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Satellite Observations Of Annual Variability In Terrestrial Carbon Cycles And Seasonal Growing Seasons At High Northern Latitudes, John S. Kimball, Maosheng Zhao, Kyle C. Mcdonald, Faith Ann Heinsch, Steven W. Running
Satellite Observations Of Annual Variability In Terrestrial Carbon Cycles And Seasonal Growing Seasons At High Northern Latitudes, John S. Kimball, Maosheng Zhao, Kyle C. Mcdonald, Faith Ann Heinsch, Steven W. Running
Numerical Terradynamic Simulation Group Publications
Global satellite remote sensing records show evidence of recent vegetation greening and an advance in the onset of the growing season at high latitudes. We apply a terrestrial net primary production (NPP) model driven by satellite observations of vegetation properties and daily surface meteorology from an atmospheric GCM to assess spatial patterns, annual variability, and recent trends in vegetation productivity across Alaska and northwest Canada. We compare these results with regional observations of the timing of growing season onset derived from satellite passive microwave remote sensing measurements from the Special Sensor Microwave Imager, SSM/I. Our results show substantial variability in …
Spaceborne Microwave Remote Sensing Of Seasonal Freeze-Thaw Processes In The Terrestrial High Latitudes: Relationships With Land-Atmosphere Co2 Exchange, Kyle C. Mcdonald, John S. Kimball, Maosheng Zhao, Eni G. Njoku, Reiner Zimmermann, Steven W. Running
Spaceborne Microwave Remote Sensing Of Seasonal Freeze-Thaw Processes In The Terrestrial High Latitudes: Relationships With Land-Atmosphere Co2 Exchange, Kyle C. Mcdonald, John S. Kimball, Maosheng Zhao, Eni G. Njoku, Reiner Zimmermann, Steven W. Running
Numerical Terradynamic Simulation Group Publications
Landscape transitions between seasonally frozen and thawed conditions occur each year over roughly 50 million square kilometers of Earth's Northern Hemisphere. These realtively abrupt transitions represent the closest analog to a biospheric and hydrologic on/off switch existing in nature, affecting surface meteorological conditions, ecological trace gas dynamics, energy exchange and hydrologic activity profoundly. We utilize time series satellite-borne microwave remote sensing measurements from the Special Sensor Microwave Imager (SSM/I) to examine spatial and temporal variability in seasonal freeze/thaw cycles for the pan-Arctic basin and Alaska. Regional measurements of spring thaw timing are derived using daily brightness temperature measurements from the …
Oak Forest Carbon And Water Simulations: Model Intercomparisons And Evaluations Against Independent Data, P. J. Hanson, J. S. Amthor, S. D. Wullschleger, K. B. Wilson, R. F. Grant, A. Hartley, D. Hui, E. R. Hunt Jr., D. W. Johnson, John S. Kimball, A. W. King, Y. Luo, S. G. Mcnulty, G. Sun, Peter Edmond Thornton, S. Wang, M. Williams, Dennis Baldocchi, R. M. Cushman
Oak Forest Carbon And Water Simulations: Model Intercomparisons And Evaluations Against Independent Data, P. J. Hanson, J. S. Amthor, S. D. Wullschleger, K. B. Wilson, R. F. Grant, A. Hartley, D. Hui, E. R. Hunt Jr., D. W. Johnson, John S. Kimball, A. W. King, Y. Luo, S. G. Mcnulty, G. Sun, Peter Edmond Thornton, S. Wang, M. Williams, Dennis Baldocchi, R. M. Cushman
Numerical Terradynamic Simulation Group Publications
Models represent our primary method for integration of small-scale, process-level phenomena into a comprehensive description of forest-stand or ecosystem function. They also represent a key method for testing hypotheses about the response of forest ecosystems to multiple changing environmental conditions. This paper describes the evaluation of 13 stand-level models varying in their spatial, mechanistic, and temporal complexity for their ability to capture intra- and interannual components of the water and carbon cycle for an upland, oak-dominated forest of eastern Tennessee. Comparisons between model simulations and observations were conducted for hourly, daily, and annual time steps. Data for the comparisons were …
Variability In Springtime Thaw In The Terrestrial High Latitudes: Monitoring A Major Control On The Biospheric Assimilation Of Atmospheric Co2 With Spaceborne Microwave Remote Sensing, Kyle C. Mcdonald, John S. Kimball, Eni G. Njoku, Reiner Zimmermann, Maosheng Zhao
Variability In Springtime Thaw In The Terrestrial High Latitudes: Monitoring A Major Control On The Biospheric Assimilation Of Atmospheric Co2 With Spaceborne Microwave Remote Sensing, Kyle C. Mcdonald, John S. Kimball, Eni G. Njoku, Reiner Zimmermann, Maosheng Zhao
Numerical Terradynamic Simulation Group Publications
Evidence is presented from the satellite microwave remote sensing record that the timing of seasonal thawing and subsequent initiation of the growing season in early spring has advanced by approximately 8 days from 1988 to 2001 for the pan-Arctic basin and Alaska. These trends are highly variable across the region, with North America experiencing a larger advance relative to Eurasia and the entire region. Interannual variability in the timing of spring thaw as detected from the remote sensing record corresponded directly to seasonal anomalies in mean atmospheric CO2 concentrations for the region, including the timing of the seasonal draw …