BCPD
Back-scatter Cloud Probe with Polarization Detection
The BCPD measures cloud droplet size distributions, which are then used to derive the total number concentrations, liquid water content (LWC), median volume diameter (MVD), and effective diameter (ED). The BCPD’s non-intrusive optical housing allows use in a range of ground-based or airborne applications with no contamination from ice crystal shattering and no airflow distortion.
TALK TO AN EXPERTDiscriminate between ice and water particles with the BCPD’s polarization feature. For example, use the BCPD to detect when an aircraft encounters abnormally high concentrations of ice crystals.
Minimize airflow disturbance and enable undisturbed particle measurement with the BCPD’s aerodynamic design. Mount the BCPD easily on aircraft, even when space is at a premium.
Monitor multiple output variables like total particles, average transit time, over-range particles, and various probe health indicators. Get particle classification by size in histogram form.
Depend on automatic correction for drifts in polarization signals through the dynamic thresholding feature.
Program the instrument's sample rate and size bin thresholds. Plus, get size distributions accumulated in the probe, with serial transmission to a computer via any standard RS-422 communications port.
PADS – Particle Analysis and Display System
The BCPD utilizes optional PADS software that provides a user-friendly virtual instrument panel for the control, data display, and data logging of the BCPD instrument. For instance, the program enables the user to do the following tasks:
- Start data recording and sampling
- View a size histogram of particles measured by the BCPD
- View particle volume and number concentrations, as well as Liquid Water Content (LWC), Median Volume Diameter (MVD) and Effective Diameter (ED)
- Monitor instrument operational parameters like optic block temperature, electronic box temperature, and the baseline monitor voltage
Particle light detection and polarization detection
- Particles passing through the laser beam scatter light in all directions.
- Some of this light is transmitted within a cone with subtending angles between 143° and 169° (156° ± 13°). These photons are directed onto a photodetector that converts their photon pulses into electrical pulses, which are then transmitted to a signal processor that amplifies and digitizes them.
- Mie theory is used to determine the particle’s size from the peak amplitude of the scattering signal. At programmable intervals, the BCPD sends out a particle size distribution. This information is then used to determine particle number concentration.
- A beam splitter separates P-polarized from S-polarized light, and a comparison of the components allows separation of water droplets from ice crystals.
| Parameter | Specification |
|---|---|
| Measured Parameters | Single-particle light scattering:
|
| Auxiliary Parameters |
|
| Derived Parameters |
|
| Particle Size Range | 2 - 50 µm |
| Number of Size Bins |
|
| Number of Concentration Range | 0 - 1,000 particles/cm3 |
| Air Speed Range | 10 - 250 m/sec |
| Sampling Frequency | Selectable, .04 sec to 20 sec |
| Light Collection Angles | Center-line: 155°, +/- 18.5° |
| Laser | 658 nm |
| Laser Power | 85 mW or less |
| Data System Interface | RS-422 serial interface |
| Environmental Operating Conditions |
|
| Weight |
|
| Probe Dimensions |
|
| Electronic Box Dimensions | 21.6 L cm x 12 cm W x 8.2 cm H |
| Power Requirements | 28 VDC, 5 A for system and heaters |
The Lifecycle Care Program ensures BCPD 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.
The backscatter cloud probe – a compact low-profile autonomous optical spectrometer
We demonstrate the [BCP's] capability for delivering useful long-term climatological, as well as aviation performance information, across a wide range of environmental conditions.
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Properties of small cirrus ice crystals from commercial aircraft measurements and implications for flight operations
Measurements of cloud ice crystal size distributions made by a backscatter cloud probe (BCP) mounted on five commercial airliners...
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Upper tropospheric water vapour and its interaction with cirrus clouds as seen from IAGOS long-term routine in-situ observation
Here, we present the analysis of 15 months of simultaneous observations of relative humidity with respect to ice (RHice) and ice crystal number concentration in cirrus (Nice) from July 2014 to October 2015.
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