Seminar: Theertha Kariyathan


  • Date: Oct 13, 2022
  • Time: 02:00 PM - 03:00 PM (Local Time Germany)
  • Speaker: Theertha Kariyathan
  • Reichstein Department, IMPRS
  • Location: Max-Planck-Institut für Biogeochemie
  • Room: Hörsaal (C0.001)
  • Host: tbd
Robust estimation of the carbon uptake period based on time series of atmospheric CO2 and analysis of its interannual variability

Analyzing trends in the timing and duration of the carbon uptake period (time of the year when the CO2 uptake is greater than the CO2 release) derived from high-quality CO2 dry air mole fraction data from flask sampling sites can help us understand the changes in CO2 exchange between the terrestrial ecosystem and the atmosphere. In this study, we use a recently developed methodology for quantifying the uncertainty in curve fitting and propagating it to the CO2 seasonal cycle metrics. We focus on two metrics, namely the timing (onset and termination) and duration of the carbon uptake period. We introduce a method for estimating these metrics based on a threshold of the first derivative (FDT), which more closely corresponds to the “actual” onset and termination of the growing season. To better understand the link between interannual variability in the seasonality of surface fluxes and the seasonality of in-situ CO2 measurements it is crucial to account for variability in atmospheric transport. For this, we generate time series with varying interannual meteorology and with fixed meteorology. We investigate if the proposed FDT method can better capture the interannual variability in the carbon uptake period by simulating synthetic time series of atmospheric mixing ratios with a transport model, using fluxes with known interannual variability of the carbon uptake period. The reduced uncertainty achieved using the FDT method and analysis of the transport fluxes provide a better understanding of the CO2 exchange between the terrestrial ecosystem and the atmosphere.


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