User:S44ean/sandbox

Background

The Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT) is a complete [CODM1] system for computing [CODM2] simple [CODM3] air parcel trajectories as well as complex [CODM4] transport, dispersion, chemical transformation, and deposition simulations ( https://www.arl.noaa.gov/hysplit/hysplit/ ). The HYSPLIT model was developed by the National Oceanic and Atmospheric Administration (NOAA) ( https://en.wikipedia.org/wiki/National_Oceanic_and_Atmospheric_Administration ) Air Resources Laboratory (https://en.wikipedia.org/wiki/Air_Resources_Laboratory) and the Australian Bureau of Meteorology Research Centre (https://en.wikipedia.org/wiki/Bureau_of_Meteorology) in 1998 (Draxler and Hess 1998). The model derives [CODM5] its name in part from a hybrid [CODM6] calculation method between Lagrangian and the Eulerian approaches (https://en.wikipedia.org/wiki/Lagrangian_and_Eulerian_specification_of_the_flow_field).

HYSPLIT Model Development

Early interest in computing air parcel trajectories stemmed from the nuclear arms race of the Cold War: the U.S. government found the first Soviet atomic test site in 1949 using backward air trajectories (Machta, 1992). In 1982 the initial version of HYSPLIT was developed. HYSPLIT version 1 (HYSPLIT1) (Draxler and Taylor, 1982, Draxler 1982) utilized meteorological data only from rawinsonde (https://en.wikipedia.org/wiki/Radiosonde) observations and dispersion calculations assumed daytime uniform mixing and no mixing at night. HYSPLIT2 improved upon HYSPLIT1 by varying mixing strength (Draxler and Stunder 1988). HYSPLIT3 utilized numerical weather prediction models to compute meteorology rather than rawinsonde data, improving spatial and temporal resolution (Draxler 1990; Draxler 1992). HYSPLIT version 4, developed in 1998 had many innovations over its predecessor models.

HYSPLIT Applications

The HYSPLIT model can be run interactively on the Real-Time Environmental Applications and Display System (READY) web site or installed on PC, Max, or LINUX applications and can be run using a graphical user interface (GUI) or automated through scripts (PySPLIT package in Python ( https://en.wikipedia.org/wiki/Python_(programming_language), ‘openair’ and ‘splitr’ in R ( https://en.wikipedia.org/wiki/R_(programming_language)).

The HYSPLIT model is widely used for both research applications and emergency response events to forecast and establish source-receptor relationships from a variety of air pollutants and hazardous materials (Stein et al. 2015). Examples of use include:

·        Back trajectory analysis to establish source-receptor relationships (Fleming et al. 2012)

·        Tracking and forecasting radioactive material (Connan et al. 2013)

·        Real-time wildland fire smoke predictions (O’Neill et al. 2009[MSC1] )

·         Wind-blown dust (Frie et al. 2019[MSC2] )

·        Stationary sources of anthropogenic emissions

Annual trainings on the installation, configuration, and use of the modeling system and its applications are offered by HYSPLIT developers ( http://www.arl.noaa.gov/HYSPLIT_workshop.php ).

HYSPLIT Limitations

Although the HYSPLIT model has been improved since its inception in the 1980s, there are several considerations for users ( https://ready.arl.noaa.gov/hypub/limitations.html ). Key among them are the model’s inability to account for secondary chemical reactions and reliance on meteorological data resolution, which can have coarse temporal and spatial resolution. Users should evaluate results carefully in areas with complex terrain. Photochemical grid models like the Community Multi-scale Air Quality Model (CMAQ) (https://en.wikipedia.org/wiki/CMAQ) are more widely used for regulatory purposes.