MODIS Aqua

MODIS Aqua Satellite System

Overview/History

MODIS stands for Moderate Resolution Imaging Spectroradiometer. MODIS is an important instrument that is aboard both Aqua and Terra Satellites. This instrument provides high radioactive sensitivity in 36 spectral bands. MODIS Terra was launched in 1999, and MODIS Aqua was launched in 2002. Both of these MODIS instruments provide an unprecedented look at our Earth’s phenomenology for a wide range of users.

Aqua, or water, is a mission named for its great amount of data collected on the Earth’s water cycle. Aqua collects data from everything on Earth involving water, for example: clouds, precipitation, water vapor, sea ice, land ice, snow cover, and evaporation from the oceans. Other variables studied by the Aqua mission are: atmospheric aerosols, soil moisture, vegetation cover on the land, radiant energy fluxes, and air, land, and water temperatures.

Aqua carries six very advanced instruments, each with unique abilities and functions, to observe the Earth. The six instruments are: Atmospheric Infrared Sounder (AIRS), the Advanced Microwave Sounding Unit (AMSU-A), the Humidity Sounder for Brazil (HSB), the Advanced Microwave Scanning Radiometer for EOS (AMSR-E), the Moderate Resolution Imaging Spectroradiometer (MODIS), and Clouds and the Earth's Radiant Energy System (CERES).

Spatial/Spectral/Time Resolution

Aqua orbits the Earth at an altitude of 705km and takes 99 minutes to make a full orbit. AIRS has a spatial resolution of 13.5km horizontal at nadir, and 1km vertical resolution. AMSU-A has a spatial resolution of 40km horizontal at nadir. HSB has a spatial resolution of 13.5km horizontal at nadir. The spectral range for MODIS is 0.4-14.5mm.

Pros

Aqua data improves weather forecasts and models. Aqua also gives a global scale of air temperature, humidity, clouds, and surface temperature measurements. Researchers get a wide range of data to study Earth science topics because the instruments cover a large portion of the electromagnetic spectrum. The ability of Aqua to gather infrared data plays a large role in climate change studies.

Cons

Aqua instruments are only able to measure radiation because it is a passive sensor. The data will have much coarser spatial resolutions because of the lower frequencies and longer wavelengths of the visible data. Cloud coverage will result in coarser spatial resolution for Aqua instruments. Most of the instruments onboard Aqua were designed to last three to five years, so the future of Aqua has to be a concern.

Examples of Use

Aqua data plays a large role in climate change studies. Sea ice cover, for example, is something Aqua can measure everyday which can help determine the changes that are going to occur with the rest of the Earth and the species that are most directly affected. Ozone studies are another example of how Aqua data is used to benefit the Earth. The Aqua team can use the infrared data to get more layers of information about the condition of the ozone. The CERES instrument plays a big role in measuring conditions after natural disasters such as volcanic eruptions. CERES provided valuable information regarding the temperature of the atmosphere after Mount Pinatubo erupted.