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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