Overview

Selected Sources Regarding the Great Salt Lake

Physiography and Variations in Lake Level

The Stansbury expedition of 1850

Chemistry of the Great Salt Lake

Biology of the Great Salt Lake

Thermodynamics of the Great Salt Lake Current Monitoring Over the Great Salt Lake

Future Monitoring of the Great Salt Lake

AVHRR Lake Temperature:

Selected Sources on the Great Salt Lake

The Great Salt Lake. U.S. Geological Survey

Commonly Asked Questions About Utah's Great Salt Lake. Utah Geological Survey

The Greater Salt Lake Ecosystem. Westminster University

Great Salt Lake Planning Project. State Department of Natural Resources

The Great Salt Lake.Dale Morgan. 1947. University of Nebraska Press. Lincoln Nebraska. 432 pp.

Great Salt Lake. A Scientific Historical and Economic Overview. Edited by J. Wallace Gwynn. 1980. Utah Geological and Mineral Survey. 400 pp.

Physiography and Variations in Lake Level

Great Salt Lake from USGS

Terminal basin of the Great Salt Lake includes the Provo, Weber, and Bear River drainages

Present elevation of the Great Salt Lake is 4202 feet (1281 m)

16,000 years ago, Lake Bonneville's elevation was approximately 5100 feet ( 1550 m)

During past 10,000 years, lake has fluctuated between 4240 feet and 4180 feet

During historical record, lake has fluctuated between 4212 feet (1985) and 4192 feet (1964) (USGS)

The Stansbury Expedition of 1849-50

First detailed weather observations on the Great Salt Lake

Captain Howard Stansbury was instructed by the Army to conduct a mile-by-mile survey of the Great Salt Lake and adjacent regions

Other participants:

• second-in-command John Gunnison
• crew forman Albert Carrington

Examples of weather observations on the Great Salt Lake:

• May 1. Sunrise 57F, cirrus. Noon 71F cirrus. 3 PM 69F cloudy. Sunset 63F calm
• April 16. About 4 oclock a violent gale came up accompanied by thunder and lightning from the west which instantly prostrated most of our tents and a copious fall of hail mingled with rain which wetted the party to the skin.
• May 8. Gunnison Island. We set out at 5 oclock on our return. When within 3 or 4 miles of camp a most furious gale of wind broke down upon us from the NW, which soon raised such a sea as to render the progress of our heavy boat so slow that we did not reach camp until 10 clock, cold tired & hungry.

Reference: Exploring the Great Salt Lake: the Stansbury Expedition of 1849-50. Edited by Brigham D. Madsen. University of Utah Press. 1989. 889 pp.

Other notable surveys: Grove Karl Gilbert. 1887-80. U. S. Geological Survey.

Chemistry of the Great Salt Lake

Much of the salt in the Great Salt Lake was originally suspended in Lake Bonneville while some dissolved salts flow into the lake each year

Prior to the completion of the causeway in 1959, the Great Salt Lake was a relatively homogeneous saline lake

Now, even with larger openings in causeway created in 1984, Gunnison Bay (north arm) is quite different from Gilbert Bay (south arm). See the accompanying table.

U.S.G.S. samples lake monthly

When differences in height of Bays are large, head drives surface flow of lighter water near surface into North Arm through gaps

When differences in salinity of Bays are large, deep flow of saltier water flows from North Arm into South Arm through permeable causeway

Small (1 foot) difference in height now; surface flow through causeway is from north to south as a result of density differences

During winter (prior to record lake levels), mirabilite (sodium-sulfate compound) precipitates out in the North Arm. As water warms, layer of mirabilite goes back into solution and forms sulfur-rich layer near bottom that persists and may flow into South Arm

During summer, sodium chloride precipitates on floor and will remain on floor until salinity decreases significantly

Strong wind storms may cause hydrogen-sulfide rich bottom layers to be mixed to surface and contribute to "Lake Stink" as well as expose decomposing sulfur-rich mud flats

Biology of the Great Salt Lake

Surface layer

• Algae blooms during winter
• Brine shrimp hatch from hard-walled eggs (cysts) in April and graze phytoplankton
• Shrimp grow and reproduce during summer molting in as many as 12 different stages
• When shrimp stressed by lack of food or environmental conditions, they switch from producing live young to cysts
• Cysts harvested commercially during Fall and persist in a semi-dehydrated state until the salinity decreases in spring
• No live brine shrimp survive temperature below 5C (42F)

Bottom layer

• During spring, shrimp consume enough phytoplankton for light to penetrate to depths
• Photosynthesis by algae in bottom layer provides source of food as well as detritus falling from surface water
• Two species of brine fly spend larval period on bottom of lake
• Flies emerge as adults in early summer
• 110 billion flies plus 10 billion pupae are estimated to hover over 300 miles of beaches (370 million flies per mile of beach)
• Flies consume algae and waste equivalent to a 78,000,000 gallon per day waste treatment plant

Thermodynamics of the Great Salt Lake

Annually averaged vertical profile of temperature indicates that North Arm is warmer near the surface and cooler at depth than the South Arm (source: unpublished summaries provided by W. Gwynn, Utah Geological Survey)

Annual cycle in temperature of the South Arm (source: unpublished summaries provided by W. Gwynn, Utah Geological Survey) indicates:

• Surface temperature varies from 33.9 F in January to 79.3F in July
• Top 20 feet fairly well mixed during year
• Thermocline (warm water above cold depths) evident at 25-30 feet from April-August while higher temperatures at depth from October-February
• Warmer water at depth is possible, since salinity increases slightly with depth (density more sensitive to salinity than temperature)

Implications for the atmosphere of thermodynamic structure:

• Strong winds and upwelling bring colder water to surface from April-August
• Strong winds and upwelling bring warmer water to surface from October-February
• lake-effect snowstorms may be more persistent during Fall-early Winter than late Winter-Spring since strong winds in post-frontal environment do not cool off lake significantly

Current Monitoring over the Great Salt Lake

Utah Mesonet

• Project began during 1994 in cooperation with National Weather Service
• On-line information: University of Utah
• Surface observations obtained from local, state, and federal agencies and private firms
• Data retrieved, processed, and displayed every 15 minutes
• Goals:
  • provide access to weather information in a timely fashion for operational decision makers and the public
  • archive and utilize weather data for research and education related to understanding weather phenomena in the intermountain region
• Unique Aspects of the Utah Mesonet
  • Relies on local, state, and federal agencies and private firms to provide most of observations; limited number of stations deployed to fill data voids
  • Cooperating agenices bear the cost of installing, maintaining, and upgrading equipment and communication costs for the most part
  • Surface observations are combined with other observations to provide a 3-dimensional analysis of the atmosphere for a limited domain of northwestern Utah

Applications of the Utah Mesonet: Utah ARPS Data Analysis System (ADAS)

• Local analysis at high temporal (1 h) and spatial resolution ( 1 km)
• On-line Information: ADAS
• Provide near real-time high resolution data over the complex terrain of northwes t Utah
• Based on the Oklahoma ADAS (ARPS Data Analysis System) developed by the Center for Analysis and Prediction of Storms (CAPS)
• Incorporation of large-scale and local data:
  • Rapid Update Cycle Version 2 (RUC2) analysis used to initialize ADAS
  • Utah Mesonet available at 15 minute intervals
  • NWS rawinsonde provides upper air data at 0 and 12 GMT
  • NWS WSR-88D velocity and reflectivity data obtained at 5-10 minute intervals (NIDS products)
  • Visible and IR Satellite imagery used to specify cloud water
• Continued Development of ADAS:
  • Incorporate other data sources:
    • Dugway profiler
    • ACAR ascents and descents
    • FAA terminal doppler radar
    • Level-2 radar data from KMTX
    • GOES sounding information
  • Use ADAS to initialize the Advanced Regional Prediction System (ARPS) to provide high resolution forecasts of mesoscale events.

Physical Linkages Between the Great Salt Lake and the Atmosphere

• Moisture flux
• Sensible heat flux
• Stability
• Surface roughness

Examples of Current Monitoring and Analysis over the Great Salt Lake

• Mesonet stations near the Great Salt Lake
  • Many stations on the periphery including several each in Tooele, Salt Lake, and Weber Counties
  • Antelope Island (Department of Air Quality)
  • Gunnison Island in North Arm (Department of Wildlife Resources). Installed 5/22/98
  • Hat Island in South Arm (Department of Wildlife Resources). Installed 9/2/98
• Daily lake temperature at Hat Island
• Lake (top), Air (middle) and dewpoint (bottom) temperature at Hat Island. October 2-20 98
• Latent Heat Flux (red) and Sensible Heat Flux (black) at Hat Island. October 2-20 98. (in w/m2)
• ADAS surface analyses
  • October 98 Mean Surface Wind and Surface Temperature
  • October 98 Mean Surface Wind and Surface Temperature at 00 GMT (Daily average removed)
  • October 98 Mean Surface Wind and Surface Temperature at 12 GMT (Daily average removed)
• Shallow Front over Great Salt Lake
  • Hat Island: July 3-4 99. Note increase in temperature as "warm" front moves north of Hat
  • Gunnison Island: July 3-4 99. Note how surge of warm air penetrated only briefly to the north of Gunnison Island.
  • Locomotive Springs: July 3-4 99. Note decrease in temperature as shallow pool of cool air moves south of Locomotive Springs
  • Plan View: July 4 2Z 99. Note baroclinic zone between Hat Island and Locomotive Springs.

Future Monitoring of the Great Salt Lake

Weather support for 2002 Winter Olympics requires high-resolution numerical guidance

Lake remains large data void in northwestern Utah

Considerable need to have reliable measure of lake temperature in open water forinitialization of forecast models

Lake temperature sensor placed off Hat Island was expected to be temporary and communication to sensor is beginning to fail

Collaborative project underway with Woods Hole Oceanographic Institution and State Department of Wildlife Resources to place buoy on the lake

Parameters to be measured and available every hour:

• Surface air temperature
• Total solar radiation
• Surface lake temperature
• Lake temperature at 3, 5, and 7 m depth
• Photosynthetically Active Radiation (PAR)
• Chlorophyll
• Turbidity

Interested in developing collaborative relationships with other researchers to study the Great Salt Lake