## 2 Temperature Lidar Observations  
Vertical temperature profiles in the middle atmosphere have been obtained with Rayleigh lidar at the Observatory of Haute-Provence (OHP) located in the south of France (44\({}^{\circ}\) N, 6\({}^{\circ}\) E) within the framework of NDACC network. The Rayleigh lidar temperature datasets were downloaded from the NDACC website ([[http://www.ndsc.ncep.noaa.gov/](http://www.ndsc.ncep.noaa.gov/)]([http://www.ndsc.ncep.noaa.gov/](http://www.ndsc.ncep.noaa.gov/))). These measurements were set up in the frame of the Network for the Detection of Stratospheric Changes [25] dedicated to stratospheric ozone monitoring. The dataset consists of a series of nightly temperature profiles from 30 to 80 km starting from 1978 [22]. Routine observations are conducted during clear sky over several hours, mainly at the beginning of the night. The rate of measurements can fluctuate with time; however, due to the quality of the sky transparency and weather, 2-3 measurements per week were obtained. The principle is based on molecular scattering. The method used to retrieve temperature profiles from molecular backscattered signals and the associated errors has been described in detail by [PERSON] and [PERSON] [26]. A description of the instrumental error sources and bias has been reported by [PERSON] et al. [23]. Temperature uncertainties are negligible in the stratosphere and grow exponentially with decreasing atmospheric density, reaching approximately 5 % near 75 km and 15 % near 90 km. Since 1987, the two existing channels have been mixed together to provide a single signal for the entire height range. This is achieved in comparing both channels in the common altitude range (30-50 km) and in calculating the ratio between both channels and the high-flux nonlinearity of the high-gain channel, considering the low gain channel as a reference. The signal-induced noise (SIN) is considerably reduced using electronic gating, but it can still be identified from the very low mean background noise. It is estimated by fitting with a parabolic function the background signal between 10 km above the top of the temperature profile and 153 km. The residual atmospheric signal at high altitudes is estimated using the MSIS model. Computation of temperature profiles requires a pressure initialization. Instead of assuming that the pressure at the top of the profile is equal to the value given by the standard atmosphere model, the scale height of the pressure (which is directly related to the temperature) is adjusted in the MSIS model. Part of the actual algorithm can be found in [PERSON] et al. [23] and in [PERSON] et al. [27]. Importantly, the accuracy in determining density and temperature is directly related to photon noise and is associated with temporal and vertical resolution. Statistical noise increases with the altitude and becomes suddenly very large as the signal amplitude reaches the noise level. Relative and absolute uncertainties have been identified and quantified using simulated data [28]. Error calculation can be found in Hauchecome and Chanin [26]. For NDSC purposes, a 2-km vertical resolution constant with altitude is obtained using a Hanning filter. The integration time is about 4 h, depending on weather conditions. The amplitude of the correction of the non-linearities of the counting is determined with an accuracy of 1 K. The error due to the initialization was estimated to be equal to 15% at the initialization level. The calculation of uncertainty shows that this error becomes negligible 15 km below, as opposed to the noise statistic. The sum of these uncertainties is reported in the NDSC archive. The system has undergone successive improvements since its initial construction in 1978 [23]; however, uncertaintiesremain smaller than \(\pm\)1 K below 70 km, and potential biases were continuously evaluated with different tools [29], including intercomparisons with a mobile lidar [30]. For the present study, the data have been processed using the V6 version of the Temper code developed by LATMOS [31].