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Assessment of Mixed-Layer Height Estimation from Single-wavelength Ceilometer Profiles
Travis N Knepp1,2, James J Szykman3, Russell Long3
1Science Systems and Applications Inc., Hampton, Virginia 23666, USA.
Atmospheric Measurement Techniques
|April 24, 2018
Summary
Comparing boundary layer height measurement methods, this study found processing algorithms are more critical than data collection. Averaging mixed-layer height data to one-hour resolution improved correlations between instruments and algorithms.
Area of Science:
- Atmospheric Science
- Boundary Layer Meteorology
- Remote Sensing
Background:
- Accurate measurement of the atmospheric boundary layer height (MLH) is crucial for air quality and weather forecasting.
- Various instruments and algorithms exist for MLH determination, leading to potential intercomparison challenges.
- The Vaisala CL51 ceilometer is a common instrument for boundary layer profiling.
Purpose of the Study:
- To assess different measurement methods for boundary/mixed-layer height, focusing on the Vaisala CL51 ceilometer.
- To compare data collection methodologies (BLView software vs. terminal emulation) and algorithms (BLView vs. STRAT) for MLH retrieval.
- To evaluate the performance of these methods against radiosonde-derived boundary layer heights.
Main Methods:
- Intercomparison of Vaisala CL51 ceilometer data collected using BLView software and terminal emulation.
- Evaluation of the STRucture of the ATmosphere (STRAT) algorithm as an alternative to BLView.
- Application of filtering criteria to remove high-frequency fluctuations and analysis of MLH distributions.
Main Results:
- Processing algorithm choice significantly impacts MLH retrievals, more so than data collection methodology.
- Local meteorology and precipitation events can introduce difficulties for MLH algorithms.
- Radiosonde-derived boundary layer heights were found to be 10-15% higher than LIght Detection And Ranging (LIDAR)-derived mixed-layer heights at midday.
- Averaging MLH retrievals to 1-hour resolution significantly improved correlations between different instruments and algorithms.
Conclusions:
- A standardized processing algorithm is essential for LIght Detection And Ranging (LIDAR)-based MLH intercomparisons and ceilometer network operations.
- The findings highlight the need for careful algorithm selection and data processing for accurate MLH determination.
- Temporal averaging of MLH data enhances consistency across different measurement approaches.
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