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This research effort assesses the performance of the High Energy Laser End-to-End Operational Simulation (HELEEOS) Climatological C2n optical turbulence model. Path-integrated C2n values of two HELEEOS optical turbulence pro les at 3 distinct operational altitudes are compared to values determined from measured thermosonde data. HELEEOS desert and mid-latitude sites are selected from the Extreme and Percentile Environmental Reference Tables (ExPERT) database for comparison to the thermosonde data. Statistical equivalence of the two datasets is determined through a Design of Experiments (DOE) factorial test to within 80% confidence. The HELEEOS profiles are shown to be equivalent to the thermosonde data for a 500 m boundary layer profile. Deterministic values of the 80% confidence intervals are established. The HELEEOS optical turbulence model is used as the input turbulence model for wave optics simulations. Long-term spot size measurements show that HELEEOS outperforms empirical turbulence models by as much as 17%. Recommendations are made to improve the HELEEOS graphical outputs and reference tables.

This paper proposed several approaches for estimating the optical turbulence of the Earth's atmosphere and their effect on solar images' resolution using ground-based telescopes based on von Kárman, Kolmogorov, and modified von Kárman PSDs models. The results showed a strong correlation coefficient for the modified von Kármán model of atmospheric representation. As can be seen in the case where solar adaptive optics have been properly designed, they typically decrease aberration considerably and provide greatly improved imagery.

Due to the threat of a possible global climate change and the greenhouse effect caused by constituents of anthropogenic origin in the atmosphere, air quality has become a major environmental issue. As a consequence, emissions into the atmosphere need to be monitored and controlled. Measurement of Atmospheric Emissions presents technologies for emission control and analysis from industrial and energy plants. The author explains the physical and chemical basis before proceeding to the practical performance. This publication provides the reader with the knowledge necessary to critically analyze and investigate emission measurement techniques. It will be of great interest to researchers and engineers in the fields of environmental technology and air pollution control. It will assist in the choice of the most appropriate instruments for various purposes and circumstances

Laser systems are finding a home in many military applications - such as Space Situational Awareness, imaging and weapons systems. With an increasing focus on programs that entail atmospheric propagations, there is a need for a cost effective method of performing proof-of-concept demonstrations. The use of one SLM (single phase screen) to model atmosphere has been investigated previously with promising results. However, some effects cannot be captured with a single SLM. This paper focuses on the addition of a second SLM and quantifying the results. Multiple screens will allow the user to independently control the Fried parameter, the isoplanatic angle, and Rytov Variance. The research is comprised of simulation and experiment. The simulation demonstrates the ability to accurately model atmospheric effects with two phase screens. Based on the simulation, a hardware implementation was tested in the lab. This thesis describes the experimental set-up and results based on measurement of phase and intensity of the propagated field. It was noted that while analytic results are replicated in simulation, similar results in the lab were difficult to achieve.

Atmospheric lidar measurements were carried out at Elandsfontein measurement station, on the eastern Highveld approximately 150 km east of Johannesburg in South Africa throughout 2010. The height of the planetary boundary layer (PBL) top was continuously measured using a Raman lidar, PollyXT (POrtabLe Lidar sYstem eXTended). High atmospheric variability together with a large surface temperature range and significant seasonal changes in precipitation were observed, which had an impact on the vertical mixing of particulate matter, and hence, on the PBL evolution. The results were compared to radiosondes, CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) spaceborne lidar measurements and three atmospheric models that followed different approaches to determine the PBL top height. These models included two weather forecast models operated by ECMWF (European Centre for MediumrangeWeather Forecasts) and SAWS (South AfricanWeather Service), and one mesoscale prognostic meteorological and air pollution regulatory model TAPM (The Air Pollution Model). The ground-based lidar used in this study was operational for 4935 h during 2010 (49% of the time). The PBL top height was detected 86% of the total measurement time (42% of the total time). Large seasonal and diurnal variations were observed between the different methods utilised. High variation was found when lidar measurements were compared to radiosonde measurements. This could be partially due to the distance between the lidar measurements and the radiosondes, which were 120 km apart. Comparison of lidar measurements to the models indicated that the ECMWF model agreed the best with mean relative difference of 15.4 %, while the second best correlation was with the SAWS model with corresponding difference of 20.1 %. TAPM was found to have a tendency to underestimate the PBL top height. The wind speeds in the SAWS and TAPM models were strongly underestimated which probably led to underestimation of the vertical wind and turbulence and thus underestimation of the PBL top height. Comparison between ground-based and satellite lidar shows good agreement with a correlation coefficient of 0.88. On average, the daily maximum PBL top height in October (spring) and June (winter) was 2260m and 1480 m, respectively. To our knowledge, this study is the first long-term study of PBL top heights and PBL growth rates in South Africa ; Partly supported by the European Union (in project EUCAARI)

A formula for the average fade time of the intensity of a spherical optical wave travelling through atmospheric turbulence is developed. The model employed involves isotropic, homogeneous statistics using a lognormal distribution for the channel. The analysis is based on the fact that the logarithm of the irradiance is normally distributed and uses the work of S. O. Rice who developed such an expression for a zero mean, Gaussian process. The analysis employs the covariance function and the Taylor frozen turbulence hypothesis which results in an expression for the autocorrelation function.

Icing conditions including atmospheric liquid water content (LWC) and size distribution of droplets were recorded close to the top of Mt. Åreskutan, 1260-m above sea level, Sweden, a place known for frequent severe icing. The findings are comparatively analyzed. Combitech IceMonitor was used to measure the ice load, and HoloOptics T41 was used to measure the atmospheric icing rate. A method to translate the digital output from HoloOptics T41 to a value between 0 and 100 is described and used. Two instruments were used for measuring LWC and the median volume diameter (MVD). We created a model of icing intensity based on the k-nearest neighbor (KNN) using wind speed, LWC, and MVD as input. The result indicates that more learning data decrease the error. An heuristic model of erosion/ablation was added to simulate the ice load, and the result was compared with that of the standard Makkonen ice load model. The Makkonen model is suitable for estimating the ice load using a 1-h temporal resolution. With a 1-min temporal resolution, the erosion/ablation needs to be modeled and included. Our observations show that conditions can alternate between icing and erosion/ablation within 1 min during an icing event. ; Funding details: European Regional Development Fund, FEDER; Funding details: Energimyndigheten, 37268-1; Funding text 1: Manuscript received July 30, 2019; revised December 30, 2019; accepted December 31, 2019. Date of publication January 15, 2020; date of current version June 24, 2020. This work was supported in part by Swedish Energy Agency under Project 37268-1 and in part by the European Union Regional Development Fund through the SMART Project. The Associate Editor coordinating the review process was Huang-Chen Lee. (Corresponding author: Stefani Rydblom.) Stefani Rydblom is with the RISE Research Institute of Sweden, 852 30 Sundsvall, Sweden (e-mail: stefani.rydblom@ri.se).