Raymetrics S.A.

Laser Based Remote Sensing Instruments for Remote Humidity Industry - Monitoring and Testing - Meteorological Monitoring

Relative humidity (RH) is a crucial parameter for atmospheric research and Meteorology, as it represents the current state of water vapor and ambient air related to saturation.  The interest in the role of RH in the modification of aerosol, precipitation and cloud microphysics, including CCN formation, has recently increased mainly due to the crucial role of aerosol–cloud interactions in climate change. Raymetrics Lidars offer 24/7 monitoring of Atmospheric RH.

Humidity measurements at the Earth’s surface are required for meteorological analysis and forecasting, for climate studies, and for many special applications in hydrology, agriculture, aeronautical services and environmental studies, in general. They are particularly important because of their relevance to the changes of state of water in the atmosphere. data.

LR111-D300 model aerosol LIDARs are capable of being upgraded with a detection channel at 408 nm, enabling retrieval of water vapour profiles. The image below shows an example of the time evolution and vertical variability of the water vapour mixing ratio.

Temporal evolution of remote water vapour (humidity) - UTC time. LR111-D300 LIDAR systems are capable of retrieving remote humidity data during nighttime up to a range of ~6 km. PBL height is also identifiable at ~2 km. *

Raymetrics model LR111-D300 LIDAR systems are capable of retrieving remote humidity data between sunset and sunrise up to a range of approximately 6 km (with good Signal to Noise Ratio). See here for a magazine article on using LIDARs for detecting water vapour (and ash).

Comparison of historical Raymetrics LIDAR data with radiosonde data

* The water vapour mixing ratio is defined as the ratio of the mass of water vapour to the mass of dry air in a sample of the atmosphere. The water vapour profile, in mixing ratio units (g/kg), is determined by inverting the ratio of the LIDAR signals corresponding to the 355 nm-Raman shifted laser beam that is backscattered by H2O (at 408 nm) and by N2 atmospheric molecules (at 387 nm). Each vertical profile corresponds to an integration time of 3 minutes and a vertical resolution of 30 m. Calibration constant is equal to 75 (lidar returns and radiosonde data were used as the calibration method).