Nephelometer (NEPH)

The Nephelometer is an instrument used for measuring light scattering properties of aerosols at multiple wavelengths.

AeroViz.rawDataReader.script.NEPH.Reader

Reader(path: Path | str, reset: bool | str = False, qc: bool | str = True, **kwargs)

Bases: AbstractReader

Nephelometer (NEPH) Data Reader

A specialized reader for integrating nephelometer data files, which measure light scattering properties of aerosols at multiple wavelengths.

See full documentation at docs/source/instruments/NEPH.md for detailed information on supported formats and QC procedures.

Attributes

nam class-attribute instance-attribute

nam = 'NEPH'

Functions

_raw_reader

_raw_reader(file)

Read and parse raw Nephelometer data files.

Parameters:

Name	Type	Description	Default
file	Path or str	Path to the Nephelometer data file.	required

Returns:

Type	Description
DataFrame	Processed Nephelometer data with datetime index and scattering coefficient columns.

_QC

_QC(_df)

Perform quality control on Nephelometer data.

Parameters:

Name	Type	Description	Default
_df	DataFrame	Raw Nephelometer data with datetime index and scattering coefficient columns.	required

Returns:

Type	Description
DataFrame	Quality-controlled Nephelometer data with invalid measurements masked.

Notes

Applies the following QC filters: 1. Value range: Valid scattering coefficients between 0-2000 Mm^-1 2. Physics consistency: Back-scattering must be less than total scattering 3. Wavelength dependence: Blue > Green > Red (where applicable) 4. Time-based outlier detection: Uses 1-hour window for IQR-based filtering 5. Complete record requirement: Requires values across all channels

Data Format

Time Record Format	T	YYYY	MM	DD	HH	NN	SS
Example	T	2022	05	08	13	29	22

Data Record Format	D	mode	time	B	G	R	BB	GB	RB
Example	D	NBXX	2258	7.527e-5	6.984e-5	4.275e-5	6.821e-6	1.070e-5	5.130e-6

Auxiliary Record Format	Y	x	pressure	Sample Temp	Inlet Temp	RH	lamp voltage	lamp current	BNC voltage	Status
Example	Y	348	973	302.8	300	91.2	12.5	5.7	2	0000

• File format: Raw data file (.dat)
• Sampling frequency: 5 minutes
• File naming pattern: *.dat
• Record types:
  • T records: Timestamp information
  • D records: Scattering measurements
  • Y records: Status and RH information

Measurement Parameters

The Nephelometer provides measurements at three wavelengths:

• B, G, R: Total scattering coefficients at blue, green, and red wavelengths (Mm⁻¹)
• BB, BG, BR: Backscattering coefficients at blue, green, and red wavelengths (Mm⁻¹)
• RH: Relative humidity inside the nephelometer (%)

Data Processing

Data Reading

• Processes different record types (T, D, Y)
• Extracts timestamp from T records
• Extracts scattering measurements from D records
• Extracts status and RH from Y records
• Converts raw scattering values to Mm⁻¹
• Handles both normal (NBXX) and total (NTXX) scattering modes

Quality Control

• Removes physically impossible values (negative or > 2000 Mm⁻¹)
• Ensures physical consistency:
  • Backscattering must be less than total scattering
  • Blue > Green > Red (Rayleigh scattering principle)
• Applies time-aware IQR filtering with 1-hour windows
• Ensures data completeness across all channels
• Filters data based on instrument status codes

Output Data

The processed data contains the following columns:

• Time index: Data acquisition time
• B, G, R: Total scattering coefficients (Mm⁻¹)
• BB, BG, BR: Backscattering coefficients (Mm⁻¹)
• RH: Relative humidity (%)

Notes

• Provides information about aerosol optical properties and size distribution
• Supports both normal and total scattering modes
• Maintains physical consistency between measurements
• Automatically handles different record types and data formats