The NASA Earth Observing System Simulators Suite (NEOS3) is a modular framework of forward simulations tools for remote sensing of Earth’s Atmosphere from space. It was initiated as the Instrument Simulator Suite for Atmospheric
Remote Sensing (ISSARS) under the NASA Advanced Information Systems Technology (AIST) program of the Earth
Science Technology Office (ESTO) to enable science users to perform simulations based on advanced atmospheric and
simple land surface models, and to rapidly integrate in a broad framework any experimental or innovative tools that they
may have developed in this context. The name was changed to NEOS3 when the project was expanded to include more advanced modeling tools for the surface contributions, accounting for scattering and emission properties of layered
surface (e.g., soil moisture, vegetation, snow and ice, subsurface layers). NEOS3 relies on a web-based graphic user
interface, and a three-stage processing strategy to generate simulated measurements. The user has full control over a
wide range of customizations both in terms of a priori assumptions and in terms of specific solvers or models used to
calculate the measured signals.This presentation will demonstrate the general architecture, the configuration procedures
and illustrate some sample products and the fundamental interface requirements for modules candidate for integration.
This paper discusses processing of interferometric signal to measure ocean topography. The method corrects for channel misregistration and geometric decorrelation using estimates of the current Earth geoid scenario. The channel misregistration is caused by slight change in the differential time delay between the signal received at one antenna with respect to the other. This algorithm corrects the misregistration over the entire swath with the Chirp-Z transform which resamples the signals appropriately. Another source of error, the geometric decorrelation (or baseline decorrelation), occurs because the targets within the resolution cell contribute different interferometric phases. In essence, the ground projected wavelengths are different for various look angles which produces a shift of the effective spectrum. This is corrected by shifting the spectra relative to one another and by applying filters to eliminate the non-overlapping part of the spectra. However, the co-registration and the spectral shift require the estimation of the current look and incidence angles. We use the Earth Ellipsoid WGS-84 and the Geoid EGM-96 to estimate the geometric parameters to describe the various viewing scenarios encountered around the Earth Geoid. We finally discuss the implications on the signal processing algorithm.