The Moderate Resolution Imaging Spectroradiometer (MODIS)

This document provides a basic overview of MODIS satellite data. Additional resources on terminology and fundamentals of remote sensing can be found here and here. and this “review of Selected MODIS Algorithms, Data Products, and Applications”.

Introduction

The Moderate Resolution Imaging Spectroradiometer (MODIS) is an optical sensor onboard two satellites named Terra (originally known as EOS AM-1) and Aqua (originally known as EOS PM-1) operated by NASA. Terra was launched on 18 December 1999 and Aqua was launched on 24 May 2002. Terra’s orbit around the Earth is such that it passes from North to South across the equator in the morning, while Aqua passes South to North over the equator in the afternoon. Terra MODIS and Aqua MODIS take images for the entire Earth’s surface every 1 to 2 days. The data collected is the intensity of the light reflected by earth in 36 different wavelengths (“colors”). Both Terra and Aqua also have other sensors besides MODIS. These two sensors have publicly available daily archive of conditions on the earth surface for the past 20 years!

Spatial and spectral properties

The table below summarized the intended use for cation and corresponding spatial resolution in which they are acquired.

MODIS spectral bands and their spatial resolution

Spectral band number

Intended use

Spatial resolution

1-2

Land/Cloud boundaries

250

3-7

Land/Cloud/Aerosol properties

500

8-16

Ocean Color/Phytoplankton/B iogeochemistry

1000

17-19

Atmospheric water vapor

1000

20-23

Surface/Cloud temperature

1000

24-25

Atmospheric temperature

1000

26

Cirrus clouds

1000

27-29

Water Vapor

1000

30

Ozone

1000

31-36

Surface/Cloud temperature cloud top altitude

1000

Processing levels

MODIS data is available at different levels of processing.

  • Level 0: Unprocessed raw satellite feeds (“ungridded orbital swath data”).

  • Level 1A: Raw un-calibrated swath data with georeference information.

  • Level 1B: radiometrically calibrated with georeference information.

  • Level 2: level 1 data atmospherically corrected to yield surface reflectance.

  • Level 2G: Levcel 2 data calibrated and stored as integers on the sinusoidal tiled gridded system.

  • Level 3: level 2 data, properly georeferenced, and often temporally composited or averaged. “Best” pixel selection (e.g. one value per pixel over a period of 7 days)

  • Level 4: data products that have been put through additional processing. Higher processing level than level 3.

More information of these products can be obtain from MODIS Nomenclature.

Products

The higher level data products can be grouped based on their application areas (see: https://modis.gsfc.nasa.gov/data/dataprod/). These products are usually distributed in different spatial resolution (250/500/1000 m) and temporal composite (daily/8-day/16-day/monthly/annual) combinations for both sensors.

Each of those products has a prefix for instance, “MOD” are products from the Terra satellite while “MYD” are products from the Aqua satellite and prefix “MCD” are products generated from a combination of the two satellites.

MODIS Land Products
- MODIS Surface Reflectance
- MODIS Land Surface Temperature and Emissivity (MOD11)
- MODIS Land Surface Temperature and Emissivity (MOD21)
- MODIS Land Cover Products
- MODIS Vegetation Index Products (NDVI and EVI)
- MODIS Thermal Anomalies - Active Fires
- MODIS Fraction of Photosynthetically Active Radiation (FPAR) / Leaf Area Index (LAI)
- MODIS Evapotranspiration
- MODIS Gross Primary Productivity (GPP) / Net Primary Productivity (NPP)
- MODIS Bidirectional Reflectance Distribution Function (BRDF) / Albedo Parameter
- MODIS Vegetation Continuous Fields
- MODIS Water Mask
- MODIS Burned Area Product
MODIS Atmosphere Products
- MODIS Aerosol Product
- MODIS Total Precipitable Water
- MODIS Cloud Product
- MODIS Atmospheric Profiles
- MODIS Atmosphere Joint Product
- MODIS Atmosphere Gridded Product
- MODIS Cloud Mask
MODIS Cryosphere Products
- MODIS Snow Cover
- MODIS Sea Ice and Ice Surface Temperature
MODIS Ocean Products
- MODIS Sea Surface Temperature
- MODIS Remote Sensing Reflectance
- MODIS Chlorophyll-a Concentration
- MODIS Diffuse Attenuation at 490 nm
- MODIS Particulate Organic Carbon
- MODIS Particulate Inorganic Carbon
- MODIS Normalized Fluorescence Line Height (FLH)
- MODIS Instantaneous Photosynthetically Available Radiation
- MODIS Daily Mean Photosynthetically Available Radiation

These products are distributed by different Distributed Active Archive Center(DAAC). For example Land Processes Distributed Active Archive Center, LP DAAC distributes the following products.

MODIS products; # is the product number variant e.g., ‘MOD’, ‘MYD’ or ‘MCD’.

I D

Name

I D

Name

1

Level-1A Radiance Counts

2 0

Chlorophyll II Fluorescence

2

Level-1B Calibrated, Geolocated Radiances

2 1

Chlorophyll a Pigment Concentration

3

Geolocation Data Set

2 2

Photosynthetically Active Radiation (PAR)

4

Aerosol Product

2 3

Suspended Solids Concentration in Ocean Water

5

Total Precipitable Water

2 4

Organic Matter Concentration

6

Cloud Product

2 5

Coccolith Concentration

7

Atmospheric Profiles

2 6

Ocean Water Attenuation Coefficient

8

Gridded Atmosphere Products (Level-3)

2 7

Ocean Primary Productivity

9

Atmospherically Corrected Surface Reflectance

2 8

Sea Surface Temperature

1 0

Snow Cover

2 9

Sea Ice Cover

1 1

Land Surface Temperature & Emissivity

3 1

Phycoerythrin Concentration

1 2

Land Cover/Land Cover Change

3 5

Cloud Mask

1 3

Vegetation Indices

3 6

Total Absorption Coefficient

1 4

Thermal Anomalies, Fires and Biomass Burning

3 7

Ocean Aerosol Properties

1 5

Leaf Area Index and FPAR

3 9

Clear Water Epsilon

1 6

Surface Resistance & Evapotranspiration

4 3

Albedo 16-Day Level-3

1 7

Vegetation Production, Net Primary Productivity

4 4

Vegetation Cover Conversion & Continuous Fields

1 8

Normalized Water Leaving Radiance

A L B

Snow and Sea Ice Albedo

1 9

Pigment Concentration

File format

MODIS data is stored in “Hierarchical Data Format - Earth Observation System” (HDF-EOS) files. HDF format was developed to support storing multiobject data sets (subdatasets) within one file (container). These subdatasets can include raster images, tables, scientific data sets (multidimensional arrays), annotations, vector files, palette information and many more formats.

Read more about use of HDF in NASA Earth Observation System data in HDF-EOS Information Center.

Converting HDF files to a common format (e.g. GeoTiff) that can be read across different software libraries has been one of the major challenges with MODIS data processing. Until recently, commercial programs like ArcGIS, ENVI were not able to read and explore HDF files. In the next section we will show how you can use R to search, download and process MODIS data..

Geographic information

Each file stores data for an area of 10 by 10 degrees, using the sinusoidal coordinate reference system.

Tiling Scheme

The tiles are identified using rows “h” (for horizontal) and columns “v” (for vertical). MODIS uses a vertical horizontal tiling systems (e.g.tile h09v04 as shown in the figure below. A kmz file with MODIS Tile boundaries can be found here

MODIS tiles indexed horizontally and vertically

MODIS tiles indexed horizontally and vertically

MOD09A1 product

Now let’s look at an example MODIS surface reflectance product. “MOD09A1” is a surface reflectance product from data acquired by the MODIS sensor onboard the Terra satellite — hence the prefix “MOD”. It provides estimated “target at surface” spectral reflectance values that have been calibrated for atmospheric conditions such as gasses, aerosols, and Rayleigh scattering. Global surface reflectance products can be obtained at either 250 m or 500 m spatial resolution, and as as daily or 8-day composite data. Below we show a table of the characteristics of the 13 layers that come with “MOD09A1”. A more in-depth description is available here.

MODIS products

B a n d

Name

Type/ units

Data Type

Fill valu e

Valid Range

Scal e fact

1

Red (620-670 nm)

Refle ctanc e

16-bit signed integer

2867 2

-100 - 16000

0.00 01

2

NIR (841-876 nm)

Refle ctanc e

16-bit signed integer

2867 2

-100 - 16000

0.00 01

3

Blue (459-479 nm)

Refle ctanc e

16-bit signed integer

2867 2

-100 - 16000

0.00 01

4

Green (545-565 nm)

Refle ctanc e

16-bit signed integer

2867 2

-100 - 16000

0.00 01

5

NIR (1230-1250 nm)

Refle ctanc e

16-bit signed integer

2867 2

-100 - 16000

0.00 01

6

SWIR (1628-1652)

Refle ctanc e

16-bit signed integer

2867 2

-100 - 16000

0.00 01

7

SWIR (2105-2155 nm)

Refle ctanc e

16-bit signed integer

2867 2

-100 - 16000

0.00 01

8

Reflectance Band Quality

Bit Field

32-bit unsigned integer

4294 9672 95

NA

NA

9

Solar Zenith Angle

Degre e

16-bit signed integer

0

0 - 18000

0.01

1 0

View Zenith Angle

Degre e

16-bit signed integer

0

0 - 18000

0.01

1 1

Relative Azimuth Angle

Degre e

16-bit signed integer

0

-18000 - 18000

0.01

1 2

500 m State Flags

Bit field

16-bit unsigned integer

6553 5

NA

NA

1 3

Day of Year

Julia n day

16-bit unsigned integer

6553 5

1 - 366

NA