by John Lewis and Susan Cobb

In his colorful history of the American West, Bernard DeVoto gives us a splendid picture of that land between the Front Range of the Rockies and the Pacific Ocean through the eyes of the mountain man Jim Clyman (see inset). About 50 years later, Marc Reisner gave us Cadillac Desert: The American West and its Disappearing Water. The message resonates deep inside--if we don't begin to manage our water resources, the American West-- and indeed the entire nation-- will fall into a calamitous state that will undermine our quality of life.

The scientific strengths of NSSL and DRI will be combined in an effort to combat this problematical aspect of our nation's well being.

Through this collaboration, DRI, in Reno, Nevada, with its multifaceted approach to understanding the broad issues of water, is planning to broaden its approach to regional climate. NSSL will benefit by being able to expand research opportunities in water-related issues. NSSL and DRI's partnership has already been established in Reno through efforts to enhance precipitation estimates using NSSL's WDSS, located in the Reno NWSFO.

The initial phase of the formal NSSL/DRI collaboration involves the assignment and relocation of NSSL scientist John Lewis. Lewis says, "I hope to be a catalyst that will bring NSSL's scientific strength to bear on these issues of water."

Lewis has spent the past 10 years working on moisture return to the U.S. from its southern flank, the Gulf of Mexico. He will continue this work but will gradually focus on the study of moisture along the country's western flank. His major thrust at the present is using deterministic models to understand the sensitivity of model output (in particular the moisture field) to the initial and boundary conditions. This work has been done in collaboration with scientists at NCAR over the past four years.

Other NSSL scientists have already expressed interest in the DRI/NSSL collaboration. Alexander Ryzhkov and Dusan Zrnic have pioneered efforts using a polarized Doppler radar to improve the estimation of rainfall amounts. They feel polarimetric radar could improve rainfall estimation in the mountains because "unbiased measurements of precipitation can be performed even in the presence of severe beam blockage," Ryzhkov says. Also, conventional radar has problems with ground clutter and anomalous propagation (AP) due to the complex terrain. "Polarimetric radar has very promising capability to identify the areas contaminated with ground clutter and AP. Moreover, rain measurements are possible if weather and ground clutter echoes are superimposed." Zrnic adds, "measurement of snow is also important in the Sierra Nevada mountains. Radar polarimetry might lead to better estimates of the type and amount of snowfall. Discrimination between rain and snow has been proven and it remains to be seen if quantitative estimation of snow amounts can be reliably obtained."

Another NSSL employee, J.J. Gourley is focussing his thesis work on exploring ways to improve precipitation estimates in mountainous terrain. Since intervening mountains often shield regions from being adequately sampled by radar, he is utilizing a "multi-sensor" approach. Gourley is obtaining the vertical structures of storms where there is good radar coverage. This information is then combined with satellite imagery and radar data from nearby WSR-88D's to improve the precipitation estimates, and feels that his work is compatible with the goals of DRI.

John Lewis spent the month of July (1998) at DRI and said, "DRI is a vital organization of scientists with strong leadership in the person of Dr. Peter Barber, head of the Atmospheric Science Center and Acting Director of DRI. The DRI scientists are anxious to learn more about NSSL and hopefully there will be exchanges of scientists in both directions."

For more information contact John Lewis at: jlewis@dri.edu