ARL Weekly News – February 27, 2025

HYSPLIT v9 approved for implemented into operations by the National Center for Environmental Protections (NCEP)

This version provides significant enhancements, including updates to the model code, the addition of a transfer coefficient matrix (TCM) capability for volcanic ash and radiological releases, and stronger integration with global weather prediction models. Developed after the Fukushima-Daiichi Nuclear Power Station radiological release in March 2011, the TCM is a mature capability now ready for operational deployment. It computes source-receptor relationships based on time-resolved, unit source emissions simulations, allowing the TCM to be multiplied by actual emissions to determine downwind impacts. This approach enables rapid updates when new emissions estimates become available, eliminating the need to rerun transport and dispersion simulations—an essential capability for ongoing events and for incorporating improved emissions estimates. The TCM can  also be used to construct ensembles that represent uncertainty in emissions and to estimate emissions using available observations through an inversion algorithm. The radiological release upgrade which supports modeling for the Regional Specialized Meteorological Center (RSMC)  meets requests from the International Atomic Energy Agency (IAEA).  The volcanic ash upgrade will help fulfill new ICAO requirements for Volcanic Ash Advisory Centers (VAACs), improving their workflow and providing uncertainty information in aviation hazard forecasts. Enhanced coupling with the GFS and GEFS models strengthens HYSPLIT’s ability to support responses to global events and assess their impact on the United States. Stakeholders who participated in the evaluation provided favorable feedback. The Environmental Modeling Center (EMC) director approved the implementation at a meeting on Monday, February 24, followed by approval from the NCEP Director on Wednesday, February 26. Implementation is scheduled for the end of May 2025. The public notification statement is available at this link. The implementation was partially funded by the Joint Technology Transfer Initiative (JTTI) and was a collaborative effort between EMC and ARL, with contributions from Tianfeng Chai, Mark Cohen, Alice Crawford, and Sonny Zinn from ARL, Fanglin Yang of EMC, Binyu Wang, Raffaele Montuoro and Jeff McQueen (now retired) from EMC.

Example of a plume produced by the HYSPLIT model. Credit: NOAA

Accepted for publication

Praveena Krishnan and  Tilden Meyers co-authored “Coupling Remote Sensing with a Process Model for the Simulation of Rangeland Carbon Dynamics” which has been accepted for publication in the Journal of Advances in Modeling Earth Systems.