GRIMM Aerosol Spectrometer

The GRIMM is an optical particle counter that measures particle size distributions across multiple size channels.

Data Format

• File format: Tab-delimited text file
• Sampling frequency: Variable
• File naming pattern:
  • A407ST*.txt (specific format)
  • Other GRIMM formats
• Data structure:
  • Header: 233 rows of metadata
  • European date format (DD/MM/YYYY)
  • Size distribution channels (columns 11-127/128)

Measurement Parameters

The GRIMM provides:

• Size range: 0.25 to 32 μm
• Resolution: Multiple size channels
• Output: Number concentration for each size bin
• Units: particles/cm³ (after scaling)

Data Processing

Data Reading

• Processes tab-delimited files
• Handles European date format
• Extracts size distribution channels
• Applies scaling factor (1/0.035)
• Uses ISO-8859-1 encoding
• Handles different file formats

Quality Control

• Basic file validation
• Empty file detection
• No additional QC currently implemented
• Future QC possibilities:
  • Value range checks
  • Total concentration consistency
  • Time-based outlier detection

Output Data

The processed data contains:

• Time index: Data acquisition time
• Size channels: Number concentration for each bin
• All measurements in particles/cm³

Notes

• High resolution size information
• Wide size range coverage
• Multiple size channels
• Standard scaling factor applied
• European date format support