Independent measurements of Raman LIDAR water vapor calibration factor

One of the goals of LIDAR scientists is to obtain long term monitoring of water vapor using Raman LIDAR [1]. Previous LIDAR research suggests that the measurement of water vapor can be improved by better analysis of the LIDAR system´s calibration factor. Currently LIDAR scientists generally use radiosonde data to calibrate LIDAR data. We are using a standard lamp calibration technique to calibrate the LIDAR data to compare with the radiosonde technique in efforts to independently calibrate the LIDAR system. The lamp calibration technique we implement here involves two motion controllers scanning a halogen lamp over the aperture of a LIDAR telescope. When we compared the calibration factor of the lamp mapping technique to the radiosonde technique we found that they agreed within 5%. Using this method, we have determined a calibration of a Raman LIDAR system with accuracy in the range of 5% [2]. Future work involves obtaining temperature measurements directly from the HURL system to improve water vapor measurements. We plan to obtain the temperature directly from the LIDAR system by extracting rotational Raman cross sections using two narrow band-pass filters and taking the ratio of the two measurements. Using the lamp calibration and the temperature measurements found directly from the LIDAR we can calculate a water vapor mixing ratio that is less dependent on radiosonde data [3].