Environmental monitoring
Express monitoring of the key water quality parameters
CALIBRATION
How we calibrate the LIF LiDAR
To recalculate fluorescence and backscattered signals in the water quality parameters concentrations, calibration curves are used. To do this, the fluorescence signal is recorded with simultaneous water sampling from the LiDAR footprint and subsequent laboratory analysis using standard methods for distinguishing phytoplankton pigments, contaminants, and organic and mineral matter in water
In the case of ground-truth data collection for validation of satellite measurements, the LiDAR survey should be made within the allowable time interval relative to the satellite overpass – as shorter as more changeable waters are. But calibration water sampling (together with lidar control measurements) can be carried out independently, before or after the under-satellite works
Calibration of 20-30 samples is obligatory for each water site. As a result, we get the possibility of remote high-speed in situ measurement by LIF LiDAR of chlorophyll a, TOC, and TSS in absolute units of concentration with a relative error of no more than 16% for chlorophyll a, and 10% for TOC and TSS (averaging over three laser pulses)
In the case of working with large satellite pixels (for example, Sentinel-3 or MODIS), the relative measurement error is even smaller due to the averaging of dozens of lidar samples inside each pixel
Examples of key water quality parameters mapping