Algorithm improvement and validation of National Institute for Environmental Studies ozone differential absorption lidar at the Tsukuba Network for Detection of Stratospheric Change complementary station

Abstract

Recently, a data processing and retrieval algorithm (version 2) for ozone, aerosol, and temperature lidar measurements was developed for an ozone lidar system at the National Institute for Environmental Studies (NIES) in Tsukuba (36 degrees N,140 degrees E), Japan. A method for obtaining the aerosol boundary altitude and the aerosol extinction-to-backscatter ratio in the version 2 algorithm enables a more accurate determination of the vertical profiles of aerosols and a more accurate correction of the systematic errors caused by aerosols in the vertical profile of ozone. Improvements in signal processing are incorporated for the correction of systematic errors such as the signal-induced noise and the dead-time effect. The mean vertical ozone profiles of the NIES ozone lidar were compared with those of the Stratospheric Aerosol and Gas Experiment II (SAGE II); they agreed well within a 5% relative difference in the 20-40 km altitude range and within 10% up to 45 km. The long-term variations in the NIES ozone lidar also showed good coincidence with the ozonesonde and SAGE II at 20, 25, 30, and 35 km. The temperatures retrieved from the NIES ozone lidar and those given by the National Center for Environmental Prediction agreed within 7 K in the 35-50 km range.

Reevaluation of long‐term Umkehr data and ozone profiles at Japanese stations

“…However, the offset between two systems is almost constant (from 5 ∼ 10%) in layers 4 to 7. These characteristics are consistent with results reported in SAGE‐II and LDR comparisons with precision less than 10% [ Nakane et al , 1993; Park et al , 2006].…”

“…The optical system of the lidar was altered in 1990 and 1995. Especially since 1995, accuracy in layers below 20 km altitude has been greatly improved [ Park et al , 2006]. For this study, we use the newest 553 profiles collected over the 1988−2007 period, as published in the NDACC site (http://www.ndsc.ncep.gov/), and unpublished data thereafter.…”

“…Satellite observation provides homogeneous global data, but the period of most data records is confined to after the 1980s [ Bhartia et al , 1981, 1996, 2004]. Lidar and millimeter wave data have even shorter time records [ Nakane et al , 1993; Park et al , 2006; Nakazato et al , 2007]. Umkehr observations provide data at many stations where total ozone observation with Dobson instruments started in late 1950s [ Dütsch , 1957, 1959].…”

Lidar observation of long-term trends and variations of stratospheric ozone and temperature over Tsukuba, Japan

“…The lidar system has been in operation since 1988, and several replacements and improvements have been made since it was first installed (Nakane et al 1992a(Nakane et al , 1992b. The system parameters and improvements were presented in detail by Park et al 2006. Currently, the NIES ozone lidar system uses wavelength channels of 308/355 nm (for the Mie/ Rayleigh scattering DIAL mode) and 332/386 nm (for the Raman scattering DIAL mode).…”

“…Photoelectrical pulses from the PMTs are processed by discriminators and are recorded by photon counters. In this study, we applied an improved data processing and retrieval algorithm (version 2) for ozone (Park et al 2006). This algorithm removed systematic errors in the signals (background signals, signal-induced noise and dead-time corrections) as well as errors due to the scattering and extinction of the atmosphere (air molecule extinction correction and aerosol corrections).…”