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 data example

MPD absolute humidity, backscatter ratio, and temperature profiles from the M2HATS field campaign

Photo of the 5 MPDs (Apr 2019)

Photo of the 5 MPDs (Apr 2019)

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.



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

5-10 minute actual resolution


NCAR/EOL MPD Team. (2018). MicroPulse DIAL (MPD). UCAR/NCAR - Earth Observing Laboratory.