The Hybrid Single-Particle Lagrangian Integrated Trajectory model (HYSPLIT), developed by NOAA’s Air Resources Laboratory, is one of the most widely used models for atmospheric trajectory and dispersion calculations. We present the model’s historical evolution over the last 30 years from simple hand-drawn back trajectories to very sophisticated computations of transport, mixing, chemical transformation, and deposition of pollutants and hazardous materials. We highlight recent applications of the HYSPLIT modeling system, including the simulation of atmospheric tracer release experiments, radionuclides, smoke originated from wild fires, volcanic ash, mercury, and wind-blown dust.

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NOAA’s HYSPLIT Atmospheric Transport and Dispersion Modeling System

This comprehensive text and reference work on numerical weather prediction, first published in 2002, covers not only methods for numerical modeling, but also the important related areas of data assimilation and predictability. It incorporates all aspects of environmental computer modeling including an historical overview of the subject, equations of motion and their approximations, a modern and clear description of numerical methods, and the determination of initial conditions using weather observations (an important science known as data assimilation). Finally, this book provides a clear discussion of the problems of predictability and chaos in dynamical systems and how they can be applied to atmospheric and oceanic systems. Professors and students in meteorology, atmospheric science, oceanography, hydrology and environmental science will find much to interest them in this book, which can also form the basis of one or more graduate-level courses.

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Atmospheric Modeling, Data Assimilation and Predictability

This article describes the governing equations, computational algorithms, and other components entering into the Community Multiscale Air Quality (CMAQ) modeling system. This system has been designed to approach air quality as a whole by including state-ofthe-science capabilities for modeling multiple air quality issues, including tropospheric ozone, fine particles, acid deposition, and visibility degradation. CMAQ was also designed to have multiscale capabilities so that separate models were not needed for urban and regional scale air quality modeling. By making CMAQ a modeling system that addresses multiple pollutants and different spatial scales, it has a “one-atmosphere” perspective that combines the efforts of the scientific community. To implement multiscale capabilities in CMAQ, several issues (such as scalable atmospheric dynamics and generalized coordinates), which depend on the desired model resolution, are addressed. A set of governing equations for compressible nonhydrostatic atmospheres is available to better resolve atmospheric dynamics at smaller scales. Because CMAQ is designed to handle scale-dependent meteorological formulations and a large amount of flexibility, its governing equations are expressed in a generalized coordinate system. This approach ensures consistency between CMAQ and the meteorological modeling system. The generalized coordinate system determines the necessary grid and coordinate transformations, and it can accommodate various vertical coordinates and map projections. The CMAQ modeling system simulates various chemical and physical processes that are thought to be important for understanding atmospheric trace gas transformations and distributions. The modeling system contains three types of modeling components (Models-3): a meteorological modeling system for the description of atmospheric states and motions, emission models for man-made and natural emissions that are injected into the atmosphere, and a chemistry-transport modeling system for simulation of the chemical transformation and fate. The chemical transport model includes the following process modules: horizontal advection, vertical advection, mass conservation adjustments for advection processes, horizontal diffusion, vertical diffusion, gas-phase chemical reactions and solvers, photolytic rate computation, aqueous-phase reactions and cloud mixing, aerosol dynamics, size distributions and chemistry, plume chemistry effects, and gas and aerosol deposition velocity estimation. This paper describes the Models-3 CMAQ system, its governing equations, important science algorithms, and a few application examples. This review article cites 114 references. DOI: 10.1115/1.2128636

Review of the Governing Equations, Computational Algorithms, and Other Components of the Models-3 Community Multiscale Air Quality (CMAQ) Modeling System

A time-split nonhydrostatic atmospheric model for weather research and forecasting applications

This paper presents a range of applications of the Regional Atmospheric Modeling System (RAMS), a comprehensive mesoscale meterological modeling system. Applications discussed in this paper include large eddy simulations (LES) and simulations of thunderstorms, cumulus fields, mesoscale convective systems, mid-latitude cirrus clouds, winter storms, mechanically- and thermally-forced mesoscale systems, and mesoscale atmospheric disperision. A summary of current RAMS options is also presented. Improvements to RAMS currently underway include refinements to the cloud radiation, cloud microphysics, cumulus, and surface soil/vegetative parameterization schemes, the parallelization of the code, development of a more versatile visualization capability, and research into meso-α-scale cumulus parameterization.

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A comprehensive meteorological modeling system?RAMS

https://pielkeclimatesci.files.wordpress.com/2009/09/r-101.pdf

Observations of Blocking-Induced Convergence Zones and Effects on Precipitation in Complex Terrain

AN INVESTIGATION OF TiE EFFECTS OF TOPOGRAPHY ON COLORADO FRONT RANGE WINTER STORMS This study utilizes both an ~xtensive set of observations and mesoscale model simulations to isolate and describe the important influences of complex terrain on Colorado Front Range winter storms, with an emphasis on snowfall distributions. Specifically, the interaction of various types of cold, low· level air masses with topography and the larger-scale flow is described. Frequently, the he.,viest snowfall does not coincide with the steepest terrain gradients, as might be expected, due to this interaction. Field measurements of several snowstorms during the 1987-89 time period include special CLASS (Cross-chain Loran Atmospheric Sounding System) vertical profiles, standard National Weather Service (NWS) and National Meteorological Center (NMC) surface and rawinsonde data, surface observations collected by a trained snollT-spotter network, profiler data, Doppler reflectivity and velocity scans, and Geostationary Operational Environmental Satellite (GOES) images. The numerical predictions are produced by the Regional Atmospheric Modeling System (RAMS) developed at Coloradc State University, using twoand three-dimensional nonhydrostatic simulations. The VE~rsions of the model employed in this study utilized both horizontally homogeneous initiaJizations and initial fields made up of NMC upper-air grids and rawinsondes. Most simulations employed full microphysics. A comparison between model-predicted dynamic and nLicrophysical fields and observational data is described for the 30-31 March 1988 snowstor:n along the Colorado Front Range. Of particular interest in this study is the role of trapped cold air masses over the foothills and adjacent plains duing the evolution of snow-producing synoptic scale disturbances. Specifically, these indude two types of precipitating easterly ("upslope") flows

Investigation of the effects of topography on Colorado Front Range winter storms, An

The diffusional mass evolution of hydrometeors in upper tropospheric clouds for various radiative conditions in the cloud and for varying ambient moisture supply is simulated using a time dependent microphysical model. Radiation can play an important role in this mass evolution when only one phase is present. When both liquid droplets and ice crystals are situated in a typical upper tropospheric environment and the moisture supply is limited, radiation produces only a minor effect on the mass evolution of the hydrometeors. In these cases ice crystals grow quickly at the expense of the droplets and the droplets evaporate within several minutes, even under water supersaturation conditions. Radiation does not significantly influence the evaporation rates of the droplets in the coexisting cases. In the absence of ice crystals and under certain radiative conditions, the droplets can survive when the environment is subsaturated. For other radiative conditiions, the droplets can evaporate when the environment is supersaturated.

Douglas A. Wesley

Papers

A comprehensive meteorological modeling system?RAMS

Observations of Blocking-Induced Convergence Zones and Effects on Precipitation in Complex Terrain

Investigation of the effects of topography on Colorado Front Range winter storms, An

Radiative Processes in Upper Tropospheric Mixed-Phase Clouds