SF43A-0769 1340h
National Polar-orbiting Operational Environmental Satellite System (NPOESS) Potential Pre-planned Product Improvement (P3I) Status
The NPOESS spacecraft is designed to provide ample resource margins that can be used to support Potential Pre-planned Product Improvement (P3I). The P3I Program Plan supports the infusion of new satellite observational technologies, and the validation of new capabilities. This paper will discuss status of the NPOESS spacecraft P3I resources and the planned processes for P3I implementation. In addition, the sensor interface requirements, the sensor information package needs, the schedule and milestones requirements for the NPOESS flights will be discussed. The information will be used for the preliminary technical assessment by the government of candidate instruments/experiments programs. This P3I effort is ongoing and the material in this report will provide a status of the work.
SF43A-0770 1340h
Development and Operation of the Americas ALOS Data Node
In the spring of 2005, the Japanese Aerospace Exploration Agency (JAXA) will launch the next generation in advanced, remote sensing satellites. The Advanced Land Observing Satellite (ALOS) includes three sensors, two visible imagers and one L-band polarimetric SAR, providing high-quality remote sensing data to the scientific and commercial communities throughout the world. Focusing on remote sensing and scientific pursuits, ALOS will image nearly the entire Earth using all three instruments during its expected three-year lifetime. These data sets offer the potential for data continuation of older satellite missions as well as new products for the growing user community. One of the unique features of the ALOS mission is the data distribution approach. JAXA has created a worldwide cooperative data distribution network. The data nodes are NOAA /ASF representing the Americas ALOS Data Node (AADN), ESA representing the ALOS European and African Node (ADEN), Geoscience Australia representing Oceania and JAXA representing the Asian continent. The AADN is the sole agency responsible for archival, processing and distribution of L0 and L1 products to users in both North and South America. In support of this mission, AADN is currently developing a processing and distribution infrastructure to provide easy access to these data sets. Utilizing a custom, grid-based process controller and media generation system, the overall infrastructure has been designed to provide maximum throughput while requiring a minimum of operator input and maintenance. This paper will present an overview of the ALOS system, details of each sensor's capabilities and of the processing and distribution system being developed by AADN to provide these valuable data sets to users throughout North and South America.
http://aadn.asf.alaska.edu
SF43A-0771 1340h
Key Features of the National Polar-Orbiting Operational Environmental Satellite System (NPOESS) System Architecture
The National Polar-Orbiting NPOESS, a tri-agency program, supports missions of the Department of Commerce (DOC)/National Oceanic and Atmospheric Administration (NOAA), the Department of Defense (DoD), and the National Aeronautics and Space Administration (NASA). NPOESS provides a critical, timely, reliable, and high quality space-based sensing capability to acquire and process global and regional environmental imagery and specialized meteorological, climatic, terrestrial, oceanographic, solar-geophysical, and other data products. These products are delivered to national weather and environmental facilities operated by NOAA and DoD, to NASA, and to environmental remote sensing science community users to support civil and military functions. These data are also provided in real time to field terminals deployed worldwide. The NPOESS architecture is built on a foundation of affordability, and the three pillars of data quality, latency, availability. Affordability refers to an over-arching awareness of cost to provide the best value to the government for implementing a converged system; some dimensions of cost include the cost for system development and implementation, the balance between development costs and operation and maintenance costs, and the fiscal year expenditure plans that meet schedule commitments. Data quality is characterized in terms of the attributes associated with Environmental Data Records (EDRs), and the products that are delivered to the four US Operational Centrals and field users. These EDRs are generated by the system using raw data from the space-borne sensors and spacecraft, in conjunction with science algorithms and calibration factors. Data latency refers to the time period between the detection of energy by a space-borne sensor to the delivery of a corresponding EDR. The system was designed to minimize data latency, and hence provide users with timely data. Availability refers to both data availability and system operational availability. Data availability is ensured by the way data is stored and routed throughout the system, on the spacecraft and on the ground, so that it can be retrieved and resent if the first transmittal is not successful. Operational availability is a measure of how well around-the-clock operations are supported, through the careful deployment of hot spares and fault tolerance of the system. Both types of availability are very high for the NPOESS architecture. Overall, the NPOESS architecture successfully delivers to the government a best-value solution featuring high data quality, low data latency, and high data/system availability.
SF43A-0772 1340h
Status of the Geostationary Spectrograph (GeoSpec) for Earth and Atmospheric Science Applications
GeoSpec will support future satellite mission concepts in the Atmospheric Sciences and in Land and Ocean Sciences by providing time-resolved measurements of both chemically linked atmospheric trace gas concentrations of important molecules such as O3, NO2, CH2O and SO2 and at the same time coastal and ocean pollution events, tidal effects, and the origin and evolution of aerosol plumes. The instrument design concept in development is a dual spectrograph covering the UV/VIS wavelength region of 310-500 nm and the VIS/NIR wavelength region of 480-940 nm coupled to all reflective telescope and high sensitivity PIN/CMOS area detectors. The goal of the project is to demonstrate a system capable of making moderate spatial resolution (1 km at nadir) hyperspectral measurements (1.0 to 1.5 nm resolution) from a geostationary orbit. This will enable studies of time-varying pollution and coastal change processes with a temporal resolution of 15 minutes on a regional scale to 1 hour on a continental scale. Other spatial and temporal resolutions can be supported by varying the focal length of the input telescope and scanning strategies. Scientific rationale and instrument design and status will be presented.
SF43A-0773 1340h
On the Potential of Existing Ocean Color Sensors for Monitoring Productive Turbid Waters
Case-1 water bio-optical algorithms for remote estimation of chlorophyll-a concentration (Chl) exploit the upwelling radiation in the blue and green spectral regions. In case-2 waters other constituents, that vary independently of Chl, absorb and scatter light in these spectral regions. As a consequence, the accurate estimation of Chl in productive turbid waters has not been so far feasible from satellite sensors. In this study we calibrated and validated Chl bio-optical models based on simulated red and near-infrared (NIR) channels of three existing ocean color sensors: the Sea Wide Field-of-View Sensor (SeaWiFS), the Moderate Imaging Spectrometer (MODIS) and the Medium Resolution Imaging Spectrometer (MERIS). Reflectance spectra and relevant water constituents were collected in 270 stations over lakes and reservoirs with a wide variability in optical parameters (i.e. 4$<=$Chl$<=$240 mg m-3; 18$<=$Secchi disk depth$<=$308 cm). The relative uncertainties in Chl prediction due to the bio-optical algorithms alone were low ranging from 24% to 28% (average bias between -6% and +5%). Then, by taking into account the radiometric sensitivities of the sensors, we determined the atmospheric correction requirements for accurate Chl estimation. The radiometric sensitivity of SeaWiFS appeared to be too low for estimating Chl using the red and NIR channels. In contrast, the higher signal-to-noise ratio of MODIS allowed accurate ($<$35%) estimation of Chl in turbid productive waters for Chl$>$15 mg m-3. For a worst case scenario (solar zenith angle 60°, Chl=15 mg m-3, uncorrelated uncertainties), the uncertainty in atmospheric correction required to obtain a $<$35% overall uncertainty in Chl was approximately three times the sensor noise. Such a requirement was less stringent at lower solar zenith angles, higher Chl and in the case of correlated atmospheric uncertainties. Thus, it appears that MODIS could be used for predicting Chl in case-2 productive turbid waters. MERIS three-band algorithms using the 705 nm channel have the additional advantages of being less affected by sensor noise and to compensate for correlated atmospheric uncertainties. This allows to accurately estimate Chl$>$10 mg m-3.
SF43A-0774 1340h
Testing Hyperspectral Indices for Crop Identification and Stress Detection
Many agricultural applications can benefit from the rapidly expanding array of remote sensing technologies. Here we evaluate recent hyperspectral images acquired by EO-1 Hyperion over an agricultural region in Mexico. Two applications that have seen limited success with multispectral sensors -- crop discrimination and stress detection -- were investigated using a combination of ground measurements, decision tree modeling, and multi-temporal image analysis. Results indicate substantial improvements over multispectral approaches for both applications.
SF43A-0775 1340h
Development of Future Active Sensors for Remote Sensing
Active optical and microwave sensors are presently being developed for Earth remote sensing and potentially for future planetary missions. These sensors include active designs for application in geostationary orbit, as well as for airborne in-situ measurements and for UAV applications. In addition to new instrument designs, active optical component development is underway to address many issues which will enhance future active sensors. This paper will describe some of the NASA investments currently underway in active remote sensing.
SF43A-0776 1340h
Remote Sensing Opportunities Beyond Exploration of the Photon's State Variables, with Examples
The evolution of Earth system observation by satellite remote sensing can be seen as a systematic exploration and exploitation of the photon or EM wave's state variables: emission (or last scattering) point and direction, wavelength, and now polarization, plus travel time in active techniques. Wavelength spawns the spectral dimension of the data, itself evolving from broadband to multi- to hyper-spectral sampling and to ever more exotic wavelengths (e.g., microwaves and sub-mm wavelengths). We are thus constantly pushing the technology to open new spectral ``windows'' or to examine the available ones in increasing detail. Polarization, a statistical property of the photon beam, offers promising applications. Position and direction are geometrical beam characteristics that simply determine the pixel of interest on the focal plane; no more is expected. Similarly the temporal dimension in active techniques is interpreted just as return-travel time, hence position along the source beam. Conventional exploitation algorithms (i.e., retrieval schemes) look for known patterns, trends, correlations, etc. between radiances at different wavelengths and/or polarizations. This strategy seems natural and enables independent pixel-by-pixel exploitation, a significant advantage for the data processing as the numbers of pixels and spectral/polarization channels increases. However, at this level, we are overlooking all the information that could be reaped from the complex spatial/directional relations that are so obvious when we examine satellite imagery visually. At best, this is left for projects in post-processing that tend to be limited to case-studies published in the research literature. We will argue that this strategy of extensive photon-state sampling and the resulting ---or is it driven by?--- pixel-by-pixel exploitation paradigm in remote sensing is suboptimal for a number of reasons. For one, it comes hand-in-hand with making horizontal homogeneity assumptions inside the pixel footprint that may not be realistic enough to approximate the actual radiative transfer processes at the accuracy of the instrument's SNR level. Furthermore, as spatial resolution increases, there will be increasing amounts of radiometric cross-talk between pixels (a.k.a. adjacency effects) at scattering/reflecting wavelengths; this impact of spatial variability will also be ignored. A cost-effective remedy for the ills caused by these internal and external variability effects is to engage the three-dimensional radiative transfer modeling community in improved algorithm development. Last but not least, there is an emerging class of instruments that are designed from the onset using the rich phenomenology of 3D radiative transfer, often with time dependence; the theory that supports these instruments is not so much about individual photon beams but about the complex interaction of the photon population as it flows within the 3D atmosphere-surface medium. The examples we will use include high-resolution O$_2$ spectrometry as a cloud-scene probe and off-beam cloud lidar systems. Because of the radically different kind of theory involved, these instrumental developments are not evolutionary but revolutionary. This poses a challenge for mission and program management as well as for the developer. How does one promote a promising but unconventional instrument design into an operational setting?
http://nis-www.lanl.gov/~adavis
SF43A-0777 1340h
The Application of Principal Component Analysis in Fast, Highly Accurate and High Spectral Resolution Radiative Transfer Modeling: A Case Study of the O$_{2}$ A-band
Radiative transfer computation is the rate-limiting step in most high spectral resolution remote sensing retrieval applications. While several techniques have been proposed to speed up radiative transfer calculations, they all suffer from accuracy considerations. We propose a new method, based on a principal component analysis of the optical properties of the system, that addresses these concerns. Taking atmospheric transmission in the O$_{2}$ A-band as a test case, we reproduced the radiance spectrum with an accuracy of 0.3%, relative to that obtained using the multiple scattering code DISORT, while achieving an order of magnitude improvement in speed.
SF43A-0778 1340h
Radiance Data Products at the GES DAAC
The Goddard Earth Sciences Distributed Active Archive Center (GES DAAC) has been archiving and distributing Radiance data, and serving science and application users of these data, for over 10 years now. The user-focused stewardship of the Radiance data from the AIRS, AVHRR, MODIS, SeaWiFS, SORCE, TOMS, TOVS, TRMM, and UARS instruments exemplifies the GES DAAC tradition and experience. Radiance data include raw radiance counts, onboard calibration data, geolocation products, radiometric calibrated and geolocated-calibrated radiance/reflectance. The number of science products archived at the GES DAAC is steadily increasing, as a result of more sophisticated sensors and new science algorithms. Thus, the main challenge for the GES DAAC is to guide users through the variety of Radiance data sets, provide tools to visualize and reduce the volume of the data, and provide uninterrupted access to the data. This presentation will describe the effort at the GES DAAC to build a bridge between multi-sensor data and the effective scientific use of the data, with an emphasis on the heritage of the science products. The intent is to inform users of the existence of this large collection of Radiance data; suggest starting points for cross-platform science projects and data mining activities; provide data services and tools information; and to give expert help in the science data formats and applications. More information about the GES DAAC Radiance data products, tools, and services can be found at http://daac.gsfc.nasa.gov.
http://daac.gsfc.nasa.gov
SF43A-0779 1340h
Data Inversion for the Constellation Observing System for Meteorology Ionosphere and Climate (COSMIC)
After launch in late 2005 the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) is expected to monitor Earth's atmosphere from orbital altitude ~800 km to near the surface with high vertical resolution about 2500 times a day. COSMIC inversion software is based on advanced algorithms and data quality checks. It starts with filtering of raw data and detection of obvious tracking errors. In the lower troposphere, under conditions of multipath propagation, the bending angle as function of impact parameter is calculated by radio- holographic methods such as Full Spectrum Inversion. Ionospheric calibration is applied for L1 and L2 bending angles above the lower troposphere and is extrapolated below. For retrieval of refractivity, the ionospheric free bending angle at high altitudes is subject to optimal estimation by use of climatology as the first guess. Refractivity is retrieved from the optimized bending angle by Abel inversion. The retrieved profiles of refractivity and bending angle are accompanied by a number of scalar parameters characterizing their quality in different respects and allowing selection of different occultations for different purposes. For example, the occultations with low effect of random ionospheric irregularities can be selected for stratospheric monitoring. Special attention has to be paid to truncating the data below the top of planetary boundary layer to avoid biases due to superrefraction. A series of tests will be performed with the open loop radio occultation data. To reduce the effect of horizontal refractivity gradients in the moist troposphere, when assimilating radio occultation data, a simple non-local linear observation operator has been developed. This talk will provide an update of data inversion system that is under development for COSMIC.
SF43A-0780 1340h
SIRAS-G, the Spaceborne Infrared Atmospheric Sounder: Applications in Earth Science Observations
The Spaceborne Infrared Atmospheric Sounder for Geosynchronous Earth Orbit (SIRAS-G) provides a new approach to infrared imaging spectrometry suitable for Earth observation from both low-Earth and geosynchronous orbit. SIRAS-G is currently in its second year of development as part of NASA's Instrument Incubator Program. This instrument concept exhibits lower mass and power requirements than heritage instruments such as AIRS and offers enhanced capabilities for measuring atmospheric temperature, water vapor, and trace gas column abundances. The flight instrument concept will measure infrared radiation in 2048 spectral channels with a nominal spectral resolution of 700 to 1100. The system employs wide field-of-view hyperspectral infrared optical system that splits the incoming radiation to four separate grating spectrometer channels. Combined with large 2-D focal planes, this system provides simultaneous spectral and high-resolution spatial imaging. In 1999, the SIRAS team built and tested SIRAS spectrometer No. 4 (12.3 - 15.4 microns) under IIP-1. SIRAS-G builds on this experience with a goal of producing a laboratory demonstration instrument including the scan assembly, telescope, a single spectrometer channel, focal plane and active cooling subsystem. In this paper, we describe the on-going development of this instrument concept, including design, fabrication and testing of the demonstration instrument, performance requirement predictions and potential future scientific instrument applications. The focus of this talk is on the application of SIRAS-G to key future Earth remote sensing observations.
SF43A-0781 1340h
Near-simultaneous Observations of Polar Mesospheric Clouds from the International Space Station and from Orbiting Optical Instruments
The orbit of the International Space Station (ISS) carried the spacecraft to latitudes high enough for observations of Polar Mesospheric Clouds (PMC). During the PMC southern-hemisphere season 2002-2003, a series of digital images and visual observations were taken over the Antarctic continent of PMC at the sunlit limb. Approximately twenty such observations, available through the ISS LAB window towards the summer pole, revealed the PMC as a distinct narrow scattering layer in the upper mesosphere, often many thousands of kilometers in horizontal expanse. The field of view from the ISS covered a sufficiently wide area of the polar region, that it was possible to co-locate measurements taken by instruments on board unmanned spacecraft in the near vicinity of the Space Station (but taken from a higher altitude). This provided an opportunity to combine accurate limb scans and nadir views of PMC with high-resolution information on the horizontal spatial structure. The SNOE and NOAA-16 and NOAA-17 SBUV/2 instruments obtained 15 orbits per day of PMC measurements at UV wavelengths. In addition, the SABER experiment on board the TIMED satellite obtained temperature profiles in the same vicinity. We will report on the first comparisons of these data, and describe the specific advantages of this unique combination of data.
SF43A-0782 1340h
FIRST - The Far-Infrared Spectroscopy of the Troposphere Project
FIRST, The Far-Infrared Spectroscopy of the Troposphere project is being developed under NASA's Instrument Incubator Program (IIP). The far-infrared encompasses the relatively unobserved portion of the Earth's emission spectrum between 15 and 100 micrometers in wavelength that controls much of the natural greenhouse effect, water vapor feedback, and cirrus radiative forcing. The objective of FIRST is to develop and demonstrate in a space-like environment the technology necessary to measure the far-infrared portion of the Earth's emission spectrum from an orbiting satellite daily and globally. To achieve this, FIRST is developing a high throughput Fourier Transform Spectrometer and broad bandpass beamsplitters. The FIRST instrument is now built and is undergoing radiometric calibration and characterization in thermal vacuum chambers at the Space Dynamics Laboratory in Logan, Utah. We will present an overview of the science afforded by far-infrared observations, a description of the FIRST instrument, and preliminary results from the FIRST radiometric testing program. The FIRST instrument and associated technologies will be demonstrated in a space-like environment from a high-altitude balloon platform in Spring, 2005, from Ft. Sumner, New Mexico.
SF43A-0783 1340h
Laser Sounder for Global Measurement of CO2 Concentrations in the Lower Troposphere from Space: Progress
We describe progress toward developing a laser-based technique for the remote measurement of the tropospheric CO2 concentrations from orbit. Our goal is to demonstrate a lidar technique and instrument technology that will permit measurements of the CO2 column abundance in the lower troposphere from aircraft at the few ppm level, with a capability of scaling to permit global CO2 measurements from orbit. Accurate measurements of the tropospheric CO2 mixing ratio from space are challenging due to the many potential error sources. These including possible interference from other trace gas species, the effects of temperature, clouds, aerosols & turbulence in the path, changes in surface reflectivity, and variability in dry air density caused by changes in atmospheric pressure, water vapor and topographic height. Some potential instrumental errors include frequency drifts in the transmitter, small transmission and sensitivity drifts in the instrument. High signal-to-noise ratios and measurement stability are needed for mixing ratio estimates at the few ppm level. We have been developing a laser sounder approach as a candidate for a future space mission. It utilizes multiple different laser transmitters to permit simultaneous measurement of CO2 and O2 extinction, and aerosol backscatter in the same measurement path. It directs the narrow co-aligned laser beams from the instrument's fiber lasers toward nadir, and measures the energy of the strong laser echoes reflected from the Earth's land and water surfaces. During the measurement its narrow linewidth lasers are rapidly tuned on- and off- selected CO2 line near 1572 nm and an O2 absorption line near 770 nm. The receiver measures the energies of the laser echoes from the surface and any clouds and aerosols in the path with photon counting detectors. Ratioing the on- to off-line echo pulse energies for each gas permits the column extinction and column densities of CO2 and O2 to be estimated simultaneously via the differential absorption lidar technique. For the on-line wavelengths, the side of the selected absorption lines are used, which due to pressure broadening, weights the measurements to the lower troposphere, where CO2 variations caused by surface sources and sinks are largest. Simultaneous measurements of O2 column abundance are made using an identical approach using an O2 line. The laser backscatter profiles from clouds and aerosols are measured with other lidar channels, which permits identifying measurements influenced by clouds and/or aerosol scattering in the path. For space use, our lidar would continuously measure at nadir in near polar circular orbit. Using dawn and dusk measurements made over the same region will make it possible to sample the diurnal variations in CO2 mixing ratios. A 1-m diameter telescope is used for the receiver for all wavelengths. When averaging over 50 seconds, our calculations show a SNR of ~1500 is achievable for each gas at each on- and off-line measurement. Measurements from such a mission can be used to generate monthly global maps of the lower tropospheric CO2 column abundance. We have demonstrated some key elements of the laser, detector and receiver approaches in the laboratory and with measurements over a 206 m horizontal path. These including stable measurements of CO2 line shapes in an absorption cell using a fiber laser amplifier seeded by a tunable diode laser, measurement of small amplitude changes at low optical signal levels with the PMT receiver, and comparison of the horizontal path measurements of CO2 against those from an in-situ instrument.
SF43A-0784 1340h
GPS Ocean Reflection Experiment (GORE) Wind Explorer (WindEx) Instrument Design and Development
This paper describes the design and development of the WindEx instrument, and the technology implemented by it. The important design trades will be covered along with the justification for the options selected. An evaluation of the operation of the instrument, and plans for continued development and enhancements will also be given. The WindEx instrument consists of a processor that receives data from an included GPS Surface reflection receiver, and computes ocean surface wind speeds in real time utilizing an algorithm developed at LaRC by Dr. Stephen J. Katzberg. The WindEx performs a windspeed server function as well as acting as a repository for the client moving map applications, and providing a web page with instructions on the installation and use of the WindEx system. The server receives the GPS reflection data produced by the receiver, performs wind speed processing, then makes the wind speed data available as a moving map display to requesting client processors on the aircraft network. The client processors are existing systems used by the research personnel onboard. They can be configured to be WINDEX clients by downloading the Java client application from the WINDEX server. The client application provides a graphical display of a moving map that shows the aircraft position along with the position of the reflection point from the surface of the ocean where the wind speed is being estimated, and any coastlines within the field of view. Information associated with the reflection point includes the estimated wind speed, and a confidence factor that gives the researcher an idea about the reliability of the wind speed measurement. The instrument has been installed on one of NOAA's Hurricane Hunters, a Gulfstream IV, whose nickname is "Gonzo". Based at MacDill AFB, Florida, "Gonzo" flies around the periphery of the storm deploying GPS-based dropsondes which measure local winds. The dropsondes are the "gold-standard" for determining surface winds, but can only be deployed sparingly. The GPS WindEx system allows for a continuous map between dropsonde releases as well as monitoring the ocean surface for suspicious areas. The GPS technique is insensitive to clouds or rain and can give information concerning surface conditions not available to the flight crew.
http://centauri.larc.nasa.gov/gps/index.html
SF43A-0785 1340h
Developing Parallel Active Tectonics Simulations Using GeoFEST and the PYRAMID Adaptive Mesh Refinement Library
The Geophysical Finite Element Simulation Tool (GeoFEST) can be used to simulate and produce synthetic observable time-dependent surface deformations over both short and long time scales. Such simulations aid in interpretation of GPS, InSar and other geodetic techniques that will require detailed analysis as increasingly large data volumes from NASA remote sensing programs are developed and deployed. The NASA Earth Science Technology Office Computational Technologies Program (ESTO/CT) has funded extensions to GeoFEST to support larger-scale simulations, adaptive methods, and scalability across a variety of parallel computing systems. The software and hardware technologies applied to make this transition, as well as additional near-term development plans for GeoFEST, will be described.
http://quakesim.jpl.nasa.gov/
SF43A-0786 1340h
The Geosat Geodetic Mission Twentieth Anniversary Edition Data Product
The Geodetic Mission (GM) of the U.S Navy's Geosat remains unique among all ocean radar altimeter satellite missions, yielding the most detailed resolution of the marine gravity field and offering the potential to extend the altimetric observation of global sea level rise back nearly a decade before the era of Topex and ERS-1. Geosat's Geophysical Data Records (GDR) structure is limited to centimeter-level precision in sea surface height, lacks the radar waveform reflected from the ocean surface, and has uncertain pedigree for some of the instrumental corrections. We are now reprocessing Waveform Data Records (WDRs) and Sensor Data Records (SDRs) from the GM and merging these into a new structure with millimeter-scale resolution of instrumental corrections wherever possible. Our new product will be available to the science community through NOAA. The ascii SDR and binary WDR were separated at birth and archived in different agencies. The only item common to both which allows their collation and merger is an oscillator tick counter, a proxy for time. We have repaired glitches in both data streams and merged them. Analysis and modeling of the oscillator counter time tags permits us to convert counts to time and obtain a model of the oscillator drift at the part-per-billion level, required for a range-dilation correction at the 1 mm level. The Doppler shift correction to range is large (13 cm) in Geosat and Topex compared to ERS1 (2.5 cm) due to their longer chirp duration. We have obtained a new Doppler correction at the 1 mm level, much smoother than that available on the SDR and used in the GDR. Retracking of the reflected waveforms [Smith and Sandwell, this meeting] improves the height precision and eliminates phase-shift errors, while also reducing correlation between errors in sea surface height and significant wave height, thereby reducing sea state bias. We will present an overall error budget and explore the possibility that this Geosat product may contribute to the resolution of late 20th-century sea level rise. Sandwell and Smith [this meeting] present seamount abundance and distribution results obtained from a new gravity field made with this new Geosat data product.
SF43A-0787 1340h
Development of an Interferometric Laser Ranging System for a Follow-On Gravity Mission to GRACE
The Gravity Recovery and Climate Experiment (GRACE) has ushered in a new era for satellite measurements of the Earth system. GRACE provides monthly estimates of the time-varying gravity field, which are largely due to the redistribution of water mass in the Earth system, with a spatial resolution of ~500 km and an accuracy of 1 cm equivalent water. This is accomplished via a suite of instruments including a microwave ranging system, precision accelerometers for measuring non-gravitational forces, and a GPS navigation system. These tremendous advances made by GRACE have led to an interest in launching a follow-on mission with even better performance. The spatial resolution can be improved by improving the ranging performance, implementing a drag-free control system, and flying at a lower altitude. This presentation will focus on our effort to develop an interferometric laser ranging system that we expect to perform near the 1 nm/sec level or better over 5 second intervals, which when coupled with other mission improvements, would improve the spatial resolution to ~100 km for 1 cm water equivalent accuracy. We have designed a laser ranging system and are building an engineering model of the instrument, with which we will demonstrate its accuracy in the laboratory over the next few years. The laser system will range directly to the proof masses of the drag-free system, eliminating many of the difficulties associated with post-processing the accelerometer data on GRACE. We will also present the results of an error analysis for the ranging system, how these errors are expected to propagate into the gravity field estimates, and discuss the potential science benefits. In addition, we will show preliminary results from our laboratory tests of the breadboard design.
SF43A-0788 1340h
Quantum Gravity Gradiometer Using Atom Interferometers for gravity Mapping
Quantum gravity gradiometers based on atom-wave interferometry hold the promise for greater sensitivity and suitability for space applications. These instruments can provide not only high-resolution mapping of mass distribution both above and below the surface of planets, but also temporal monitoring of dynamical processes. Funded in part by NASA, we have been developing an atom interferometer-based gravity gradiometer for Earth science application. The inertial sensors use atomic particles as free fall test mass and the matter-wave interferometry to measure inertial forces acting upon the test masses. The overall approach is based on the recent development of laser cooling and manipulation of atoms in fundamental physics and high precision measurements. Atom interferometers have been demonstrated in research laboratories for gravity and gravity gradient measurements, and the scheme is specially suited for applications in space where atoms are truly drag-free and microgravity makes long interaction time possible for achieving high sensitivity and precision. In this paper, we will review the underlying principles of the atom interferometers as inertial force sensors and describe the instrument design and operation. We will also report the progress in the technology developments towards a portable and eventually a flyable system.
SF43A-0789 1340h
Processing and Correcting Master Images to Analyze and map Metamorphic Core Complexes in the Southern Basin and Range Province
Metamorphic core complexes (MCCs) have been of great interest to geologists and geophysicists and our goal is to facilitate integrated studies of these intriguing features. Our specific targets are the exposed Whipple Mountains in Southeastern California and the spectrally similar Mohave Mountains in Western Arizona. These two ranges were selected for study using the MODIS/ASTER airborne sensor also known as MASTER, and NASA/JPL acquired the data for us. These two ranges were chosen because of their close proximity to each other in the imagery. This sensor was chosen because it has a good resolution (15m) and 50 different bands ranging from the visible to thermal infrared. However, because it is flown on a light aircraft its flight line patterns and photogrammetric distortions make it hard to georeference and mosaic with other images from adjacent flight lines. The distortions become misalignments of images during mosaicing. This project involved two efforts: 1) developing a method for correcting and processing MASTER multispectral images; and 2) using those images to analyze and map MCCs in the southern Basin and Range Province. Standard image processing techniques available within the ENVI software package were applied to this imagery to geometrically correct, mosaic, and spectrally process it in order to locate defining characteristics of MCCs that are mappable with the imagery. These techniques include the use of warping, histogram matching, mosaicing, classification, Principal Component Analysis, decorrelation stretching, Minimum Noise Fraction Transformation, Pixel Purity Index, and end member analysis.