In recent times, the way we observe our environment has been completely transformed by satellite data. Thanks to tools like Google Earth Engine, we can now delve deep into satellite images, unraveling the secrets of our atmosphere’s composition. This allows us to gain vital insights into the dynamics of air quality, particularly by examining the levels of gases like formaldehyde (HCHO) and nitrogen dioxide (NO2) using the TROPOspheric Monitoring Instrument (TROPOMI).
Why It Matters?
Ozone, a crucial component of Earth’s atmosphere, resides in two layers: the stratosphere and the troposphere. While stratospheric ozone shields us from harmful UV radiation, the ozone formed in the troposphere, due to a complex mix of pollutants, poses risks to both human health and the environment. Understanding the formation of tropospheric ozone involves studying precursor gases like nitrogen oxides (NOx) and volatile organic compounds (VOCs), such as formaldehyde.
Formaldehyde acts as a significant marker for VOCs, while nitrogen dioxide serves as a precursor for NOx, both playing pivotal roles in the creation of tropospheric ozone. By analyzing their ratio, we can gauge the likelihood of ozone levels surpassing safe limits in a particular area. Measuring the ratio The formaldehyde to nitrogen dioxide ratio (FNR) holds immense significance in unveiling the secrets of atmospheric dynamics. The measurement of ratios allows us to identify patterns and correlations, shedding light on potential areas where ozone levels might exceed safe limits.
Understanding the FNR:
The FNR, expressed as HCHO/NO2, provides valuable information about ground-level ozone sensitivity and assists in devising strategies to mitigate its effects. A high FNR, resulting from a high HCHO value relative to NO2, indicates a region sensitive to NO2 (where NOx is the limiting factor in ozone formation). On the other hand, a low FNR, indicating a region sensitive to VOCs (where VOCs limit ozone formation), is characterized by a low HCHO value compared to NO2.
Interpreting the FNR
An FNR below 3.2 signifies a hotspot that is sensitive to VOCs. When the FNR falls between 3.2 and 4.1, it indicates a transitional phase where the hotspot shifts between VOC and NO2 sensitivity. If the FNR exceeds 4.1, it suggests the hotspot is within the NO2-sensitive zone.
Implications and Solutions:
The implications of analyzing TROPOMI’s formaldehyde to nitrogen dioxide ratios for potential ozone exceedances are profound. Identifying regions prone to heightened ozone levels enables the implementation of proactive measures, such as stricter emission controls, urban planning strategies, and public awareness campaigns. Furthermore, these insights contribute to refining atmospheric models, improving the accuracy of ozone forecasting, and formulating effective policies.
As we grapple with environmental complexities, leveraging such innovative technologies becomes crucial in safeguarding the health of our planet for generations to come.
Links for further reference:
- How to use GEE? — https://earthbound.substack.com/p/plot-air-pollution-in-your-city-using
- FNR measurements using GEE— https://haqast.org/publications/satellite-data-to-inform-ozone-sensitivity-a-practical-methodology-using-google-earth-engine/
- In depth analysis of FNR — https://acp.copernicus.org/articles/23/7867/2023/acp-23-7867-2023.pdf
