Great Lakes Environmental Research Laboratory (GLERL) CLIMATE CHANGE AND VARIABILITY Program 1996/1997 Update

The Great Lakes region is an excellent location for climate change research because of the existence of both physical and biological/chemical measurable signals, the existence of long­term records, ongoing physical process studies, and the importance of resources (a multibillion dollar sport and commercial fishery, fresh drinking water for a large segment of the US population, a multibillion dollar commercial transportation waterway, etc.). Large lakes, including the Laurentian Great Lakes, are "closed systems" with boundaries on spatial scales that make them more tractable for study than the oceans. Many of the environmental conditions and processes related to climate that make oceanic systems important for studying climate change and variability are also present in the Great Lakes and can be studied with smaller logistical budgets.

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Project Index

• Effect of Climate Change on Lake Ice
  
  
• Improved Great Lakes Ice Climatology
  
  
• Great Lakes Water Level Statistics
  
  
• Great Lakes - St. Lawrence Basin Project on Climate Change and Variability
  
  
• Thermal Structure Monitoring for Climate Change

ERL Research Task: GLERL 11 ­ Climate Variability

GLERL conducts studies under this Research Task to improve our knowledge and understanding of the interactions among climate, socio-economic frameworks, and the ecosystem within the Great Lakes basin and midwest United States, in order to plan and develop regional strategies for adapting to climate change and variability. This research involves analyzing and modeling climate variables over the last 100 years to identify implications for water resources, ice cover, ecosystem health, and Great Lakes water levels.

Principal Investigator: Raymond Assel (734-741-2268; ray.assel@noaa.gov)

Collaborating Scientists: S. Rodinov (University of Colorado); J. Magnuson (University of Wisconsin); D. Robertson (USGS); L. Herche, D. Norton (GLERL).

The duration and extent of ice cover on the Great Lakes have a major impact on the economy of the region by impeding commercial navigation, interfering with hydropower production and cooling water intakes, and damaging shoreline structures. The ice cover also has an impact on the water balance of the lake, by affecting lake evaporation and other heat and momentum transfers, and on the biology and chemistry of the lakes, which are affected by the length and extent of ice cover. The significance of reduced ice cover on the biota of the Laurentian Great Lakes include: greater over­winter mortality of whitefish eggs (and thus potentially lower year class size), lower diatom production, both due to loss of the stable environment afforded by formation of a continuous ice cover, and perhaps a temporal displacement of both physical and biological processes in the Great Lakes, such as the recurrent springtime plume in southern Lake Michigan and associated offshore and long-shore sediment transport and increased biological activity within the plume.

Climate change associated with global warming will possibly affect the ice cover, which in turn will affect other physical, chemical, and biological processes. Objectives of this project include (1) development of improved models of ice cover for analysis of impact of global warming on ice cover regime and perhaps for development of improved ice cover forecasting techniques, (2) identification of anomalous winters for contemporary ice cycles, and (3) analysis of historical ice cover and ice cover related information for trends and variations in ice cover extent, ice-on dates, ice-off dates, and other ice characteristics that will be useful in placing the ice cover beyond the 1990s in historical perspective.

FY96 Progress and Accomplishments

A review of previously published studies on Great Lakes ice cover trends and implications of global warming over the past 170 years in bays and harbors of the Great Lakes was made as part of a study on changes in the global cryosphere and its impacts and included in the 1995 IPCC report. Ten-year moving averages and cumulative z-scores were used to analyze changes in mean ice cover since 1851 at Grand Traverse Bay and Lake Mendota in a previous study. Average freeze-up dates became 8 to 12 days later and average ice-loss dates became 7 to 11 days earlier from the 1850s to 1890. Average freeze-up date remained relatively steady after 1890 but average ice-loss dates again shifted toward earlier dates between 1940-1993 at Grand Traverse Bay (8 days earlier) and between 1980-1993 at Lake Mendota (7 days earlier). The timing of freeze-up and break-up at the two locations represents an integration of air temperatures over slightly different seasons (months). Thus, the second shift to earlier ice-loss dates at Grand Traverse Bay is associated with a trend toward warmer March temperatures starting in the 1940s and the second shift in Lake Mendota's average ice-loss dates is associated with a warming of average January through March temperature starting in the 1980s. Freeze-up and ice-loss dates for bays of the Great Lakes and for inland lakes in that region correlate with autumn and winter air temperatures. A 1.5 degree C rise in late-autumn-to-mid-winter air temperature and about a 2.5 degree C rise in mid-winter-to-early spring temperatures between 1851 and 1993 are associated with approximately a 10 day retreat (later) in average freeze-up dates and about a 17-day advance (earlier) in average ice-loss date, respectively. The sensitivity of both freeze-up and break-up for sites with long-term records in the Great Lakes averages approximately 7 days per degree C. Continued warming at a rate similar to that of the 1980s will likely result in a new norm in ice covers, similar to the extremely mild 1983 ice season in which mid-lake ice cover did not form and ice duration was much less than the current normal. Under this milder climate, complete freezing will become increasingly infrequent for the larger and deeper embayments in the Great Lakes, winters without freeze-up will begin to occur at small inland lakes in the region, and the duration of the ice cover will decrease as freeze-up dates become later and ice-loss dates become earlier. Winter lake evaporation may also increase due to the decreased ice cover.

Changes in the annual maximum ice cover of the Great Lakes over the 28 winters 1963-1990 were identified, as were hemispheric circulation patterns and teleconnections associated with these changes and with the extreme winters (highest and lowest quartile ice cover winters). Models of Great Lakes ice formation on monthly to seasonal to interannual time scales have application to regional climate and climate change models, lake ecosystem models, lake hydrology models, and navigation and hydropower related operational activities. Analysis of a 28 winter record of annual maximal Great Lakes ice cover reveals: a low (1964-1976), a high (1977-1982), and once again a low (1983-1990) ice cover regime. The high ice cover regime corresponded with a hiatus in El Nino Southern Oscillation events and the beginning of a interdecadal change in Northern Hemisphere atmospheric circulation that started in the late 1970s. About 46% of the lowest quartile maximum ice covers occurred during year +1 winter of warm ENSO events. Anomaly maps of 700 hPa geopotential height for the lowest quartile ice cover reveal a zonal flow pattern and anomaly maps of 700 hPa geopotential height for highest quartile ice cover winters portray a meridional flow pattern with circulation from the Polar and Arctic regions directed toward the Great Lakes. The difference map between high and low quartile ice cover is similar to the 700 hPa difference map between composite maps of high and low Pacific North American teleconnection indices, providing evidence of teleconnectivity for extremes in the annual Great Lakes ice cycle. Correlations between all 28 winters of annual maximum ice cover for individual lakes and 700 hPa geopotential heights at National Meteorological Center (NMC) grid points indicate teleconnections centers over: the Pacific Ocean, the west coast of North America, northern Mexico., eastern North America, north central Siberia, and western Europe and adjacent the North Atlantic Ocean.

A review of previously published studies on current ice climatology, ice trends over the past 140 years in bays and harbors, and models of mid-lake ice cover from 1900 to 1990 was made as part of a study on climate changes on aquatic systems. The findings indicate that if greenhouse warming occurs, changes in ice cover regime would likely impact the biota and the timing and magnitude of physical processes in the Great Lakes and inland lakes. The Great Lakes are inland seas. The timing of ice-on, ice-off, and ice concentration (percentage of lake area covered by ice) for smaller inland lakes in the region is comparable to protected shallow nearshore zones of the Great Lakes but not to the deeper and larger mid-lake areas. Ice forms later and is more dynamic in mid-lake areas due to their greater thermal inertia and longer wind fetch. Ice usually forms in shallow bays and over most of Lake Erie, because it is shallow, in December and January. Ice forms in the deeper embayments and in mid-lake areas in February, reaches it annual maximum extent in February or March, and is usually lost by the end of April. The Great Lakes do not freeze-over completely because of their large heat storage capacity and the action of winds. During mild winters mid-lake areas remain relatively ice free, during severe winters ice forms two to three weeks earlier than usual and ice extent can approach 100% coverage. Air temperature models indicate that the decadal averages of maximum ice cover was about 61% during the decades from 1900 ­ 1920, decreased to about 50% during the decades between 1930 and 1960, then increased over the next two decades [1970s (61%) and 1980s (64%)] before declining again [1990s (55%)]. These trends are in agreement with ice cover models developed for lakes Erie and Superior that show decadal average February ice cover was about 10­25% greater during the first quarter of this century (1900­1925) and from 1960 to 1983, than it was in the intervening years (1926­1959). Recent average February ice cover is approximately 90% and 56% for lakes Erie and Superior, respectively. Simulations of ice phenologies on the Great Lakes made for lakes Erie and Superior over a 30 year base period (1951-1980) for a single 1xCO₂ scenario and for three GCM (GFDL, GISS, and OSU) 2xCO₂ suggest ice cover formed every year for Lake Superior and for 29 of the 30 years for Lake Erie under the 1xCO₂ scenario. Under the 2xCO₂ scenarios, lakes Erie and Superior, respectively, had ice free winters for 17% and 43% of the GFDL scenarios, 10% and 3% of the GISS scenarios and 7% to 0% of the OSU scenarios. Ice duration was reduced by 5 to 13 weeks under the three 2xCO₂ scenarios and mid-lake areas of the Great Lakes were ice free most of the2xCO₂ winters. Average ice cover duration for the 1951-80 base period ranged from 13 to 16 weeks.

An analysis of winter weather and ice conditions resulting in the below average Great Lakes ice cover during the winter of 1994/95 was not undertaken due to higher priority research activities.

FY97 Plans

• Document and present results of the Great Lakes ice cover teleconnection study.
• Participate in University of WI. sponsored International Workshop on Lake Ice and Climate.
• Analyze long-term (>100 yr ) ice-on/-off dates (Northern Hemisphere lakes) to identify trends.

Improved Great Lakes Ice Climatology

Principal Investigator: Ray Assel (734-741-2268; ray.assel@noaa.gov)

Collaborating Scientists: D. Benner (NOAA/NESDIS/National Ice Center); W. Lumsden (Canadian Ice Services); F. Fetterer (National Snow and Ice Data Center); D. Norton, L. Herche (GLERL); P. Trimble (CILER).

Historic Great Lakes ice charts from 1980 to 1994 are being digitized (under the Earth System and Data Information Management Program) to create a high quality computer accessible database of Great Lakes ice cover. These data will first be used to update the NOAA Great Lakes Ice Atlas. The data and updated climatology will then be made available to the National Ice Center and Canadian Ice Service for operational use. The data will also be used in other GLERL projects to develop and calibrate ice cover models for lake hydrology, Great Lakes forecasting system, and winter ecosystem applications. At the completion of this project the data and climatology will be archived and made available to the public at large through the National Snow and Ice Data Center.

FY96 Accomplishments

Quality control vector files of the ice charts were completed using ARC/INFO GIS software.

Federal agencies with interests in Great Lakes ice cover were briefed about progress on this project at the Nov. 95 meeting of the International Great Lakes ­St. Lawrence Ice Information Work Group meeting (held at NWS Cleveland) and at the May 96 meeting of the Canada/United States Joint Ice Working Group, (held at the U.S. Coast Guard Academy, New London CT).

FY97 Plans

• Convert ice chart computer polygon files to geo-referenced grids and quality control grids to prepare these data for analysis.
• Begin development of methods for analysis of computer ice cover grids data for use in Great Lakes Ice Atlas update.

Great Lakes Water Level Statistics

Principal Investigator: Frank Quinn

Collaborating Scientists: Brooks Widder (NOAA/NOS)

Extreme Great Lakes water levels (both high and low) periodically cause major social, economic and ecosystem disruption throughout the Great Lakes system. Reliable lake level frequency distributions are a critical component of any comprehensive strategy for coping with lake level fluctuations. Historical records of monthly lake levels reflect secular changes in connecting channel hydraulics, watershed hydrologic response, and climate. The objective of this research is to develop improved water level statistics that reflect l) existing hydrologic and hydraulic conditions, 2) the long lag-response of the lakes to meteorologic variability, 3) secular changes due to changing climatic regimes, and 4) the needs (e.g., varied planning horizons, understanding the limits of lake level statistics) of diverse Great Lakes decision makers.

FY96 Progress and Accomplishments

A method for assessing risk in operational decisions using Great Lakes probabilistic water level forecasts, adapted from the National Weather Service's Extended Streamflow Prediction technique, was applied retrospectively to three Great Lakes case studies to show how risk assessment using probabilistic monthly water level forecasts could have contributed to the decision-making process. The first case study examined the 1985 International Joint Commission (IJC) decision to store water in Lake Superior to reduce high levels on the downstream lakes. Probabilistic forecasts were generated for Lake Superior and Lakes Michigan-Huron and used with riparian inundation value functions to assess the relative impacts of the IJC's decision on riparian interests for both lakes. The second case study evaluated the risk of flooding at Milwaukee, Wisconsin, and the need to implement flood control projects if Lake Michigan levels were to continue to rise above the October 1986 record. The third case study quantified the risks of impaired municipal water works operation during the 1964-1965 period of extreme low water levels on Lakes Huron, St. Clair, Erie, and Ontario. This study concluded that if risk assessment had been used in each of these cases, different decisions resulting in cost savings may have been realized. Improvements to the technique and other potential applications were also presented. The results of the study are being documented for publication.

Lake St. Clair is a major component of the Great Lakes System. Its aquatic and coastal ecosystems, as well as riparian uses, have evolved based upon the historical range in water levels and the well developed seasonal cycle. Thus, changes in the seasonal range in water levels as well as the seasonal timing could have both environmental and economic impacts. A well defined and quality controlled monthly water level data base for Lake St. Clair is available from 1900 through the present. This data set was used to examine the timing and range of the seasonal cycle from 1900 through 1992. In general the seasonal cycle usually has a minimum in the winter due to increased lake evaporation and a maximum in the early summer driven by snowmelt runoff. The analysis shows major changes in the seasonal maximum, the seasonal minimum and the seasonal range for Lake St. Clair. The seasonal range has decreased by about 50 percent, from 0.6 m to 0.3 m, and the seasonal variability by about 15 percent between the first three and the last three decades of the study. The primary cause of these changes appears to be due to dredging the Cutoff Channel in the St. Clair River Delta and increased icebreaking by the Coast Guard which has lead to less ice jams in the St. Clair River.

FY97 Plans

• A study of secular changes in the seasonal cycle of the Great Lakes from 1860 through the present will be completed to assess possible changes in seasonal water levels due to changing climatic regimes.

Improved Great Lakes - St. Lawrence Basin Project on Climate Change and Variability

Principal Investigator: Frank Quinn

Collaborating Scientists: John Kangas (Corps of Engineers); Linda Mortsch (Environment Canada); Michael Donahue (Great Lakes Commission), Dennis Heydenek (Dow Chemical); William Bolhofer (NOAA/NWS); Norman Granneman (USGS), Michel Slivitzky (Institut nationale de le recherche scientifique-Eau).

The goal of the GLSLB Project is to improve our understanding of the complex interactions between climate variability and change, the environment, and social and economic systems so that informed regional adaptation responses can be developed for the sustainable management of the Basin.

FY96 Progress and Accomplishments

A special session was also held at the 1996 Great Lakes Research Conference (International Association for Great Lakes Research) in Toronto documenting studies supported by the Project.

Planning was undertaken for a major international symposium to document the Project, to be held in Toronto, Ontario in May 1997.

Products

Mortsch, L.A., and F.H. QUINN, 1996. Climate Change Scenarios for Great Lakes Basin Ecosystem Studies. Limnology and Oceanography, 41(5):903-911

FY97 Plans

• Complete a paper on the impact of the GLERL climate transpositions on Great Lakes water levels and flows to define potential climate impacts on water resources.
• Publish a paper on the potential impacts of the transposed Mississippi Flood on Great Lakes water levels and flows to define potential climate impacts on water resources.
• To cosponsor a major binational climate symposium on "Adapting to the Impacts of Climate Variability and Change in the Great lakes-St. Lawrence Basin" in Toronto, Canada.

Thermal Structure Monitoring for Climate Change

Principal Investigator: Michael McCormick (734-741-2277; Mike.McCormick@noaa.gov)

Collaborating Scientists: W. Schertzer (National Water Research Institute, Canada)

The main objectives of this project are (1) to develop improved climatological information by means of observations, new instrumentation, and improved analyses of the distribution and variability of coastal and offshore temperatures and by studying their dependence on meteorological and hydrological forces, with emphasis on potential changes in climate, and (2) to concurrently provide data for improving numerical models that can simulate and predict the thermal structure in the lakes.

FY96 Progress and Accomplishments

A successful test of an integrated thermistor chain/VACM mooring was completed. The new mooring system integrates into one mooring what previously required two separate moorings. It also provides for higher data returns by having each thermistor posses its own data logger. Also, the single mooring system allows for higher accuracy in determining the relative location of each sensor. This is particularly critical for tracking storm induced mixing events.

All thermistor data from this site has been archived, in addition all VACM data has been translated into a readable format and archived.

Water intake temperature data from 8 Great Lakes sites have been documented in NOAA Technical Memoranda and will be made available on the GLERL web site for a wide variety of research and engineering applications.

FY97 Plans

• Procure and prepare an additional set of thermistors and data loggers for the offshore monitoring site in order to maintain long-term data gathering reliability.
• Retrieve the mid-lake subsurface VACM and thermistor chain mooring in late spring. Two new moorings will be deployed at that time with one of them being a surface thermistor chain mooring. The surface mooring will be retrieved in late fall.
• Document the long-term water intake temperature data set.

Last updated: September 10, 2002 mbl

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