Study of absolute detection technique with the rotational Raman lidar for atmospheric temperature

Abstract

The rotational Raman lidar is a valid tool to profile atmospheric temperature. But the fact that its proper operation generally needs a certain collocated device for calibration seriously restricts application in the meteorology and environment fields. We propose an absolute detection technique of atmospheric temperature with the rotational Raman lidar, which is based on the dependence of rotational Raman spectral envelope on temperature. To retrieve atmospheric temperature without calibration, six rotational Raman spectra of nitrogen molecule are chosen from the anti-Strokes branch. A temperature retrieval algorithm is presented and analyzed based on the least square principle. A two-cascade Raman spectroscopic filter is constructed by one first-order diffraction grating, one convex lens, one linear fiber array and 6 groups of fiber Bragg gratings. This lidar is configured with a 300-mJ pulse energy laser and a 250-mm clear aperture telescope. Simulation results show that it can extract the nitrogen molecules rotational Raman spectral lines, and that atmospheric temperature profile obtained through absolute retrieval algorithm can be up to 3.5 km with less than 0.5-K deviation within 17 minutes interval.