Atmospheric Physics and Chemistry Group

Abhijit Basu

Project summary

Here at IMAU, I am involved in the modeling of tropical wetland methane emission using LPJ, a dynamic vegetation model.
There is large uncertainty in constraining global wetland methane budget, which constitutes approximately 30% of the total. Among the global wetlands, tropical ones are notable and known for their distinctive hydrological characteristics, occurring from excess of water from flooded river channels. However, they are poorly represented in the global models and inflict biases in the overall methane budget estimation. The recent climate model studies with a top-down approach using satellite measurements also indicate to missing methane source from tropics, mainly from wetlands.
In the current work, I put focus on regional process-based modeling of tropical wetland methane using LPJ with the objective to reduce the persisting uncertainty in wetland methane budget, which will attempt to bridge the gap among various estimates. In the modeling framework, a new floodplain ecosystem is introduced in LPJ from the output of a hydrology model, PCR-GLOBWB, which represents tropical wetlands and corresponding vegetation. It helps to see the details of various dynamics taking place within the floodplains, like transformation of plant types, re-distribution of soil carbon pools with changing floodplain areas etc. They influence the process of methane production within the wetland anoxic soil layers and its transport to the atmosphere. Since tropical floodplains show strong seasonal and inter-annual variability, emphasis is also given to represent them suitably in the model.
The results from this study will be used by atmospheric transport model TM5 to validate with the observation data. The recent availability of aircraft measurements of methane over South America also provides the tool for further validation of the modeling approach on regional scale.