ARL Weekly News – April 14, 2023

Upcoming Events

Earth Day Seminar

The Montgomery County Maryland Public Library is hosting an Earth Day seminar on Saturday, April 22 from 2:00pm – 3:30pm. The speaker is Howard J. Diamond, Ph.D. of NOAA’s ARL. Titled “A Climate Change Conversation, the Reality,” it will be held via zoom, and is open to the public. Registration and access information is available at:

Maryland Day at the University of Maryland: April 29, 2023.

NOAA’s Air Resources Car will be on display at the University of Maryland’s annual Maryland Day festival on Saturday, April 29, 2023 from 10 am to 4pm at the University of Maryland College Park. ARL and the ARC will be on display at McKeldin Mall as part of the Emergency Preparedness Village. More details on Maryland Day are available here:


The Use of Small Uncrewed Aircraft System Observations in Meteorological and Dispersion Modeling is now available online. It was authored by ARL’s Fong Ngan, along with ARL’s Christopher P. Loughner, Sonny Zinn, Mark Cohen, Temple R. Lee, Edward Dumas, Travis J. Schuyler, C. Bruce Baker and Joseph Maloney, David Hotz, and George Mathews of NOAA’s Morristown TN Weather Forecast office.

Abstract: A series of meteorological measurements with a small Uncrewed Aircraft System (sUAS) was collected at Oliver Springs Airport, Tennessee. The sUAS provides a unique observing system capable of obtaining vertical profiles of meteorological data within the lowest few hundred meters of the boundary layer. The measurements benefit simulated plume predictions by providing more accurate meteorological data to a dispersion model. The sUAS profiles can be used directly to drive HYSPLIT dispersion simulations. When using sUAS data covering a small domain near a release and meteorological model fields covering a larger domain, simulated pollutants may be artificially increased or decreased near the domain boundary due to inconsistencies in the wind fields between the two meteorological inputs. Numerical experiments using the Weather Research and Forecasting (WRF) model with observational nudging reveal that incorporating sUAS data improves simulated wind fields and can significantly affect mixing characteristics of the boundary layer, especially during the morning transition period of the planetary boundary layer. We conducted HYSPLIT dispersion simulations for hypothetical releases for three case study periods using WRF meteorological fields with and without assimilating sUAS measurements. The comparison of dispersion results on 15 and 16 December 2021 shows that using sUAS observational nudging is more significant under weak synoptic conditions than strong influences from regional weather. Very different dispersion results were introduced by the meteorological fields used. The observational nudging produced not just a sUAS-nudged wind flow but also adjusted meteorological fields that further impacted the mixing calculation in HYSPLIT.