Improving Resolution: A Description of the Characteristics and Capabilities of the Advanced Baseline Imager

1. by Randall Bass and Laura Jairam
Improving
resolution
hen Explorer 7 was launched in
1959 by Verner Suomi and
colleagues at the University of
Wisconsin, it marked the first successful
meteorological instrument on board an
orbiting spacecraft and the age of space-
based meteorology was born. Finally
humans were able to see weather from above
the atmosphere instead of from within it.
When TIROS-1 was launched in 1960, we
were able to view the Earth and its weather
systems as a whole for the first time,
changing our perception of the Earth to an
integrated, inseparable system of land,
ocean, and atmosphere. The Applications
Technology Satellite was launched into
geostationary orbit in 1966, and time
domain images of weather patterns became
a reality. The Geostationary Operational
Satellite (GOES) program began in 1975 and
heralded the beginning of operational
geostationary satellite imagery that
continues to this day.
Over time, satellite meteorology has
become routine. Images of storm systems
and hurricanes taken from space flash
across the local news broadcasts on a daily
basis. Today’s younger meteorologists have
never known a time without weather
satellite data to help prepare a forecast. But
real-time pictures of weather systems and
weekend forecasts are not the only use of
meteorological satellite (METSAT) imagery.
The demand for more and more information
on clouds, water vapor and other
atmospheric constituents is increasing as the
understanding of our complex atmosphere
grows. This growing demand is driving the
trend toward better, more elaborate weather
satellites. Toward this end, ITT Corporation
is building the newest imaging sensor, the
Advanced Baseline Imager (ABI), for
integration on the next-generation GOES
series, GOES-R and GOES-S.
ABI characteristics
The meteorological community awaits the
upcoming launch of the GOES-R satellite with
the ABI on board, currently scheduled for 2015.
New capabilities in satellite imaging
A new imaging sensor promises huge improvements in meteorological
satellite-imaging information and products
W
Satellite imaging
Simulation, derived from NASA MODIS data,
showing how ABI clearly captures the over-shooting
(cold) cloud tops, while the GOES Imager does
not (Courtesy of CIMSS at the University of
Wisconsin-Madison
112 • METEOROLOGICAL Technology International NOVEMBER 2010
The ABI will provide significant advancements
over the current fleet of GOES satellite
instruments in several key areas, including the
introduction of new spectral channels from
geostationary orbit and a remarkable
improvement in spatial and temporal resolution
over current GOES imagery.
The spectral characteristics of ABI
combine visible, Near IR, and IR channels
spanning the range of 0.5-13.3 microns
(Table 1). The advantages of ABI’s channel
design are multifold. Heritage GOES
channels, highlighted in Table 1, will
continue long-standing data sets and
support traditional GOES imagery products.
In addition, several new channels will
provide novel science benefits, as well as
measurements complimentary to current
polar orbiting sensors. Like previous GOES
satellites, the ABI will image clouds and
weather systems, monitor water vapor at
three levels, and estimate sea-surface
temperatures, total column ozone, wind
speed, and rainfall rates.
With the addition of the 0.47 micron
visible channel, the 0.865-2.25 micron NIR
channels, and the 8.5 and 10.35 micron IR
channels, ABI will greatly enhance the
monitoring of vegetative growth, the
identification of fire hot spots and volcanic
eruptions, the discrimination of snow and
ice, and the prediction of hurricane
intensities. The ABI will also be capable of
onboard calibration, meaning more reliable
data and more accurate forecasting. Overall,
ABI’s channel characteristics represent the
combined knowledge of several decades of
satellite research and engineering and will
continue the GOES satellite programs’ more
than 30 year trend of advancement in Earth
monitoring and atmospheric remote sensing.
ABI’s spectral advancements will be
further augmented by improvements in both
spatial and temporal resolution over the
current GOES satellite capabilities. The
current GOES imager has a ground
resolution of approximately 1km for visible
images, and 4km in all other bands. ABI
image resolution will be twice as fine at
100% ground coverage with a 0.5km grid
for visible images, a 1-2km grid for its Near
IR channels, and 2km for MWIR and LWIR
bands (Table 1).
The current GOES Imager performs full
disk, CONUS, and mesoscale imaging
functions. However, the operational scan
system can only actively task one of the
functions at a time, therefore each image
must be scheduled for collection in a serial
fashion. For example, the current GOES
imager takes roughly 26 minutes to collect a
full Earth image, which are typically
scheduled once every three hours to collect
CONUS and regional images more regularly.
The rapid-scan mesoscale function can image
a regional area every minute, but at the
expense of losing all METSAT coverage for

2. the rest of the hemisphere. In normal mode,
the current GOES imager collects
approximately four CONUS images per hour.
In contrast, the new ABI sensor will be able
to take a full Earth image in just five minutes.
Furthermore, ABI has a flexible scan mode
where one full Earth disk, three CONUS
images, and 30 mesoscale (aka regional scale,
approximately 1,000 x 1,000km) snapshots
are collected every 15 minutes. ABI’s ability to
focus on regional atmospheric phenomena
with a 30-second refresh rate, while still
monitoring weather on a hemispheric scale, is
truly an exciting advancement for
meteorologists. This feature will greatly aid
efforts to comprehensively track weather
systems affecting North America (see figures
left). It is estimated that ABI will provide 48
times the amount of data available from the
current GOES Imager.
ABI products
ABI will enable more accurate nowcasting
and short-term forecasting than current
METSAT data can provide, based solely on
its finer spatial, spectral, and temporal
resolution. The enhanced resolution and
additional channels on ABI will also offer
new opportunities for remote sensing.
The list of potential applications entices
meteorologists, land-use planners and the
casual weather enthusiast. Supercell
detection, fire detection and characterization,
upper-level sulfuric acid detection, air-quality
analysis, vegetation monitoring, cloud-top
phase/particle-size data, rainfall-rate
detection, and hurricane-intensity estimation,
to name a few, are new and enhanced
products. They can be divided into three
categories: weather and atmospheric
monitoring products, climate monitoring,
and hazard detection. There are far too many
individual products to describe here, but
several of significance are highlighted.
The improved detection of clouds will
benefit the weather community, as well as
climatologists and the aviation community. A
GOES-R Cloud Application Team has been
created and its members have already
Satellite imaging
METEOROLOGICAL Technology International NOVEMBER 2010 • 113
Hurricanes have always been of interest to
maritime and coastal communities. Better
hurricane track and intensity prediction are
a priority for tropical meteorologists.
Hurricanes such as Andrew, Mitch and
Katrina have demonstrated both the
potential destruction of these storms and
the difficulty in accurately predicting their
strength and path.
Although hurricane detection products
are well established using current GOES
imagers, details about the eye of the storm
are underdeveloped. Temporal and spatial
enhancements in the ABI will allow
scientists to monitor storm-eye
development in a similar way to watching
every frame of a movie in high definition
rather than every 10th
frame in standard
definition (below). This capability should
provide insight to better hurricane intensity
estimation. The Hurricane Intensity
Estimate product has been developed to
generate hurricane central pressure data
and maximum sustained winds in near real
time. An intensity estimate analysis and an
intensity trend of the storm will be created
using this product.
The National Hurricane Center will utilize
this information to make more accurate
forecasts and advanced warnings. Data
from ABI not only helps forecasters warn
the public of impending disasters, it will
give meteorologists and climatologists
insight into atmospheric conditions that
cause these storms. Finally, ABI data may
help answer questions on whether climate
change has an effect on the number and
intensity of hurricanes in the ocean basins.
Hurricane
application
developed many new cloud products. ABI’s
higher spatial- and temporal-resolution data
allows forecasters to closely monitor the
development of clouds in all weather
situations. It will be used in conjunction with
a radiative transfer model to generate cloud-
type and cloud top-phase products. These
products will classify the various types of
clouds. The phase (ice, water or mixed) of a
cloud can impact aircraft icing conditions, and
therefore plays a key role in aviation routing
and planning. The cloud top-height product
monitors convective developments, and along
with the cloud-top temperature and cloud-top
pressure products, will provide information
for satellite-derived wind monitoring. Cloud
optical depth, cloud-particle size distribution,
cloud liquid water and cloud-ice water
products round out the cloud-application
suite. In addition to improving aircraft safety,
these products will also provide vital
information for climate research.
Many people around the world are
affected by flooding each year, particularly
Simulated images of the
16 ABI bands for
Hurricane Katrina. These
images were simulated
via a combination of high
spatial-resolution
numerical model runs
and advanced ‘forward’
radiative transfer models
(Courtesy of CIMSS at
the University of
Wisconsin-Madison)

3. 114 • METEOROLOGICAL Technology International NOVEMBER 2010
Satellite imaging
ABI Channels Spectral Spatial
Band Ch. Center Width IFOV Imagery Use Heritage Instruments
Wavelength (µm) FWHM (µm) at nadir (km)
VIS 1 0.47 0.04 1 Daytime aerosol over land, vegetative MODIS*
health, coastal mapping
2 0.64 0.1 0.5 Daytime clouds, fog, insolation, winds Current GOES Imager
and Sounder
NIR 3 0.865 0.039 1 Daytime vegetation, burn scar, VIIRS**, AVHRR†
aerosol over water, winds
4 1.378 0.015 2 Daytime cirrus clouds VIIRS, MODIS
5 1.61 0.06 1 Daytime cloud-top phase and particle size, VIIRS, AVHRR
snow and cloud discrimination
6 2.25 0.05 2 Daytime land properties, cloud particle size, VIIRS, MODIS
vegetation, snow, hot-spot identification
MWIR 7 3.9 0.2 2 Surface, clouds, nighttime fog, winds, Current GOES Imager
fire/hot-spot, volcanic eruption/ash, snow/ice
detection, urban heat islands
8 6.185 0.83 2 High-level atmospheric water vapor, winds, rainfall Current GOES Imager
9 6.95 0.4 2 Mid-level atmospheric water vapor, winds, rainfall Current GOES Sounder
10 7.34 0.2 2 Lower-level water vapor, winds, upper-level Spectrally modified
sulfuric acid (SO2
) current GOES Sounder
11 8.5 0.4 2 Total water for stability, cloud phase, dust, MODIS Airborne
SO2
aerosols Simulator (MAS)
LWIR 12 9.61 0.38 2 Total ozone, turbulence, winds Spectrally modified
current GOES Sounder
13 10.35 0.5 2 Hurricane intensity, surface moisture, cloud particle size MAS
14 11.2 0.8 2 Detection of hazardous weather conditions, Sea Surface Current GOES Sounder
Temp (SST), clouds, rainfall rates
15 12.3 1 2 Total water, ash, dust, SST, cloud particle size Current GOES Sounder
16 13.3 0.6 2 Air temp, cloud heights and amounts, Current GOES Imager
tropopause delineation and Sounder
*MODerate Resolution Imaging Spectroradiometer (MODIS)
** Visible and Infrared Imager and Radiometer Suite (VIIRS)
† Advanced Very High Resolution Radiometer (AVHRR)
in low-lying regions like the Gulf of Mexico
and the south-eastern coastlines of the USA.
Three new products have been designed for
anticipated ABI data: rainfall rate, rainfall
potential, and probability of rainfall. These
precipitation-estimation products are
expected to reduce economic and human
costs associated with flooding events.
Rainfall rate is designed to retrieve cloud
phases and particle sizes from the new
SWIR and MWIR bands on ABI. It will use a
statistical model that will account for
natural variation between, and within,
regions rather than assuming one regional
base model. The improved 2km spatial
resolution will enable better accuracy in the
calculation of rainfall rates. The rainfall
potential product will extrapolate
information from the rainfall rate to aid in
forecasting areas of heaviest rain and flood
potential, with up to three hours of warning.
The rainfall probability product is a three
hour forecast, predicting the geographical
areas where rain is expected. The Advance
Baseline Imager on the GOES series will be
an excellent asset to meteorologists and
climatologists around the world. Its spectral,
spatial, and temporal advancements will
provide more accurate measurements of
cloud properties, convective development,
rainfall rates and hurricane intensities. As a
result, improved forecasts and advanced
warning systems will allow forecasters and
the public to take more preventative
measures when faced with weather
phenomena. This short list of products is
only a small preview of the benefits that the
ABI suite will offer the weather community
and the general public. A prototype model of
the ABI is currently undergoing thermal-
vacuum testing at ITT’s Rochester, NY
facility. This prototype model was built with
the specific design requirements of the
actual flight model for GOES-R, which is
currently in production and on track for a
successful integration and, most
importantly, a successful launch in 2015. z
Randall Bass is a senior meteorologist with ITT
Geospatial Systems, Herndon, Virginia and Laura
Jairam is a senior image scientist with ITT Geospatial
Systems in Herndon. Cooperation came from Rachel
Fitzhugh, an image scientist with ITT Geospatial
Systems, Rochester, and Marie Knappenberger, a
geoscientist in Rochester, New York
Prototype model of ABI
Table 1: Channel Characteristics of the Advanced Baseline Imager