GFAS-DPOL
Ground-based Fog & Aerosol Spectrometer with Polarization Detection
The GFAS-DPOL combines a high-sensitivity forward & back scatter intensity particle size measurement with a polarization detection measurement and a wind direction and wind-speed measurement. It is used for understanding fog formation, development and decay, and deriving number concentration, liquid water content, extinction coefficient and visibility in warm and mixed-phase fog.
TALK TO AN EXPERTMeasure the properties of complex fog/smog particles to better understand their composition and forecast their occurrence
The shape factor is used to differentiate liquid droplets from ice crystals, dust particles or ash from biomass burning. The complex refractive index determines if fog droplets are mixed with either dissolved or insoluble material.
Instrument Features include integrated sample aspiration pump, integrated control & data logging computer, integrated ultrasonic anemometer for wind-speed & -direction, Self-orientation to wind direction, Power filter and transient suppressor
PADS – Particle Analysis and Display System
The GFAS-DPOL utilizes PADS to provide a user-friendly virtual instrument panel. PADS allows the user to control the GFAS-DPOL and display real-time data and logs. For instance, the program enables the user to do the following tasks:
- Sample and record data
- View particle volume and number concentrations, as well as Median Volume Diameter (MVD) and Effective Diameter (ED)
- View LWC as measured by the GFAS-DPOL
- Monitor laser health and temperatures at various instrument locations
- Reprocess data with new parameters for additional analysis
Particle light-scattering and polarization detection
- GFAS-DPOL single particle optical spectrometer that is a ground-based version of Droplet’s airborne Cloud and Aerosol Spectrometer with Polarization
- A forward-scattering optical spectrometer accepts and sizes only particles that pass through a region of the laser beam with uniform power.
- Forward-scattered light is collected, directed through a 50/50 optical beam splitter, then measured by photodetectors to determine size and depth of field.
- The shape factor is used to differentiate liquid droplets from ice crystals, dust particles or ash from biomass burning.
- The complex refractive index determines if fog droplets are mixed with either dissolved or insoluble material.
| Parameter | Specification |
|---|---|
| Measured Parameters | Forward & back scatter measurements Polarization detection measurements |
| Auxiliary Parameters | Wind speed Temperature Pressure |
| Derived Parameters | Particle diameter Particle number concentration Polarization ratio Liquid water content Effective diameter Median volume diameter |
| Particle Size Range | 0.5-50 µm diameter |
| Number of Size Bins | 30 |
| Typical Sample Area | 0.24 mm² |
| Sample Flow Volume | 1 m3/min |
| Sampling Frequency | Standard Data Rate: Selectable, 0.04 sec to 20 sec PBP Data Rate: No limit until particles are coincident |
| Refractive Index | Non-absorbing, 1.33 (the industry standard for water) |
| Light Collection Angles | Forward: ~3.5º - 12º Back: ~ 183.5° - 192° |
| Data System Interface | Ethernet |
| Environmental Operating Conditions | Temperature: -40 to 45 °C (except in heavy icing
conditions) Relative Humidity: 0 - 100%, non-condensing Altitude: 0 - 4,000 meters |
| Probe Dimensions | 63 cm H x 39 cm W x 75 cm L |
| Power Requirements | Universal Power Supply: 85 – 265 VAC / 50/60 Hz / 600 W |
The Lifecycle Care Program ensures GFAS-DPOL integrity and performance vital to your research mission for 3 years or 3 calls (whichever comes first). When conducting complex and time intensive laboratory or field measurements it is critical to avoid down time, and ensure data collection accuracy. The program consists of 3 key deliverables for each year or call:
- Instrument Logistics
- Instrument Integrity
- Instrument Performance
Lifecycle Care Program Includes:
LOGISTICS
- Shipping to and from Droplet Measurement Technologies facility
- Customs handling, including CARNET ATA if required
INTEGRITY
- Incoming instrument evaluation and health check
PERFORMANCE
- Software and firmware validation
- 100%-unit functionality test
- Calibration data
- Calibration report
- Certificate of calibration
At times, our technician might discover an instrument issue, which might not be covered by the Lifecycle Care Program or by our product warranty. In such case we will reach out to you with a service & repair estimate to allow you to provide us with the next steps of action.
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