ARL Weekly News – April 17, 2020

Recent Events

In the News: Dr. Patrick Campbell was quoted in a recent article titled “As economy sputters, scientists race to gauge effects of pollution decline.” Written by Zack Colman, the story appeared in Politico on April 13. Campbell was asked to provide data/observations of changes in small particulate matter (PM2.5) amid the economic slowdown resulting from the coronavirus disease 2019 (COVID-19). His response was: NOAA analysis of EPA data from 2019 and 2020 for the same periods of January 5 to April 5 shows a decline in fine particulate matter (PM2.5), which is generally produced by emissions from transportation, industry, agriculture, and power generation. Slight declines in PM2.5 in the eastern and western United States have occurred as a result of the economic slowdown due to mandated closures and stay-at-home orders. There is also an increasingly stronger signal developing in the reduction of ground-level ozone, also known as smog, from the East Coast to the Central Plains, and in parts of the Western U.S.

Research Flights: ARL scientist Xinrong Ren was involved in two research flights over the Washington, D.C. and Baltimore region during COVID-19. Preliminary results show smaller enhancements of air pollutants and greenhouse gases in the urban plumes compared to pre-COVID-19 flights, indicating the large impacts of travel restrictions. More analyses will be conducted, coupled with surface observations and model simulations.

Upcoming Events

Conference Presentation: Dr. Pius Lee will present a new wildfire emission model being tested for possible implementation in the National Air Quality Forecasting Capability (NAQFC) in this week’s 3rd International Smoke Symposium, to be hosted virtually by the International Association of Wildland Fire. Pius’ presentation on April 21 is entitled “Campaign-support forecast and its evaluation — testing of the Global Biomass Burning Emission Product Extension (GBBEPx) for NAQFC.” The new scheme resulted from close collaboration with the National Environmental Satellite, Data, and Information Service (NESDIS) and the Environmental Modeling Centers in the National Weather Service. The highlights of Pius’ talk will be about the advances in quantifying GBBEPx into NAQFC-ready emission projections, as devised by ARL’s Drs. Daniel Tong, Youhua Tang and Patrick Campbell, and applying it to a real time forecast of a wildfire event during the NOAA-NASA FIREX-AQ measurement intensive in the summer of 2019. This new ARL wildfire emission model using satellite-based input from NESDIS was proven to be capable of competently capturing the pollutants emitted from wildland fires and is both comparable and superior to the current schemes in NAQFC operations. It is hopeful that further real time test of this method in 2020 can accumulate enough statistics of the performance of this new wildfire modeling capability and promote it for NAQFC operations.


A manuscript entitled “Evaluation of Monin-Obukhov and Bulk Richardson Parameterizations for Surface-Atmosphere Exchange” by Temple Lee and Michael Buban was accepted for publication in the Journal of Applied Meteorology and Climatology. The manuscript evaluates classical similarity functions for parameterizing surface-layer exchange of heat, moisture, and momentum using data sets from the Land Atmosphere Feedback Experiment. Departures from these classical relationships are documented, and new parameterizations are suggested that use a bulk Richardson approach. The revised relationships are tested using datasets from VORTEX-SE, where the bulk Richardson parameterizations are found to work better than classical relationships. The findings motivate the need to modify the functional forms of the similarity equations that represent the basis for surface-layer parameterizations used in numerical weather prediction models.

A paper titled “Fluxes of Atmospheric Greenhouse-Gases in Maryland (FLAGG-MD): Emissions of Carbon Dioxide in the Baltimore, MD-Washington, D.C. area”, on which Xinrong Ren, Mark Cohen, and Barbara Stunder were listed as coauthors, was accepted for publication in the Journal of Geophysical Research – Atmospheres.

A paper on austral summer heatwaves around New Zealand (NZ), that was second authored by Dr. Howard Diamond, was accepted for publication in the journal on Climatic Change on April 16th. Unparalleled Coupled Ocean-Atmosphere Summer Heatwaves in the New Zealand Region: Drivers, Mechanisms and Impacts examines the conditions and explanation for the three most intense coupled ocean-atmosphere heatwaves in the NZ region in 1934/35, 2017/18, and 2018/19, an area covering approximately four million square kilometers, in the southwest Pacific. All three heatwaves exhibited: (1) maximum sea surface temperature anomalies to the west of the South Island of NZ; (2) atmospheric circulation anomalies with a strong blocking centered over the Tasman Sea between Australia and NZ, and extending southeast of NZ; (3) strong positive Southern Annular Mode conditions, and (4) reduced trough activity over NZ. In addition, the paper documents effects of these events on:
(a) Ice loss in the Southern Alps;
(b) Sauvignon Blanc and Pinot Noir wine grape production;
(c) Austral summer fruit harvest (cherries and apricots) blooming;
(d) Austral spring wheat grain yields and tuber quality in the potato crop; and
(e) Major species disruption that occurred in marine ecosystems around NZ.

Land and ocean heatwaves are becoming a bigger and more frequent climate issue and, therefore, understanding how these are caused and what their effects are on various aspects of the environment are an important area of global climate science research.

Citation: Salinger, M.J., H.J. Diamond, E. Behrens, D. Fernandez, B. B. Fitzharris, N. Herold, P. Johnstone, H. Kerckhoffs, A. B. Mullan, A. K. Parker, J. Renwick, C. Schofield, A. Siano, R. O. Smith, P. M South, P. J. Sutton, E. Teixeira, M. S Thomsen, and M.C .T. Trought, 2020: Unparalleled Coupled Ocean-Atmosphere Summer Heatwaves in the New Zealand Region: Drivers, Mechanisms and Impacts, Climatic Change, accepted for publication on April 16, 2020.