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Abstract
We present a Differential Absorption Lidar (DIAL) for routine measurements of tropospheric ozone profiles. This instrument is used in a project to validate OMI/AURA satellite data and is located at the RIVM in Bilthoven, The Netherlands (52°07'N, 05°12'E).
The system was built in the 1990's and has now been modernized. It operates at wavelengths in the Hartley band and is suited for daytime and nighttime operation. Under clear sky conditions, a full profile from 1 km to about 10 km altitude can be measured in approximately 90 minutes. Our measurement strategy allows observations during partially cloudy conditions, up to 4 octa.
The system is based on two frequency-quadrupled Nd:YAG lasers, operating at 30 Hz. The emitted 266 nm laser light is converted to 289 nm and 299 nm by stimulated Raman shifting in deuterium and hydrogen mixtures. The backscattered light is received by a 60 cm telescope, whose overlap function determines the lower measurement range. A mechanical chopper can block the close-range return signal to improve the linearity of the detectors in the far range.
The consistency of the measurements is checked in two ways: internally by comparing the backscatter profile with a modeled backscatter profile in a standard atmosphere (USSA 1976) and externally by comparison with weekly ozone soundings, performed close by at KNMI (52°07'N, 05°12'E).
An intensive observation campaign is scheduled for June-July 2009. Measurements from this campaign and time series from the past are presented.