Noise performance of the NPOESS Airborne Sounder Testbed Interferometer (NAST-I) sounder: flight and model results

摘要

Abstract: NAST-1 is a Fourier transform interferometric sounder that provides very high spectral and spatial resolution measurements of the Earth's atmosphere. The interferometer provides two dimensional, low noise data from the NASA ER-2 aircraft suitable for synthesizing data products of future satellite-borne sounding instrument candidates. It is the first such high altitude aircraft or satellite borne instrument. The instrument provides a 2.6 km nadir footprint and a cross-track field of regard of $POM 48.2 degrees. The instrument has a continuous spectral range of 3.6-16.1 $mu@m, spectral resolution of 0.25 cm$+$MIN@1$/, and radiometric noise on the order of 0.25 K. NAST-1 has proven to be an extremely reliable instrument generating over 100 hours of high-quality flight data, and was delivered to the sponsor on a very tight schedule. Using a first principles model, the noise performance of the instrument was modeled and found to be in close agreement with noise measured in- flight. Alignment jitter has been identified as the major contributor to the system NEdN. This paper describes the mode used to predict the instrument noise performance and discusses the comparison to actual flight data. !10