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The new era of high spectral resolution infrared instruments for atmospheric sounding offers great opportunities for
climate change applications. A major issue with most of our existing IR observations from space is spectral sampling
uncertainty and the lack of standardization in spectral sampling. The new ultra resolution observing capabilities from the
AIRS grating spectrometer on the NASA Aqua platform and from new operational FTS instruments (IASI on Metop,
CrIS for NPP/NPOESS, and the GIFTS for a GOES demonstration) will go a long way toward improving this situation.
These new observations offer the following improvements:
1. Absolute accuracy, moving from issues of order 1 K to <0.2-0.4 K brightness temperature,
2. More complete spectral coverage, with Nyquist sampling for scale standardization, and
3. Capabilities for unifying IR calibration among different instruments and platforms.
However, more needs to be done to meet the immediate needs for climate and to effectively leverage these new
operational weather systems, including
1. Place special emphasis on making new instruments as accurate as they can be to realize the potential of
technological investments already made,
2. Maintain a careful validation program for establishing the best possible direct radiance check of long-term
accuracy--specifically, continuing to use aircraft-or balloon-borne instruments that are periodically checked
directly with NIST, and
3. Commit to a simple, new IR mission
that will provide an ongoing backbone for the climate observing system. The new mission would make use of Fourier Transform Spectrometer measurements to fill in spectral and
diurnal sampling gaps of the operational systems and provide a benchmark with better than 0.1K 3-sigma accuracy based on standards that are verifiable in-flight.
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