About the PTAAGMB Project

The PTAA-GMB project seeks to calculate the historical and current mass balances of 200 glaciers to determine the cause of their rapid and unprecedented decline during the past 3-5 decades. Many of the world's large glaciers are now thinning at a rate of over one meter per year, and a number of small glaciers have disappeared entirely.  The wastage of these glaciers is raising sea level at a record rate and altering the timing of seasonal water supplies of nearly two billion people.

The mass balances will be displayed in both graphical and tabular formats and eventually shown in near real-time, depending on the availability of daily weather observations.

The PTAA model is used to calculate the daily and annual balances of these glaciers by application of precipitation and temperature observations at established weather stations to the unique area-altitude distribution (its AA profile) of each glacier's surface.

The model relies on the glacier's response to the historical climate that has produced its current AA profile by glacier flow and bedrock erosion.  Therefore, each glacier's climate history is embedded in its AA profile and responds to the current climate by producing a compatible mass balance. 

The PTAA-GMB project also seeks to establish a worldwide glacier monitoring system that will track daily mass balance changes in each of the 200 glaciers using the algorithms developed and meteorological data collected for the project.

A long-term goal is to understand and explain the physical mechanisms that can produce the daily and annual mass balance of a glacier using only meteorological observations from nearby weather stations and the area-altitude distribution of a glacier's surface.

The daily and annual mass balances collected for 200 glaciers using the same standardized model for each glacier is essential for accomplishing this goal.

One outcome of analyzing mass balances of 200 glaciers simultaneously may be detection of unusual climate perturbations that are causing the current glacier decline.  Glaciers and a large proportion of Earth's human population have co-existed for at least the last 50,000 years.  Both have endured climate extremes and as entities have survived.  Climate change now threatens both glaciers and humans.

Of the approximate 160,000 glaciers in the world, two hundred (about 0.12%) will be selected, primarily on the basis of data availability.  The PTAA-GMB website contains a partial list of glaciers that will be monitored.

Completed glacier reports display the historical and current mass balance of the glacier.  Glaciers with records of manually measured balances will used for comparison with the PTAA model balances.


Principal, HyMet Inc.

Member: American Geophysical Society (AGU)
Member: Glaciological Society (GS)


The following are representative examples of projects for which I have had primary responsibility.

Hydrologic Forecasting Models

Designed, programmed and calibrated the following computer models over the past 20 years:

*    Seasonal forecasting model for the Columbia River at The Dalles, Oregon, Grand Coulee Dam and Ice Harbor Dam, Washington (1991-92), for the Bonneville Power Administration, Portland, Oregon).  Initially this model had proven to be significantly more accurate than other Columbia River forecasting models.  However, the NWS-NOAA recently developed an ESP model that seems to be invincible.

*    Seasonal forecasting model for the Kings River, California (1990, for California Department of Water Resources, Sacramento, CA)

*    Seasonal forecasting model for the Skokomish, Nisqually and Cowlitz Rivers, Washington.  (1987, for Tacoma City Light)

*    Short-term and seasonal forecasting model for the Baker River Hydro project.  (1986-87, for Puget Sound Power and Light)

*    Seasonal forecasting model for the Sultan River for operation of the Spada Lake reservoir.  (1987, for Snohomish Co. PUD)

*    Seasonal forecasting model for the enhancement of water quality and fisheries in the Green River, Washington.  (1986, for King County)

*    Seasonal forecasting model for the Salt and Verde Rivers in Arizona.  (1981, for the Salt River Project, Phoenix)

*    Seasonal forecasting model for the Deschutes River, Oregon.  (1979, for Portland General Electric, Portland)

 *  A hydrologic rainfall/runoff model to simulate the flow of the North Platte River, Nebraska for the State of Wyoming, Office of the Attorney General (1999).

The North Platte River in Wyoming and Nebraska was the subject of a lengthy interstate lawsuit in the 1930's and another lawsuit filed in 1986. In dispute were the impacts of water development activities on the flow of the river over the last 40-50 years with Nebraska making the charge that the reduced flow of the North Platte was due to excessive water-use in Wyoming. The study conducted by HyMet examined changes in streamflow and consumptive use for the 120-mile reach of the North Platte River between the Wyoming-Nebraska state-line and the gage at Lewellen, Nebraska over the period from 1953 to 1995.  The study determined that the decreased flow of the North Platte was caused by a significant increase in irrigation acreage and groundwater pumping in Nebraska. Shortly after this report was published on the HyMet website in 1999, the $250 million lawsuit was settled out of court.  The state of Wyoming had already spent $40 million in defense from the lawsuit so this report undoubtedly saved them millions of dollars.

To read the North Platte report, see:  http://www.hymet.com/docs/plattitude2.pdf

International Activities

*    Organized a snow hydrology workshop for India's Central Water Commission for technology transfer of snowmelt forecasting.  (Manali, 1988, for Harza Engineers and US Agency for International Development)

*    Presented an invited paper on streamflow forecasting at the Hydropower '87 conference in Trondheim, Norway

*    Worked in Norway for six months with Norwegion Water and Electricity Board on problems associated with hydroelectric development in glacierized basins (Oslo, 1967).      

*    Developed a forecasting model and assisted in other aspects of hydrology for Sutluj River in the Himalyas, India, for Central Water Commission & Bhakra-Beas Management Board (New Delhi, 1988-89).

*    Participated in an evaluation and field survey of a Snow and Glacier Hydrology project in the Himalaya Mountains of Nepal for the German Technical Cooperation Agency (Langtang, March 1992).

Research, US Geological Survey, 1958-79

  • Performed hydrologic and glaciologic research in Cascade Mountains, Alaska and California.  Work included all aspects of hydrology and meteorology.  Much of the first ten years involved developing a glacier research program at South Cascade Glacier.  I designed new methods of measuring streamflow and precipitation that would operate under adverse conditions in remote regions.  From this work, I developed several new concepts  in glaciology that have been accepted by the international scientific community and published a number of professional papers on the results of this research. 


*    Determined water losses due to irrigation in the upper Rio Grande of Colorado and New Mexico, and made other hydrological analysis for the region.  (1981-82, for Bureau of Indian Affairs, Albuquerque)

*    Reconstructed the daily discharge and potential hydroelectric generation for a large number of streams in Washington and California for small hydro development and other purposes.  (1980-87, for Western Power, Puget Sound Power & Light, CH2M Hill, Pacific Lighting, others)

*    Constructed and operated gaging stations in the Cascade and Olympic Mountains of Washington. 
(1980 - 1995, for Mitex Inc, Boston, MA, Meridian Land & Mineral Co., Weatherly Securities, others)

*    Presented invited paper, A Time-Lapse Analysis Of Drought In North America, at the Oceans '89 conference held in Seattle, September 18-22, 1989.

*    Presented invited paper, Hidden Signals in the Washington State Climatic Records, at the Puget Sound Research '91 conference held in Seattle, January 4-5, 1991.

*    Reconstructed daily discharge of the Columbia River at Astoria and Pacific slope basins, for the 1931-90 period.  (1992, for Evans-Hamilton, Inc., Seattle, Wa.)

*   With Austin Post, developed IMP (Iceberg Monitoring Project) to document and analyze iceberg production of Columbia Glacier in Alaska to reduce  hazards  iceberg/oil tanker collisions  1995-1998 (the Exxon Valdez was attempting to avoid these icebergs when it went aground in 1989) 


B.SC., Geological Engineering,  University of Minnesota  (1958)


Superior Achievement award from Geological Survey for development of HM streamflow forecasting model (1979).



Tangborn, W. V., and Rassmussen, L. A., 1976 Hydrology of the North Cascades region, Washington: Part II A proposed hydrometeorological streamflow prediction method: Water Resources Research, v. 12, p. 203-216.

Tangborn, W.V., and Rassmussen, L.A., 1977, Application of a hydrometeorological streamflow prediction model to the South-Central Sierra Nevada of California: U.S. Geological Survey Research. p.33-48.

Tangborn, W.V., 1987, Forecasting Seasonal Runoff of the Baker River, North Cascades, Washington.  Invited paper: Hydropower 87, Trondheim, Norway.

Tangborn, W.V., 1988, Calculation of Snowpack Water Content and Snowcover Area. Paper presented at Workshop on Snow Hydrology, November 23-26, Manali, India.

Tangborn, W.V., 1989, A Time-Lapse Analysis Of Drought in North America, 1930-88.  Paper presented at Oceans '89, September 18-22, 1989, Seattle, Washington.

Tangborn, W.V. and Fountain, A.,1990, Effect of Area Distribution on Glacier Mass Balance - A Comparison of North and South Klawatii Glaciers, Washington State, USA, Annuals of Glaciology, 14.

Tangborn, W.V., Ebbesmeyer, C., LaChapelle, E., 1991, Hidden Signals in the Washington State Climate Record,  Presented at Puget Sound Research '91 Conference, January 4-5, 1991, Seattle, Washington.

Tangborn, W.V., 1999, A Mass Balance Model That uses Low-Altitude Meteorological Observations and the Area-Altitude Distribution of a Glacier, Geografiska Annaler 81A, (1999)  4.

Tangborn W.V. and Rana B., 2000, Mass balance and runoff of the partially debis-covered Langtang Glacier, Nepal.  Debris-covered Glaciers (Proceedings of a workshop held in Seattle, Washington USA, September 2000) IAHS publ. No.264, 2000

Tangborn, W.V. 2003, Winter Warming Indicated by Recent Temperature and Precipitation Anomalies, Polar Geography, 2003, 27, No. 4, pp320-338