IEEE Geoscience and Remote Sensing Magazine - June 2014 - 92

percentile-based exposure to the trapped radiation environment based on more than a decade of data. This information is highly useful to the satellite engineering and
mission planning communities. By focusing the effort on a
well-defined and finite set of needs, the effort avoided the
common problems of requirements creep, cost overruns,
schedule delays, and the consequent difficulties with technology transition and insertion.
5. TesT Bed for sensor simulaTion/evaluaTion
The development cycle of a remote sensing instrument
and/or retrieval algorithm, from its inception to its deployment in a real-time production environment, is a complex
multi-phase process that requires inputs from multiple disciplines. The primary phases of this process are the algorithm design phase, the implementation phase, the deployment phase and maintenance phase. Even though this life
cycle is commonly broken up into these distinct phases it
is by no means a "linear" process and requires well-defined
mechanisms for incorporating knowledge acquired at each
stage into the overall system. This feedback process and the
ability to rapidly assimilate information gained through
this process into the development cycle are critical to
timely and cost effective design. Sensor hardware vendors
and manufacturers benefit from the ability to simulate
sensor performance prior to actual fabrication. By combining our radiative transfer models, retrieval algorithms,
and extensive scene simulation capabilities, we can simulate what a sensor measures from orbital altitudes. Once
having a simulated satellite data stream, we can investigate
how overall noise affects the sensor's ability to reproduce
the expected spectrum and conversely, the ability of the
sensor data to reveal, through inversion, the underlaying
atmospheric state vector. The Interactive Algorithm ToolBox (IATB) and other advance test environments developed at AER are prototyping systems that provide common
software frameworks for effectively accomplishing these
tasks. There primary focus has been to provide a software
environment for the rapid and effective implementation of
the first two phases of this process (design and implementation), however the concepts embodied in this approach
could easily be extended to the entire process. The IATB
design attempts to balance the programmatic needs for
a structured development environment, which in many
cases is very application specific, with the needs of the
individual contributors.
The basic concept behind the IATB approach is to provide a set of common tools and well-defined interface standards that can be used across the entire algorithm development cycle. This approach was implemented in the IATB
structure by providing the following general infrastructure: 1) A defined set of input and output data interface
specifications, and a set of generic software modules that
can be used to ingest and export data in these formats. Further, a living library/database of "scenes" containing both
observed and modeled environmental variables as well as
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simulated and observed radiances covering the spectrum
from the microwave to visible was developed. 2) A library
of basic remote sensing modules that could be used as
building blocks for design, analysis and algorithm implementation. 3) A set of common analysis/display tools and
4) An easy to use interactive execution frame work to aid in
the testing/analysis required at each phase.
In addition to the modules described above, the IATB
also provides a protocol for developing new tools that can
be used in both current and future applications. One of the
primary goals of this design was to minimize the amount
of software redevelopment that occurred during the development of suites of algorithms with common interface
requirements or data needs.
The IATB approach has been used at AER on a number of nationally and internationally prominent programs including instrument assessments and algorithm
development NPP Suomi/JPSS Advanced Temperature
and Moisture Sounder (ATMS), the Cross-Track Infrared
Sounder (CrIS) and Visible Infrared Imaging Radiometer
Suite (VIIRS). These software elements were re-deployed
to assess overall sensor/system performance during the
definition of mission requirements for future programs
such as the Active Sensing of CO2 Emissions over Nights,
Days, and Seasons (ASCENDS) mission proposed as part
of the NASA Earth Science Decadal Survey Studies, and
the analysis of field data from advanced concept initiatives such laser differential absorption spectroscopy
(LAS) instruments for measuring CO column amount
and other trace gases [19]-[20] and the NASA Langley
Research Center ASCENDS CarbonHawk Experiment
Simulator (ACES). In addition, the same technology has
been used to provide rapid development prototype decision aid tools for advance US Air Force Programs, e.g. the
Airborne Laser (ABL) program, and to provide graphical user interfaces to AER's RT models, e.g. LBLRTM and
monoRTM.
6. Physical oceanograPhy
Advances in operational oceanography have been spurred
in the last two decades by routine space observations of sea
level, sea surface temperature, and other ocean variables.
Sea level and ocean bottom pressure research carried out
at AER has been instrumental in designing algorithms for
dealiasing both altimetry and gravimetry satellite missions and determining respective data uncertainties (e.g.,
[21]-[23]). Vinogradova et al. [24] demonstrated the use
of multi-platform SST satellite retrievals to develop a highresolution operational product for the Gulf of Maine. More
recently, AER researchers have been involved in studies of
sea surface salinity related to NASA's Aquarius mission and
the quest to develop operational measurements of salinity
from space [25]-[26]. Extensive work has also been done in
the development of quasi-operational state estimation systems and in the assessment of current and future observing
system needs for the ocean (e.g., [27]-[29]).
ieee Geoscience and remote sensing magazine

june 2014

Table of Contents for the Digital Edition of IEEE Geoscience and Remote Sensing Magazine - June 2014