Mapping emissions in Cyprus using TROPOMI observations: evaluation of the flux-divergence scheme using multiple...

Area of Science:

• Atmospheric chemistry and air quality monitoring
• Environmental science and pollution studies
• Remote sensing and geospatial analysis

Background:

• Nitrogen oxides (NOx) emissions from urban areas and power plants cause significant air pollution and health issues.
• Accurate emission inventories are crucial for air quality policy, but are systematically unavailable for the divided island of Cyprus.
• Previous emission estimations often rely on reported data, which may not reflect actual emissions.

Purpose of the Study:

• To map NOx emissions in Cyprus for 2021 and 2022 using a flux-divergence approach.
• To assess the limitations of the flux-divergence method for NOx emission estimation in Cyprus.
• To compare satellite-derived emission estimates with bottom-up data and explore differences between power plants in different regions.

Main Methods:

• Utilized spaceborne nitrogen dioxide (NO2) column retrievals from the TROPOMI instrument at high spatial resolution.
• Employed a flux-divergence scheme incorporating horizontal wind data and chemical process indicators (OH, NO, NO2 concentrations).
• Estimated emissions using three parameter sets derived from ECMWF data and WRF-Chem simulations with varying spatial resolutions and atmospheric compositions.

Main Results:

• The flux-divergence method's accuracy was limited by wind and hydroxyl radical resolution, signal-to-noise ratio of NO2 columns, and the NO:NO2 ratio.
• Calculated NOx emissions showed large discrepancies across the three parameter sets, leading to high uncertainties for individual power plants.
• Derived emissions exhibited higher seasonality than inventory data, and estimates for two southern power plants were significantly higher than bottom-up data.

Conclusions:

• Despite methodological limitations, satellite-derived NOx emissions offer insights into seasonality and regional differences in Cyprus.
• Emission estimates suggest disparities in environmental norms, technology, and fuel use between the two political entities on the island.
• The study highlights the potential and challenges of using satellite remote sensing for air quality management in regions with data gaps.