Gradient field mapping measurement concept demonstration with a geostationary severe storm imager (IFTS)

摘要

Abstract: A unifying theme throughout the ESE science objectivesis the identification of regions with large temporaland spatial gradients. Severe storm formation occurs inthe boundary regions between airmasses with verydifferent temperatures, pressures, water content,aerosol loading. Severe storm tracking and forecastingutilizes the discontinuities in observed fields andgradient fields to diagnose and forecast the formation,evolution, and motion of severe storms. In a similarfashion, heat islands, super-regional pollution, andrain shower formation are each the result of temporaland spatial gradients present in the atmosphere.Diagnosing and forecasting these events requires anability to map atmospheric gradients anddiscontinuities in real-time on micro to meso-scales inthe atmosphere (0.5 - 500 km). A new measurementconcept, the Imaging Fourier Transform Spectrometer(IFTS) is capable of demonstrating a class ofautonomous event identification, monitoring andtracking sensors. In order to provide this capability asensor with the ability to combine high spatialresolution (0.5 - 1 km) imaging with high spectralresolution (0.25 cm - 1 across the mid infrared 3 -10microns) in time intervals of a few seconds isrequired. An electronically programmable infraredcamera that combines a large-format focal plane arraywith a Fourier transform spectrometer can deliver thiscapability. It also builds on currently fieldedairborne demonstration systems and an instrumentconcept in development for the Next Generation SpaceTelescope (NGST). The IFTS concept is revolutionary inseveral aspects. It can produce 2 - 10 fold increase inspatial resolution, 2 fold increases in spectralresolution, and 30 fold increases in temporalresolution. In combination the measurement conceptwould require a 100 - 600 fold increase in telemetrybandwidth without a new approach to imaging. IFTSbreaks this paradigm with a new approach tohyperspectral imaging. Severe storm forecastingrequires gradient fields (i.e., first and secondderivatives of atmospheric observations). Hence, thismeasurement concept for IFTS is enabled by fourinnovations: (1) directly observe the derivativefields, (2) Nyquist sample the image plane to enablefull utilization of the telescope performance, (3) havemulti-channel detection of gradient regions, and (4)provide an autonomous targeting and tracking systemthat identifies, subsets, and follows regions withsignificant discontinuities (i.e., regions where severestorms, toxic pollution, heat islands, orrain/thunderstorms will form). !3