9

Monitoring the Global Environment

GOES-R

The POES Earth Observing Satellite (EOS) Program - II

AQUA

TERRA

"Aqua" is the Latin word for "water". The Aqua mission is named for the large amount of information it collects about the Earth's water cycle, including ocean surface water, evaporation from the oceans, water vapor in the atmosphere, clouds, precipitation, soil moisture, sea ice, land ice, and snow cover. Aqua also hosts three high powered sounders that provide high precision vertical profiles of the Earth's atmosphere.

Instruments

Aqua and its six instruments

There are six instruments on the Aqua satellite:

  • AIRS – Atmospheric Infrared Sounder
  • AMSR-E – Advanced Microwave Scanning Radiometer for EOS
  • AMSU – Advanced Microwave Sounding Unit
  • CERES – Clouds and the Earth’s Radiant Energy System
  • HSB – Humidity Sounder for Brazil
  • MODIS – Moderate-resolution Imaging Spectroradiometer
  • AIRS

    Specifications:

    AIRS is a high-resolution infrared sounder with the central purpose of obtaining atmospheric temperature and humidity profiles from the surface upward to 40 kilometers. The AIRS instrument has 2,382 channels. 2378 measure infrared radiation at wavelengths between 3.74 and 15.4 µm with a resolution of 13.5 kilometers, the remaining four channels measure in the visible/near-infrared range of 0.4 to 1.1 µm at a resolution of 2.3 kilometers.

    The AIRS instrument is expected to provide substantial improvements in temperature measurements over any previous sounder flown in space, not to mention 20th century radiosondes (weather balloons). It will greatly enhance the traditional land-based record since it covers the entire globe.

  • AMSU

    Specifications:

    AMSU will aid in atmospheric temperature profiling for the upper atmosphere. AMSU has 15 channels that sample atmospheric radiation in different frequencies, rather than wavelengths. 12 channels are predominately for atmospheric temperature soundings while 3 are for water vapor and precipitation estimates. The horizontal resolution provided by AMSU is approximately 40.5 kilometers.

  • CERES

    Specifications:

    CERES consists of two scanning radiometers that will measure the Earth's radiation balance and provide detailed information on cloud properties. There are two identical CERES radiometers on Aqua & Terra because they operate in different, overlapping scanning modes (crosstrack and biaxial) for more complete data collection.

    Each CERES instrument has three channels- a short wave channel for measuring reflected sunlight (0.3 to 5.0 µm), a longwave channel for total radiation in the 8 to 12 µm "window" region, and a total radiation channel. (0.3 to 200 µmm)

    CERES data will be used to:

    • Study cloud properties;
    • Develop an observational baseline of clear-sky radiation fluxes;
    • Determine radiation input to atmospheric and oceanic models;
    • Validate general circulation models;
    • Enhance extended-range numeral weather predictions for weather forecasting
  • HSB

    Specifications:

    HSB is a four-channel radiometer that measures atmospheric radiation at different frequencies, rather than wavelengths. The HSB is particularly important for obtaining accurate humidity profiles under overcast conditions. The HSB will obtain humidity soundings through the atmosphere for determining cloud liquid water, precipitation, and integrated precipitable water.

  • MODIS

    Specifications:

    MODIS is a scanning imaging radiometer with a viewing swath width of 2330 kilometers. MODIS will provide high-resolution images of daylight-reflected solar radiation and 24 hour thermal (IR) information over all regions of the globe. Its spatial resolution ranges from 250 meters to 1 kilometer. The broadband spectral coverage of the instrument (0.4 to 14.4 µm) is divided into 36 bands of various bandwidths optimized for imaging surface and atmospheric features.

    MODIS measures:

    • Surface temperature (land and ocean) and fire detection;
    • Ocean color (sediment , phytoplankton);
    • Global vegetation maps and change detection;
    • Cloud characteristics;
    • Aerosol concentrations and properties

Technically the spacecraft has eight EOS instruments since there are two identical copies of CERES and the AMSU. Collectively they will gather radiation data from a large portion of the electromagnetic spectrum, ranging from the ultraviolet, visible, infrared and microwave wavelengths. By having multiple types of measurements, scientists can gain a more complete understanding of the Earth/atmosphere system.

The key science topics addressed by Aqua are atmospheric temperature, sea ice cover, deforestation and other changes in vegetation cover, changes in the stratospheric "ozone hole", weather forecasting, clouds, and natural hazards. Alarm systems using satellite observations to monitor fire, famine, floods and volcanoes are currently under development. The applications are endless.