7. Summary

Satellite observations at high latitudes present unique challenges due to geometric, seasonal, and atmospheric factors. Below is a summary of key limitations and considerations:


  • Limited Sunlight in Winter:
    One of the primary constraints for geostationary satellite imagery at high latitudes is the reduced duration of daylight during winter months, which limits the availability and quality of visible channel data.
  • Seasonal and Diurnal Variability:
    Some satellite products, such as those containing solar channels, in high-latitude regions exhibit strong seasonal and daily variations. The observed hues, especially in RGB composites, are influenced by the solar zenith angle, affecting interpretation.
  • Parallax Shift:
    The parallax effect becomes more pronounced at higher latitudes, particularly in convective situations. This shift increases with both the height of the observed feature and the distance from the satellite's nadir, potentially leading to misplacement of cloud tops.
  • Optical Path:
     At high latitudes, the optical path—the trajectory light takes from the Earth's surface to the satellite sensor—is more slanted. This results in:

    • Limb cooling, where longer atmospheric paths increase absorption in certain channels (e.g., water vapor, ozone, CO₂), causing color shifts near image edges.
    • Enhanced scattering in shortwave visible channels, which can improve the visibility of thin features like cirrus clouds, dust, or smoke.
  • Reduced Spatial Resolution:
    Due to the slanted viewing angle, geostationary satellites provide lower spatial resolution at high latitudes, making it more difficult to detect small-scale features.

    • Advancements with MTG:
      The Meteosat Third Generation (MTG) satellites offer significantly improved spatial resolution, enhancing image quality and feature detection even in high-latitude regions.
    • Value of Polar-Orbiting Satellites at high latitudes:
      Polar-orbiting satellites provide much higher spatial resolution and more frequent coverage of high-latitude areas. Their data is highly valuable for operational meteorology and should be fully integrated into forecasting workflows.
  • Limitations of SAF Products:
    Satellite Application Facilities (SAF) products may have limitations at high latitudes, such as inaccurate cloud top temperature readings or missing data due to low sun elevation angles.