The possibilities of retrieving the mean relative concentration of methane using pseudo-inverse matrices, fully connected and convolutional neural networks based on signals from the Earth received by a 450 km orbit space-based lidar are considered. It is shown that the random error of methane concentration retrieving for lidar with laser pulse energy of 9 mJ and repetition rate 20 Hz, receiving system size of 68 cm, resolution of 50-60 km is not higher than 30 ppb.
A technique is developed for lidar measurements of atmospheric gases on the basis of differential absorption lidar and differential optical absorption spectroscopy. The DIAL-DOAS technique is tested for possibilities of lidar sounding of trace atmospheric gases. Simulation results of lidar measurements of trace atmospheric gases in the 3–4 μm range are described.
We consider the algorithms that implement a broadband (‘multiwave’) radiative transfer with allowance for multiple (aerosol) scattering and absorption by water vapor. In the spectral range of 0.9 – 0.98 μm, a closed numerical simulation of modifications of the supercontinuum component of a probing femtosecond pulse is performed. The ability of water vapor concentration measurements with white-light femtosecond lidar on the path 100–200 m is discussed.
Possibilities of measuring the CO2 column concentration by spaceborne integrated path differential lidar (IPDA) signals in the near IR absorption bands are investigated. It is shown that coherent detection principles applied in the nearinfrared spectral region promise a high sensitivity for the measurement of the integrated dry air column mixing ratio of the CO2. The simulations indicate that for CO2 the target observational requirements (0.2%) for the relative random error can be met with telescope aperture 0.5 m, detector bandwidth 10 MHz, laser energy per impulse 0.3 mJ and averaging 7500 impulses. It should also be noted that heterodyne technique allows to significantly reduce laser power and receiver overall dimensions compared to direct detection.
High measurement sensitivity of troposphere CO2 and CH4 is expected from using of integrated path differential absorption (IPDA) lidar, where the strong lidar echoes on two wavelengths from cloud tops or the Earth’s take place. We consider a software system for the radiation transport simulation in the atmosphere by Monte-Carlo method that applied in the greenhouse gas (CH4 and CO2) sensing space-based IPDA-lidar. This software is used to evaluate the accuracy of measurement of the green house gas concentration. The paper investigates the impact of multiple scattering in presence of clouds. So multiple scattering can influence on signal power, but differential absorption method eliminates this drawback.
The spectral transparency method has been tested experimentally in the terahertz spectral region. The aerosol particle size distribution spectrum has been reconstructed from measurements of the spectral transparency coefficient by the method of Time-Domain THz spectroscopy. The particle size distribution spectra obtained by the spectral transparency method in the terahertz region and by the method of optical microscopy have been compared.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print format on
SPIE.org.