MicroPulse DIAL (MPD)
The MicroPulse Differential Absorption Lidar (MicroPulse DIAL, or MPD) is a compact, field-deployable, eye-safe lidar that offers continuous unattended monitoring of water vapor, temperature, and quantitative cloud/aerosol properties in the lower troposphere. A network of five water vapor MPD units has been constructed with four currently available to the research community. These instruments can be used to advance knowledge in a variety of areas, including the temporal and spatial distribution of boundary layer temperature and water vapor, convection initiation, and land-atmosphere exchange.
MPD is a combination of three lidars in one unit. A water vapor DIAL measures absolute humidity, a High Spectral Resolution Lidar measures calibrated aerosol backscatter coefficient, and an oxygen DIAL measures temperature. These techniques provide accurate and calibration-free measurements requiring a minimal set of assumptions.
The use of a diode-laser-based architecture has distinct benefits. The lasers are considerably more compact, reliable, and less expensive than typically used for lidar instrumentation. The transmitted laser beam is eye-safe and invisible (Class 1M). For high-quality daytime operation, suppression of the solar background is achieved with a narrow receiver field-of-view and extremely narrow-band optical filters. The received light is measured with single photon counting detectors.
Specifications
Parameter | Specification | |
Nominal Wavelengths | 828 nm, 770 nm | |
Pulse length | 0.6 μs to 1.0 μs | |
Nominal Pulse Energy | 5 µJ | |
Pulse repetition rate | 7-9 kHz | |
Receiver Field of View | 100 µrad | |
Receiver bandpass | 10-20 pm full-width half max) | |
Vertical resolution | 150 m | |
Vertical range | 250-4000 m | |
Temporal resolution |
2-sec sample resolution 1-40 min (variable dependent) resolution |
NCAR/EOL MPD Team. (2018). MicroPulse DIAL (MPD). UCAR/NCAR - Earth Observing Laboratory. https://doi.org/10.5065/d6st7nkg.