Start Date
26-6-2015 11:10 AM
End Date
26-6-2015 11:30 AM
Abstract
Interactions between the biosphere and atmosphere are an important part of the global carbon cycle, and quantifying the carbon dioxide exchanges between them is helpful in predicting the uptake of carbon dioxide from anthropogenic sources by the biosphere in the future. In the Midwestern United States, agricultural systems cover a large part of the landscape, so understanding their role in influencing the global carbon budget is crucial as anthropogenic sources of carbon dioxide grow larger. Carbon dioxide exchanges can be measured by eddy covariance at the ecosystem level (bottom-up approach) or regionally by inversion techniques (top-down approach). Here we describe a novel approach to estimate the exchange at an intermediate spatial In this methodology used in the summer of 2014, two launches were conducted in one day and the rate of uptake between the two ascents was calculated. The carbon dioxide concentrations measured during the ascents were converted to a molar difference using the observed temperature and pressure of the atmosphere, and a flux was calculated by summing the molar differences at altitudes under 4000 m and dividing by the time difference between flights. This value is the Net Ecosystem Exchange (NEE). It was found that uptake was highest (the most negative values of NEE were observed) in mid-July as well, with uptake becoming more positive throughout August and September. Only four data points were collected using the second-generation methodology, so significance of this trend is limited. During peak growing season over the summer, uptake rates of -30 μmol m-2 s-1 were observed, while as fall approached this rate became positive. The methodology established here will be used to explore new hypotheses related to the NEE of crops, and data will continue to be collected in the summer of 2015.
Included in
A High-Altitude Balloon Platform for Determining Regional Uptake of Carbon Dioxide over Agricultural Landscapes
Interactions between the biosphere and atmosphere are an important part of the global carbon cycle, and quantifying the carbon dioxide exchanges between them is helpful in predicting the uptake of carbon dioxide from anthropogenic sources by the biosphere in the future. In the Midwestern United States, agricultural systems cover a large part of the landscape, so understanding their role in influencing the global carbon budget is crucial as anthropogenic sources of carbon dioxide grow larger. Carbon dioxide exchanges can be measured by eddy covariance at the ecosystem level (bottom-up approach) or regionally by inversion techniques (top-down approach). Here we describe a novel approach to estimate the exchange at an intermediate spatial In this methodology used in the summer of 2014, two launches were conducted in one day and the rate of uptake between the two ascents was calculated. The carbon dioxide concentrations measured during the ascents were converted to a molar difference using the observed temperature and pressure of the atmosphere, and a flux was calculated by summing the molar differences at altitudes under 4000 m and dividing by the time difference between flights. This value is the Net Ecosystem Exchange (NEE). It was found that uptake was highest (the most negative values of NEE were observed) in mid-July as well, with uptake becoming more positive throughout August and September. Only four data points were collected using the second-generation methodology, so significance of this trend is limited. During peak growing season over the summer, uptake rates of -30 μmol m-2 s-1 were observed, while as fall approached this rate became positive. The methodology established here will be used to explore new hypotheses related to the NEE of crops, and data will continue to be collected in the summer of 2015.