Quantifying and modeling methane emissions from the North Sea region with ICON-ART

The release of greenhouse gases (GHG) like methane plays a key role in driving the climate change. With the optimization of atmospheric chemistry climate models, the accuracy in predicting future scenarios is improved, which is an important factor in our efforts to mitigate climate change.

The objective of this work is to introduce three methods for the quantification and adjustment of wrong or missing emissions in well-established GHG-inventories, which are used as input data for emissions in atmospheric chemistry transport or climate models. Beside a straight-forward upscaling method and a regridding method based on reported emission data, we present the WALLACE workflow, a new and efficient method to quantify GHG emissions based on satellite measurements. The overall goal of WALLACE is to highlight emission hotspots and it therefore includes spatiotemporal proxy data and a selection algorithm. For the North Sea as a show case region we apply WALLACE to quantify methane emission fluxes of oil and gas platforms.

The adjusted emissions are implemented as pointsources into the ICOsahedral Nonhydrostatic model with Aerosols and Reactive Trace gases (ICON-ART) and idealized simulations are performed to compare the three methods with reference simulations to derive their impact on the spatial distribution of methane and its global and regional budget. ... mehrFor all three adjustment methods our model reveals a distribution of methane on the northern hemisphere and an effect on the European continent. For a quantification of the impact we evaluate the influence of the adjusted North Sea platform emissions on the radiative forcing. Additionally, we take a look at the anti-correlation between methane and its main sink in the atmosphere, the hydroxyl radical (OH), which is implemented as a simple OH-chemistry mechanism into the routines of the model.

This work makes a new and innovative contribution to achieve an accurate quantification of environmentally harmful gases that drive man-made climate change.