Professor Ya-Qiu Jin

Talk Abstract: Research on the modeling and simulation of polarimetric scattering and information retrieval for microwave remote sensing

Remote sensing physics is essentially the interaction of electromagnetic wave with terrain surface media. Fully understanding this interaction and developing both simulation and inversion approaches are of great importance for retrieving quantitative information from microwave remote sensing.

As one of most important and recent advances in space-borne remote sensing, polarimetric SAR (synthetic aperture radar) has been utilized for remote sensing of the earth terain surfaces. This lecture presents some research progress on theoretical modeling of the terrain surface for polarimetric scattering simulation, image simulation and analysis of mono-static and bistatic SAR observations, new parameters for unsupervised terrain surface classification, DEM inversion, change detection from multi-temporal SAR images, and reconstruction of 3D objects from multi-aspect SAR images, etc.

Also, radiative transfer of multi-layered natural media, for modeling of vegetation canopy, snowpack etc., is also further developed for application of microwave remote sensing. Some data validation of satellite-borne remote sensing and applications of natural events are presented.

Talk Abstract: Modeling, simulation, inversion and Chang E data validation for microwave observation in China’s lunar project

In China’s first lunar exploration project, Chang-E 1 (CE-1), a multi-channel microwave radiometer in passive microwave remote sensing, was first aboard the satellite, with the purpose of measuring microwave brightness temperature from lunar surface and surveying the global distribution of lunar regolith layer thickness.

In this lecture, the multi-layered model of lunar surface media is presented, and numerical simulations of multi-channel brightness temperature (Tb) from global lunar surface are obtained. It is applied to study of retrieving the reggolith layer thickness and evaluation of global distribution of 3He content in regolith media.

Multi-channel Tb measurements by CE-1 microwave radiometers are displayed, and applied to inversion of the reggolith layer thickness, which are verified and validated by the Apollo in situ measurements. It is the first time to retrive the regolith thickness using microwave remote sensing technology.

In active microwave remote sensing, based on the statistics of the lunar cratered terrain, e.g. population, dimension and shape of craters, the terrain feature of cratered lunar surface is numerically generated. Electromagnetic scattering is simulated, and SAR (synthetic aperture radar) image is then numerically generated, e.g. making use of the digital elevation and Clementine UVVIS data at Apollo 15 landing site as the ground truth, an SAR image at Apollo 15 landing site is simulated.
Utilizing the nadir echoes time delay and intensity difference from the surface and subsurface, high frequency (HF) radar sounder is an effective tool for investigation of lunar subsurface structure in lunar exploration. Making use of rough surface scattering and ray tracing of geometric optics, a numerical simulation of radar echoes from lunar layering structures with surface feature, the topography of mare and highland surfaces is developed. Radar echoes and its range images are numerically simulated, and their dependence on the parameters of lunar layering interfaces are described.

Dr. Howard A. Zebker

Talk Abstract: Measuring Earth Crustal Deformation with Interferometric Synthetic
Aperture Radar

The Earth’s surface is composed of about a dozen major crustal plates, each floating on the interior mantle and in constant motion. Consequences of plate motion include the formation of mountain ranges and other geologic features, plus the more localized processes of earthquakes and volcanism. Here we examine the use of space technology to measure and map the accumulation of strain within the crust. Both the Global Positioning System satellites and synthetic aperture radar (SAR) interferometry now enable us to observe surface deformation with such sensitivity that it may be possible to measure strains accumulating before earthquakes strike or volcanoes erupt. For example, consider the San Andreas transform fault, located at the boundary of the North American and Pacific plates. The sensitive new measurement methodologies may lead to our ability to localize buildup of strain in the crust and aid in forecasting and hazard assessment. These new technologies have already produced graphic images of surface displacements that occur during and immediately after major earthquakes, and it is the goal of current research to measure pre-seismic motions. Measurement of surface displacements of similar magnitude, such as on active volcanoes and flowing glaciers, are becoming commonplace and it is likely that comprehensive investigations of complex fault systems like the San Andreas will lead to a more complete understanding of tectonic hazard potentials in many areas around the world.

Talk Abstract: Time-Lapse Imaging of Subsurface Flow Using SAR Interferometry

A sensitive technique for observing subtle surface deformation patterns with time permits inference of many subsurface flow processes. Interferometric synthetic aperture radar, or InSAR, uses data acquired by an orbiting satellite that revisits the same ground area multiple times. The satellite measures precise changes in distance to each 10 m size resolution element on the ground, over a swath 100 km wide, and hence presents an image of crustal deformation. Combined with inverse methods design to recover pressure changes or dislocations at depth, the deformation map may be interpreted to yield subsurface flow. Here we present several examples of InSAR analysis, which retrieve i) water flow patterns in an aquifer, ii) magma flow in active volcanic regions, and iii) viscous flow of salt diapirs through cracks in the overlying cap rock. In each case we are able to describe properties of flow patterns help us understand the geophysical description of the subsurface environment. In the case of water aquifers, the experiments reveal permeability distributions and capacities of the reservoirs. For volcanoes, tracing the flow of magma defines the plumbing system of the volcano and can aid in predicting eruptions. And for the salt domes, we are able to determine the viscosity and grain size of naturally occuring salt at depth.

Dr. Werner Wiesbeck

Digital Beam-Forming in Remote Sensing

The invention of the Synthetic Aperture Radar (SAR) principle dates back to the early 1950s. The basic idea is to filter targets in a side looking radar according to their Doppler history in azimuth and by pulse or FM modulation compression in range. Since this time SAR systems have been, from a technical point of view, considerably refined to the state of the art where resolution and accuracy are close to the theoretical limits. The best innovations have been reached in polarimetry and interferometry. Nevertheless, the principles are still the same: The SAR is a side-looking radar where resolution is achieved in range by bandwidth and in azimuth by Doppler processing. The beam-forming concepts for coverage are still the same: dish antennas (scanned or fixed), antenna arrays (phased or fixed) or switchable antenna systems. All these have the drawback that the coverage defines the synthetic aperture length and by this the azimuth resolution or for scanned beams the loss of coverage has to be taken into account. These drawbacks can be overcome by Digital Beam-Forming. Significant advantages result by this. In its simplest form the transmit antenna illuminates a usually larger footprint, as do the multiple receive antennas. The beam-forming is accomplished in a digital process. Multiple beams may be processed simultaneously. The RF losses can significantly be reduced, allowing lower gain for the antennas, and thus larger footprints. This talk will present the principles and applications of Digital Beam-Forming in Remote Sensing.

Timeframe: 40 – 50 min
Required: Beamer

Dr. Byron Tapley

Talk Abstract: The GRACE Mission, It’s Status and Early Results

The Gravity Recovery and Climate Experiment (GRACE) is a dedicated satellite mission whose objective is to map the global gravity field with unprecedented accuracy over a spectral range from 500 km to 40,000 km. The measurement precision will support gravity field solutions in this frequency range that are between 10 and 1000 times better than our current knowledge. Highly accurate measurements, with both high spatial and temporal resolution, will allow studies of the gravitational signals associated with the mass exchange between the solid Earth and the hydrological, ocean and atmospheric components. The primary measurement provided by the High Accuracy Inter-satellite Ranging System (HAIRS) is the range change between two satellites orbiting one behind the other at an approximate distance of 200 km. The range change will be measured with a precision better than 10 microns. A highly accurate three-axis accelerometer, located at the satellite mass center, will be used to measure the surface force and attitude control induced accelerations. Satellite GPS receivers will position the satellites over the earth with centimeter level accuracy. With this set of measurements, GRACE will provide highly accurate measurements of the global gravity field once every thirty days. The two satellites, scheduled were launched on March 17, 2002, and were designed to operate for a period of five years. The satellites will fly in coplanar nearly polar orbits, at an altitude between 500 and 300 km, separated by approximately 200 km along track. The mission, which is one of the first NASA Earth System Pathfinder Missions, is implemented through a collaborative arrangement by NASA and DLR. The presentation will summarize the mission structure, the satellite and instrument performance, the data system and ancillary data requirements and will describe some of the early data results.

Dr. Calvin T. Swift

Talk Abstract: Remote Sensing of Ocean Surface Winds with Microwave Radiometers

As part of a subcontract with the manufacturer of the Defense Meteorological Space Program (DMSP) special sensor microwave/imager (SSM/I), an operational wind speed algorithm was developed by Environmental Research and Technology, Inc. (ERT). The ERT algorithm is based on the “D-Matrix” approach, which seeks a linear relationship between measured SSM/I brightness temperatures and environmental parameters. D-matrix performance was validated by comparing algorithm derived wind speeds with near-simultaneous and colocated measurements made by offshore ocean buoys maintained by the National Oceanic and Atmospheric Administration. The DMSP accuracy requirement of +- 2m/s for wind speed predictions in the range of 3 m/s to 25 m/s was not obtainable with the original version of the D-matrix, which had severe bias and scaling problems. Revisions to the algorithm made at the University of Massachusetts caused it to perform within specifications. Other topics include error budget modeling, alternate wind speed algorithms, and D-matrix performance with one of more inoperative SSM/I channels. Additional research is being done from aircraft to measure high wind speeds in hurricanes. The C-band instrument used for this purpose has measured wind speed as high as 70 m/s.

Talk Abstract: Synthetic Aperture Microwave Radiometers

Aperture synthesis represents a new technology being developed for passive microwave remote sensing of the environment. The concept employs an interferometric technique in which the product from pairs of antennas is sampled as a function of pair spacing. Substantial reductions in the antenna aperture needed for a given spatial resolution can be achieved with this technique. As a result, aperture synthesis could lead to practical passive microwave remote sensing instruments in space to measure parameters such as soil moisture and ocean salinity which require observations at long wavelengths and, therefore, large antennas.

ESTAR is an L-band, aircraft prototype built as part of research to develop this technique. ESTAR is a hybrid real-and synthetic aperture radiometer which employs stick antennas to achieve resolution along track and uses aperture synthesis to achieve resolution across track. Experiments to validate the instrument’s ability to measure soil moisture have recently been conducted at the USDA watersheds at Walnut Gulch in Arizona and the Little Washita River in Oklahoma. The results of both experiments indicate that a valid image reconstruction and calibration have been obtained for this remote sensing technique. A more advanced instrument operating at 33 GHz is presently under evaluation.

Dr. Vince Salomonson

Talk Abstract: An Overview of the Earth Observing System (EOS) MODIS Instrument, Associated Data Systems Performance, Data Archiving and Delivery, plus Prospects for Operational MODIS-like Observations in the 21st Century

The Moderate Resolution Imaging Spectroradiometer (MODIS) operating on both the Earth Observing System (EOS) Terra and Aqua Missions began to produce data from the Terra MODIS in February 2000 and the Aqua MODIS in June 2002. Both instruments continue to produce excellent data that have made and are making very considerable contributions to better understanding of land, oceans, and atmospheres processes and trends as well as contributing to better natural resources management. All subsystems of the instruments are performing as expected. The signal-to-noise (S/N) performance meets or exceeds specifications, band-to-band registration meets specifications, geodetic registration of observations is nearing 50 meters (one sigma) and the spectral bands are located where they were intended to be pre-launch and attendant gains and offsets are stable to date. The data from both instruments have been reprocessed several times. “Collection 4″ has been completed and MODIS data products are available from the three EOS Distributed Active Archive Centers (DAAC’s) responsible for archiving and distributing MODIS data. A new reprocessing effort (”Collection 5″) of land and atmosphere products is getting underway and will be completed in 2006 (atmospheres products) or early 2007 (land products). Collection 5 will offer some considerable improvements in all land and atmosphere products. Land products are available and distributed by the Land Processes DAAC at the EROS Data Center in Sioux Falls, South Dakota. The atmospheres products are archived and distributed by the NASA Goddard DAAC. Cryosphere Products are archived and distributed by the National Snow and Ice Data Center in Boulder, Colorado. Producing MODIS ocean color products that are well characterized and validated over time has been problematic, but considerable progress has been made in getting Aqua MODIS ocean color data products to merge successfully with SeaWiFS products. Aqua MODIS ocean products (both ocean color and sea surface temperature) are being produced and distributed by the Ocean Color Data Processing System (OCDPS) at the Goddard Space Flight Center. Reprocessing of Terra MODIS ocean products will be reprocessed by the OCDPS at some point in the future after review and concurrence by NASA Headquarters and the science community. A MODIS-like instrument called the Visible and Infrared Imaging Sensor Suite (VIIRS) is being developed to fly on the National Polar Orbiting Environmental Satellite Series (NPOESS) Preparatory Project (NPP). The planned NPP is a “bridge mission” spanning the operations of the EOS Terra and Aqua spacecraft with the NPOESS operations that are scheduled to begin the 2009-2010 time frame. These activities should ensure that MODIS-like observations will be operationally available well into the second decade of the 21st century.

Dr. John Reagan

New Generation Miniature / Micro-Pulse Lidars: Technology, Design Considerations and Applications

Technological advances in lasers, detectors and high-resolution spectral filters during the 1990’s have enabled the development of relatively low-cost, eye-safe miniature lidars, generally referred to as MPL’s (Micro-Pulse Lidars). The basics of lidar and particular technological innovations critical to the realization of MPL’s are first presented. Design considerations including impacts and trade-offs of laser pulse energy/rep rate, detector quantum efficiency/noise effects, transmitter/receiver beam widths and implicit overlap limitations, narrow-band receiver filter requirements, and optical system thermal stability limitations are then addressed. Finally, examples of MPL applications are presented including results from field experiments demonstrating MPL approaches for sensing atmospheric aerosols and progress reports of development efforts to realize water vapor and wind sensing MPL’s.

Dr. Keith Raney

Talk Abstract: From Geosat into the ABYSS

To catch the moon from the bottom of the sea” is a very high-scoring combination in the game of Mah-Jong. The National Oceanic and Atmospheric Administration (NOAA) and the Johns Hopkins University Applied Physics Laboratory (APL) are planning to catch the bottom of the sea from the International Space Station (ISS), using an original instrument named ABYSS. It turns out that ABYSS and the ISS are a very high-scoring combination. Sea-bottom topography has been mapped by inverting sea surface slope data from height measurements provided by the Geosat radar altimeter, a 1980’s mission designed, built, and operated by APL. ABYSS will measure sea-surface slopes down to one micro-radian, to spatial scales down to 6-km, and with balanced NS and EW slope measurement accuracy. These data will support an order-of-magnitude improvement in bathymetric maps, due primarily to the favorable inclination of the ISS orbit, and to the unique precision and attitude-tolerance of the altimeter. ABYSS relies on new concepts invented and flight-proven at APL. These same concepts also pave the way toward miniaturized dedicated radar altimeter satellites, radar altimeters that can measure the heights of sloping continental ice sheets, and improved ground-penetrating radar.

Talk Abstract: Catching the Bottom of the Sea from Space

“To catch the moon from the bottom of the sea” is a very high-scoring combination in the game of Mah-Jong. The National Oceanic and Atmospheric Administration (NOAA) and the Johns Hopkins University Applied Physics Laboratory (APL) are planning to invert this combination, by catching the bottom of the sea from space, through a radar altimeter mission named ABYSS-Lite. Sea-bottom topography can be mapped by analyzing sea surface slope data from height measurements provided by a precision radar altimeter. Sea-surface slope data are a direct expression of local gravity anomalies. ABYSS-Lite will measure sea-surface slopes down to one micro-radian, to spatial scales down to 6-km, and with balanced NS and EW slope measurement accuracy. These data will support an order-of-magnitude improvement in oceanic gravimetry and bathymetric maps, compared to the current state-of-the-art. This improvement is due primarily to the unique precision of the delay-Doppler altimeter. This altimeter relies on new concepts invented and flight-proven at APL. These same concepts also pave the way toward miniaturized dedicated radar altimeter satellites, radar altimeters (such as CryoSat) that can measure the heights of sloping continental ice sheets, and improved space-based ground-penetrating radar.

Prof. Yoshio Yamaguchi

Polarimetric detection of buried objects

Detection of buried objects by polarimetric radar has been attractive attention both in technology and in applications. Buried objects, for example, are archaeological historical remains, human body encountered by snow avalanche, land mines, gas pipes, electric pipes, etc. The best instrument (radar, sonar, electric current method) depends on the depth and target size. Polarimetric FM-CW radar is suited for shallow objects detection.

Since FM-CW radar is low power instrument, easy to handle for short range sensing, and can be equipped with polarimetric data take function, it is expected to play essential role in the detection field.

The basic principle of radar, together with polarimetric SAR imaging scheme are reviewed. This is then followed with the field experiments using several targets including myself in deep snowpack and sandy ground. Polarimetric signal processing based on scattering matrix helps target identification and recognition, which includes decomposition of scattering matrix, enhancement of target, ellimination, anisotropy, entropy, etc. Some experimental results with 2-D and 3-D polarimetric detection images can be presented.

Dr. Jay Pearlman

The Global Earth Observation System of Systems (GEOSS)

The Global Earth Observation System of Systems (GEOSS) is a complex system of sensors, communication devices, storage systems, computational and other devices used to observe the Earth and gather data needed for a better understanding of the EarthÕs processes. In addition, GEOSS includes models and methods to create information from the observation data.

GEOSS is focused on using this Earth Observation information to address major issues of society on a regional and global scale. There are nine societal benefit areas that are the initial focus on GEOSS:

• Reducing loss of life and property from natural and human-induced disasters
• Understanding environmental factors affecting humans
• Improving management of energy resources
• Understanding climate variability and change
• Improving water resource management through understanding of the water cycle
• Improving weather information, forecasting, and warning
• Improving the management and protection of terrestrial, coastal, and marine ecosystems
• Supporting sustainable agriculture and combating desertification
• Understanding, monitoring, and conserving biodiversity

GEOSS is being built initially from existing systems and initiatives, with an emphasis on the creation of synergies among GEOSS components that provide increased benefits to society. Realizing such benefits will require the exchange of data and information between disparate data and information systems, an interoperability challenge of unprecedented magnitude. Dr. Pearlman is a co-chair of the GEO Architecture and Data Committee and chair of the IEEE Committee on Earth Observation. In this presentation he provides insights into the challenges and opportunities of establishing a global observation system of systems and an overview of the progress in fulfilling the ten year development plan.

Dr. Richard. K. Moore

Talk Abstract: Microwave Remote Sensing from its Beginning to its Current State of the Art

After discussing the nature of a radar remote-sensing system, we trace the development of radar sensing of oceans, vegetation, geology, and sea ice. This is followed by a brief discussion of system-development history. This leads to an assessment of the current state of knowledge in each area, and of unsolved problems that we can see today.

We conclude with some ideas on the philosophy and ultimate goals of microwave remote sensing. Finally, some suggestions follow on the future of spaceborne remote sensing.

Talk Abstract: What? No Clouds? Radar Observation of the Earth

You need aerial or space photographs of an area, but it is cloudy or dark. What can you do? You can use an imaging radar. It can look through clouds and rain and make a picture similar to a photograph. Moreover, radar is more sensitive to soil and plant moisture than optical sensors. Radar also penetrates thin vegetation and a little soil, so the pictures are some different, but give extra information not in photos. Thus, when both can be used together, they are complementary just as having more colors gives more information.

Radar also has special uses not available with other sensors. Special radars measure winds at the ocean surface. Imaging radars show ocean features not easily seen on photos. They also allow better monitoring of ice on the sea and continental ice sheets, and permit some measurements of snow properties.

After discussion of these topics, we will describe briefly how radar works. Then examples will be shown of various radar images from space, and of some results of wind measurements over the oceans.

Talk Abstract: Radar in Oceanography

Radars in space can add much to our knowledge of the dynamics of the world’s oceans. Wind-vector scatterometers provide inputs to global meteorological and wave-forecast models. Imaging radars in space initially were intended to find wave spectra, but now we know that they provide much information on current boundaries, storm effects, shallow-water bottom topography, and other features. Imagers also give us up-to-date information on details of the ice cover on the oceans. Altimeters, the most mature space radars, give information on tides and the geoid

Radar backscatter strength from the ocean is, surprisingly, governed largely by the small-scale features, capillary waves and short gravity waves. It is this that allows the wind-vector scatterometer to work. We will discuss briefly the mechanisms and their application to scatterometry.

Spaceborne imaging radars usually use synthetic apertures to achieve resolutions of the order of tens of meters, although mesoscale features can also be seen on images from real-aperture radars. Many complications arise in interpreting SAR images of the sea because SAR uses the Doppler effect to produce its fine resolution, and the motions on the sea affect this process. We will discuss SAR principles briefly and point to the complications.

Airborne radars have been used in Russia and Canada for sea-ice monitoring for about 25 years. The Canadian RADARSAT provides much information, especially on sea ice. Images now available from ESA’s ERS-1/2 and Envisat SAR, and ship-based experiments show some differences between typical ice responses in Arctic and Antarctic.

Jean-Bernard Minster

Airborne and Spaceborne InSAR and Lidar: New tools for Solid Earth Science

Airborne and satellite-based Synthetic Aperture Radar (SAR) and Lidar are active remote sensing techniques that have matured substantially over the past decade. In the Earth Sciences, the use of repeat-pass interferometry (InSAR) to study surface deformations associated with earthquakes and volcanoes has received considerable attention. Because it offers continuous spatial coverage, InSAR is a natural complement to permanent, continuously operating GPS networks which are being deployed in tectonic areas worldwide. Yet, these spectacular results have all been obtained using data from non-US spacecraft, which were not optimized for this class of scientific applications. For this reason, the Earth science research community has recently recommended that a NASA-led multi-agency SAR mission should become an important component of the NSF-led EarthScope initiative.

Airborne imaging lidar, now commercially available, is a powerful tool to conduct geomorphological studies, even in inaccessible vegetated areas with rather dense canopies. Imaging lidars are capable of delivering extremely detailed Digital Elevation Models never before available for environmental and geological research, with applications as diverse as the mitigation of natural hazards or land use and urban studies. With the launch of the ICESat mission in 2002, satellite-based lidar will provide researchers with global access, and deliver precisely geolocated data sets for studies of such topics as ice sheet mass balance, land surface and land cover change, or structure and dynamics of clouds and aerosols.

Dr. Didier Massonnet

Talk Abstract: Radar Imagery : looking from space with wavelengths 100000 times larger than the ones of visible light

Radar instruments are used to observe the Earth with radio waves. The resulting image reflects both the physical properties of the waves and the technological choices that have to be made to obtain a usable image from the raw data gathered by the instrument. The means by which a radar image is obtained through a computer can be described as a twofold image. The first part, the amplitude, conveys a similar, but different information than conventional imagery, such as the geometry of pixel layout on the ground and the estimation of the speed of mobile targets on land or sea. The second part, the phase, cannot be visualized by itself and gains value only through the comparison with the similar part of a companion image. An accurate description of terrain elevation can be obtained from the slight difference of point of view between the images. A much more accurate assessment of terrain displacement, down to millimeters, between the acquisition dates of the images can also be obtained. In addition, otherwise invisible meteorological phenomena can be mapped. Several examples are used to illustrate the way these various pieces of information are obtained jointly or separately, as well as ways to combine the results into a single color image.

Talk Abstract: Interferometric Cartwheel Concept

Radar images can be compared very precisely through the technique of radar interferometry, which takes advantage of tiny differences of point of view between two radar images to compute the topography. As an extension, a difference in time on the order of one second between the acquisitions of two images also allows mapping the velocity of ocean currents. The principle of interferometric cartwheel consists of using a set (three in the standard implementation) of receive-only satellites with a small antenna. This modest requirement allows the payload to be put on microsatellites, which in turn fly in formation while following a conventional radar satellite at a distance. The lead satellite illuminates the ground, while the receive-only systems in turn point at the same area.

In order to obtain stable differences in viewing geometry, as well as of acquisition times all along the orbit, the three receivers are given a slightly higher eccentricity than the conventional radar satellite they follow, while keeping the same orbital period. They describe an ellipse around the orbital position they would have without the additional eccentricity. The uniform distribution of the perigees results in receivers also being uniformally distributed along the ellipse, which features a horizontal axis twice as long as the vertical axis. It can be shown that, with three receivers, the horizontal and vertical baselines vary only by 7.5% along the orbit, with respect to their average value, provided we consider the two satellites best positioned for the purpose. Another advantage of the constellation is that the diversity in point of view also allows creation of radar images with a better resolution than that of the emitter and are difficult to jam because the constellation is distanced from the emitter, fully passive, and therefore silent.

The primary applications of this invention are very accurate global topographic modeling, with vertical accuracy of one meter or better, and mapping the velocity of ocean currents by taking advantage of the horizontal baseline. After actual testing of the super-resolution principle, distributed radar systems could be build, creating very high resolution results from many, passive microsatellites and a dedicated or opportunistic radar illuminator. Cost-effectiveness results from the fact that the necessary resources, in particular telemetry and antenna surfaces, are distributed between the receivers, which do not need to produce the radio illumination of the ground.

Talk Abstract: SAR Interferometry and its Application to Tectonics

SAR interferometry has been applied to tens of earthquakes and to many volcanoes and caldera using ERS-1 as well as J-ERS radar satellites. The average results were good (RMS misfit ~1-2 cm) and led to accurate modelling of the phenomena using elastic half space models. Even interferograms of poor quality contribute significantly to the success of the modelling as we observed, for instance, in the study on Mount Etna.

The accuracy of the results is mainly limited by the contribution of atmospheric propagation heterogeneities. The limitation is especially important in the study of very small displacements such as the centimeter-sized rift that was observed in Iceland over several years. This contribution can be detected using a pair-wise logic which requires many observations. In analyzing this large data set, we learn that data acquired by night tend to be superior. However, daytime acquisition is required when an observation along different angles of view is needed. An alternate solution is to observe the site combining satellites with different geometries, as in the example of the Northridge earthquake.

Dr. David M. Le Vine

Aquarius: Monitoring Ocean Salinity from Space

Aquarius is a microwave remote sensing system designed to obtain global maps of the surface salinity field of the oceans from space. It will be flown on the Aquarius/SAC-D mission, a partnership between the USA (NASA) and Argentina (CONAE) with launch scheduled for launch early 2009. The objective of Aquarius is to monitor the seasonal and interannual variation of the large scale features of the surface salinity field in the open ocean to address questions associated with ocean circulation and its impact on climate. For example, salinity is needed to understand the large scale thermohaline circulation, driven by buoyancy, which moves large masses of water and heat around the globe. Salinity also has an important role in energy exchange between the ocean and atmosphere, for example in the development of fresh water lenses (buoyant water that forms stable layers and insulates water below from the atmosphere) which alter the air-sea coupling. Aquarius is a combination radiometer and scatterometer (radar) operating at L-band (1.413 GHz for the radiometer and 1.26 GHz for the scatterometer). The primary instrument for measuring salinity is the radiometer which responds to salinity because of the modulation salinity produces on thermal emission from sea water. The scatterometer will provide a correction for surface roughness (waves) which is one of the greatest unknowns in the retrieval. This talk will provide an introduction to remote sensing of sea surface salinity and then describe the Aquarius instrument and the Aquarius/SAC-D mission.

Dr. Ricardo Lanari

Differential SAR Interferometry: techniques and applications

Differential SAR Interferometry (DIFSAR or DInSAR) is a technique that allows estimation of earth surface deformations occurring in an area of interest, by exploiting the phase difference (phase interferogram) of SAR images relative to that zone and obtained by processing data acquired at different times; the DIFSAR technique has already shown its capability in detecting, with a centimetric (in some cases millimetric) accuracy, surface deformations caused by different natural and antropogenic phenomena.

The aim of this talk is to introduce the basic concepts involved in the DIFSAR technique and to summarize which are the key applications of this method. In particular, a discussion on the rationale of the DIFSAR approach will be given first; in the following, the main limitations and the attainable resolutions will be analyzed. Moreover, the possibility of combining several SAR acquisitions relative to the investigated zone will be explored to follow the evolution of the detected deformation. Some examples will be presented for underlining the capability of the technique to analyze deformations caused by different phenomena such as volcano deformations, earthquakes, and urban subsidence.

Differential SAR Interferometry: basic principles, key applications and new developments

Differential SAR Interferometry (DInSAR or DIFSAR) is a microwave imaging technique that allows to investigate earth surface deformations occurring in an area of interest with a centimetre (in some cases millimetre) accuracy. In particular, the DInSAR technique exploits the phase difference (interferogram) of temporally separated SAR images relative to the investigated zone and has already shown its capability in detecting surface deformations caused by different natural and anthropogenic phenomena.

The aim of this talk is to introduce the basic concepts involved in the DInSAR technique, summarize the key applications of this method and present it new developments. In particular, a discussion on the rationale of the DIFSAR approach will be given first, highlighting the key points and the main limitations. Several examples will be presented for underlining the capability of the technique to analyze deformations caused by different phenomena such as volcano deformations, earthquakes and urban subsidence. Moreover, the possibility of combining several SAR acquisitions relative to the investigated zone will be explored; in particular, it will be shown how the integration of the information relevant to different radar observation directions can be exploited to retrieve the different components of the detected deformations. The last part of the talk will be dedicated to present the Persistent Scatterers algorithms that represent a development of the basic DInSAR technique, allowing to analyze the temporal evolution of the detected deformations from a data set of subsequently acquired SAR images.

Dr. Kenneth C. Jezek

Antarctica: Its ice, land and ocean as viewed by RADARSAT-1

Antarctica is Earth’s coldest, windiest, and on average highest of continent. Because of its harsh climate and because it is often covered by clouds or shrouded in darkness during the long polar night, much of Antarctica remained poorly mapped till the end of the last decade. Then in 1997, NASA and the Canadian Space Agency embarked on a collaboration to obtain the first, high resolution synthetic aperture radar image of the southern continent. The first imaging campaign was successfully completed in October 1997 and achieved the primary goal of producing a stunning, new view of Antarctica. It revealed in unprecedented detail extensive networks of ice streams, the positions of ice divides and the ice margin, and even hinted about processes occurring at the base of the ice sheet. Following up on results from the 1997 effort, a second acquisition campaign occurred in the fall of 2000. Along with providing a second benchmark for measuring changes in ice sheet extent, the 2000 campaign collected interferometric data over much of the ice sheet. These data are being used to measure the surface velocity of the ice sheet, an important parameter for estimating ice sheet mass balance and for understanding the response of the ice sheet to changing climate.

This presentation summarizes results from the 1997 and 2000 imaging campaigns. In addition to describing glaciological processes captured in the image mosaics, the RADARSAT 1997/00 data are compared to assess spatial patterns in ice margin advance/retreat, which are themselves contrasted with earlier estimates of ice sheet behavior. Surface velocity data over newly discovered East Antarctic ice streams. These are used to estimate ice stream mass balance the role of these ice streams on the stability of the East Antarctic Ice Sheet.

Additional information on the RADARSAT-1 Antarctic Mapping Project is available at: http://bprc.osu.edu/rsl/radarsat/

Dr. Scott Hensley

Mapping Beneath the Vegetation – The GeoSAR Mapping Instrument

GeoSAR is a program to develop a dual frequency airborne radar interferometric mapping instrument designed to meet the mapping needs of a variety of users in government and private industry. Program participants are the Jet Propulsion Laboratory (JPL), Earthdata International, Inc., and the California Department of Conservation with funding provided initially by DARPA and currently by the National Imagery and Mapping Agency. Begun to address the critical mapping needs of the California Department of Conservation to map seismic and landslide hazards throughout the state, GeoSAR is currently undergoing tests of the X-band and P-band radars designed to measure the terrain elevation at the top and bottom of the vegetation canopy. Maps created with the GeoSAR data will be used to assess potential geologic/seismic hazard (such as landslides), classify land cover, map farmlands and urbanization, and manage forest harvests. This system is expected to be fully operational in 2002. This talk present an overview of the system and show some examples of X-band and P-band data and maps generated using the GeoSAR systems and comparison with other sensor data such as LIDAR and photogrammetric data.

Mapping the World’s Topography from Space – The Shuttle Radar Topography Mission
A highly accurate global topographic map of the Earth’s surface has been an elusive goal for at least three decades that will soon be achieved with the newly acquired Shuttle Radar Topographic Mission (SRTM) data. The National Aeronautics and Space Administration (NASA) in conjunction with the National Imagery and Mapping Agency (NIMA) of the US developed SRTM to meet this critical mapping requirement. SRTM collected data for 99.97% of the Earth’s landmass between –57° and 60° latitude during an 11 day mission in February 2000. A modified version of the SIR-C radar that previously flew on the shuttle in 1994 augmented with a radar mounted on a 62 m boom was used to collect radar interferometric data at C (5.6 cm wavelength) and X (3 cm wavelength) bands. The C-band radar was operated in the SCANSAR mode in order to extend the swath width to 225 km, the minimal amount required to achieve contiguous coverage at the equator. By combining the data from both ascending and descending orbits a seamless mosaic of the Earth’s topography will be created. This talk will present a mission overview, how the data was collected and being processed, and show some examples of SRTM data and how it may be used.

Dr. David G. Goodenough

Methods and Systems for Applications

In order to monitor the resources and environment of the planet, it is necessary to use remote sensing from multiple sensors and integrate these data with historical information contained within geographical information systems (GIS). Multiple sensors are required to identify attributes of interest. In forestry, resource managers want to know the amount of the resource by species, area, timber volume, etc., the spatial distribution, the health (chemistry) of the forests, and the temporal changes of the resource, both past and predicted for the future. The technologies of the IEEE Geoscience and Remote Sensing Society are used to create information systems to support resource and environmental management. In this presentation we describe hyperspectral and radar methods and systems to obtain valuable forest information, such as chemistry, above-ground carbon, species, and biomass.

Models of forests are used to predict remote sensing results. The inversion of these results can lead to the estimation of forest parameters. National and global monitoring requires systems for distributed data management. We have created a system (www.saforah.org) using GRID architecture, optical light paths, and a petabyte data store at the University of Victoria. SAFORAH serves out to the public and research community remotely sensed data of Canada and forest information products for land cover, biomass, and change. Hyperspectral sensing is used to obtain species distribution and forest chemistry. Examples of this work for forest applications and the generation of Kyoto Protocol products are presented.

Dr. Adrian K. Fung

Talk Abstract: Microwave Remote Sensing of Soil Moisture

Major developments on active and passive microwave remote sensing of soil moisture over the last twenty five years are reviewed. The basic principles and experimental studies with ground truth on active and passive sensing of soil moisture are discussed. This is then followed with the indications of field experiments on the applicability and practicality of anticipated emission and scattering behaviors. Reported results include ground-based, airborne and spaceborne emission and backscattering measurements as a function of soil moisture and other system, geometric and soil surface parameters. Based upon the observed scattering and emission characteristics and measured soil conditions, various approaches to soil moisture retrieval have been developed. The requirements and practical aspect of these retrieval methods are briefly summarized. Finally, the complementary nature and the relative merits of active and passive sensing are discussed and a possible approach to soil moisture retrieval is presented.

Talk Abstract: Scattering Models and Their Applications in Microwave Remote Sensing

Useful surface and volume scattering models for bare soil, sea surface, vegetation, and snow and ice are reviewed. Applications of models to numerically simulated, laboratory contolled, and field meausrements are shown for surface scattering in vertical and horizontal polarizations over a wide range of angles and frequencies. It is noted that the sea surface is generally skewed by the wind and hence its scattering properties cannot be explained by the use only of the surface spectrum. In particular, upwind and downwind difference is due to the surface bispectrum which has been widely overlooked in applications.

Generally, scattering from vegetation can be explained by a combined surface and volume scattering model using the radiative transfer method. One needs only the phase functions for a leaf, a branch and a trunk to put into the radiative transfer model. However, some vegetations have specific leaf patterns. The leaf pattern effect can show up at certain frequencies. In this case, the phase function for leaves that form a pattern will be needed. An example, based on field measurements, is given to illustrate this point.

Snow and ice form a dense medium. It may be spatially dense meaning that the scatterers are close together so that the adjacent scatterers are not in the far field of each other. It may also be electrically dense meaning that the spacing between adjacent scatterers is smaller than the exploring wavelength. Hence, in modeling both of these effects should be included. Here again, both surface and volume scattering are generally present and one can use the radiative transfer method to integrate them. Applications to field and laboratory measurements of such a dense medium model are shown.

Dr. Robert Bindschadler

Talk Abstract: Waking Giants: Ice Sheets in a Warming World

The great ice sheets of Greenland and Antarctica are shrinking faster and faster, increasing the rate of sea level rise. Observations of this accelerating ice loss have surprised the experts and confounded the predictive models that policy makers might rely on to take action. The distant future is easy to forecast—less ice on Earth—one million years of paleoclimate data say so, but more detail is needed. Direct field studies have identified a number of causes for the sudden awakening of the ice sheets. Whether it is ponded meltwater that destroys thick floating ice shelves, flowing meltwater that cascades through nearly a mile of ice to lubricate the base of the ice sheet, or warmer water circulating underneath floating ice shelves to thin them allowing a faster release of grounded ice, water is the primary agent of change. In a warmer world, ice sheets will be forced to respond to more water. The analogue of tidewater glacier retreat casts a disheartening picture that continued ice sheet mass loss may well be irreversible.