359
What Is Aqua and What Does It Do?
Terra and Aqua are designed to work in concert with one another—their
Sun- synchronous orbits are set up similarly so that while Terra is on a descending path, Aqua is ascending (and vice versa). Because of this setup,
Terra crosses the Equator in the morning while Aqua crosses in the afternoon (Aqua was originally called EOS-PM to complement Terra’s original
EOS-AM-1 name). This connection is further strengthened as both satellites
carry a MODIS and a CERES instrument, in essence doubling the data collection performed by these two tools.
Beyond duplicate MODIS and CERES instruments, Aqua carries four others that are unique to its mission of examining Earth’s water cycle: AMSU-A,
HSB, AIRS, and AMSR-E. The AMSU-A (Advanced Microwave Sounding Unit)
instrument is used for creating profiles of the temperature in the atmosphere.
AMSU-A uses 15 microwave bands and is referred to as a “sounder” because
its instruments are examining a three-dimensional atmosphere, similar to the
way “soundings” were used by ships to determine water depths. AMSU-A’s
data provides estimates of not only temperature data but also precipitation
and atmospheric water vapor. Similarly, the HSB (Humidity Sounder for Brazil) instrument’s four microwave bands are used for measuring atmospheric
water vapor levels (in other words, humidity) in the atmosphere (but HSB
unfortunately stopped operating in 2003). Aqua’s fifth instrument is AIRS
(Advanced Infrared Sounder), whose uses include measuring temperature
and humidity levels of the atmosphere as well as information about clouds.
AMSU-A and HSB data is used in close conjunction with AIRS to comprise
a sounding system for Aqua. Data products derived from this suite of instruments include three-dimensional maps of atmospheric temperature, cloud
types, ozone profiles, carbon dioxide levels, and sea surface temperature. This
kind of information can be used for improving weather forecasting as well as
studying Earth’s atmosphere and climate system.
Figure 12.8 on page 360 shows an example of these three instruments
(sometimes referred to as the “AIRS Suite”) working together for one purpose—
namely, tracking and monitoring a tropical cyclone. The four images show (1)
the visible portion of the spectrum, sensed by AIRS, showing the extent and dimension of tropical cyclone Ramasun in 2002, (2) a temperature profile of the
cyclone sensed by AIRS, (3) imagery of the surface below the clouds as sensed
by AMSU-A, which can see through the cloud cover of the hurricane, and (4)
the level of precipitation produced by the hurricane as sensed by HSB. All of the
AIRS Suite instruments provide different “snapshots” of the same feature, allowing a wealth of data to be collected about different kinds of weather phenomena.
AMSR-E (the Advanced Microwave Scanning Radiometer for EOS) is the
last of the Aqua instruments. It uses 12 microwave bands to cover most of the
planet in one day and completes a global dataset in the second day. AMSR-E
monitors a variety of environmental factors that affect global climate conditions, including sea ice levels, water vapor, wind speed, and amounts of global
rainfall. For example, by assessing the amount of rain across the planet on a
near-daily basis, AMSR-E can provide measures of how much precipitation
storms can produce as they move across land or oceans.
AMSU-A the Advanced
Microwave Sounding
Unit instrument
onboard Aqua.
HSB the Humidity
Sounder for Brazil
instrument onboard
Aqua.
AIRS the Advanced
Infrared Sounder
instrument onboard
Aqua (used in
conjunction with Aqua’s
HSB and AMSU-A
instruments).
AMSR-E the Advanced
Microwave Scanning
Radiometer for EOS
instrument onboard
Aqua.
What Is Aqua and What Does It Do?
Terra and Aqua are designed to work in concert with one another—their
Sun- synchronous orbits are set up similarly so that while Terra is on a descending path, Aqua is ascending (and vice versa). Because of this setup,
Terra crosses the Equator in the morning while Aqua crosses in the afternoon (Aqua was originally called EOS-PM to complement Terra’s original
EOS-AM-1 name). This connection is further strengthened as both satellites
carry a MODIS and a CERES instrument, in essence doubling the data collection performed by these two tools.
Beyond duplicate MODIS and CERES instruments, Aqua carries four others that are unique to its mission of examining Earth’s water cycle: AMSU-A,
HSB, AIRS, and AMSR-E. The AMSU-A (Advanced Microwave Sounding Unit)
instrument is used for creating profiles of the temperature in the atmosphere.
AMSU-A uses 15 microwave bands and is referred to as a “sounder” because
its instruments are examining a three-dimensional atmosphere, similar to the
way “soundings” were used by ships to determine water depths. AMSU-A’s
data provides estimates of not only temperature data but also precipitation
and atmospheric water vapor. Similarly, the HSB (Humidity Sounder for Brazil) instrument’s four microwave bands are used for measuring atmospheric
water vapor levels (in other words, humidity) in the atmosphere (but HSB
unfortunately stopped operating in 2003). Aqua’s fifth instrument is AIRS
(Advanced Infrared Sounder), whose uses include measuring temperature
and humidity levels of the atmosphere as well as information about clouds.
AMSU-A and HSB data is used in close conjunction with AIRS to comprise
a sounding system for Aqua. Data products derived from this suite of instruments include three-dimensional maps of atmospheric temperature, cloud
types, ozone profiles, carbon dioxide levels, and sea surface temperature. This
kind of information can be used for improving weather forecasting as well as
studying Earth’s atmosphere and climate system.
Figure 12.8 on page 360 shows an example of these three instruments
(sometimes referred to as the “AIRS Suite”) working together for one purpose—
namely, tracking and monitoring a tropical cyclone. The four images show (1)
the visible portion of the spectrum, sensed by AIRS, showing the extent and dimension of tropical cyclone Ramasun in 2002, (2) a temperature profile of the
cyclone sensed by AIRS, (3) imagery of the surface below the clouds as sensed
by AMSU-A, which can see through the cloud cover of the hurricane, and (4)
the level of precipitation produced by the hurricane as sensed by HSB. All of the
AIRS Suite instruments provide different “snapshots” of the same feature, allowing a wealth of data to be collected about different kinds of weather phenomena.
AMSR-E (the Advanced Microwave Scanning Radiometer for EOS) is the
last of the Aqua instruments. It uses 12 microwave bands to cover most of the
planet in one day and completes a global dataset in the second day. AMSR-E
monitors a variety of environmental factors that affect global climate conditions, including sea ice levels, water vapor, wind speed, and amounts of global
rainfall. For example, by assessing the amount of rain across the planet on a
near-daily basis, AMSR-E can provide measures of how much precipitation
storms can produce as they move across land or oceans.
AMSU-A the Advanced
Microwave Sounding
Unit instrument
onboard Aqua.
HSB the Humidity
Sounder for Brazil
instrument onboard
Aqua.
AIRS the Advanced
Infrared Sounder
instrument onboard
Aqua (used in
conjunction with Aqua’s
HSB and AMSU-A
instruments).
AMSR-E the Advanced
Microwave Scanning
Radiometer for EOS
instrument onboard
Aqua.