Jackson Receives 2003 Hydrology Section Award

Thomas J. Jackson received the Hydrology Section Award at the 2003 AGU Fall Meeting in San Francisco, California, last December. The award recognizes outstanding contributions to the science of hydrology.


jackson_thomasjLadies and gentlemen, it gives me great pleasure to introduce Dr. Thomas J. Jackson, of the United States Department of Agriculture, for the 2003 Hydrology Award.

Tom got his B.S. in fire protection engineering, his M.S. in civil engineering, and a Ph.D. under Bob Ragan at the University of Maryland in 1976. He has been a research hydrologist with the USDA Agricultural Research Service Hydrology and Remote Sensing Lab since 1977. His research involves the application and development of remote sensing technology in hydrology and agriculture. These studies have ranged from small-scale controlled condition field experiments utilizing truck-mounted radiometers to large-scale multitemporal aircraft mapping and most recently satellite retrievals.

He is a Fellow of the American Geophysical Union. He is also a Fellow of the IEEE, and currently serves on the Administrative Committee of the IEEE Geoscience and Remote Sensing Committee. He has received three awards for outstanding papers, and in the year 2002 was the ARS Distinguished Scientist of the Year. In 2003, he received the Department of Agriculture’s Plow Honor Award for Maintaining and Enhancing the Nation’s Natural Resources and Environment.

Tom has made fundamental contributions through the use of multisensor (specifically in the microwave region) satellite data that have greatly enhanced distributed land surface hydrological modeling of water and energy fluxes. Dr. Jackson was the first scientist to develop a method for removing the effects of the vegetation layer from microwave remote sensing measurements, which allows the estimation of the underlying soil moisture. Dr. Jackson’s research and the techniques he developed solved one of the most significant problems blocking the widespread application of remote sensing to soil moisture studies. Specifically, the papers by T. J. Jackson, T. J. Schmugge, and J. R. Wang: Passive microwave sensing of soil moisture under vegetation canopies (Water Resources Research, 18(4), 1137-1142, 1982) and T. J. Jackson and T. J. Schmugge: Vegetation effects on the microwave emission of soils (Remote Sensing of Environment, 36, 203-212, 1991) are widely cited as methodology to remove the effects of vegetation canopy from remote sensing data.

Dr. Jackson was the first to demonstrate that surface soil moisture retrieval algorithms based on remotely sensed microwave observations developed and verified at high spatial resolution can be applied at coarser resolutions over large regions. This was accomplished within a broad experiment, the Southern Great Plains 1997 Hydrology Experiment (SGP97). SGP97 successfully demonstrated the ability to map and monitor soil moisture using low-frequency microwave radiometers. Conclusions supported a satellite-based implementation. These results elevated the importance of soil moisture measurement within NASA’s Earth Science Program and were recently cited by the Associate Administrator as a major achievement. As a result, NASA has given a soil moisture mission the highest priority for the next decade. Dr. Jackson’s leadership of SGP97 has resulted in one of the most comprehensive observing programs in the world.

Soil moisture forms an important basis for agriculture (planting, harvesting, and irrigation scheduling of crops), meteorology (development and evolution of the boundary layer), and natural hazards (floods, droughts, and landslides). Spatially distributed hydrological modeling has been hampered in the past by the absence of spatially distributed hydrological data for validation of these models. The advent of microwave remote sensing and the retrieval of spatially distributed soil moisture using Dr. Jackson’s algorithms provide us with the means of applications to various scientific problems.

He is indeed one of the few scientists to bridge the new areas of technology to hydrological modeling. I cannot think of another person who has made such an impact on land surface hydrology. Indeed, his contribution to scientific research and the community, especially over the past 5 years, through the organization and execution of the field experiments is monumental. This is evident by the 100+ scientists, faculty and graduate students who have participated in SGP97, SGP99, SMEX02, SMEX03, and the forthcoming SMEX04. The number of research theses and publications that have been spawned from these endeavors are a tribute to Tom’s vision, dedication, and persistence. On a personal note, Tom is one whose activities have a diverse spectrum; that is, he has made time in his busy schedules to mentor many a student and at the same time he has never turned away anyone who has come to him for scientific advice or with a request to participate in one of his many field experiments. I many times have been a beneficiary of his advice.

Venkat Lakshmi, University of South Carolina, Columbia


Thank you, Venkat, for your very kind interpretation of my recent research career. Thank you, President Smith, and the members of the Hydrology Award Committee for honoring me with your selection. Having been involved in the supporting side of the awards process, I also want to thank those individuals who took the time to write the very important supporting letters.

The honor of this award is two-fold. First is the recognition by your peers, and second is joining the list of distinguished hydrologists who have preceded me. A number of these individuals are here this evening.

I attribute whatever success I have had in my research career to at least three factors: the right path, the right job, and a network of colleagues and friends. The right path I owe to my advisor Bob Ragan, who steered me away from environmental engineering and into the then emerging research area of remote sensing. I began my Ph.D. work the same year that Landsat-1 or, as we called it then, ERTS-1, was launched.

As to the right job, the Agricultural Research Service and in particular the Hydrology and Remote Sensing Lab has been a good home. I’ve been given freedom to pursue my ideas and the time to address problems that required long-term efforts, which has been necessary for soil moisture remote sensing. Although the times are changing, one of the greatest benefits of the ARS research organization was that for my early career I spent nearly all my time doing actual research.

My friends and colleagues include my long-time coworkers and collaborators at the Hydrology and Remote Sensing Lab: Walter Rawls, Bill Kustas, Ted Engman, and Jerry Ritchie. Of particular value to my research experience has been my association with my friend Tom Schmugge. He has spent much time tutoring me in microwave remote sensing.

Although many have strong opinions against working in the Washington, D.C. area, I can’t imagine a better place to do hydrologic remote sensing research. The ability to interact with other agencies such as NASA and NOAA without two days of travel is a unique advantage.

I have benefitted greatly from a long association with NASA. At the scientist level, Peggy O’Neill’s rigorous attention to detail and procedure contributed to the success of our early series of field experiments. More recently, I have been fortunate to work with two outstanding instrument scientists at NASA: David LeVine on synthetic aperture radiometry and Eni Njoku on the Advanced Microwave Scanning Radiometer (AMSR) and the HYDROS mission.

At the programmatic level, the Terrestrial Hydrology Program under the management of Ming Ying Wei, Dennis Lettenmaier and Eric Wood during their IPAs, Mike Jasinski and Paul Houser during their temporary assignment, and the current program manager Jared Entin has made possible the experiments we have conducted over the past few years. Another important partner in this work has been the Aqua AMSR Science and Validation Program.

The role of soil moisture within hydrology has changed since the late 1970s when I began my research in this area. There were few observational studies, and modeling often used soil moisture as an error term. At the same time, there seemed to be great potential but possibly insurmountable problems in using the new remote sensing technologies to provide a direct measurement of soil moisture. We were also very focused on the small-scale hydrology, which seemed incompatible with our measurement capabilities.

Things have changed over the years. Soil moisture is now a well-defined focus area in hydrology, there are now some solutions to major problems in remote sensing technology, there are several in situ soil moisture observing networks, and there is increased recognition of the importance of large-scale hydrology.

More significant changes are coming. In 2002, NASA launched the Aqua satellite with AMSR. This mission will for the first time attempt to provide a standard soil moisture product. We can expect that these capabilities will transfer to the next generation of operational satellites.

Even more exciting is that we will see two low-frequency (L-band) soil moisture missions within this decade. The European Space Agency will launch the Soil Moisture Ocean Salinity (SMOS) Mission in 2007, and NASA has just approved the Hydrospheric States (HYDROS) Mission in 2010. Both of these new satellites will offer remarkable new opportunities in hydrology, and each will explore a different technology path that may lead to future systems with even better spatial resolutions and capabilities. The research in this field is still on the rising side of the growth curve, and many opportunities exist for young scientists to contribute.

Another aspect of my research cited in this award is the series of large-scale soil moisture- field experiments we’ve conducted in recent years. These experiments have given me the opportunity to work with young scientists and graduate students. Some of these talented individuals have decided to focus on soil moisture related research as a result of the experience. It has been very rewarding to see the excellent theses and papers that have resulted.

One final thanks: My wife, Lynn, is not here this evening. She has always enjoyed accompanying me to the AGU Fall Meeting, but she had previously committed to a trip to Hawaii. She has put up with the peculiarities of my research for many years, in particular, my abandoning her for a month every summer for these field campaigns.

Once again, thank you very much for the honor of this year’s Hydrology Award.

Thomas J. Jackson, U.S. Department of Agriculture, Beltsville