ARL Weekly News – October 30, 2020

Recent Events

2020 OAR Awards Recognize ARL-developed Locust Forecasting Application

2020 OAR Awards recognized ARL’s Mark Cohen and Rick Jiang in the Personal & Professional Excellence Category for developing the ARL’s Locust Forecasting Web Application for the United Nations (UN) Food and Agriculture Organization (FAO). Late 2019 saw the rise of locust swarms in the horn of Africa, the worst in a quarter century. The UNFAO turned to ARL to see whether the HYSPLIT dispersion model could be used to issue forecasts and warnings to affected countries about a potentially devastating second wave of locust swarms. A core team including Mark, Rick, software engineer Sonny Zinn and Network Administrator Fred Shen, quickly developed a user friendly, web-based application using the HYSPLIT model at its core. Within a few weeks, Cohen and Zinn created the web application which now supports FAO’s operational forecasts. The product was well received and upgrades and improvements to the model are already being developed. The site is available to the public at:

U.S. Climate Reference Network (USCRN) and Hurricane Zeta

Dr. Howard Diamond, the Climate Science Program Manager for ARL reports that Hurricane Zeta made landfall as a very strong Category 2 storm with maximum sustained winds of 110 miles per hour (mph) on the afternoon of Wednesday October 28, 2020 in southeastern Louisiana. Zeta’s landfall was about 80 miles south of the USCRN station in Lafayette, LA; however, it was a very fast moving storm with a forward speed of over 25 mph, and as such was more of a wind versus rain event and the station in Lafayette recorded a total of only 0.60 inches of rain. Due to its robust engineering, the station in Lafayette remained up and running during the entire event, and demonstrated the ability to capture data from a climate extreme event such as Hurricane Zeta. The USCRN station in Selma, AL was directly under the eye of Zeta and recorded a total of 2.48 inches of rain. The storm weakened soon after landfall, and we did not experience any performance problems with any other USCRN stations in the path of Hurricane Zeta. Zeta is the seventh tropical storm or hurricane to make landfall in Louisiana alone this season, and through now, all USCRN stations in the region have operated flawlessly.

Tropical Cyclone Outlook for American Samoa

While the North Atlantic hurricane season formally ends on November 30, 2020, in the southwest Pacific, the tropical cyclone season begins on November 1, and ends on April 30, 2021. American Samoa is the only US territory in the southern hemisphere, and as such the NWS Weather Service Office (WSO) in Pago Pago, American Samoa, has begun to issue a tropical cyclone outlook for the citizens of American Samoa. Dr. Howard Diamond, the Climate Science Program Manager for ARL has been involved in the team that puts this outlook together; with the onset of La Niña conditions in the Pacific, tropical cyclones in the southwest Pacific follow a particular pattern where the focus of activity shifts westward from American Samoa. The outlook was issued to the public and media in American Samoa by the WSO in Pago Pago.

Recent Presentations

NAQFC presentations to CMAS Meeting

The 19th Annual Community Modeling and Analysis System (CMAS), directed by the US EPA and hosted by the University of NC in Chapel Hill, was held October 26-30, 2020.  This conference is internationally noted for its two decades of advances in chemistry and epidemiology to evaluate the impacts of air pollution on human health. ARL’s National Air Quality Forecasting Capability (NAQFC) team has a strong presence in the CMAS conference. The ARL team presented their work with prerecorded videos as well as Q&A. Patrick Campbell’s “Improved NAQFC Using the NOAA Global Forecast System. Part I: Model Development and Community Application” introduced a cutting edge new NAQFC to be implemented in 2022. Youhua Tang’s presentation complemented this talk by elaborating capability improvements: “Part II: Science Advancements and Evaluation”. Lastly, Pius Lee further reinforced the system improvements by their application during the large measurement intensive Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) in a talk entitled “NAQFC-β deployed to support measurement intensives – e.g., Firex-AQ”. There was an active Q&A following these talks and the virtual conference format yielded about 80 participants for the NAQFC talks. ARL’s NAQFC team actively engages other conferees with forecasting comparisons and innovations to advance the science of the NAQFC.

AmeriFlux Annual Meeting

An overview of “Parameter optimization at multiple AmeriFlux semi-arid sites improves terrestrial biosphere model prediction of CO2 exchange” by Kashif Mahmud, Joel A. Biederman, Russell L. Scott, Marcy Litvak, Thomas Kolb, Tilden P. Meyers, Praveena Krishnan, Vladislav Bastrikov, Natasha MacBean was presented at 2020 AmeriFlux Annual Meeting held during October 6-8, 2020.

Recent Publications

Papers Accepted:

The Impact of Height-independent Errors in State Variables on the Determination of the Daytime Atmospheric Boundary Layer Depth

A manuscript entitled “The Impact of Height-independent Errors in State Variables on the Determination of the Daytime Atmospheric Boundary Layer Depth using the Bulk Richardson Approach,” authored by ARL’s Temple R. Lee and Sandip Pal, a professor at Texas Tech University, was accepted for publication in the Journal of Atmospheric and Oceanic Technology. The study quantified errors in boundary layer depths using 35 years of rawinsonde-derived thermodynamic and kinematic measurements from multiple sites in the US. Knowledge of errors in boundary layer depths is critical in, for example, intercomparison studies where rawinsonde-derived boundary-layer depths are used as references.

Correcting model biases of CO in East Asia: impact on oxidant distributions during KORUS-AQ. 

ARL’s Xinrong Ren coauthored the study that investigates the reasons for the underestimation of carbon monoxide using aircraft measurements taken in May and June 2016 from the Korea United States Air Quality (KORUS-AQ) experiment in South Korea and the Air chemistry Research In Asia (ARIAs) in the North China Plain (NCP), which was accepted by Atmospheric Chemistry and Physics.

Papers Published:

Errors in top-down estimates of emissions using a known source

ARL’s Alice Crawford and Christopher Loughner coauthored this study in Atmospheric Chemistry and Physics. Air pollutant emissions estimates by top-down methods are subject to a variety of errors and uncertainties. This work uses a known source, a coal-fired power plant, to explore those errors.  HYSPLIT is run forward in time from the known source, and virtual measurements of the resulting tracer plume are compared to actual measurements from research aircraft.