MODIS Rapid Response

A MY NASA DATA Guide to MODIS Rapid Response

You can find MODIS images of the Earth in two places on the site: in the Real-Time section and in the Gallery. The Gallery contains images of important events or images that the MODIS team has selected to highlight. The Real-Time section displays all of the images that MODIS collects every day. It takes at least two hours, sometimes more, before the MODIS images are posted to the Rapid Response site.

MODIS scans back and forth as it takes an image. The edges of the image are distorted. The Real-Time images are displayed as they are scanned by MODIS, without correction for geometric distortion. Since the observed pixels at the edge of the swath are bigger than they are in the center, they appear to be scrunched into a too-small grid box when displayed “as-is” in the Real-Time imagery. The distortion is more obvious in the higher resolution images (i.e., 250 m pixels). The images in the Gallery have been corrected for distortion.

Click here to access the MODIS Rapid Response System

How to find images in the Real-Time section:

Click on the Real-Time button. Images posted for today will be shown. You can also choose other dates by clicking on the calendar.

If you know the Coordinated Universal Time (UTC) of the satellite overpass:

  1. Simply look for the nearest image (they are posted at 5-minute intervals).
    Note: Terra appears first on this page, with Aqua below.
  2. Click on the thumbnail to see the image in multiple resolutions and band combinations.

If you do not know the UTC of the satellite overpass:

  1. Click on either the Terra or Aqua “Orbit Tracks” map.
  2. Find the area you want to see on the map.
    • On the Terra Orbit Track map, the lines that run from the top right to the lower left show where it was during the day when MODIS can take true-color images. The other lines show Terra’s night-time orbit tracks. Since only day-time images are posted on the site, find the day time line that runs closest to the area you want to see. Note the time stamp to the north of the area you want to see.
    • On the Aqua Orbit Track map, locate the nearest line running from the bottom right to the top left. This traces Aqua’s daytime orbit. Note the time to the south of the area you want to see.
  3. Close the orbit map, and scroll to the right time – remembering that Terra appears first on the page, followed by Aqua.
  4. Remember that images aren’t posted until at least two hours after they are taken.
  5. Click on the thumbnail to see the image in multiple resolutions and band combinations.

How to find images in the Gallery:

  1. Click on the Gallery link. The most recent images appear on the page.
  2. Enter the name of the country or state you want to see in the search box, OR
  3. Scroll to the bottom of the page and select the date, if you want an image from a particular day.

What are the red boxes in some of the MODIS images?:

Click on the FAQ link and then click on the question “What do the red boxes mean?” for the explanation.