Tunable Optical Profiler for Aerosol and oZone lidar (TOPAZ)
The NOAA Earth System Research Laboratory CSD designed and built the Tunable Optical Profiler for Aerosol and oZone lidar (TOPAZ). TOPAZ is capable of measuring ozone concentration in the lower troposphere from an airborne platform with uncertainties of only a few ppbv at 90-m vertical and 600-m horizontal resolution. It also provides uncalibrated aerosol backscatter profiles. TOPAZ incorporates state-of-the-art technologies to make it compact and lightweight as well as having low power consumption. These features allow it to be deployed on smaller aircraft. Its wavelength flexibility permits optimization for differing atmospheric conditions including interference from other atmospheric components and allows dual-DIAL operation.
This lidar was deployed in the Texas Air Quality Study (TexAQS) 2006 field campaign to help examine pollution development and transport in the vicinity of Houston, Texas. During the experiment, TOPAZ proved to be a useful tool for the study of urban air quality by its ability to provide detailed coverage over a wide area for the mapping of ozone and aerosol plumes from an airborne platform. Additional information obtained from the lidar data included boundary height determination and ozone plume flux measurements. More recently TOPAZ has been used to measure the ozone distribution in the Denver, Colorado area.
Typical Specifications
| Tuning range | 285-310 nm (three wavelengths) |
| Pulse energy | 0.2-0.8 mJ/pulse |
| Pulse rate | 1 kHz with pulse-to-pulse tuning capability (333 Hz for each individual wavelength) |
| Laser | Diode-pumped Nd:YLF laser quadrupled in LBO (intracavity) and CLBO (external) to 262 nm to pump Ce:LiCAF in a tunable cavity |
| Minimum range | 0.3 km |
| Maximum range | 4 km |
| Eye-safe range | 150 m |
| System weight | 800 lbs (including chiller and control electronics) |
| Dimensions | 30" x 56" x 45" laser/optics frame, 15" x 25" x 24" chiller Electronics in standard 19" equipment racks ~49" (28U) |
| System power | 3 kW, 110VAC |
| Digitizer | FPGA-based digitizer (14 bits, 100MHz sample rate) |
| Output | Real-time ozone and aerosol profiles displayed in flight. Data is recorded to a solid state disk drive. |
| Vertical/horizontal resolution | 90 m / 600 m (10 s at a flight speed of 60 m/s) |
| Accuracy | ±3 - ±15 ppbv (depends on range and ozone concentration) |
Schematic of lidar optical design
