1. Using Aircraft-based NAST Interferometer Data to Perform HES Trade-off Studies
Michael J. Jun Li#, Daniel K. Zhou%, and Timothy J.
@NOAA/NESDIS Center for Satellite Applications and Research - Madison, WI
#Cooperative Institute for Meteorological Studies, University of Wisconsin – Madison, WI
%NASA Langley Research Center – Hampton, VA
1. Introduction
3. Preliminary Results – THORPEX (2003)
The National Polar-Orbiting Operational Environmental Satellite System (NPOESS) Airborne Sounder Testbed Interferometer (NAST-I), which flies on high altitude aircraft, provides radiometric measurements with continuous spectral coverage between 645 – 2700 cm-1, with a spectral resolution of 0.25 cm-1 and a nominal spatial resolution of 2.6 km from an aircraft altitude of 20 km. The instrument properties of the NAST-I make it ideal for simulating the spectral coverage and resolution of the IR-sounding component of the Hyperspectral Environmental Suite (HES), which is slated to be part of the next generation geostationary observing system GOES-R. While the exact HES instrument specifications have not yet been finalized, NAST-I interferograms can be convolved to accurately simulate any proposed HES spectral resolution specification, and the NAST-I spectral coverage allows for the simulation of the various HES spectral coverage options.
NAST-I
HES1a
HES1b
HES2
Preliminary Observations:
The default NAST-I case seems to have the most vertical structure.
The inclusion of the LW portion of the water vapor absorption band results in a very moist boundary layer (e.g. HES1a versus HES1b).
Options HES2 and HES3b seem to produce similar results.
Options HES3a and HES3c produce similar results.
HES3a
HES3b
HES3c
Comparisons of temperature and water vapor cross sections for each instrument configuration.
2. Methodology S1
5. Future Work S1 S2 S3
A linear statistical regression (Zhou et al., 2002) atmospheric profile retrieval is applied to the NAST-I spectra and each convolved NAST-I spectra. The basic methodology is as follows:
NAST-I measured and calculated spectra were convolved to the spectral resolution of the HES instrument design options by applying the Fast Fourier Transform (FFT).
The convolved spectra were then sampled appropriately to match the various HES spectral coverage options.
Twice the nominal NAST-I instrument noise was added to the calculated spectra in order to reduce the sensitivity of the regression retrieval to the number of Empirical Orthogonal Functions (EOF).
Additional cases need to be processed along with comparisons to dropsondes and rawinsondes.
We need to study in more detail the impact of instrument noise and the number of EOF’s on the retrievals.
Study the influence of the HES instrument design on products derived from atmospheric profiles such as CAPE, LI, TPW, etc… This sort of analysis will help characterize the performance of HES products in diagnosing the pre-convective storm environment.
Compare the results to current GOES sounder and NWP profiles. S2 S3
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