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AE33 Aethalometer

The AE33 is a multi-wavelength aethalometer used for measuring black carbon aerosol concentrations in the atmosphere.

Data Format

  • File format: Tab-delimited text file (.dat)
  • Sampling frequency: 1 minute
  • File naming pattern: [!ST|!CT|!FV]*[!log]_AE33*.dat
    • log file is not included ex. AE33_log_AE33-S05-00494_20220401.dat
  • Header: 5 rows of header information
  • Data columns: 67 columns including timestamp and measurements

Measurement Parameters

The AE33 provides black carbon concentration measurements at seven wavelengths:

  • BC1-BC7: Black carbon concentrations at different wavelengths (ng/m³)

Data Processing

Data Reading

  • Automatically skips the first 5 rows of header information
  • Parses timestamps from date and time columns (columns 0 and 1)
  • Extracts black carbon concentration data for seven wavelengths
  • Strips semicolons from column names
  • Validates file size (warns if < 550KB)

Quality Control

  1. Instrument Status Check:

    • Filters data based on instrument status codes:
      • Status = 1: Tape advance (tape advance, fast calibration, warm-up)
      • Status = 2: First measurement – obtaining ATN0
      • Status = 3: Stopped
      • Status = 4: Flow low/high by more than 0.5 LPM or F1 < 0 or F2/F1 outside 0.2 – 0.75 range
      • Status = 16: Calibrating LED
      • Status = 32: Calibration error (at least one channel OK)
      • Status = 384: Tape error (tape not moving, end of tape)
      • Status = 1024: Stability test
      • Status = 2048: Clean air test
      • Status = 4096: Optical test
    • Removes data points with other status codes indicating instrument problems

  2. Value Range Check:

    • Removes physically impossible values (negative or > 20000 ng/m³)

  3. Data Representativeness:

    • Requires at least 50% of expected data points in each 1-hour window
    • Ensures temporal consistency of measurements

  4. Complete Record Requirement:

    • Ensures data completeness across all wavelengths

Output Data

The processed data contains the following columns:

  • Time index: Data acquisition time
  • BC1-BC7: Black carbon concentrations at seven wavelengths (ng/m³)

Notes

  • The AE33 provides real-time black carbon concentration measurements, useful for distinguishing between biomass burning and fossil fuel combustion contributions
  • Files smaller than 550KB may indicate incomplete data
  • Supports data filtering based on instrument status codes
  • Handles duplicate timestamps and invalid indices automatically