Spatial resolution and processing tradeoffs for HYDROS: application of reconstruction and resolution enhancement techniques

Abstract

Abstract-Recent developments in reconstruction and resolution enhancement for microwave instruments suggest a possible tradeoff between computation, resolution, and downlink data rate based on postcollection reconstruction/resolution enhancement processing. The Hydrospheric State mission is designed to measure global soil moisture and freeze/thaw state in support of weather and climate prediction, water, energy, and carbon cycle studies, and natural hazards monitoring. It will use an active and passive L-band microwave system that optimizes measurement accuracy, spatial resolution, and coverage. The active channels use synthetic aperture radar-type processing to achieve fine spatial resolution, requiring a relatively high downlink data rate and ground processor complexity. To support real-time applications and processing, an optional postcollection reconstruction and resolution enhancement method is investigated. With this option, much lower rate real-aperture radar data are used along with ground-based postprocessing algorithms to enhance the resolution of the observations to achieve the desired 10-km resolution. Several approaches are investigated in this paper. It is determined that a reconstruction/resolution enhancement technique combining both forward-and aft-looking measurements enables estimation of 10-km resolution or better backscatter values at acceptable accuracy. Key tradeoffs to achieve this goal are considered.

The TropSat mission: An observatory for mesoscale convective system processes in the global tropics

“…As has been demonstrated with SeaWinds data, reconstruction/resolution enhancement processing enables high-resolution wind and rain retrieval from the backscatter measurements [6]- [8]. By designing the instrument with this processing in mind, we can optimize the reconstruction resolution enhancement [9].…”

Spatial resolution enhancement of Cassini Titan Radar mapper data

“…SIR been applied to scatterometers such as SeaWinds [3] as well as radiometers such as AMSRE and SMM/I [6]. SIR has also been studied for use with the proposed HYDROS, which includes a radiometer, scatterometer, and low resolution SAR [5].…”

“…A practical limitation to the recovery is a response function spectral gain more than 40-50 dB down from the peak, though this number is reduced when the measurement SNR is low [5]. Unfortunately, low SNR is common for the Titan Radar.…”

“…Due to the instrument characteristics, the SRFs of the two modes have somewhat different shapes. The reconstruction exploits this in the processing as suggested in [4], [5]. Figure 7 illustrates how the relative orientations of the SRFs improve the resolution of the Cassini T16 modes.…”

Resolution enhancement of passive microwave images from geostationary Earth orbit via a projective sphere coordinate system

“…[2][3][4][5][6] The SIR algorithm is a variation of the multiplicative algebraic-reconstruction technique which could find the optimal estimate of brightness temperature by iterative algorithms. [7][8][9] The Wiener filter method using filter and Fourier transform theory to invert the convolution processing in measurement could also reconstruct the brightness temperature. [10][11][12] These methods have been widely used in microwave radiometer data from LEO.…”