Decadal changes in atmospheric circulation detected in cloud motion vectors.

Area of Science:

• Atmospheric Science
• Climate Science
• Remote Sensing

Background:

• Global weather patterns are influenced by atmospheric circulation, which is changing.
• Existing climate models and reanalysis data show discrepancies in observed circulation changes.
• Validation with independent, climate-quality measurements is crucial for understanding these changes.

Purpose of the Study:

• To detect and validate statistically significant changes in tropospheric circulation using satellite data.
• To assess the accuracy of widely used reanalysis products against independent observations.
• To provide benchmarks for improving climate models.

Main Methods:

• Utilized satellite-observed, height-resolved cloud motion vectors from the Multi-angle Imaging SpectroRadiometer (MISR).
• Analyzed upper tropospheric cloud motion speeds and latitudinal shifts of tropical and polar fronts over two decades.
• Compared MISR data with ERA5 reanalysis winds.

Main Results:

• Observed statistically significant increases in upper tropospheric mid-latitude cloud motion speeds (up to 4 m/s/decade).
• Detected poleward shifts in Northern Hemisphere tropics (0.42°/decade) and polar fronts (0.37°/decade).
• Found good agreement between MISR and ERA5 climatology but identified probable ERA5 biases in the upper troposphere.

Conclusions:

• MISR satellite data provides critical, independent evidence of significant changes in tropospheric circulation.
• The findings highlight potential biases in current reanalysis products, particularly in the upper troposphere.
• These observations are essential for refining climate models and improving our understanding of climate change impacts.