Research Sites

Imnavait Creek

Imnavait Creek is located on Alaska's North Slope, north of the Brooks Range in the Kuparuk River basin about 12km from Toolik Field Station (TFS) and Toolik Lake. The Kuparuk River is one of numerous parallel rivers on the broad slope running from the Brooks Range into the Arctic Ocean. The Imnavait basin (2.2 km2) lies at about 68.62°N and 149.30°W at an average elevation of 930m above sea level.  The surrounding landscape is piedmont hills with a predominant soil of porous organic peat underlain by silt and glacial till, all in a permafrost state.


Typical vegetation types at Imnavait Cr. include wet sedge tundra in the riparian zone, tussock tundra on the hillslopes and dry heath tundra on the ridgelines.  Precipitation falls throughout the whole year, 66% as rain during the summer season. The snow season typically starts in early September and ends by the first week of June. The mean annual temperature is -7.4°C, extremes of -45°C and +24°C have been observed.  Maximum permafrost thaw depth is 25-100cm depending on vegetation, slope and soil type.  Further site information and references can be found in this publication.


Imnavait Cr. and TFS have been important research areas for studies of Arctic ecosystems for over 30 years. TFS is the site of the Arctic Long Term Ecological Research (LTER) program and dozens of other major projects. The Arctic LTER and associated projects have produced several decades of carbon flux measurements, providing a clear to interpreting our measurements. An extensive database is maintained by the LTER project, click here to visit


Our study area is comprised of three eddy covariance towers at Imnavait Cr, along the gradient from valley bottom to ridge top in wet sedge, tussock and dry heath tundra ecosytems, respectively. Over the past five years, two of the towers (Fen and Ridge) operated year-round, while the third tower (Tussock) operated Mar-Oct as the solar power supply permitted.  As of 2012, all three towers will operate year-round, providing better resolution of annual C budgets.  Additionally, we have improved the data communications system to include all three towers on satellite link for optimal data retrieval.

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View Cherskiy, Russia in a larger map

The Northeast Science Station (NESS), Cherskiy, Russia, located near the Kolyma River, Yakutia (69oN, 161oE), serves as a year-round base for international research in arctic biology, climate change and other fields.  Cherskiy is in a region of forest tundra at the latitudinal treeline 100km south of the Arctic Ocean. The Kolyma is one of five major rivers draining into the Arctic Ocean.

Research sites near the Northeast Science Station are representative of the coastal plain of Northeast Siberia, a one-million km2 area of carbon-rich loess soils (the Yedoma ice complex) that accumulated carbon during the Pleistocene and have gradually been releasing this carbon to the atmosphere and ocean through thawing of soils previously frozen during the Holocene. The ice content of these soils is much greater than that of permafrost soils in North America, and hence the North Siberian landscape is undergoing intense thermokarst erosion (permafrost thaw that results in ground subsidence). Huge amount of carbon yet remain in Yedoma permafrost. Given projections of the complete degradation of surface permafrost by 2100, the release of this carbon as CO2 and CH4 will be an important feedback to global as well as high-latitude warming. There are nearly 20 years of CO2 and CH4 exchange measurements, providing a basis for extrapolating across a series of years with substantial interannual variation in climate.


We have established a 35m eddy covariance tower in Pleistocene Park, a 160 km2 extension of the Northeast Science Station located about 20 km south of Cherskiy. The height of this tower is necessary to account for the heterogeneity in landscape and vegetation.  We have been measuring CO2 and CH4 water and energy fluxes at this location since 2008.

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