Fall 2006

 

Seminars will be held on 4:00-5:00pm, Friday at Loeffler room BSB 3.03.02

(Special talk will be held on 2:00-3:00pm, Friday at room UC 2.03.06 ASH)

For more information please call Dr. Hongjie Xie (5445)/Dr. Dibs Sarkar (5453)

Snack and drinks will be provided 

Sept.15                        Dr. Srinivas Bettadpur from UT Austin (pdf)

Sept.22                        Dr. G. Randy Keller from U of Oklahoma (pdf)

Sept.29                        Dr. Jennifer Ren from Texas A&M University - Kingsville (pdf)

Oct. 6                          Dr. Donghui Yi from NASA/GSFC (pdf)

Oct. 13 (Special talk)   Prof. Steve F. Ackley from UT San Antonio (pdf)

Oct. 27                        Dr. Zong-liang Yang from UT Austin (pdf)

Nov. 10                       Dr. Fan Qiu from UT Dallas (pdf)

 

                            A fly can be downloaded for posting

Sept. 15, 2006      

The Gravity Recovery And Climate Experiment (GRACE): Status & Future

Dr. Srinivas Bettadpur

Senior Research Scientist

Center for Space Research

University of Texas at Austin

Austin, Texas 78759

 

          GRACE is a cooperative, NASA/DLR mission for the precise mapping of the gravity field of the Earth. The science motivation for this mission is that the mass transport within the Land, Ocean and Atmosphere can be measured through the resulting changes in the exterior gravity field of the Earth. GRACE has been providing global measurements of the mass transport at monthly time scales since launch in March 2002. The results have been applied to a wide range of studies in oceanography, hydrology, glaciology and the solid Earth sciences.

           This presentation reviews the GRACE mission concept, and describes its evolution since launch, as well as anticipated future plans. A survey of the science results is presented, with particular attention to the lessons learnt so far in developing GRACE product applications. A brief discussion of possible future improvements in the interpretation of the data will also be presented.
 

 

Sept. 22, 2006                                       

Integrated geological and geophysical studies of basins in the Rocky Mountain region

 G. Randy Keller, Ph.D., Professor

School of Geology and Geophysics

University of Oklahoma

         The Rocky Mountains have intrigued researchers and explorationists ever since the gold rush days. These mountains are a tectonic puzzle because of their complex history and their distance from plate margins that usually make driving mechanisms for deformation evident. The region’s crustal formation in the Precambrian, the formation of the Ancestral Rocky Mountains in the late Paleozoic, the Laramide orogeny, and late Cenozoic extension and uplift are topics of great current scientific interest. There has been an increasing emphasis on the use of gravity, magnetic and remote sensing data in studies of this region, and these data have been particularly effective when used in an integrated fashion with seismic and drilling data. Rifting during the late Precambrian and Cambrian effected large areas of the southwest and created sedimentary basins that have in many cases survived to the present. In addition, younger structures such as those associated with the Ancestral Rocky Mountains have often been affected by older rift structures preserving Cambrian and older strata. Integrated studies have played a major role in efforts to reveal the deep manifestation of Ancestral Rocky Mountain structures including the deep basin structure and structure of the uplifts, and these efforts show that the scale of these structures is impressive in a global context. The deformation that formed the Ancestral Rocky Mountains is a massive inversion of these rift structures and is due to a plate collision in the late Paleozoic. The Laramide orogeny also produced considerable crustal scale deformation in the form of large basement uplifts and deep basins. Finally, late Cenozoic uplift and extension formed the Rio Grande rift whose surface manifestation is a series of basins, and our integrated studies show that these basins are deep and are underlain by complex subsurface structures. These basins are bounded by large active faults that pose a moderate level of seismic hazard, and the basin fill contains large but dwindling groundwater resources.

 

Sept. 29, 2006      

Particle Dynamics and Contaminant Transport in River Systems: Fundamentals and Implications

Dr. Jennifer Ren, Assistant professor

Department of Environmental Engineering

Texas A&M University - Kingsville      

       Assessment of contaminated rivers and effective remediation of streams affected by acid mine drainage require a thorough understanding of the dominant mechanisms controlling particle and contaminant dynamics.  Studies of the fate and transport of these reactive substances are generally complicated due to the complex coupling of hydrologic and geochemical processes, which vary spatially and temporally.  The importance of hyporheic exchange has becoming increasingly recognized because of its important role in regulating the transport of particles, contaminants, and ecologically relevant substances.  In this presentation, fundamental mechanisms controlling hyporheic exchange processes, overall study approaches including modeling and experimental methodology, and accomplishments of understanding these transport processes will be reviewed.  Implications of these results on determination of ecological risk along with the current and future research will be discussed.

 

Oct. 6, 2006       

ICESat Measurement of Antarctic Sea Ice

Dr. Donghui Yi, a chief scientist at SGT Inc.,

Cryospheric Sciences Branch

NASA Goddard Space Flight Center

         The precision of ICESat-measured mean surface elevation of flat surfaces is 2 cm. The 70 m laser footprints are spaced 172 m apart along track. This provides an important tool for the study of sea ice. The ICESat orbit has an inclination of 94° and its ground tracks cover all sea ice surrounding Antarctica. Using open water and thin ice as reference sea level, a novel technique has been developed to measure sea-ice freeboard using ICESat-measured elevation data. With estimates of snow, brine, and sea-ice density, combined with snow thickness data from AMSR-E, sea-ice thickness is derived from the freeboard. Sea-ice freeboard is first calculated along ICESat ground tracks and then gridded into 50 x 50 km cell. Sea-ice thickness is derived from gridded freeboard and AMSR-E snow thickness data. Overall, ICESat measurements provide unprecedented accuracy and spatial and temporal coverage of sea-ice freeboard and thickness and can be used to monitor sea-ice volume, which is an indicator of climate change.

 

Oct. 13, 2006 (Special Talk) 

AUTOSUB-UNDER-ICE:  Exploration of the environment under sea ice and an ice shelf using an Autonomous Underwater Vehicle

Steve F. Ackley, Research Associate Professor

Department of Earth and Environmental Science

 University of Texas at San Antonio

         Since 2000, the UK government’s environmental science agency, NERC, has sponsored a thematic program, Autosub-Under-Ice.    The program was a combined technology development of a versatile autonomous underwater vehicle and ship-based science projects using that vehicle in both the Arctic and Antarctic.  The program development described is perhaps unique in the polar sciences since it required the concurrent development of a new technology and nearly simultaneous application of that technology to conduct science in previously unreachable areas under sea ice and an ice shelf.   Management of the program was conducted by a Science Steering Group composed about equally of independent appointees as well as several of the projects’ Principal Investigators. Three ship expeditions were conducted, two to the Antarctic and one (split into two legs) to the Arctic.  The vehicle’s capabilities included ability to navigate over long distances(400km)  and return to a position with less than 0.1% error and used inertial navigation combined with either top or bottom surface tracking to achieve this accuracy.  Other technical advances successfully trialed include the capability to launch in heavy ice conditions, detect and avoid obstacles, and return to a homing beacon (when the original location programmed became inaccessible because of ice cover). New sensors fitted into the AUV included an up or down looking swath bathymeter, a water sampler, and digital camera, along with continuous CTD and up and down looking ADCP previously used.   Results presented include the currents and ice shelf bottom topography obtained from under the Fimbul Ice Shelf, Antarctica; morphology of the sea ice cover, ocean currents and water properties under fast ice off NE Greenland; water sampling from a Greenland fjord; and sea ice thickness distributions and concurrent krill swarm densities observed under Antarctic sea ice.   New efforts of the project are to transfer the technology internationally, educate students in AUV technology, and development of risk assessment procedures for use by equipment owners and investigators to evaluate potential missions.

 

Oct. 27, 2006      

Developing a Regional Environmental Prediction System for Central and Eastern Texas

Dr. Zong-liang Yang, Associate Professor

Department of Geological Sciences

Jackson School of Geosciences

The University of Texas at Austin

 

Will Texas’ summers become longer and hotter in the coming decades? Will a warmer climate mean less frequent but more intense thunderstorms? How will these potential changes in extreme weather patterns affect flash flooding, agriculture, ecosystems, air quality, and water resources in Texas? These are some the questions being addressed by the Climate Science Program at the Jackson School of Geosciences at the University of Texas at Austin.

 
           Over the past five years, we have been developing an integrated environmental system modeling framework that consists of multi-scale and multi-disciplinary sciences. Individual components include climate modeling, air quality modeling, hydrological modeling, remote sensing, biogeochemistry, and in situ measurements.  The integrated system model is designed to benefit a wide range of applications. Although the model development has been focused on the State of Texas, the model framework can be applied elsewhere. Meteorological simulations will also be directly compared to instrumental measurements made at weather stations, radiosondes, eddy flux towers, rain gauges, and by weather radars, aircrafts and satellites to improve upon model calibration. In the presentation, I will provide highlights of results in climate dynamic downscaling, biogenic emissions, seasonal climate forecasts, and regional-scale flood forecasting for Central Texas. The flood forecasting will be the focus of my talk. The Weather Research and Forecasting (WRF) Model, created with the purpose of improving upon the current Pennsylvania State University / National Center for Atmospheric Research Fifth-Generation Mesoscale Model (PSU/NCAR MM5), is specifically designed for regional resolutions of 1-10 km. Previous research by the authors resulted in the development of a regional-scale prediction system over the San Antonio River Basin, using a GIS database, a hydrologic model, and a hydraulic model. Observed precipitation drives the prediction system; the authors hypothesize that the WRF model has the potential to predict flooding, at a lead time of several days, with an accuracy near that of observed precipitation.  Causes of model bias are also investigated, to determine the relative errors caused by model physics, initialization interval, buffer zone and domain size, and small-amplitude random errors.  Results show that the Betts-Miller-Janjic cumulus and Lin microphysics schemes, 48-hour initialization interval, and two-domain configuration covering minimal ocean and having a parent-to-nest area ratio of greater than ten best simulates the 2002 storm event. Location errors in rainfall are most significant because of the inherent difficulties in their prediction. Errors in intensity and timing show a more predictable watershed response that may be useful in estimation of streamflow ranges for flood forecasting.

 

Nov. 10, 2006   

Synergy of LIDAR and High-Resolution Digital Orthophotos to Support Urban Feature Extraction and 3d City Models Construction

Dr. Fang Qiu, Associate Professor

Geospatial Information Sciences

University of Texas at Dallas

       The development of automated algorithms for urban feature extraction and 3D city models (3DCMs) construction is of great importance, because traditional surface reconstruction based on manual digitization and photogrammetry is both costly and time consuming. LIDAR (Light Detection and Ranging), a relatively new technology based on high density surface sampling, can expedite the obtaining of accurate digital surface models (DSMs) with less expense. This research focused on the extraction of urban features (e.g. buildings and trees) and construction of 3D city models (3DCMs) on the basis of integrated usage of LIDAR data and digital orthophotos. For urban feature extraction, three methods were compared and applied in the city of Dallas: first, the object oriented image classification of high spatial resolution digital orthophotos utilizing not only spectral, but also edges, texture and spatial context information; second, the analysis of LIDAR data to derive urban features using digital terrain model; and third, the fusion of object oriented image classification results with the normalized digital surface model (nDSM) drawn from LIDAR data. It was demonstrated that the third method built upon the synergy of LIDAR and digital orthophotos data greatly improved the accuracy of urban feature extraction. To construct 3DCMs, this research first classified the buildings to those of flat roof and pitched roof using the roof slopes derived from LIDAR nDSM. The heights of flat roof and pitched roof buildings were then calculated using zonal majority and zonal maximum, respectively, where the zones are obtained from the feature extraction process.