|Universitatea Bucuresti, Facultatea de Fizica
||November 20 2019 12:22:11|
Model 3563 Integrating Nephelometer
Three-wavelength Integrating Nephelometer with backscatter shutter (Model 3563) is designed for short- and long-term measurements of the light-scattering coefficient of atmospheric and laboratory aerosols. Particularly well-suited for studies involving climate, visibility, and air quality, the Model 3563 offers these key features:
• Sensitivity to light-scattering coefficients as low as 2.0 × 10-7 per meter (60-second averaging time)
• High vacuum integrity that ensures accurate measurements, even when sampling much cleaner or more polluted air than the instrument’s immediate surroundings
• Real-time background subtraction of Rayleigh scattering of the air itself from the total scattering signal by measuring sample pressure and temperature
• Real-time, PMT dark-current and light-source compensation using a rotating reference chopper
• Measurement of total (7- to 170-degree) and backscatter (90- to 170-degree) signals using a rotating backscatter shutter to block the illuminated sample volume from 7 to 90 degrees
• Simultaneous three-color detection for wavelength- dependent measurements
Other features include:
• Internal relative-humidity and temperature sensors
• Built-in heater to minimize condensation on the instrument walls caused by high humidity
• Minimal sample heating to preserve the relative humidity of the aerosol sample
• Onboard microprocessors to collect and process data, control all instrument functions, and communicate with an external computer
• A variety of signal outputs to accommodate various computers and data loggers
• Automatic filter loop to purge the sample volume with clean air for zero-reference calibration
• Minimal aerosol sample loss through the system
• Selectable averaging time (from 1 to 4096 seconds)
• Internal clock with battery backup
TSI Integrating Nephelometers are designed specifically for studies of direct radiative forcing of the Earth’s climate by aerosol particles, or studies of ground-based or airborne atmospheric visual air quality in clean areas. They may also be used as an analytical detector for aerosol particles whenever the parameter of interest is the light-scattering coefficient of the particles after a pretreatment step, such as heating, humidification, or segregation by size. The light-scattering coefficient is a highly variable aerosol property. Integrating Nephelometers measure the angular integral of light scattering that yields the quantity called the scattering coefficient, which is used in the Beer-Lambert Law to calculate total light extinction.
Figure1. The backscattering coefficients daily (left) and monthly averages, respectively (right).
Figure 2. Angstrom parameter computed for one year from scattering coefficients data.
Figure3. Backscattering coefficients and backscattering ratio values for a clear day.
Figure 4. Angstrom parameter values for a chosen clean day.
Figure 5. A turbid day backscattering coefficients and them corresponding angstrom parameters.
The Vaisala Ceilometer CL-31 is a compact and lightweight instrument for cloud base height and vertical visibility measurements. It is able to detect three cloud layers simultaneously. The CL31 is ideal for aviation as well as meteorological applications.
The CL31 employs a pulsed diode laser LIDAR technology, where short powerful laser pulses are sent out in a vertical or near vertical direction.
The reflection of light (backscatter) caused by clouds, pp or other obscuration is analyzed and used to determine the cloud base.
Measurement range: 0...7.5 km (0...25,000 ft)
Measurement interval: 2...120 s
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