Air Resources Laboratory – Scientific Publication Highlights

State of the Climate 2021 Published

September 2, 2022

Cover of the Tropics Section of the State of the Climate. Hurricane Ida hit near the Louisiana and Mississippi border on August 29, 2021 bringing high
winds, flooding and a dangerous storm surge. © Warren Faidley, Getty

The 2021 edition of the annual State of the Climate Report was published and released on August 31, 2022. The report, compiled by NOAA’s National Centers for Environmental Information (NCEI), is based on contributions from scientists from around the world. It provides a detailed update on global climate indicators, notable weather events, and other data collected by environmental monitoring stations and instruments located on land, water, ice, and in space. This is the 32nd annual assessment, now known as State of the Climate, published in the Bulletin of the American Meteorology Society since 1996. This year’s report is based on contributions from more than 530 scientists from over 60 countries around the world and reflects tens of thousands of measurements from multiple independent dataset. It provides the most comprehensive update on Earth’s climate indicators, notable weather events and other data collected by environmental monitoring stations and instruments located on land, water, ice and in space.

Among its findings, the Tropics Chapter of the report documented, for 2021:

  • There were 97 named tropical storms during the Northern and Southern Hemisphere storm seasons, well above the 1991–2020 average of 87.
  • Seven tropical cyclones reached Category 5 intensity on the Saffir–Simpson Hurricane Wind Scale.
  • The North Atlantic hurricane basin recorded 21 named storms, the third most for the basin, behind the record 30 cyclones in 2020 and 28 in 2005.
  • Category 4 Hurricane Ida was the most impactful storm in the Atlantic. At $75 billion (U.S. dollars) in damage, Ida was the costliest U.S. disaster of 2021 and the fifth most expensive hurricane on record since 1980.
  • Super Typhoon Rai was the third-costliest typhoon in the history of the Philippines causing about $1 billion (U.S. dollars) in damages and more than 400 deaths.

Evaluation and Bias Correction of Probabilistic Volcanic Ash Forecasts

May 11, 2022

Graphic Abstract for

Crawford, A., Chai, T., Wang, B., Ring, A., Stunder, B., Loughner, C., Pavolonis, M., and Sieglaff, J.: Evaluation and Bias Correction of Probabilistic Volcanic Ash Forecasts, EGUsphere,, 2022.

Abstract. Satellite retrievals of column mass loading of volcanic ash are incorporated into the HYSPLIT transport and dispersion modeling system for source determination, bias correction, and forecast verification of probabilistic ash forecasts of a short eruption of Bezymianny in Kamchatka. The probabilistic forecasts are generated with a dispersion model ensemble created by driving HYSPLIT with 31 members of the NOAA global ensemble forecast system (GEFS). An inversion algorithm is used for source determination. A bias correction procedure called cumulative distribution function (CDF) matching is used to very effectively reduce bias. Evaluation is performed with rank histograms, reliability diagrams, fractions skill score, and precision recall curves. Particular attention is paid to forecasting the end of life of the ash cloud. We find indications that the simulated dispersion of the ash cloud does not represent the observed dispersion well, resulting in difficulty simulating the observed evolution of the ash cloud area. This can be ameliorated with the bias correction procedure. Individual model runs struggle to capture the exact placement and shape of the small pieces of ash left near the end of the clouds lifetime. The ensemble tends to be overconfident, but does capture the range of possibilities of ash cloud placement. Probabilistic forecasts such as ensemble relative frequency of exceedance and agreement in percentile levels are suited for strategies in which areas with certain concentrations or mass loadings of ash need to be avoided with a chosen amount of confidence.

Sensitivity of total column NO2 at a marine site within the Chesapeake Bay during OWLETS-2

May 15, 2022

In coastal environments like the Chesapeake Bay, the presence of the sea/bay breeze circulation can contribute to poor air quality and makes modeling the meteorological and chemical impacts of the sea/bay breeze in air quality forecast models a challenge. The Ozone Water-Land Environmental Transition Study 2 field campaign aimed to better quantify the mechanisms affecting surface, profile, and columnar trace gas amounts between the land and water.
Alexander Kotsakis, John T. Sullivan, Thomas F. Hanisco, Robert J. Swap, Vanessa Caicedo, Timothy A. Berkoff, Guillaume Gronoff, Christopher P. Loughner, Xinrong Ren, Winston T. Luke, Paul Kelley, Phillip R. Stratton, Ruben Delgado, Nader Abuhassan, Lena Shalaby, Fernando C. Santos, Joel Dreessen, Sensitivity of total column NO2 at a marine site within the Chesapeake Bay during OWLETS-2, Atmospheric Environment, 277, 2022, 119063,

Microplastics and nanoplastics in the marine-atmosphere environment

May 10, 2022
In a Nature Reviews article, working groups from the Joint Group of Experts on Scientific Aspects of Marine Environmental Protection, GESAMP, reports on ways to understand where microplastics originate, how quickly they are transported and where they may end up. A number of processes that transport microplastics are not well understood, such as: how are they captured in sea spray or condensed water; how do they interact with other chemicals in the atmosphere; and what happens as they degrade?

D. Allen, S. Allen, T. Jickells, S. Abbasi, A. Baker, M. Bergmann, J. Brahney, T. Butler, M. Dusan, S. Eckhart, M. Kanakidou, P. Laj, J. Levermore, D. Li, P. Liss, K. Liu, N. Majowald, P. Masque, A. Mayes, P. McGinnity, I. Osvath, K.A. Prather, J.M. Prospero, L.E. Revell, S.G. Sander, W.J. Shim, J. Slade, A.F. Stein, O. Tarasova, S. Wright, The Atmospheric Cycle of Microplastics in the Marine Environment Nature Reviews Earth & Environment (2022), 10.1038/s43017-022-00292-x

Development and evaluation of an advanced National Air Quality Forecasting Capability using the NOAA Global Forecast System version 16

April 21, 2022

Development and implementation of the NACC-CMAQ model is an important step to (i) advance the NAQFC closer to the state of the science for regional air quality forecasting, (ii) improve community applications of NOAA’s FV3GFS-driven atmospheric composition models, and (iii) facilitate the future development of regional high-resolution inline air quality forecasting systems within the UFS framework at NOAA.
Campbell, P. C., Tang, Y., Lee, P., Baker, B., Tong, D., Saylor, R., Stein, A., Huang, J., Huang, H.-C., Strobach, E., McQueen, J., Pan, L., Stajner, I., Sims, J., Tirado-Delgado, J., Jung, Y., Yang, F., Spero, T. L., and Gilliam, R. C.: Development and evaluation of an advanced National Air Quality Forecasting Capability using the NOAA Global Forecast System version 16, Geosci. Model Dev., 15, 3281–3313,, 2022.