Spatiotemporal Patterns in Data Availability of the Sentinel-5P NO2 Product over Urban Areas in Norway

Remote Sensing

Arve Kylling¹  PaulD. Hamer¹  Shobitha Shetty¹  Philipp Schneider¹  Kerstin Stebel¹ 

[1] NILU—Norwegian Institute for Air Research, P.O. Box 100, 2027 Kjeller, Norway;

关键词: air quality;    remote sensing;    Sentinel-5P;    TROPOMI;    nitrogen dioxide;    Norway;   

DOI  :  10.3390/rs13112095

来源: DOAJ

【 摘 要 】

Due to its comparatively high spatial resolution and its daily repeat frequency, the tropospheric nitrogen dioxide product provided by the TROPOspheric Monitoring Instrument (TROPOMI) onboard the Sentinel-5 Precursor platform has attracted significant attention for its potential for urban-scale monitoring of air quality. However, the exploitation of such data in, for example, operational assimilation of local-scale dispersion models is often complicated by substantial data gaps due to cloud cover or other retrieval limitations. These challenges are particularly prominent in high-latitude regions where significant cloud cover and high solar zenith angles are often prevalent. Using the example of Norway as a representative case for a high-latitude region, we here evaluate the spatiotemporal patterns in the availability of valid data from the operational TROPOMI tropospheric nitrogen dioxide (${\mathrm{NO}}_2$) product over five urban areas (Oslo, Bergen, Trondheim, Stavanger, and Kristiansand) and a 2.5 year period from July 2018 through November 2020. Our results indicate that even for relatively clean environments such as small Norwegian cities, distinct spatial patterns of tropospheric ${\mathrm{NO}}_2$ are visible in long-term average datasets from TROPOMI. However, the availability of valid data on a daily level is limited by both cloud cover and solar zenith angle (during the winter months), causing the fraction of valid retrievals in each study site to vary from 20% to 50% on average. A temporal analysis shows that for our study sites and the selected period, the fraction of valid pixels in each domain shows a clear seasonal cycle reaching a maximum of 50% to 75% in the summer months and 0% to 20% in winter. The seasonal cycle in data availability shows the inverse behavior of ${\mathrm{NO}}_2$ pollution in Norway, which typically has its peak in the winter months. However, outside of the mid-winter period we find the TROPOMI ${\mathrm{NO}}_2$ product to provide sufficient data availability for detailed mapping and monitoring of ${\mathrm{NO}}_2$ pollution in the major urban areas in Norway and see potential for the use of the data in local-scale data assimilation and emission inversions applications.

【 授权许可】

Unknown