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Site-Wide Glossary

This is the collection of glossary terms from all projects. New terms may be added via a project's glossary page.

Climate observations can be historical Time Series data for individual weather stations or, alternatively, the station observations can be used as an input to develop a gridded historical dataset or...
Time series data are continuous and sequential data for a give period of time and usually consist of equal intervals between data points.
The area of land including the lake and all areas from which runoff into the lake occurs. This can refer to the basin of the entire Great Lakes system or the basin of any one of the individual lakes.
 
Scientific Definition:
from Climate Prediction Center Climate Glossary
The Arctic Oscillation is a pattern in which atmospheric pressure at polar and middle latitudes fluctuates between negative...
Runoff in the Great Lakes basin consists of inflow to any of the Great Lakes from tributaries as well as any other water that flows over the land into the lakes.
Runoff is affected by meteorological...
Over-lake precipitation refers to precipitation that falls directly over the surface of the lakes. This has a direct effect on the levels of the lakes. If more precipitation falls, assuming no other...
Over-land precipitation is one of the factors contributing to runoff into the lakes. The amount of precipitation that falls can change the amount of runoff as well as the composition of the water...
Evapotranspiration is defined as the combination of evaporation and transpiration. Evapotranspiration from the land portion of the basin is a contributing factor for runoff into the lakes. Assuming...
Evaporation directly from a lake surface has a direct effect on water levels of the lakes. If nothing else changes, and evaporation increases, the levels of the lakes will decrease. If evaporation...
The NAO is a large-scale fluctuation in atmospheric pressure between the subtropical high pressure system located near the Azores in the Atlantic Ocean and the sub-polar low pressure system near...
The El Niño–Southern Oscillation affects the location of the jet stream, which alters rainfall patterns across the West, Midwest, the Southeast, and throughout the tropics. The shift in the jet...
The quantity of water flowing out of a lake through surface rivers or streams, measured in time units at a given point
The regulated release of water from Lake Superior is made through the various structures located on the St. Mary’s River. The allocation of flow to these facilities is determined monthly, based on...
Established by the International Joint Commission.  Among other objectives, the commission laid out the objectives for and limits to Lake Superior’s outflow.  Since 1978, the commission supplemented...
Constructed between 1913-1919 near the twin cities of Sault Saint Marie and Ontario by three hydropower plants and a 16 gate control structure.  Its purpose is to control Lake Superior outflow,...
See plans for the Great Lakes here
from EPA site:
A Lakewide Management Plan (LaMP) is a plan of action to assess, restore, protect and monitor the ecosystem health of a Great Lake.
It is used to...
Water withdrawn from the basin that is not returned due to evaporation or use in a process.
The rate at which a connecting channel carries water.
The transfer of water from one basin to another.
The act of removing sediment and debris from the bottom of a body of water.  This is often done to deepen passages for ships or for other environmental reasons.
Vaporization from the surface of a liquid.
A combination of evaporation and transpiration.
A buildup of ice at the outflow of a river that prevents flow of water.  These jams can cause flooding upstream.
The enlarging of large water basins due to movement of mantle material to fill previously glaciated areas.
Any form of water vapor that condenses in the atmosphere and falls to the ground. This includes rain, snow, sleet, hail, etc.
The watershed a withdrawal originates from.
The process of water moving through a plant and evaporating into the atmosphere.
The removal of water from surface water or groundwater.
The quantity of water flowing into a lake through surface rivers or streams, measured in time units at a given point
This is the time of year when water is evaporating off the surface of the Great Lakes.  The highest rates typically occur in late summer/early fall when surface water temperatures are warmest but...
The Straights of Mackinac are an approximately 10km long by 8km wide span of waterway connecting Lake Michigan and Lake Huron.  Water generally flows eastward from Lake Michigan to Lake Huron, but...
Flowing from the mouth of Lake Huron into Lake Erie, the Huron-Erie Corridor (HEC) consists of the St. Clair River, Lake St. Clair, and the Detroit River. The southwestern Ontario and southeastern...
Scouring is an erosion process that occurs due to the movement of water. As water flows forcefully it can remove sediment and rock, creating a channel or pool. Scouring is also often accelerated due...
(In progress)
The Chicago River is a major source of diversion from Lake Michigan.
History
Before the 20th century, the Chicago River flowed into Lake Michigan.  Flow was reversed by the city in 1900...
A diversion into Lake Superior from the Albany River system in Northern Ontario. One of only two major diversions into the entire Great Lake basin. When combined with the Long Lac diversion, the two...
A diversion into Lake Superior from the Albany River system in Northern Ontario. One of only two major diversions into the entire Great Lake basin. When combined with the Ogoki diversion, the two...
scientific defintion from the Climate Prediction Center:
The positive phase of the NAO reflects below-normal heights and pressure across the high latitudes of the North Atlantic and above-normal...
"Blocking" is the result of a high pressure system persisting over an area for several days leading to a stagnation of weather patterns (see this description for more detail).
Affects of Blocking (...
From the National Climate Assessment:
The frost-free season length, defined as the period between the last occurrence of 32°F in the spring and the first occurrence of 32°F in the fall...

Bias = difference between the modeled and the observed evaluation metric for a given variable or index.
Example: bias of the 95th percentile of the annual maximum daily temperature; or bias of the...
Evaluation metrics are quantitative measures of quality describing a particular data set.  Please see our Model Evaluation page for a list of the evaluation metrics used in the Great Lakes Ensemble.
The following explanation is source from: http://www.flowworks.com/rainfall-blog/idf-curves-explained
Definition
An Intensity-Duration-Frequency curve (IDF Curve)  is a graphical representation of...
A design storm is a mathematical representation of a precipitation event that reflects conditions in a given area for design of infrastructure. It provides guidelines for computing flows and sizing...
The difference between energy absorbed by the earth and energy radiated back into space. A positive radiative forcing warms the earth, while a negative value cools the earth. 
Groups that study the effect of global warming on the climate as well as how the emissions impact our environment. 
Groups that gather information to analyze the relationship between emissions and socio-economic scenarios. 
Groups that focus on the impacts of climate change in areas including human health, food security, society and their settlements, etc.
A group of emissions scenarios developed by the Intergovernmental Panel on Climate Change (IPCC) in 2000. These scenarios were created using a sequential approach, and are based on socio-economic...
A group of four greenhouse gas concentration scenarios developed by the IPCC in 2014 to replace SRES. Unlike SRES, RCPs were based on radiative forcing pathways using a parallel approach. Since they...
Any gas in the atmosphere that absorbs and emits radiation in the thermal infrared range. This absorption and emission is the primary cause of the greenhouse effect that results in the warming of the...
When creating RCPs, SSPs are socioeconomic scenarios that are created in the absence of climate change and policies. These pathways are then used to create emissions and land use scenarios intergral...
A description of future releases of any substance that can affect the earth's atmosphere; examples of these substances include greenhouse gases and aerosols. They are not predictions, but rather...
A change in the state of the climate that exists for an extended period of time, usually decades or longer. This change can be identified by changes in the properties of climate (temperature, sea...
In the spectrum of climate change, coral bleaching occurs when water temperatures increase, causing the coral to expel the algae living in their tissues. This causes the coral to turn very pale or...
Shrubs or small trees that grow along coastal waters, usually in tropical areas. These plants have been known to provide a buffer against tsunamis and cyclones; however, there has been a noticeable...
A description of potential radiative forcing changes that will lead to an overall warming trend on Earth. Radiative forcing scenarios are the basis of development for the newer representative...
Socio-economic scenarios are projections that help characterize demographic, economic and technological factors driving man-made greenhouse gas emissions that exacerbate climate change. These...
A climate model scenario is a series of projections of how greenhouse gas emissions will affect the environment; this includes potential warming of the Earth, potential sea level rise, potential...