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Coherent Doppler lidar signal spectrum with wind turbulence
1Research Application Program, National Center for Atmospheric Research, Boulder, Colorado 80307, USA. rgf@cires.colorado.edu
Applied Optics
|March 8, 2008
Summary
Coherent Doppler lidar signal spectra analysis reveals how turbulence affects wind measurements. Accurate turbulence assessment is possible for larger range gates, overcoming spectral leakage issues in high-resolution lidar data.
Area of Science:
- Atmospheric Science
- Optical Remote Sensing
- Fluid Dynamics
Background:
- Coherent Doppler lidar systems are crucial for remote wind field measurements.
- Turbulence introduces complexities in interpreting lidar signal spectra.
- Accurate wind turbulence characterization is vital for meteorological and atmospheric studies.
Purpose of the Study:
- To calculate the average signal spectrum (periodogram) for coherent Doppler lidar in turbulent wind fields.
- To compare simple approximations with exact calculations for lidar signal spectra.
- To analyze the impact of various error sources on turbulence measurements.
Main Methods:
- Calculation of the average signal spectrum (periodogram) for coherent Doppler lidar.
- Inclusion of effects from zero velocity reference errors, spectral averaging, and range-dependent signal power.
- Comparison of exact spectral calculations with simplified approximations.
Main Results:
- High spatial resolution measurements suffer from spectral leakage, complicating turbulence interpretation.
- For range gates larger than the lidar pulse volume, signal power spreads across multiple spectral bins.
- Accurate turbulence determination is achievable when signal power is spread over many bins, especially with constant or far-field range dependence.
Conclusions:
- The study provides a framework for understanding lidar spectral characteristics in turbulent flows.
- Signal processing strategies are essential to mitigate errors and accurately quantify turbulence.
- Larger range gates offer advantages for reliable turbulence estimation using coherent Doppler lidar.
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