Grasslands Ecological Monitoring System (GEMS)
OverviewThe Grasslands Ecological Monitoring System (GEMS) integrates climate, weather, and remote sensing data in archives and in current datastreams with simple models of plant growth to help producers improve forage management within the context of the high interannual variability of environmental conditions in the High Plains. Forecasts of forage production are based on current and recent weather, including the influence of atmospheric teleconnections, and compared with historical trajectories of weather and observed land surface conditions. This project involves a collaboration of researchers from South Dakota State University, University of Nebraska-Lincoln, Kansas State University, and Oklahoma State University. Funding for this project was provided by the USDA Risk Management Agency. |
Weather & ClimateWeather describes the current state of atmospheric conditions. Weather is what we experience each day. Climate describes the weather experienced at a particular place and time observed over a long period. Climate is an expectation of the weather based on prior experience. The National Climatic Data Center (NCDC) has a defined observing period for climate: 30 years. Each decade NCDC updates these climate "normals" for each observing location. The current normal period is 1971-2000. Find these data on a national basis here and for the Great Plains region specifically here. For the GEMS project we are also using a 30 year window of weather observations to characterize our expectations of weather, but we are updating each year. This 30 year "moving window" approach allows us to detect trends more readily. |
Change vs. VariationChange is a concept distinct from variation. We use the term variation to describe undirected fluctuations around a reference baseline. Change implies a persistent shift that is significantly different from the baseline condition (e.g., movement towards a wetter or drier climate). For GEMS, we expect variation around the baseline from one growing season to the next. Predicting grassland production would be easy if variation did not occur, but variation is the rule rather than the exception. GEMS is designed to identify sources of variation in environmental conditions within a growing season and forecast grassland production based on these conditions. Variability in forage production arises from the interaction of high interannual and intraseasonal variability in the availability of key resources for photosynthesis —sunlight and water— with management practices. |
Climate Modes & TeleconnectionsAtmospheric circulation is characterized by coherent patterns of temperature, pressure, and winds that exert significant seasonal controls over local and regional weather and climate. These patterns or modes often show a persistent interannual geography and are identified and described by their spatial characteristics. In addition to their local and regional effects, these persistent circulation features are capable of influencing weather and climate patterns at great distances. Remote linkages between distant and seemingly disconnected climate anomalies are called teleconnections. |
Observing the EarthPlants appear green because they preferentially absorb about 90-97% sunlight in the red and blue regions of the spectrum. Just beyond the visible at the red end of the spectrum is the near infrared (NIR). The sun shine down lots of NIR but humans cannot perceive it. And that is a good thing because healthy green plants reflect about 50% of the NIR in contrast to only about 15% of the green. Thus, vegetation is very bright in the NIR and very dark in the red. Spaceborne sensors can detect green vegetation at the surface (in the absence of obscuring clouds) using this contrast in reflectance. |
Data Access using Google EarthWe have chosen to use Google Earth as the visual gateway to access the GEMS data. Google Earth is a virtual globe that displays geospatial data through an easy-to-navigate interface. A free version of Google Earth is available here. The current kmz file to open within Google Earth for access to GEMS data is available here. More... |
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