa.gov (no subject or text is required).
• Global Imagery Browse Services and Worldview - for information about updates to GIBS and Worldview
  • To subscribe: e-mail eosdis-gibs-announce-join@lists.nasa.gov (no subject or text is required).
  • To unsubscribe: e-mail eosdis-gibs-announce-leave@lists.nasa.gov (no subject or text is required).

For both MODIS and VIIRS, the Corrected Reflectance algorithm utilizes Level 1B data (the calibrated, geolocated radiances). It is not a standard, science quality product and is available only as near real-time imagery. The imagery can be visualized in Worldview and GIBS.

For MODIS, the sensor resolution is 500 m and 250 m (Bands 1 and 2 have a sensor resolution of 250 m, Bands 3 – 7 have a sensor resolution of 500m, and Bands 8 - 36 are 1 km. Band 1 is used to sharpen Band 3, 4, 6, and 7), imagery resolution is 250 m, and the temporal resolution is daily.The purpose of this algorithm is to provide natural-looking images by removing gross atmospheric effects, such as Rayleigh scattering, from MODIS visible bands 1-7. The algorithm was developed by the original MODIS Rapid Response team to address the needs of the fire monitoring community who want to see smoke. Corrected Reflectance shows smoke more clearly than the standard Surface Reflectance product. In contrast, the MODIS Land Surface Reflectance product (MOD09) is a more complete atmospheric correction algorithm that includes aerosol correction, and is designed to derive land surface properties. In clear atmospheric conditions, the Corrected Reflectance product is very similar to the MOD09 product, but they depart from each other in presence of aerosols. If you wish to perform a complete atmospheric correction, please do not use the Corrected Reflectance algorithm. An additional difference is that the Land Surface Reflectance product is only tuned for calculating the reflectance over land surfaces.

The VIIRS Corrected Reflectance imagery provides continuity from the MODIS Corrected Reflectance imagery and was developed to provide natural-looking images by removing gross atmospheric effects such as Rayleigh scattering from the visible bands. By contrast, the Surface Reflectance product is available in near real-time and as a standard product. Surface Reflectance provides a more complete atmospheric correction algorithm that includes aerosol correction and is designed to derive land surface properties. In clear atmospheric conditions the corrected reflectance product is similar to the Surface Reflectance product but they depart from each other in the presence of aerosols.

What is MODIS?

MODIS stands for Moderate Resolution Imaging Spectroradiometer. The MODIS instrument is aboard the Earth Observing System (EOS) Terra (EOS AM) and Aqua (EOS PM) satellites. The orbit of the Terra satellite goes from north to south across the equator in the morning and Aqua passes south to north over the equator in the afternoon resulting in global coverage every 1 to 2 days. The EOS satellites have a ±55 degree scanning pattern and orbit at 705 km with a 2,330 km swath width.The MODIS instrument provides 36 spectral bands from wavelengths of 0.4µm to 14.4µm. For more information, please visit the NASA MODIS website.

When were the Terra and Aqua satellites launched?

Terra (EOS AM) was launched 18 December 1999 and Aqua (EOS PM) was launched 4 May 2002. High quality hotspot/active fire observations are available from the Terra satellite starting November 2000 and from the Aqua satellite starting 4 July 2002 onwards.

What time does the satellite pass over my area?

Terra (EOS AM) passes over the equator at approximately 10:30 am and 10:30 pm each day, Aqua (EOS PM) satellite passes over the equator at approximately 1:30 pm and 1:30 am. The sun-synchronous orbit allows the satellites to pass over the same area at the same time in every 24 hour period (at every 99 minute orbit the satellites cross the equator at the above mentioned times; every other spot on Earth has similarly constant overpass times). The time of satellite pass will vary according to your location. To estimate when the satellite will pass over your area, you can use the satellite overpass predictor provided by NASA.

Daily Terra and Aqua global and regional orbit tracks are provided by the Space Science and Engineering Center (SSEC) at the University of Wisconsin-Madison. The maps show a series of white lines with tic marks showing what time the satellite will pass over a certain location on the Earth. The white lines represent the center of the swath and the tic marks and time show at what time in UTC the satellite has passed over that location.

Image

A cut-away from an orbit track map showing the Terra satellite overpass time near the Great Lakes (daytime granule starting at 17:10 UTC, nighttime granule starting at 03:35 UTC).

The maps have a series of white lines with tick marks on them that show what time (using Coordinated Universal Time, or UTC) the satellite will be passing over a particular location on Earth on a given day. The white lines represent the center of the swath. The time stamps mark the start of the northern (Terra) or southern (Aqua) edge of each 5-minute data collection period. An image acquired at that location will span roughly 1150 kilometers on either side of the tick mark. Every day there are two passes over most areas: one daylight pass, and one nighttime pass.

How often are data acquired?

The MODIS instrument aboard the Terra and Aqua EOS satellites acquire data continuously providing global coverage every 1-2 days. Therefore there are at least 4 daily MODIS observations for almost every area on the equator – with the number of overpasses increasing (due to overlapping orbits) the closer an area is to the poles. See What time does the satellite pass over my area?

What are MODIS Data "Collections"?

A MODIS data Collection is a MODIS data version. When new and improved science algorithms are developed, the entire MODIS dataset (from launch) is reprocessed and then tagged and distributed as a new "Collection". During the process of a Collection, an attempt is made to use the same version of the Science Algorithms or Program Executables (PGEs). However, sometimes a bug is found in one or more of the PGEs in the middle of Collection processing; and if the bug is not serious, processing will complete with the new corrected PGE. These anomalies and problems in processing are noted on the Known Problems page. One can always identify the Collection number for a particular HDF file as it's always included (as a 3 digit number) as part of the HDF filename. There have been six MODIS data Collections (or Versions) processed since MODIS/Terra was launched in early 2000. The Collection versions created thus far are 001, 003, 004, 005, 051, 006 and 06.1. MODIS Collection 6.1 (C6.1) was added in October 2017 to correct a number of issues in the Collection 6 (C6) Level-1B (L1B) data. The decision to create a new improved C6.1 was driven by the MODIS Atmosphere team to address a number of issues in the current C6 L1B data. These L1B issues had a negative impact in varying degrees in downstream MODIS Atmosphere Level-2 (L2) and Level-3 (L3) products. More information can be found at the MODIS Atmosphere website.
Starting in November 2017, C6 Land processing stream will use the C6.1 L1B as input, with no change to the land-science processing algorithms. We do not expect to see any significant impact to most land products from using upstream C6.1 as inputs except for some minor differences in Terra MODIS snow and sea-ice products because of differences in the Terra cloud mask. Therefore, C6 processing of NRT Terra- and Aqua-MODIS Land products will continue until sometime around the middle of 2018, when C6.1 processing of Land products will start.

What is VIIRS?

Image

VIIRS stands for Visible Infrared Imaging Radiometer Suite (VIIRS). The VIIRS sensor was launched aboard the joint NASA/NOAA Suomi National Polar-orbiting Partnership (Suomi NPP) satellite on October 28th, 2011 and again on the NOAA-20 / Joint Polar Satellite System-1 (JPSS-1) satellite. (Note: JPSS-1 was renamed NOAA-20 after launch). 

Suomi NPP crosses the equator at approximately 13:30 PM (ascending node) and 1.30 AM (descending node). NOAA-20 (JPSS-1) leads Suomi NPP by a half orbit so it crosses the equator approximately 50 minutes earlier.

The 3,040 km VIIRS swath enables ~15% image overlap between consecutive orbits at the equator, thereby providing full global coverage every 12 hours and mid-latitudes will experience 3-4 looks a day. VIIRS has 5 high resolution imagery channels (I-bands), 16 moderate resolution channels (M-bands) and a Day/Night Band (DNB). The VIIRS detectors have a constant angular resolution that results in an increasing pixel footprint size as the scan is further from nadir (see figure 1 below). This means the actual area of each scan has the shape of a bow-tie, as consecutive scans overlap away from nadir. The bow-tie effect is reduced during processing through a combination of aggregation and deletion of overlapping pixels.

What VIIRS products are available in LANCE?

The VIIRS I-band (375 m) Active Fire product and Corrected Reflectance imagery are the newest near real-time products available through LANCE. More will follow. The active fire product will be available in FIRMS and images created from these data products, and Corrected Reflectance images are now available through GIBS for viewing using EOSDIS Worldview and similar clients. The new VIIRS images available through GIBS are Corrected Reflectance (True Color; Bands M3, I3, and M11; and Bands M11, I2, and I1) and Fires and Thermal Anomalies (Day/Night).

View Recording of NASA's Earthdata Webinar: Discover NASA's Near Real-Time Data Using LANCE (February 2020)