031608-F Polarimetric Radar Observations of Forest State for Determination of Ecosystem Process Final Report Technical Report 031608-F, 026511-F JPL Grant: Submitted To: Submitted By: JPL-951869 Gregory T. Rosalia Jet Propulsion Laboratory 4800 Oak rove Drive Pasadena, California 91109-8099 Dr. Fawwaz T. Ulaby M. Craig Dobson 31608-1-F = RL-2446 Submission Date: May 1999

031608-F Polarimetric Radar Observations of Forest State for Determination of Ecosystem Process Final Report Technical Report 031608-F, 026511-F JPL Grant: Submitted To: Submitted By: Submission Date: JPL-951869 Gregory T. Rosalia Jet Propulsion Laboratory 4800 Oak rove Drive Pasadena, California 91109-8099 Dr. Fawwaz T. Ulaby M. Craig Dobson May 1999

1.0 Introduction.................................................................................. 1 2.0 Research Objectives and Goals....................................1 3.0 Summary of Research Results....................................2 4.0 Students Supported and Publications...............................3 4.1 Journal Publications.........................................4 4.2 Symposia and Workshops.....................................6 4.3 Technical Reports.......................................... 12

1.0 Introduction This is the final report for research funded by NASA under JPL Grant JPL-951869 during the period March 30, 1989 to March 31, 1999. This report briefly presents (1) the objectives of the research, (2) a summary of the research effort and the technical results, and (3) listings of the students supported and the publications resulting from this effort. This project supported the efforts of 22 graduate students and resulted in the publication of 5 Ph.D. dissertations, 20 journal articles and 82 presentations at symposia and workshops. In addition, we gave over 20 interviews with print and broadcast journalists during the SIR-C/X-SAR mission. We also supported SIR-C educational outreach activities in conjunction with the SIR-C Ed program, the Ann Arbor Public Schools and two summer field programs for high school students supported by the Durfee Foundation through Earthwatch and the Johns Hopkins Center for Talented Youth. 2.0 Research Objectives and Goals The goal of this research has been to determine to what extent the polarimetric orbital SIRC/X-SAR system could ascertain several ecologically significant parameters of forest state. These include aboveground biomass, plant water status, and near-surface soil moisture. The objectives of the research were to establish theoretically the expected sensitivities, to experimentally validate and/or refine these expectations, and to develop and test inversion algorithms for estimation of biomass and moisture-related quantities. Test sites were chosen to be in Northern Michigan at the ecotone of the boreal and temperate forest such that a wide diversity of vegetation communities would be treated and thereby enhance the probability that the results would be geographically robust. In order to accomplish these goals, the study was conducted in three phases. In the first phase, the dielectric and geometric properties of selected forest canopies were monitored on a diurnal and seasonal basis. These properties were then used by the MIMICS model to simulate radar backscatter as functions of frequency, polarization and angle of incidence. The simulation results were used to (1) determine experimentally testable hypotheses, (2) establish the experimental sampling protocols and procedures, and (3) create a simulated database for development and testing of inverse algorithms. The second phase consisted of development and execution of airborne SAR experiments using the JPL AirSAR. at test sites in Northern Michigan. Two principal test sites were established. A test site at the University of Michigan Biological Station at Douglas Lake near Pellston, Michigan was overflown a number of times in 1990. AirSAR data were acquired as a function of viewing geometry for several seasons and weather conditions. An additional test site was established at the eastern end of Michigan's Upper Peninsula. The landscape of this area is characterized by large patch sizes and is therefor ideal as a SIR-C/X-SAR test site. This area was also overflown by the JPL AirSAR a number of times to examine seasonal effects on dielectric and geometric properties that determine radar backscatter. Tche third phase consisted of activities related to conduct of the SIR-C/X-SAR mission itself with flights in April and October of 1994 and subsequent analyses of the data. The analyses focussed upon (1 ) land cover classification and determination of community structure, (2) estimation of forest biophysical attributes such as tree height, diameter and 1

stocking density, and (3) estimation of aboveground biomass, total carbon and monitoring of forest disturbances. 3.0 Summary of Research Results In the first phase of this study we developed canopy scattering models and evaluated the models on the basis of data collected by the University of Michigan truck-mounted polarimetric scatterometer and the JPL AirSAR. These data sets consisted of measurements of both agricultural canopies such as corn, alfalfa and grasses and forest canopies of both needle-leaf and broadleaf trees. These models are presented in the Ph.D. dissertations of Kyle McDonald, Michael Whitt, Paul Polatin, and James Stiles. These models, inverse formulations and retrieval algorithms based upon model simulated databases have been extensively presented and published as listed in Section 4. The second phase of the study examined the spatial and temporal behavior of radar backscatter from forest canopies observed by the JPL AirSAR during a large number of overflights beginning in 1990. We examined the within-class and between-class variance of radar response to various land-cover classes and forest types. The dependence of backscatter on structural properties (geometry) of the scene was exploited to develop a series of classification algorithms. We published upon use of supervised and unsupervised Bayesian, knowledge-based, and neural network classifiers. Superior results were achieved for hierarchical, physiognomic classification schemes using multifrequency and polarimetric data. We also examined the temporal variations in backscatter arising from seasonal changes in phenology and plant dielectric properties and from weather related effects such as temperate, cloud-cover and precipitation (rain and snow). These studies consisted of field measurements of the dielectric and geometric properties in conjunction with AirSAR flights. Analyses of the data showed that short wavelengths (i.e., C-band) are most affected by phenologic changes in the forest crown-layer while longer wavelengths (i.e. at P- and L-band) are most affected by changes in the dielectric properties of the trunk layer. Rainfall effects were found to be negligible at P-band, but become significant (up to 3-dB) at shorter wavelengths and the effects are dependent upon vegetation class. Consequently, SAR-based land-cover classification is weather independent only for very simple high-level categories (i.e., water, bare soil, short vegetation, trees, urban); tests of simple classifiers were found to yield high accuracy results (better than 90%) when the same decision rules were applied to different dates and different sites. However, the temporal variance of backscatter leads to non-robust algorithms for classification of forest types at the community level. At any given time, classification results were found to generally exceed 90% accuracy, but the decision rules are not stable with time if phenology has changed seriously (i.e., leaf-on and leaf-off) or if there is intercepted precipitation on the foliage. The results on the effects of forest structure and dielectric variations on radar backscatter and classification have been widely presented at symposia and published. The third phase of the study developed and tested approaches to retrieve forest biophysical parameters from SAR-data. Prototype algorithms were developed and tested using AirSAR data acquired at the Duke Forest, Landes and Michigan test sites. Careful attention was paid to the calibration of the data and cross-calibration experiments were conducted linking the University of Michigan truck-mounted scatterometer the JPL AirSAR and the SIR-C/XSAR instrument to reference targets (point targets and distributed targets). A multi-year effort at the Michigan test site provided what is probably the most detailed set of ancillary data ever on forest structural attributes. The strength of this data-base and antecedent 2

AirSAR experience allowed us to apply prototype algorithms to the very first data take of both the SRL-1 and the SRL-2 missions and create products within less than 24 hours of data acquisition. The products included land-cover classification, tree height, basal area and above ground biomass. Subsequent analysis of the SIR-C/X-SAR data set examined the dependence of land-cover classification and retrieval of forest biophysical attributes (1) on scene properties such as season (spring vs. fall) and snow, wet snow, no snow), and (2) on sensor parameters of frequency, polarization and angle of incidence. We developed a SAR-based technique for estimation of average tree height, basal area, timber volume, crown biomass, trunk biomass, and above ground biomass. These were extended to estimation of above and belowground biotic carbon pools. SAR-derived estimates were found to be at least as accurate as the supporting ground measurements and allometric models. Multi-temporal studies examined both (1) the stability of classification rules and the power of multi-temporal classification and (2) the capability of SAR to monitor landcover change, forest disturbance (i.e., harvest), and annual changes in biomass and biotic carbon sequestration. These studies are presented in the Ph.D. dissertation of Kathleen Bergen. Finally, additional efforts developed new approaches to SAR image segmentation, specklesuppression filters, and advances in SAR orthorectification. We examined the synergistic use of electro-optical data such as SPOT with SIR-C/X-SAR for purposes of land-cover classification. We reported upon the use of interferometric SAR for extraction of tree heights. We used SIR-C/X-SAR to evaluate the expected performance of future spaceborne SAR systems (i.e., Envisat, PALSAR, Radarsat 2 and LightSAR) for classification and retrieval of forest biophysical properties. 4.0 Students Supported and Publications This research effort supported the following graduate students: James Ahne Kathleen Bergen Ian Brodie T.C. Chiu Rueben DeLaSierra Roger DeRoo Josef Kellndorfer John Kendra Yanni Kouskoulas Eric Ku Y.C. Lin Kyle McDonald Adib Nashashibi Yisok Oh Paul Polatin Paul Siqueira James Stiles Ahad Tavakoli Eric Wilcox Michael Whitt Hua Xie 3

Andrew Zambetti The following Ph.D. dissertations were derived from this research: Kathleen Bergen, "Classification, biomass estimation, and carbon dynamics of a northern forest using SIR-C/X-SAR Imagery", 1997 University of Michigan dissertation. Ian Brodie, 1993 Michigan Technological University, School of Forestry. Kyle McDonald, "Modeling microwave backscatter from tree canopies", 1991 University of Michigan dissertation. Paul Polatin, "Modeling and inversion of the radar response of vegetation canopies", 1993 University of Michigan dissertation. James Stiles, "A coherent, polarimetric microwave scattering model for grassland structures and canopies", 1996 University of Michigan dissertation. Michael Whitt, "Microwave scattering from periodic row-structured vegetation", 1991 University of Michigan dissertation. In addition to the 6 dissertations, we have published our findings in 20 journal articles, presented the results in 82 papers at symposia and workshops, and documented data in 9 technical reports. 4.1 Journal Publications Bergen, K.M. and M.C. Dobson, "Integration of Remotely Sensed Radar Imagery in Modeling and Mapping of Forest Biomass and Net Primary Production," accepted for publication in a special issue of Ecological Modeling in 1999. Xie, H., F.T. Ulaby, and L. Pierce, "Performance metrics for SAR speckle-suppression filters," IEEE Trans. Geosci. Remote Sensing, submitted for publication. Bergen, K.M., M.C. Dobson, L.E. Pierce and F.T. Ulaby, "Characterizing Carbon Dynamics in a Northern Forest Using SIR-C/X-SAR Imagery," Remote Sensing of Environment, 63(1):24-39, 1998. Dobson, M.C., L.E. Pierce, and F.T. Ulaby, "Evaluation of SAR Sensor Configurations for Terrain Classification and Forest Biophysical Retrievals", Submitted to Int. J. Remote Sensing, March 1998. Pierce, L.E., K.M. Bergen, M.C. Dobson and F.T. Ulaby, "Multi-Temporal Land-Cover Classification Using SIR-C/X-SAR Imagery," Remote Sensing Environment, vol 64, pp. 20-33, April 1998. Bergen, K.M. and M.C. Dobson, "Opportunities for Integration of Remotely Sensed Microwave Imagery in Estimation and Modeling of Forest Biomass and Net Primary Production," accepted to Ecological Modeling, Nov. 1997. Kasischke, E. S., J. M. Melack and M. C. Dobson, "The Use of Imaging Radars for Ecological Applications - A Review," Rem. Sens. Env., 59:141-156, 1997. 4

Pierce, L.E., F.T. Ulaby and M.C. Dobson, "Segmentation and Spatial Filtering for SAR Classification," submitted to IEEE Trans. Geoscience and Remote Sensing, Nov. 1997. Dobson, M.C., L. Pierce, and F.T. Ulaby, "Knowledge-Based Land-Cover Classification Using ERS-1/JERS-1 SAR Composites," Trans. on Geosci. and Rem. Sens., V. 34, No. 1, pp. 83-99, January 1996. Dobson, M.C., F.T. Ulaby, and L.E. Pierce, "Land-Cover Classification and Estimation of Terrain Attributes Using Synthetic Aperture Radar," Special Issue in Rem. Sens. of Environ., V. 51, No. 1, pp. 199-214, January 1995. Dobson, M.C., F.T. Ulaby, L.E. Pierce, T.L. Sharik, K.M. Bergen, J. Kellndorfer, J.R. Kendra, E. Li, Y.C. Lin, A. Nashashibi, K. Sarabandi and P. Siqueira, "Estimation of Forest Biophysical Characteristics in Northern Michigan with SIR-C/X-SAR,"IEEE Transactions on Geoscience and Remote Sensing V. 33, No. 4, 8877-895, July 1995. Sarabandi, K., L. Pierce, M.C. Dobson, F.T. Ulaby, J. Stiles, T.C. Chiu, R. DeRoo, R. Hartikka, and A. Zambetti, "Polarimetric Calibration of SIR-C Using Point and Distributed Targets," IEEE Transactions on Geoscience and Remote Sensing V. 33, No. 4, 858-866, July 1995. Pierce, L.E., K. Sarabandi and F.T. Ulaby, "Application of an Artificial Neural Network in Canopy Scattering Inversion," Int. J. Remote Sensing, V. 15, No.16, pp. 3263-3270, November 1994. Pierce, L.E., F.T. Ulaby, K. Sarabandi, and M.C. Dobson, "Knowledge-Based Classification of Polarimetric SAR Images," IEEE Trans. on Geosci. and Rem. Sens., V. 32, pp.1081-1086, September 1994. Polatin, P.F., K. Sarabandi and F.T. Ulaby, "An Interative Inversion Algorithm with Application to the Polarimetric Radar Response of Vegetation Canopies," IEEE Trans. on Geosci. and Rem. Sens., V. 32, pp. 62-71, January 1994. Sarabandi, K., L.E. Pierce, Y. Oh, M.C. Dobson F.T. Ulaby, A. Freeman, and P. Dubois, "Cross Calibration Experiment of JPL AIRSAR and Truck-Mounted Polarimetric Scatterometer," IEEE Trans. on Geosci. and Rem. Sens., V. 32, pp.975-986, September 1994. Whitt, M.W. and F.T. Ulaby, "Radar Response of Periodic Vegetation Canopies," Int. J. of Remote Sensing, V. 15, pp. 1813-1848, June 1994. McDonald, K.C. and F.T. Ulaby, "Radiative Transfer Modeling of Discontinuous Tree Canopies at Microwave Frequencies," Int. J. of Remote Sensing, V. 14, No. 11, July 1993. Sarabandi, K., P.F. Polatin and F.T. Ulaby, "Monte Carlo Simulation of Scattering from a Layer of Vertical Cylinders," IEEE Trans. on Ant. and Prop., V. 41, No. 4, pp. 465-475, February 1993. Dobson, M.C., F.T. Ulaby, T. LeToan, A. Beaudoin, E.S. Kasischke, and N. Christensen, "Dependence of Radar Backscatter on Coniferous Forest Biomass," IEEE Trans. on Geosci. and Rem. Sens., V. 30, No. 2, pp. 412-412, March 1992. 5

4.2 Symposia and Workshops Kouskoulas, Y., L. Pierce, F.T. Ulaby and M.C. Dobson. "Classification of Short Vegetation Using Multifrequency SAR," Proc. IGARSS'99, June 28 - July 2, 1999, Hamburg, Germany. Xie, H., F.T. Ulaby, L. Pierce and M.C. Dobson, "Performance Metrics for SAR Speckle-Suppression Filters," Proc. IGARSS'99, June 28 - July 2, 1999, Hamburg, Germany. Bergen, K.M., M.C. Dobson, L.E. Pierce and F.T. Ulaby, "Future Directions in Modeling Net Primary Productivity of Forest Ecosystems," North America ISEM Annual Meeting, August, Montreal. Bergen, K. and M.C. Dobson, "Monitoring Forest Biomass, Harvest and ANPP Using SAR," Proc. Soc. Amer. For. Meeting, Traverse City, Michigan, Sept. 19-23, 1998, 10 pp. Dobson, M.C. and K. Bergen, "Land-Cover Classification and Forest Biophysical Retrieval from SAR," Proc. Soc. Amer. For. Meeting, Traverse City, Michigan, Sept. 19 -23, 1998, 9 pp. Kobayashi, Y., K. Sarabandi, L. Pierce and M.C. Dobson, " Assessment of TOPSAR DEM for Extracting Tree Heights," IGARSS'98, July 6-10, 1998, Seattle, Washington. Pierce, L.E., G. Samples, M.C. Dobson and F.T. Ulaby, "An Automated Unsupervised/Supervised Classification Methodology," IGARSS'98, July 6-10, 1998, Seattle, Washington. Ulaby, F.T., "SAR Biophysical Retrievals: Lessons Learned and Challenges to Overcome," International Workshop on Retrieval of Bio- and Geo-physical Parameters from SAR Data for Land Applications, ESTEC, The Netherlands, 21-23 October, 1998. Ulaby, F.T., "Terrain Applications of Multichannel SAR," ESLAB Symposium, ESTEC, The Netherlands, 15-20 September, 1998. Xie, H, L.E. Pierce and M.C. Dobson, "Combining Orbital SAR and Optical Data for Global Classification," Proc. of IEEE Geoscience and Remote Sensing Symp. (IGARSS'98), Seattle, WA, July 6-10, 1998, 3:1599-1601. Bergen, K., M. C. Dobson, L. E. Pierce and F. T. Ulaby, "Effects of Within-Season Dielectric Variations on Terrain Classification Using SIR-C/X-SAR," IGARSS'97, August 4-8, 1997, Singapore. Dobson, M. C., L. E. Pierce, J. M. Kellndorfer and F. T. Ulaby, "Use of SAR Texture in Terrain Classification," IGARSS'97, August 4-8, 1997, Singapore. Dobson, M. C., A. Kwarteng and F. T. Ulaby, "Use of SIR-C/X-SAR to Monitor Environmental Damages of the 1991 Gulf War in Kuwait," IGARSS'97, August 4-8, 1997, Singapore. Dobson, M. C., L. E. Pierce and F. T. Ulaby, "The Role of Frequency and Polarization in Terrain Classification Using SAR Data," IGARSS'97, August 4-8, 1997, Singapore. 6

Dobson, M. C., A. Kwarteng and F. T. Ulaby, "Use of SIR-C/X-SAR to Monitor Environmental Damages of the 1991 Gulf War in Kuwait," Proc. 1st Saudi-Japanese Symp. on Remote Sensing Application, October 19-21, 1997, Riyadh, Saudi Arabia, pp105-117. Dobson, M.C. and F.T. Ulaby, "Renewable Resource Pilot Projects for LightSAR," LightSAR Applications Workshop, Gulfport, LA, Nov. 12-14, 1997. Pierce, L. E., M. C. Dobson and F. T. Ulaby, "An Exploration of Features for SAR Classification," IGARSS'97, August 4-8, 1997, Singapore. Ulaby, F.T. "Terrain Classification Using Multi-frequency Radar Observations", Japanese-Saudi Arabian Symposium on Remote Sensing, Riyadh, Saudi Arabia, October, 1997. Bergen, K. M., L. E. Pierce, M. C. Dobson and F. T. Ulaby, "A Multi-Temporal Classifier for SIR-C/X-SAR Imagery," 1996 Int. Geoscience and Remote Sensing Symposium (IGARSS'96), IGARSS'96 Digest, Vol. III, pp. 1568 - 1570, May 27 - 30, 1996, Univ. of Nebraska, Lincoln, Nebraska. Bergen, K. M. and M. C. Dobson, "Carbon Dynamics in Northern Forests Using SIRC/X-SAR Imagery," 1996 Int. Geoscience and Remote Sensing Symposium (IGARSS'96), IGARSS'96 Digest, Vol. I, pp. 580 - 582, May 27 - 30, 1996, Univ. of Nebraska, Lincoln, Nebraska. Bergen, K.M. and M.C. Dobson, "Monitoring Carbon Dynamics in Northern Forests," 1996 Ecol. Soc. Am. Symp., Aug. 11-15, 1996, Providence, RI., Sup. Bull. Ecol. Soc. Am., 77:3:33, July 1996. Dobson, M. C. and K. C. McDonald, "Microwave Dielectric Properties of Soil and Vegetation and Their Estimation from Spaceborne Radar," 2nd Workshop on Electromagnetic Wave Interaction with Water and Moist Substances, 1996 IEEE MTT-S Int. Microwave Symp., June 17, 1996, San Francisco, CA. Dobson, M. C., L. E. Pierce, K. M. Bergen and i. T. Ulaby, "Temporal Stability of Northern Forest Biophysical Retrievals Using SI Z-C/X-SAR," 1996 Int. Geoscience and Remote Sensing Symposium (IGARSS'96), IGj.RSS'96 Digest, Vol. II, pp. 1092, May 27 - 30, 1996, Univ. of Nebraska, Lincoln, Net raska. Pierce, L., J. Kellndorfer, F. Ulaby and L. Norik me, "Practical SAR Orthorectification," IGARSS '96 Symposium, Lincoln, Nebraska, N ay 1996. Ulaby, F.T. and M.C. Dobson, "Extraction of Mi ti-Level Terrestrial Information from Satellite Radar Observations," Int. Symp. on Re: i. Sens., 12th Fall Symp. of Korean Soc. Rem. Sens. and 5th Workshop of EMSA, Oct. 2-,-25, 1996, Cheju, Korea. Ulaby, F.T. "Multi-dimensional SAR, Terrain Classification, and Biophysical Mapping: A Winning Combination," IGARSS '96 Symposium, Lincoln, Nebraska, May 1996. Ulaby, F.T., "Developments in Radar Remote Sensing Science", Light SAR Workshop, Sioux Falls, South Dakota, August, 1996. 7

Bergen, K. M., M. C. Dobson and L. E. Pierce, "Radar Aboard Space Shuttle Endeavor Images the Hiawatha for Purposes of Land-Cover Classification, Biomass Estimation and Detection of Forest Disturbance," Conference on Adding a Multiscale and Ecological Perspective to Wildlife and Vegetation Management in the Upper Peninsula of Michigan, Clear Lake, Hiawatha National Forest, Sept. 19 - 21, 1995, (Invited). Dobson, M., L. Pierce, K. Bergen, J. Kellndorfer, and F. Ulaby, "Retrieval of AboveGround Biomass and Detection of Forest Disturbance Using SIR-C/X-SAR," 1995 Int. Geoscience and Remote Sensing Symposium (IGARSS'95), IGARSS'95 Digest, Vol. 2, pp. 987-989, July 10-14, 1995, Florence, Italy. Dobson, M. C., "Terrain Classification and Estimation of Forest Biophysical Properties Using SIR-C/X-SAR," Proc. CoHEMIS Workshop on Remote Sensing and Environmental Monitoring for the Sustainable Development of the Americas, San Juan, Puerto Rico, March 21-22, 1995, (Invited). Dobson, M. C. and F. T. Ulaby, "Preliminary Results from SIR-C/X-SAR at the Raco Supersite," SIR-C/X-SAR Team Meeting, Uberlingen, Germany, Feb. 6-8. 1995. Dobson, M. C., F. T. Ulaby, L. E. Pierce, and K. Sarabandi, "Land-Cover Classification and Estimation of Forest Biophysical Properties Using SIR-C/X-SAR," NASA Remote Sensing Science Workshop, NASA Goddard Space Flight Center, Feb. 27 - March 1, 1995. Kasischke, E., J. Melack, J. B. Way, and M. Dobson, "Ecological Applications of Imaging Radar," 1995 Int. Geoscience and Remote Sensing Symposium (IGARSS'95), IGARSS'95 Digest, Vol. 1, pp. 593, July 10-14, 1995, Florence, Italy. Pierce, L., K. Bergen, C. Dobson, and F. Ulaby, "Land-Cover Classification with SIRC/X-SAR Data," 1995 Int. Geoscience and Remote Sensing Symposium (IGARSS'95), IGARSS'95 Digest, Vol. 2, pp. 918-920, July 10-14, 1995, Florence, Italy. Sarabandi, K., L. Pierce, J. Stiles, M. Dobson, T. Chiu and F. Ulaby, "Polarimetric Calibration of SIR-C Using Point and Distributed Targets," Int. Geoscience and Remote Sensing Symposium (IGARSS'95), IGARSS'95 Digest, Vol. 1, pp. 593, July 10-14, 1995, Florence, Italy. Ulaby, F. T., M. C. Dobson, L. Pierce, and K. Sarabandi, "Scene Classification and Biomass Estimation Using SIR-C/X-SAR Data," Int. Symp. on Retrieval of Bio- and Geophysical Parameters from SAR Data for Land Applications, Toulouse, France, Oct. 10 -13, 1995. van Zyl, J., C. Dobson, J. Dozier, P. DuBois, D. Evans, J. A. Kong, T. Le Toan, J. Melack, E. Rignot, S. Saatchi, J. C. Shi, and F. T. Ulaby, "Preliminary Science Results from the SIR-C/X-SAR Mission," Int. Symp. on Retrieval of Bio- and Geophysical Parameters from SAR Data for Land Applications, Toulouse, France, Oct. 10-13, 1995. Dobson, M. C., L. E. Pierce, and F. T. Ulaby, "Empirical Method for Estimation of Forest Biophysical Properties from Multifrequency Polarimetric SAR," 1994 International Geoscience and Remote Sensing Symposium (IGARSS'94), August 8 - 12, 1994, California Institute of Technology, Pasadena, CA. 8

Dobson, M. C., "Retrieval of Forest Biomass Using SAR", Ecology Panel Workshop for the Committee on Earth Sciences, Space Studies Board, National Research Council, Univ. of CA at Santa Barbara, Nov. 14-17, 1994. Pierce, L. E., F. T. Ulaby, and M. C. Dobson, "Knowledge-Based Land-Cover Classification Using ERS-1/JERS-1 Composites," 1994 International Geoscience and Remote Sensing Symposium (IGARSS'94), August 8 - 12, 1994, California Institute of Technology, Pasadena, CA. Saatchi, S. S., R. Treuhaft, and M. C. Dobson, "Estimation of Leaf Area Index Over Agricultural Areas from Polarimetric SAR Images," 1994 International Geoscience and Remote Sensing Symposium (IGARSS'94), August 8 - 12, 1994, California Institute of Technology, Pasadena, CA. Sarabandi, K., L. E. Pierce, J. M. Stiles, M. C. Dobson, T. C. Chiu, and F. T. Ulaby, "Polarimetric Calibration of SIR-C Using Point and Distributed Targets," Proc. SAR Calibration Workshop, pp. 18, CEOS Calibration/Validation Working Group: SAR Calibration Workshop, Sept. 28-30, 1994, The University of Michigan, Ann Arbor, MI. Sarabandi, K., L. Pierce, J.M. Stiles, M.C. Dobson, F.T. Ulaby, and T.C. Chiu, "Polarimetric Calibration of SIR-C using point and Distributed targets," Proceedings of CEOS SAR Calibration Workshop, Ann Arbor, Michigan, September 1994. Ulaby, F. T., L. Pierce, Y. Oh, K. Sarabandi and M. Dobson, "Scene Classification and Radar Polarimetry for Mapping of Soil and Vegetation Parameters," Sixth International Symposium: Physical Measurements and Signatures in Remote Sensing, January 17 - 21, 1994, Val D'Isere, France, (Invited). Ulaby, F. T., L. E. Pierce, M. C. Dobson, S. Chacon, and K. Sarabandi, "Land Cover Classification by SAR," 1994 International Geoscience and Remote Sensing Symposium (IGARSS'94), August 8 - 12, 1994, California Institute of Technology, Pasadena, CA. Ulaby, F.T., "Land Cover Mapping and Geoscience Applications With Imaging Radar," 16th Space Station Utilization Workshop, Tokyo, Japan, January 1994. Ahne, J.J., K. Sarabandi and F.T. Ulaby, "Design and Implementation of Single Antenna Polarimetric Active Radar Calibrators," International Antennas and Propagation Symposium, Ann Arbor, Michigan, June 1993. DeRoo, R.D. and F.T. Ulaby, "Experimental Observations of the Forward Scattering of Microwaves from a Rough Dielectric Surface," International Geoscience and Remote Sensing Symposium, Tokyo, Japan, August 1993. Dobson, M. C., E. Wilcox and F. T. Ulaby, "Effects of Forest Structure on Radar Response to Forest Biomass," 1993 International Geoscience and Remote Sensing Symposium (IGARSS'93), August 18 - 21, 1993, Kogakuin University, Tokyo, Japan. Pierce, L. E., K. Sarabandi, F. T. Ulaby and M. C. Dobson, "Knowledge-Based Classification of SAR Images," 1993 International Geoscience and Remote Sensing Symposium (IGARSS'93), August 18 - 21, 1993, Kogakuin University, Tokyo, Japan. Pierce, L. E., M. C. Dobson, E. Wilcox and F. T. Ulaby, "Artificial Neural Network Inversion of Tree Canopy Parameters in the Presence of Diversity," 1993 International 9

Geoscience and Remote Sensing Symposium (IGARSS'93), August 18 - 21, 1993, Kogakuin University, Tokyo, Japan. Sarabandi, K., F. T. Ulaby and M. C. Dobson, "AIRSAR and POLARSCAT CrossCalibration Using Point and Distributed Targets," 1993 International Geoscience and Remote Sensing Symposium (IGARSS'93), August 18 - 21, 1993, Kogakuin University, Tokyo, Japan. Ulaby, F. T. and M. C. Dobson, "Radar Response of Vegetation: An Overview," Proceedings of the Third Spaceborne Imaging Radar Symposium, Jan. 18 - 21, 1993, Jet Propulsion Laboratory, Pasadena, CA, JPL Pub. 93-16, pp. 151-183, 1993 (Invited). Ulaby, F. T., M. Craig Dobson, L. Pierce and K. Sarabandi, "SAR Terrain Classifier and Mapper of Biophysical Attributes," The 4th Annual Airborne Geoscience Workshop, October 25-29, 1993, Washington, D.C.. Waring, R., M. C. Dobson, R. Hunt, R. Lang, L. Morrisey, R. Oren, D. Schimel, J. Ranson, J. B. Way and J. Weishempel, "Synthetic Aperture Radar: Applications in Ecosystem Studies," 1993 Annual Meeting of the Ecological Society of America, August 1 -4, 1993, Madison, Wisconsin. Dobson, M. C. and E. Wilcox, "Role of Crown Structure in Radar Backscatter Dependence on Forest Biomass", 1992 International Geoscience and Remote Sensing Symposium (IGARSS'92), Houston, Texas, May 26 - 29, 1992. Dobson, M. C., "Radar Backscatter from Soils and Vegetated Terrain," ISLSCP Americas Workshop: Remote Sensing of the Land Surface for Studies of Global Change, June 23 - 26, 1992, Columbia, MD, (Invited). Dobson, M. C., "ERS-1 SAR Studies of Mid-Latitude Coniferous and Deciduous Forests of Michigan," First ERS-1 Symposium, ESA, Nov. 4 - 6, 1992, Cannes, France. Dobson, M. C. and T. L. Sharik, "Assessment of Forest Ecosystems in the Lake Superior Basin Using Imaging Radar," Symposium on Understanding Lake Superior Through Research: Status and Future Prospects, November 8 - 10, 1992, Duluth, MN. Nashashibi, A., K. Sarabandi, and F.T. Ulaby, "The Effect of Azimuthal Asymmetry of Particle Orientation on the Phase Statistics of Distributed Targets," International Geoscience and Remote Sensing Symposium, Houston, Texas, June 1992. Pierce, L.E., K. Sarabandi, J.M. Stiles, and F.T. Ulaby, "Application of an Artificial Neural Network in a Canopy Scattering Model Inversion," International Geoscience and Remote Sensing Symposium, Houston, Texas, June 1992. Polatin, P.F., K. Sarabandi, and F.T. Ulaby, "An iterative Method for Inversion of the Polarimetric Radar Response of Vegetation Canopies," International Geoscience and Remote Sensing Symposium, Houston, Texas 1992. Sarabandi, K., P.F. Polatin, and F.T. Ulaby, "Monte Carlo Simulation of Scattering from a Layer of Vertical Cylinders," International Geoscience and Remote Sensing Symposium, Houston, Texas, June 1992. Sarabandi, K., L. Pierce, Y. Oh, M. C. Dobson, A. Freeman, and P. Dubois, "Cross Calibration Experiment Using JPL AIRSAR and Truck-Mounted Polarimetric 10

Scatterometers," 1992 International Geoscience and Remote Sensing Symposium (IGARSS'92), Houston, Texas, May 26 - 29, 1992. Ulaby, F. T. and M. C. Dobson, "ERS-1 and Airborne SAR Observations of Soil Moisture Variations and Forest Parameters," URSI Specialist Meeting on Microwave Signatures, Innsbruck, Austria, July 1-3, 1992, (Invited). DeRoo, R., Y. Kuga, M. C. Dobson, and F. T. Ulaby, "Bistatic Radar Scattering from Organic Debris of a Forest Floor," 1991 International Geoscience and Remote Sensing Symposium (IGARSS'91), IGARSS'91 Digest. Vol. 1, pp. 15-18, Espoo, Finland, June 3 -6, 1991. Dobson, M. C., K. McDonald, and L. Pierce, "Diurnal Variation in Radar Backscatter from a Loblolly Pine Forest in Late Summer," 1991 International Geoscience and Remote Sensing Symposium (IGARSS'91), IGARSS'91 Digest, Vol. 3, pp. 1115, Espoo, Finland, June 3 - 6, 1991. Dobson, M. C., T. Sharik, L. Pierce, and K. McDonald, "Seasonal Change in Radar Backscatter from Mixed Conifer and Hardwood Forests in Northern Michigan," 1991 International Geoscience and Remote Sensing Symposium (IGARSS'91), IGARSS'91 Digest. Vol. 3, pp. 1121-1124, Espoo, Finland, June 3 - 6, 1991. Dobson, M. C., R. DeLaSierra, and N. Christensen, "Spatial and Temporal Variation of the Microwave Dielectric Properties of Loblolly Pine Trunks," 1991 International Geoscience and Remote Sensing Symposium (IGARSS'91), IGARSS'91 Digest, Vol. 3, pp. 1107-1110, Espoo, Finland, June 3 - 6, 1991. Dobson, M. Craig, Terry L. Sharik and Jim Weber, "Seasonal Change in Northern, Mixed Hardwood and Coniferous Forests as Monitored by Imaging Radar," 1991 Annual Meeting of the Ecological Society of America, August 4-8, 1991, San Antonio, Texas. Haney, Eric, Norman Christensen, Eric Kasischke and M. Craig Dobson, "The Impact of Variations in Tree Architecture and Density on Synthetic Aperture Radar Signatures of Loblolly Pine Forests in the Duke University Research Forest," 1991 Annual Meeting of the Ecological Society of America, August 4-8, 1991, San Antonio, Texas. Kasischke, E. S., L. L. Bourgeau-Chavez, N. L. Christensen and M. C. Dobson, "The Relationship Between Aboveground Biomass and Radar Backscatter as Observed on Airborne SAR Imagery," Proceedings of the Third Airborne Synthetic Aperture Radar (AIRSAR) Workshop, Jet Propulsion Laboratory, Pasadena, CA, May 23-24, 1991, JPL Publication 91-30, pp. 11 - 21, August 1, 1991. McDonald, K. C., M. C. Dobson and F. T. Ulaby, "Modeling Multi-Frequency Diurnal Backscatter from a Walnut Orchard," 1991 International Geoscience and Remote Sensing Symposium (IGARSS'91), IGARSS'91 Digest. Vol. 3, pp. 1125-1130, Espoo, Finland, June 3 - 6, 1991. McDonald, K.C. and F.T. Ulaby, "Sensitivity of Tree Canopy Backscatter to variations in Open Canopy Parameters," North American Radio Science Meeting and International IEEE/AP-S Symposium, The University of Western Ontario, London, Canada, June 1991. Sarabandi, K., L. E. Pierce, F. T. Ulaby, M. W. Whitt and M. C. Dobson, "Comparison of Several Polarimetric SAR Calibration Techniques," Committee on Earth Observation 11

Satellites CEOS SAR Calibration Workshop, October 9 to 11, 1991, DLR Institute fur Hochfrequenztechnik, Oberpfaffenhofen, Germany. Sarabandi, K., L.E. Pierce and F.T. Ulaby, "Calibration of a Polarimetric Imaging SAR," Second Annual JPL Airborne Geosciences Workshop, Pasadena, California, pp. 167-176, May 1991. Sarabandi, K., Y. Oh and F.T. Ulaby, "Application and Performance Characterization of Polarimetric Active Radar Calibrators," Second Annual JPL Airborne Geosciences Workshop, Pasadena, California, May 1991. Tavakoli, A., K. Sarabandi and F.T. Ulaby, "Horizontal Propagation through Periodic Vegetation Canopies," International Geoscience and Remote Sensing Symposium, Helsinki, Finland, June 1991. Ulaby, F. T., M. C. Dobson, and D. R. Brunfeldt, "Microwave Probe for In Situ Observations of Vegetation Dielectric", IEEE Instrumentation Measurement Technology Conference (IMTC/91), May 14-16, 1991, Atlanta, Georgia. Way, JoBea, Eric Rignot, M. Craig Dobson and Kyle McDonald, "Monitoring the Environmental and Phenologic State of Alaskan Forests Using Synthetic Aperture Radar," 1991 Annual Meeting of the Ecological Society of America, August 4-8, 1991, San Antonio, Texas. Whitt, M.W. and F.T. Ulaby, "Observation and Modelling of Look-direction Effects in Microwave Backscatter from Corn," International Geoscience and Remote Sensing Symposium, Helsinki, Finland, June 1991. Whitt, M.W. and F.T. Ulaby, "Modelling the Polarimetric Backscatter from Periodic Bare Soil Surfaces," International Geoscience and Remote Sensing Symposium, Helsinki, Finland, June 1991. 4.3 Technical Reports Bergen, K. M., M. C. Dobson, T. L. Sharik and I. Brodie, "Report on Structure, Composition, and Above-ground Biomass of SIR-C/X-SAR and ERS-1 Forest Test Stands 1991-1994, Raco Michigan Site," Radiation Lab Tech Rept. 026511-7-T, EECS Dept., The University of Michigan, Ann Arbor, Michigan, January 1996. Bergen, K. M., M. C. Dobson, L. E. Pierce, J. Kellndorfer and P. Siqueira, "October 1994 SIR-C/X-SAR Mission: Ancillary Data Report Raco, Michigan Site," Radiation Lab Tech. Rept. 026511-6-T, EECS Dept., The University of Michigan, Ann Arbor, Michigan, December 1995. Bergen, K. M., M. C. Dobson, L. E. Pierce, J. R. Kendra, J. Kellndorfer, and P. Siqueira, "April 1994 SIR-C/X-SAR Mission: Ancillary Data Report Raco, Michigan Site," Radiation Lab Tech. Rept. 026511-5-T, EECS Dept., The University of Michigan, Ann Arbor, Michigan, December 1994. Dobson, M. C., "University of Michigan SIR-C/X-SAR Forest Experiment Status and Mission Operations Plan," Radiation Laboratory Technical Report 026511-5-T, EECS Department, University of Michigan, Ann Arbor, Michigan, October, 1993. 12

Dobson, M. C. and R. DeLaSierra, "Soil Measurements for the Michigan Forest Test Sites: Moisture, Density and Dielectric Properties (1990-1991)", Radiation Laboratory Technical Report 026511-5-T, EECS Department, University of Michigan, Ann Arbor, Michigan, May, 1992. Dobson, M. C., T. Sharik and I. Brodie, "Stand Architecture and Biomass for the Michigan Forest Test Sites (1990-1992)", Radiation Laboratory Technical Report 026511 -6-T, EECS Department, University of Michigan, Ann Arbor, Michigan, November, 1992. McDonald, K. and F.T. Ulaby, "Modeling Microwave Backscatter from Discontinuous Tree Canopies," Technical Report 026511-2-T, The University of Michigan, Ann Arbor, June 1991. Tavakoli, A., K. Sarabandi, and F.T. Ulaby, "Microwave Propagation through Cultural Vegetation Canopies," Technical Report 026511-3-T, The University of Michigan, Ann Arbor, July 1991. Whitt, M. and F.T. Ulaby, "Microwave Scattering from Periodic Row-Structured Vegetation," Technical Report 026511-4-T, The University of Michigan, Ann Arbor, June 1991. 13