A review of progress and applications of pulsed doppler wind LiDARs

Doppler wind LiDAR (Light Detection And Ranging) makes use of the principle of optical Doppler shift between the reference and backscattered radiations to measure radial velocities at distances up to several kilometers above the ground. Such instruments promise some advantages, including its large scan volume, movability and provision of 3-dimensional wind measurements, as well as its relatively higher temporal and spatial resolution comparing with other measurement devices. In recent decades, Doppler LiDARs developed by scientific institutes and commercial companies have been well adopted in several real-life applications. Doppler LiDARs are installed in about a dozen airports to study aircraft-induced vortices and detect wind shears. In the wind energy industry, the Doppler LiDAR technique provides a promising alternative to in-situ techniques in wind energy assessment, turbine wake analysis and turbine control. Doppler LiDARs have also been applied in meteorological studies, such as observing boundary layers and tracking tropical cyclones. These applications demonstrate the capability of Doppler LiDARs for measuring backscatter coefficients and wind profiles. In addition, Doppler LiDAR measurements show considerable potential for validating and improving numerical models. It is expected that future development of the Doppler LiDAR technique and data processing algorithms will provide accurate measurements with high spatial and temporal resolutions under different environmental conditions

Lower Atmosphere Meteorology

The Atmosphere Special Issue “Lower Atmosphere Meteorology” deals with the meteorological processes that occur in the layer of the atmosphere close to the surface. The interaction between the biosphere and the atmosphere is made through the lower layer and can greatly influence living beings and materials. The analysis of the meteorological parameters provides a better understanding of processes within the lower atmosphere and involved in air pollution, climate, and weather. The mixed layer height, the wind speed, and the air parcel trajectory have a relevant interest due to their marked impact on population and energy production. The research also comprises aerosols, clouds, and precipitation, analysing their spatiotemporal variations. This issue addresses features of gases in the atmosphere and anthropogenic greenhouse emission estimates, which are also conditioned by the lower atmosphere meteorology

Exploring Tornadogenesis with High-Resolution Simulations Initialized with Real Data

Despite large advances in our understanding of tornadogenesis over the past fifty years, a comprehensive dynamical understanding of the processes behind tornado formation remains elusive. The purpose of this dissertation is to augment the current body of knowledge by exploring the dynamical processes responsible for tornadogenesis using high-resolution numerical weather prediction. To accomplish this goal, two high-resolution numerical simulations of tornadic storms were performed with the Advanced Regional Prediction System (ARPS) model. Both simulations were nested within lower-resolution domains that were initialized via high-frequency (5 min) data assimilation cycles conducted with the ARPS three dimensional variational (3DVAR) data assimilation package. Radar reflectivity and radial velocity, in addition to conventional observations, were assimilated in these five-minute assimilation cycles. In both simulations, tornadogenesis timing and location were well forecast.The first simulation examined used 100-m grid spacing to simulate a tornadic mesovortex. The mesovortex was one of two tornadic mesovortices spawned by a mesoscale convective system (MCS) that traversed southwest and central Oklahoma on 8-9 May 2007.Results from the 100-m simulation provide a detailed picture of the development of a mesovortex that produces a sub-mesovortex-scale tornado-like vortex (TLV). Closer examination of the genesis of the TLV suggests that a strong low-level updraft is critical in converging and amplifying vertical vorticity associated with the mesovortex. Vertical cross-sections and backward trajectory analyses from this low-level updraft reveal that the updraft is the upward branch of a strong rotor that forms just northwest of the simulated TLV. The horizontal vorticity in this rotor originates in the near surface inflow and is caused by surface friction. An additional simulation with surface friction turned off does not produce a rotor, strong low-level updraft, or TLV. Comparison with previous two-dimensional numerical studies of rotors in the lee of mountains shows striking similarities to the rotor formation presented herein.This study is the first to simulate, analyze, and propose a dynamical mechanism responsible for mesovortex tornadogenesis. This dynamical mechanism is summarized in a four-stage conceptual model that describes the evolution of the event from mesovortexgenesis through rotor development and finally TLV genesis and intensification.The second case examined is a 50-m grid spacing simulation of the 8 May 2003 Oklahoma City tornadic supercell. This thunderstorm produced a strong, long-track tornado that produced F-4 damage on the south side of Oklahoma City. A 40-min forecast run on the 50-m grid produces two tornadoes that track within 10 km of the location of the observed long-track tornado.The development of both simulated tornadoes is analyzed and presented with unprecedented detail in order to determine the processes responsible for tornadogenesis. This analysis reveals that tilting of low-level vorticity generated by surface drag plays an important role in the origin of vertical vorticity near the ground for both tornadoes. This result represents the first time that such a mechanism has been shown to be responsible for generating near-surface vertical vorticity leading to tornadogenesis. Two conceptual models are presented that summarize the development of the first and second tornado, respectively.A simulation run without surface drag was found to be considerably different from the simulated with drag included. A tornado still developed in the no-drag simulation, but it was shorter-lived and took a substantially different track than the tornadoes in the drag simulation. Tilting of environmental vorticity in an outflow surge was determined to be the most likely cause of the tornado in the no-drag simulation.Baroclinic vorticity generation was found to be unimportant in the development of the tornadoes in both the drag and the no-drag simulation. This is a marked departure from current theories of tornadogenesis and the broader implications of this finding, in addition to the important discovery of the substantial role of surface drag in the origins of near-surface vertical vorticity in the drag simulation, are discussed.Errors in trajectory analysis are also discussed. A simple, one-dimensional flow is invoked to demonstrate the sensitivities of trajectory analysis to divergent/convergent flows. Possible remedies and alternatives to trajectory analysis are proposed for future work

CIRA annual report FY 2016/2017

Reporting period April 1, 2016-March 31, 2017

3D-in-2D Displays for ATC.

This paper reports on the efforts and accomplishments of the 3D-in-2D Displays for ATC project at the end of Year 1. We describe the invention of 10 novel 3D/2D visualisations that were mostly implemented in the Augmented Reality ARToolkit. These prototype implementations of visualisation and interaction elements can be viewed on the accompanying video. We have identified six candidate design concepts which we will further research and develop. These designs correspond with the early feasibility studies stage of maturity as defined by the NASA Technology Readiness Level framework. We developed the Combination Display Framework from a review of the literature, and used it for analysing display designs in terms of display technique used and how they are combined. The insights we gained from this framework then guided our inventions and the human-centered innovation process we use to iteratively invent. Our designs are based on an understanding of user work practices. We also developed a simple ATC simulator that we used for rapid experimentation and evaluation of design ideas. We expect that if this project continues, the effort in Year 2 and 3 will be focus on maturing the concepts and employment in a operational laboratory settings

Advances in Hurricane Research

This book provides a wealth of new information, ideas and analysis on some of the key unknowns in hurricane research. Topics covered include the numerical prediction systems for tropical cyclone development, the use of remote sensing methods for tropical cyclone development, a parametric surface wind model for tropical cyclones, a micrometeorological analysis of the wind as a hurricane passes over Houston, USA, the meteorological passage of numerous tropical cyclones as they pass over the South China Sea, simulation modelling of evacuations by motorised vehicles in Alabama, the influence of high stream-flow events on nutrient flows in the post hurricane period, a reviews of the medical needs, both physical and psychological of children in a post hurricane scenario and finally the impact of two hurricanes on Ireland. Hurricanes discussed in the various chapters include Katrina, Ike, Isidore, Humberto, Debbie and Charley and many others in the North Atlantic as well as numerous tropical cyclones in the South China Sea

The 1991 research and technology report, Goddard Space Flight Center

The 1991 Research and Technology Report for Goddard Space Flight Center is presented. Research covered areas such as (1) earth sciences including upper atmosphere, lower atmosphere, oceans, hydrology, and global studies; (2) space sciences including solar studies, planetary studies, Astro-1, gamma ray investigations, and astrophysics; (3) flight projects; (4) engineering including robotics, mechanical engineering, electronics, imaging and optics, thermal and cryogenic studies, and balloons; and (5) ground systems, networks, and communications including data and networks, TDRSS, mission planning and scheduling, and software development and test

Research and technology, 1990: Goddard Space Flight Center

Goddard celebrates 1990 as a banner year in space based astronomy. From above the Earth's obscuring atmosphere, four major orbiting observatories examined the heavens at wavelengths that spanned the electromagnetic spectrum. In the infrared and microwave, the Cosmic Background Explorer (COBE), measured the spectrum and angular distribution of the cosmic background radiation to extraordinary precision. In the optical and UV, the Hubble Space Telescope has returned spectacular high resolution images and spectra of a wealth of astronomical objects. The Goddard High Resolution Spectrograph has resolved dozens of UV spectral lines which are as yet unidentified because they have never before been seen in any astronomical spectrum. In x rays, the Roentgen Satellite has begun returning equally spectacular images of high energy objects within our own and other galaxies