In-Orbit Attitude Determination of the UVSQ-SAT CubeSat Using TRIAD and MEKF Methods.

Ultraviolet and infrared sensors at high quantum efficiency on-board a small satellite (UVSQ-SAT) is a CubeSat dedicated to the observation of the Earth and the Sun. This satellite has been in orbit since January 2021. It measures the Earth's outgoing shortwave and longwave radiations.

Tentative detection of clear-air turbulence using a ground-based Rayleigh lidar.

Atmospheric gravity waves and turbulence generate small-scale fluctuations of wind, pressure, density, and temperature in the atmosphere. These fluctuations represent a real hazard for commercial aircraft and are known by the generic name of clear-air turbulence (CAT). Numerical weather prediction models do not resolve CAT and therefore provide only a probability of occurrence.

Tidal effects on stratospheric temperature series derived from successive advanced microwave sounding units.

Stratospheric temperature series derived from the Advanced Microwave Sounding Unit (AMSU) on board successive NOAA satellites reveal, during periods of overlap, some bias and drifts. Part of the reason for these discrepancies could be atmospheric tides as the orbits of these satellites drifted, inducing large changes in the actual times of measurement. NOAA 15 and 16, which exhibit a long period of overlap, allow deriving diurnal tides that can correct such temperature drifts.

Description and evaluation of a tropospheric ozone lidar implemented on an existing lidar in the southern subtropics.

Rayleigh-Mie lidar measurements of stratospheric temperature and aerosol profiles have been carried out at Reunion Island (southern tropics) since 1993. Since June 1998, an operational extension of the system is permitting additional measurements of tropospheric ozone to be made by differential absorption lidar. The emission wavelengths (289 and 316 nm) are obtained by stimulated Raman shifting of the fourth harmonic of a Nd:YAG laser in a high-pressure deuterium cell.

Implementation and validation of a Raman lidar measurement of middle and upper tropospheric water vapor.

Implementation of a Raman lidar measurement of middle and upper tropospheric water vapor is described for a system that uses a 532-nm exciting wavelength, fiber-optic signal transfer, and Q-branch selection. Particular attention is given to the minimization of systematic biases introduced by fluorescent reemission of energy associated with elastic backscatter returns. We compare lidar profiles with collocated radiosonde measurements by using the Vaisala H-Humicap capacitive captor.

An instrumented station for the survey of ozone and climate change in the southern tropics.

The assessment of changes induced by human activities on Earth atmospheric composition and thus on global climate requires a long-term and regular survey of the stratospheric and tropospheric atmospheric layers. The objective of this paper is to describe the atmospheric observations performed continuously at Reunion Island (55.5 degrees east, 20.

Methodological uncertainties in multi-regression analyses of middle-atmospheric data series.

Multi-regression analyses have often been used recently to detect trends, in particular in ozone or temperature data sets in the stratosphere. The confidence in detecting trends depends on a number of factors which generate uncertainties. Part of these uncertainties comes from the random variability and these are what is usually considered.

Improved retrievals of the optical properties of cirrus clouds by a combination of lidar methods.

We focus on improvement of the retrieval of optical properties of cirrus clouds by combining two lidar methods. We retrieve the cloud's optical depth by using independently the molecular backscattering profile below and above the cloud [molecular integration (MI) method] and the backscattering profile inside the cloud with an a priori effective lidar ratio [particle integration (PI) method]. When the MI method is reliable, the combined MI-PI method allows us to retrieve the optimal effective lidar ratio.

Stratospheric temperature monitoring using a vibrational Raman lidar. Part 1: aerosols and ozone interferences.

Lidar measurements of temperature for the upper troposphere and lower stratosphere are commonly derived by the Raman technique. Lidar signals derived from vibrational Raman processes have been subjected to numerous simulation tests to examine their sensitivity to the presence of aerosols and ozone in the atmosphere. The influence of aerosols characteristics (wavelength dependence of aerosol extinction and particle phase function) and of ozone concentration on Raman temperature profiles is estimated.

Review of ozone and temperature lidar validations performed within the framework of the Network for the Detection of Stratospheric Change.

The use of assimilation tools for satellite validation requires true estimates of the accuracy of the reference data. Since its inception, the Network for Detection of Stratospheric Change (NDSC) has provided systematic lidar measurements of ozone and temperature at several places around the world that are well adapted for satellite validations. Regular exercises have been organised to ensure the data quality at each individual site.

Stratosphere temperature measurement using Raman lidar.

Temperature measurements using vibrational Raman scattering from molecular nitrogen were performed simultaneously with temperature obtained by Rayleigh scattering in the amplitude range between 12 and 30 km. The downward extension of the Rayleigh temperature described in this paper leads to the possibility of obtaining a continuous temperature profile from 12 to nearly 100 km. The temperature profiles have been obtained using an instrument made up basically as a Rayleigh lidar with an extra channel.